EP1207718A2 - Method for the fitting of hearing aids, device therefor and hearing aid - Google Patents

Abstract

A setting method for a hearing aid and a device therefor are proposed, by means of which a model for the perception of a psychoacoustic quantity, especially the loudness, is parametrised for a standard group of persons (LN) and for an individual (LI). Setting information is determined on the basis of differences in the models, especially with respect to their parametrisation, by means of which information the signal transmission is designed or adjusted at a hearing aid (HG) ex situ, or controlled in situ, respectively. <IMAGE>

Description

The present invention relates to a method according to the The preamble of claim 1, an apparatus according to that of claim 23 and a hearing aid according to claim 39.

definitions

A psycho-acoustic perceptual quantity becomes one Size understood, which is non-linear, through individual laws perception, from physical-acoustic Variables such as frequency spectrum, sound pressure level, phase position, Course of time, etc.

Hearing aids known to date change physical, acoustic Signal sizes such that a hearing aid hearing impaired individual hears better. The adaptation the hearing aid is done by setting physical Transmission quantities, such as frequency-dependent amplification, Level limitation etc. until the individual with the Satisfied hearing aid within the possibilities presented is.

Although it is known what for the attached references be referenced that human acoustic perception complex psycho-acoustic individual assessments followed, these known phenomena were used to optimize a Hearing aid has not been used so far.

This allowed essentially with previously known hearing aids only averaged over all acoustic in practice Stimulus signals, satisfactory corrections are made; mutual influences of signal sizes of the acoustic If at all, stimulus signals could only be unsatisfactory be taken into account. Nonlinear phenomena of the psycho-acoustic perception, such as using loudness in particular Loudness summation, frequency and time masking were not taken into account.

From EP-A-0 535 425 it is known to be a psycho-acoustic Perceptual magnitude, namely the loudness, at different, individual test frequencies both on a standard and on a hearing impaired person, an individual quantify. The individual results by comparison Hearing loss. On a hearing aid, one becomes momentarily occurring, any broadband acoustic signal "Replacement" sinusoid formed, with a frequency and amplitude, the function of the total energy of the currently occurring acoustic signals. The sound level of the replacement sound is called "loudness". The spectrum continues of the acoustic sound smoothed, categorized and so corrected that it has the same energy as the "Substitute" -Sinuston. As a function of the norm at discrete Frequencies quantified loudness as well as the corrected smoothed spectrum is the adjustment of the hearing aid performed.

Starting from a method or a device or a hearing aid of the latter type is the present one Invention to task, an individual hearing correction under more extensive consideration of the psycho-acoustic To realize perception.

This is demonstrated by a method of the type mentioned at the outset Execution according to the characteristic of claim 1 achieved, in the case of a device of the aforementioned type when it is implemented according to the characterizing part of claim 23 or in a hearing aid according to the wording of claim 39.

Preferred embodiment variants of the method according to the invention are specified in claims 2 to 22 of the invention Device in claims 24 to 38 and of the hearing aid according to the invention in claim 40.

As will be seen, the device according to the invention can designed as a fitting device separately from the hearing aid his. However, it also includes adjustment measures on the hearing aid the perceived size taken into account for the individual correct.

The inventive device defined in the claims, the inventive method and the inventive Hearing aids are then, for example, based on Figures explained.

Fig. 1

schematisch, eine Quantifizierungseinheit zur Quantifizierung einer individuell wahrgenommenen, psycho-akustischen Wahrnehmungsgrösse;

Fig. 2

schematisch, in Form eines Blockdiagrammes, ein grundsätzliches Vorgehen;

Fig. 3

in Abhängigkeit des Schallpegels, die wahrgenommene Lautheit der Norm (N) sowie eines schwerhörigen Individuums (I) in einem kritischen Frequenzband k;

Fig. 4

in Form eines Funktionsblock-Signalflussdiagrammes, eine erste Ausführungsvariante einer erfindungsgemässen Vorrichtung, nach dem erfindungsgemässen Verfahren arbeitend, womit erfindungsgemäss Stellgrössen für die Uebertragung eines Hörgerätes ermittelt werden;

Fig. 5

anhand einer Darstellung analog zu Fig. 3, eine vereinfachte graphische Darstellung des mit der Vorrichtung gemäss Fig. 4 vorgenommenen erfindungsgemässen Vorgehens;

Fig. 6a

vereinfacht, das Vorgehen nach Fig. 5, mit in

Fig. 6b

vereinfachter Darstellung des resultierenden Verstärkungsverlaufes in einem betrachteten kritischen Frequenzband, einzustellen am Uebertragungsverhalten eines erfindungsgemässen Hörgerätes, das in

Fig. 6c

in seinem prinzipiellen Aufbau betreffs Uebertragungsstrecke dargestellt ist;

Fig. 7

eine ausgehend von der Anordnung nach Fig. 4 weiterentwickelte Anordnung, bei der das in Fig. 4 implementierte Lautheitsmodell verfeinert implementiert ist;

Fig. 8

in Analogie zu Fig. 5, graphisch vereinfacht, das Verarbeitungsvorgehen an der Vorrichtung gemäss Fig. 7;

Fig. 9

über der Frequenzachse, schematisch, kritische Frequenzbänder der Norm und beispielsweise eines Individuums (a) mit einer beispielsweise resultierenden Korrekturverstärkungsfunktion (b), schallpegel- und frequenzabhängig, für einen einem betrachteten kritischen Frequenzband entsprechenden Hörgerät-Uebertragungskanal;

Fig. 10

analog zur Darstellung der Vorrichtung nach Fig. 4, deren Weiterentwicklung zur Mitberücksichtigung beim Individuum bezüglich der Norm veränderter kritischer Frequenzbandbreiten;

Fig. 11

in Analogie zur Darstellung von Fig. 10, eine erfindungsgemässe Vorrichtung, mittels welcher "in situ" ein erfindungsgemässes Hörgerät betreffs Uebertragungsverhalten eingestellt wird;

Fig.12a) und b)

je in Form eines Funktionsblock-Signalflussdiagrammes, die Struktur erfindungsgemässer Hörgeräte, woran die Uebertragung einer psycho-akustischen Grösse korrigierend gesteuert wird, insbesondere die Lautheitsübertragung;

Fig. 13

eine Ausführungsvariante eines erfindungsgemässen Hörgerätes, woran die Vorkehrungen der Vorrichtung nach Fig. 11 sowie diejenigen nach Fig. 12a) kombiniert am Hörgerät implementiert sind;

Fig. 14

als Beispiel ausgehend von einer erfindungsgemässen Vorrichtung nach Fig. 11, deren Weiterentwicklung zur Mitberücksichtigung des Klangempfindens eines Individuums;

Fig. 15

ausgehend von der Darstellung eines erfindungsgemässen Hörgerätes nach Fig. 12b), eine bevorzugte Realisationsform, bei der die Korrekturübertragung einer psycho-akustischen Wahrnehmungsgrösse, am bevorzugten Beispiel der Lautheit, im Frequenzbereich aufbereitet wird;

Fig. 16

ausgehend von der Darstellung eines erfindungsgemässen Hörgerätes nach Fig. 15, dessen Weiterentwicklung zur Mitberücksichtigung einer weiteren psycho-akustischen Wahrnehmungsgrösse, nämlich der Frequenzmaskierung;

Fig. 17

schematisch, das Frequenzmaskierungsverhalten der Norm und eines schwerhörenden Individuums mit daraus sich ergebendem, qualitativ dargestelltem, zu realisierendem Korrekturverhalten an einem erfindungsgemässen Hörgerät nach Fig. 16;

Fig. 18

anhand einer Frequenz/Pegelcharakteristik, das Vorgehen zur Eruierung des Frequenzmaskierungsverhaltens eines Individuums;

Fig. 19

in Form eines Funktionsblock-Signalflussdiagrammes eine Messanordnung zur Durchführung des Ermittlungsverfahrens, wie anhand von Fig. 18 erläutert;

Fig. 20

über der Zeitachse einem Individuum präsentierte Signale bei der Eruierung, wie sie anhand von Fig. 18 erläutert wurde;

Fig. 21

ausgehend von einem erfindungsgemässen Hörgerät mit der in Fig. 15 bzw. 16 dargestellten Struktur, dessen Weiterentwicklung zur Mitberücksichtigung des Zeitmaskierungsverhaltens als eine weitere psychoakustische Wahrnehmungsgrösse;

Fig. 22

das vereinfachte Blockdiagramm eines erfindungsgemässen Hörgerätes, welches wie das in Fig. 21 dargestellte als weitere psycho-akustische Wahrnehmungsgrösse das Zeitmaskierungsverhalten berücksichtigt, aber in anderer Ausführungsform;

Fig. 23

die am erfindungsgemässen Hörgerät gemäss Fig. 22 vorgesehene Zeitmaskierungs-Korrektureinheit;

Fig. 24

schematisch, das Zeitmaskierungsverhalten der Norm und eines Individuums als Beispiel zur Erläuterung daraus resultierender Korrekturmassnahmen, um mit einem erfindungsgemässen Hörgerät das Zeitmaskierungsverhalten eines Individuums auf dasjenige der Norm zu korrigieren;

Fig. 25

schematisch, über der Zeitachse, bei der Eruierung des Zeitmaskierungsverhaltens einem Individuum zu präsentierende Signale.

Show it:

Fig. 1

schematically, a quantification unit for quantifying an individually perceived, psycho-acoustic perceptual quantity;

Fig. 2

schematically, in the form of a block diagram, a basic procedure;

Fig. 3

depending on the sound level, the perceived loudness of the norm (N) and a hearing impaired individual (I) in a critical frequency band k;

Fig. 4

in the form of a function block signal flow diagram, a first embodiment variant of a device according to the invention, operating according to the method according to the invention, with which actuating variables according to the invention are determined for the transmission of a hearing aid;

Fig. 5

based on a representation analogous to FIG. 3, a simplified graphic representation of the procedure according to the invention carried out with the device according to FIG. 4;

Fig. 6a

simplified, the procedure according to FIG. 5, with in

Fig. 6b

Simplified representation of the resulting amplification curve in a critical frequency band under consideration, to be set on the transmission behavior of a hearing device according to the invention, which in

Fig. 6c

the basic structure of the transmission link is shown;

Fig. 7

an arrangement developed further from the arrangement according to FIG. 4, in which the loudness model implemented in FIG. 4 is implemented in a refined manner;

Fig. 8

in analogy to FIG. 5, graphically simplified, the processing procedure on the device according to FIG. 7;

Fig. 9

above the frequency axis, schematically, critical frequency bands of the standard and, for example, an individual (a) with a correction gain function (b), for example, resulting from sound level and frequency, for a hearing aid transmission channel corresponding to a critical frequency band under consideration;

Fig. 10

analogous to the representation of the device according to FIG. 4, its further development to take account of the individual with regard to the norm of changed critical frequency bandwidths;

Fig. 11

in analogy to the representation of FIG. 10, a device according to the invention, by means of which a hearing device according to the invention is set "in situ" with regard to transmission behavior;

Fig.12a) and b)

each in the form of a functional block signal flow diagram, the structure of hearing aids according to the invention, by means of which the transmission of a psycho-acoustic variable is correctively controlled, in particular the loudness transmission;

Fig. 13

an embodiment variant of a hearing aid according to the invention, on which the precautions of the device according to FIG. 11 and those according to FIG. 12a) are implemented in combination on the hearing aid;

Fig. 14

as an example, starting from a device according to the invention according to FIG. 11, its further development for taking into account the sound sensation of an individual;

Fig. 15

based on the representation of a hearing aid according to the invention according to FIG. 12b), a preferred form of implementation in which the correction transmission of a psycho-acoustic perceptual quantity, using the preferred example of loudness, is processed in the frequency range;

Fig. 16

starting from the representation of a hearing aid according to the invention according to FIG. 15, its further development to take into account a further psycho-acoustic perceptual variable, namely frequency masking;

Fig. 17

schematically, the frequency masking behavior of the norm and of a hearing-impaired individual with the resultant, qualitatively represented, to be realized correction behavior on a hearing aid according to the invention according to FIG. 16;

Fig. 18

based on a frequency / level characteristic, the procedure for determining the frequency masking behavior of an individual;

Fig. 19

in the form of a functional block signal flow diagram, a measuring arrangement for carrying out the determination method, as explained with reference to FIG. 18;

Fig. 20

Signals presented to an individual over the time axis during the investigation, as explained with reference to FIG. 18;

Fig. 21

starting from a hearing aid according to the invention with the structure shown in FIGS. 15 and 16, its further development to take the time masking behavior into account as a further psychoacoustic perceptual variable;

Fig. 22

the simplified block diagram of a hearing aid according to the invention which, like the one shown in FIG. 21, takes into account the time masking behavior as a further psycho-acoustic perceptual variable, but in another embodiment;

Fig. 23

22 the time mask correction unit provided on the hearing aid according to the invention;

Fig. 24

schematically, the time masking behavior of the norm and an individual as an example to explain the resulting corrective measures to correct the time masking behavior of an individual to that of the standard with a hearing aid according to the invention;

Fig. 25

schematically, signals to be presented to an individual over the time axis when determining the time masking behavior.

Psycho-acoustic perception, especially loudness and their quantification

The loudness "L" is a psycho-acoustic quantity, which indicates how "loud" an individual is at presented acoustic Signal senses.

Loudness has its own unit of measurement; a sinusoidal 1kHz frequency signal at a sound pressure level of 40dB-SPL, produces a loudness of 1 "Sone". A sine of same frequency with a level of 50dB-SPL is exactly double perceived so loud; the corresponding loudness is so 2 sone.

With natural acoustic signals, which are always broadband the loudness is wrong with the physical transmitted energy of the signal. It is psycho-acoustic in the ear a rating of the incoming acoustic Signals in individual frequency bands, the so-called critical Bands. The loudness results from a band-specific Signal processing and a cross-band Superimposition of the band-specific processing results, known as "loudness summation". These basics were developed by E. Zwicker, "Psychoakustik", Springer-verlag Berlin, university text, 1982, described in detail.

If you now consider loudness as one of the most essential the psycho-acoustic which determines acoustic perception Sizes, the present invention has as its object propose a method and suitable devices for this, with which a hearing aid to be adapted to an individual can be adjusted so that the acoustic perception of the individual at least in the first approximation of that one Norm, namely the normal hearing.

One way to experience the individually felt loudness selected acoustic signals as a usable variable to be recorded at all, the one shown schematically in FIG. 1, for example from O. Heller, "Hörfeldaudiometrie with the procedure of category subdivision ", psychological Posts 26, 1985, or V. Hohmann, "Dynamic Compression for Hearing aids, psychoacoustic fundamentals and algorithms ", dissertation UNI Göttingen, VDI-Verlag, row 17, No. 93, known Method. An individual I becomes an acoustic one Signal A presented, which is related to a generator 1 spectral composition and transmitted sound pressure level S is adjustable. The individual I rated or "categorized" by means of an input unit 3 that currently belonged to acoustic signal A according to e.g. thirteen loudness levels or - Categories, as shown in Fig. 1, which levels numerical Weights, for example from 0 to 12, can be assigned.

With this procedure it is possible to feel the individual Measure loudness, i.e. to quantify, however only punctual with respect to given acoustic signals, with which such Measurements initially do not allow for the individual to perceive perceived loudness, which broadband signals is perceived.

If in the following as influencing the psycho-acoustic perception Size primarily the loudness is considered, so it is because this size is the psycho-acoustic perception acoustic signals significantly determined. As below will be carried out, but the procedure according to the invention can certainly also for the consideration of other psychoacoustic Sizes are used, such as for the consideration of the size "masking behavior in the Time domain and / or in the frequency domain ".

In Fig. 2, the basic principle for Preferred according to the invention described in more detail below Procedure shown.

The norm, N, is used to determine a psycho-acoustic perception variable, in particular the loudness L _N , by means of standardized acoustic signals A _o and compared with the values of this variable, corresponding to L _{I of} an individual, with the same acoustic signals A _o . From the difference corresponding to ΔL _NI , setting data are determined which act directly on a hearing aid or on the basis of which, manually, a hearing aid is set. L _I is determined on the individual without a hearing aid or with a hearing aid that has not yet been adapted, possibly progressively adapted.

The loudness itself is a variable, which in turn is of depends on several variables. On the one hand, this is the number Measurements that must be made on an individual to get even approximate information, with the interventions on the hearing aid, for everyone in a natural environment occurring broadband signals that are desired To be able to correct perception, great. On the other hand, is the correlation between recorded size differences Interventions in the transmission behavior of a hearing aid ambiguous and extremely complex.

This is now a reduction for the time being in a preferred manner of the measurements to be made on the individual and thereby searched for a solution that allows Measurement results on the individual and their comparison with standard results relatively easy to make the necessary adjustments close.

Basically, a quantifying model of the Perception size, especially loudness, used. In Such a model is intended to be used with all types of acoustic signals can be received; at least approximate results the corresponding size sought. On the other hand, should relatively few measurements the model can be identified, that is valid for the individual. The identification should be able to be canceled if the model is in predeterminable Extent is identified.

Such a quantifying model of a psycho-acoustic Perception size does not have to be closed mathematical expression can be given, but may well be defined by a multidimensional table from where with the prevailing frequency and sound level ratios a real acoustic signal as a variable the perceived size can be called up.

Although different mathematical models for loudness are conceivable, it was recognized according to the invention that the model based on Zwicker according to A. Leijon, "Hearing Aid Gain for Loudness-Density Normalization in Cochlear Hearing Losses with Impaired Frequency Resolution", Ear and Hearing, Vol. 12, No. 4, 1990, is particularly suitable for the goals pursued here. It is said:

k:

Laufparameter mit 1 ≤ k ≤ k_o, Numerierung der Anzahl k_o berücksichtigter kritischer Bänder;

CB_k:

spektrale Breite des betrachteten kritischen Bandes mit der Nummer k;

α_k:

Anstieg einer linearen Approximation der in Kategorien skalierten Lautheitsempfindung bei logarithmischem Auftrag des Pegels eines präsentierten sinusförmigen oder schmalbandigen akustischen Signals, dessen Frequenz circa bandmittig des betrachteten kritischen Bandes CB_k liegt;

T_k:

Hörschwelle beim erwähnten Sinussignal;

S_k:

den mittleren Schalldruckpegel eines präsentierten akustischen Signals im betrachteten kritischen Frequenzband CB_k.

Denote therein:

k:

Running parameters with 1 ≤ k ≤ k _o , numbering of the number k _o considered critical bands;

CB _k :

spectral width of the considered critical band with the number k;

α _k :

Increase in a linear approximation of the loudness perception scaled in categories when the level of a presented sinusoidal or narrow-band acoustic signal is logarithmically applied, the frequency of which lies approximately in the middle of the band of the critical band CB _k under consideration;

T _k :

Hearing threshold for the mentioned sine signal;

S _k :

the average sound pressure level of a presented acoustic signal in the critical frequency band CB _{k considered} .

As can be seen from this, the band-specific, mean sound pressure levels S _k form the model variables defining a presented acoustic signal, which determine the current spectral power density distribution. The spectral width of the considered critical bands CB _k , the linear approximation of the loudness perception, α _k , and the hearing threshold T _k are parameters of the model or the mathematical simulation function according to (1).

It has now been further recognized that the parameters α _k , T _k , CB _k on this model can be determined relatively easily on the one hand by means of relatively fewer acoustic tests on individuals, and that these coefficients are also relatively easily correlated with transmission variables on a hearing aid and thus can be changed for an individual by interventions on a hearing aid.

The model parameters α _k , T _k and CB _k have been determined using the standard N, ie for people with normal hearing.

The linear approximation of loudness in categories per increase in the mean sound pressure S _k in dB in the respective critical bands CB _{N of} the norm is given in the literature, for example in E. Zwicker, "Psychoacoustics" as the same for all bands.

In FIG. 3, the curve L _{kN represents} the loudness curve of the standard as a function of the sound level S _{k of} an acoustic signal presented in a respective critical band k, recorded as explained with reference to FIG. 1. A sinusoidal signal or a narrowband noise signal is presented. As can be seen from this, the parameter α _{N represents} the slope of a linear approximation or regression line of this course L _kN at higher sound levels, ie at sound pressure levels from 40 to 120 dB SPL, where the acoustic useful signals also predominantly occur. This is also referred to below as "large signal behavior". As mentioned, in the norm this increase can be assumed to be the same, α _N , in each of the frequency bands.

3 with a view to the mathematical model according to (1) also shows that disregarding the level dependence of the gradient steepness of L _kN , ie approximating this curve with a regression line, can only lead to a model of the first approximation. The model becomes more precise if the parameter values are used in each critical band, depending on the sound pressure level, i.e. α _N = α _N (S _k ), ie if k α _kN ( S _k ) = dL _Nk / dS _{k is} set in each band ,

In contrast to the parameter α _N , the hearing threshold T _kN also differs in the norm and in a first approximation in every critical frequency band CB _kN and is not a priori identical to the 0dB sound pressure level. The typical hearing threshold curve of the standard is precisely defined by ISO R226 (1961).

Furthermore, the bandwidths of the critical bands CB _kN for the standard and their number k _o in ANSI, American National Standard Institute, American National Standard Methods for the Calculation of the Articulation Index, Draft WG S. 3.79, May 1992, V2.1 , standardized.

In summary, this is what is preferably used mathematical loudness model according to (1) known for the standard.

As can be easily seen, large deviations can occur between the perceived loudness of individuals and that of the statistically determined norm. In particular, in the case of individuals I deviating from the norm, in particular hearing _impaired persons, a specific coefficient α _kI can be determined for each critical frequency band; _Furthermore , there are deviations from the norm with regard to the hearing threshold T _kI and the width of the critical bands CB _kI .

Leijon has described a procedure that allows the further band-specific coefficients or model parameters α _kI and CB _kI to be estimated from the hearing thresholds T _kI of individuals. However, the estimation errors are usually large when considering individual cases. Nevertheless, when identifying individual loudness models, it is possible to start with estimated parameters, for example those estimated from diagnostic information. This drastically reduces the effort and the burden on the individual.

Metrological determination of the coefficients α _kI , CB _kI and T _kI

As already indicated, the loudness L, recorded with a category scaling according to FIG. 1, is plotted in FIG. 3 as a function of the mean sound pressure level in dB-SPL for a sinusoidal or narrow-band signal of the frequency f _k in a critical band of the number k considered , As has been mentioned further, the loudness L _{N of} the standard increases non-linearly with the signal level in the selected representation, the gradient curve is in a first approximation for normal hearing people for all critical bands with the regression line with the gradient α _N entered on the curve N in FIG. 3 reproduced in [categories per dB-SPL].

From this representation it is readily apparent that the model parameter α _N corresponds to a nonlinear amplification, the same for normal hearing people in every critical band, but to be determined for individuals with α _kI in every frequency band. Due to the straight line with the slope α _k , the non-linear loudness function in band k is approximated by a regression line.

In FIG. 3, L _kI typically denotes the course of the loudness L _{I of the} hearing _impaired in a band k.

As can be seen from the comparison of the curves L _kN and L _kI , the curve of a hearing _impaired person has a larger offset to the zero point and is steeper than the curve of the norm. The larger offset corresponds to an increased hearing threshold T _kI , the phenomenon of the fundamentally steeper loudness _curve is referred to as loudness recruitment and corresponds to an increased α parameter.

It is known to fundamentally determine hearing thresholds using classic threshold audiometry. However, it is also possible, also in the sense of threshold _audiometry, to detect the hearing thresholds T _kI on individuals with an arrangement according to FIG. 1 by threshold _detection between inaudible and audible. However, larger errors must be accepted around the threshold. In the following it is assumed that the respective hearing thresholds T _{kI have} already been recorded and known, simply by audiometry.

Referring to the remaining model parameters according to (1), the width of the respective critical bands CB _kI , it can be stated that the presence of several such bands only becomes effective when psycho-acoustic processing of broadband audio signals, i.e. broadband signals, the spectrum of which is at least two adjacent critical bands. In hearing impaired people, a widening of the critical bands is typically noticeable, whereby primarily the loudness summation is impaired even after (1).

There are several ways to determine the bandwidth of the critical bands Measurement methods have been described. In this regard refer to B.R. Glasberg & B.C.J. Moor, "Derivation of the auditory filter shapes from notched-noise data ", hearing Research, 47, 1990; P. Bonding et al., "Estimation of the Critical Bandwidth from Loudness Summation Data ", Scandinavian Audiolog, Vol. 7, No. 2, 1978; V. Hohmann, "Dynamic Compression for hearing aids, psychoacoustic basics and algorithms ", Dissertation UNI Göttingen, VDI-Verlag, series 17, No. 93. The measurement of loudness summation with specific Broadband signals according to the latter literature reference, both with normal as well as with hearing impaired, is well suited for experimental measurement of the respective bandwidths of the critical bands.

• die individuellen α_kI-Parameter sich aus den Regressionsgeraden gemäss Fig. 1 ermitteln lassen,
• die individuellen Hörschwellen T_kI sich durch Schwellenaudiometrie bestimmen lassen,
• die individuellen Bandbreiten CB_kI der kritischen Bänder sich, wie in obgenannter Literatur angegeben, bestimmen lassen, wobei
• diese Grössen für die Norm, d.h. für die Normalhörenden, bekannt und normiert sind.

It can thus be stated that:

• the individual α _kI parameters can be determined from the regression lines according to FIG. 1,
• the individual hearing thresholds T _kI can be determined by threshold _audiometry ,
• the individual bandwidths CB _{kI of} the critical bands can be determined as indicated in the above-mentioned literature, where
• these values are known and standardized for the norm, ie for the normal hearing.

However, the individual recording of the loudness or scaling _curves L _kI according to FIG. 3 for the subsequent determination of the model parameters α _kI and possibly T _kI and the known procedure for determining the width of the critical bands CB _{kI are} so time-consuming that they, except in the frame scientific investigations, an individual present to clarify his perceptual behavior can hardly be expected.

A preferred procedure is therefore explained with reference to FIG. 4 become.

It is based on the knowledge that when using standard acoustic narrow-band signals A _o , which are essentially centered in the critical frequency bands CB _N , the model parameters CB _kI, which are still unknown to the individual, can be equated to the known CB _kN without intolerable errors.

_Furthermore , it is assumed that the hearing thresholds T _{kI of} the individual I were determined in a different measurement environment by means of classic threshold audiometry, since an individual to be clarified with regard to hearing behavior is only subjected to such an examination in the vast majority of cases. It can be seen that are primarily call in the T _{kI kI} α and for identification of the individual loudness model, its individual parameterization.

4, individual I, as shown, for example via headphones, electrically or by means of an electrical-acoustic transducer, is supplied with narrow-band norm-acoustic norm signals A _ok lying in the frequency bands CB _Nk . For example, via an input unit 5 according to FIG. 1, the individual I evaluates and quantifies the perceived loudness, L _S (A _ok ).

Corresponding to the channel or band membership of the signal A _ok , the associated standard bandwidth CB _kN and the parameter α _N are provided on the output side via a selection unit 7 from a standard storage unit 9. The electrical signal S _e (A _ok ) corresponding to the sound pressure level of the signal A _ok is fed together with the associated bandwidth CB _{kN to} a computing unit 11 which, according to the preferred mathematical loudness model according to (1), calculates a loudness value L '(A _ok ) , namely from S _e , CB _kN , α _N and, as previously mentioned, predetermined hearing threshold _value T _kI stored in a memory unit 13.

5, it is to be shown which loudness L 'the computing unit 11 calculates on the basis of these predetermined parameters. Based on the use of the hearing threshold T _{kI of} the individual and the parameter α _{N of} the standard, a loudness value L 'is determined on the computing unit 11 at the given sound level, corresponding to S _{e of} the signal A _ok , as it corresponds to a scaling function N', which is determined by the Regression line with α _N and the hearing threshold T _{kI is defined} in a first approximation.

4, on the output side of the computing unit 11, this loudness value L 'is compared at a comparison unit 15 with the loudness value L _I by the input unit 5. The difference .DELTA. (L ', L _I ) appearing on the output side of the comparison unit 15 acts on an incrementing unit 17. The output of the incrementing unit 17 is superimposed on a superposition unit 19 with the α _N parameter supplied to the computing unit 11 by the storage unit 9 with the correct sign. The incrementing unit 17 thus increments the signal corresponding to α _N by increments Δα according to the number of increments n until the difference appearing on the output side of the comparison unit 15 reaches or falls below a predeterminable minimum dimension.

5, this means that α _N on the curve N 'is changed until the loudness value L' calculated on the unit 11 matches the loudness value L _I to the extent required. The computing unit 11 has thus found the regression line of the individual scaling curve I, starting from the course N '.

The output signal of the comparison unit 15 in FIG. 4 is compared on a comparator unit 21 with an adjustable signal Δr in accordance with a predeterminable, maximum error - as an abort criterion. When the difference signal Δ (L ', L _I ) appearing on the output side of the comparison unit 15 reaches the value Δr, as shown schematically, opening the switch Q ₁ and closing the switch Q ₂ on the one hand aborts the incrementation of α, and on the other hand it reaches it α value accordingly α '= α N + nΔα output to the output of the measuring arrangement; the following applies: α '= α kI ,

The parameter α _{kI of} the individual is thus found with the required accuracy corresponding to Δr in the critical frequency band k considered.

By defining the termination criterion Δr so that the α _{kI identification} meets practical accuracy requirements, the process is optimally short or only as long as necessary.

In Fig. 6a, analogous to Fig. 5, the scaling function N of the norm and I of a hearing impaired individual is shown again. At a given sound pressure level S _kx , an amplification G _x must therefore be provided on the hearing device so that the individual perceives the loudness L _x with the hearing device as the norm N. 6a, depending on various, for example, entered sound pressure levels S _kx , a plurality of amplification values G _{x to be} provided on the hearing aid are entered.

FIG. 6b shows the gain curve resulting from the considerations of FIG. 6a as a function of S _k , as can be realized on a transmission channel on the hearing aid corresponding to the critical frequency band k, as shown in FIG. 6c. The non-linear gain curve G _k (S _k ) shown in FIG. 6b is determined heuristically and schematically from the parameters T _kI and α _kI and the differences T _kN -T _kI and nΔα as determined with reference to FIGS. 4 and 5.

The described procedure is optimally used in every critical one Frequency band k repeated. It has to be critical Frequency band and approximation with a regression line only presented a norm-acoustic signal to the individual become; more can be checked if necessary of the regression lines found are used.

From the considerations, in particular to FIGS. 4 to 6, is but now it is readily apparent that the proposed Procedure by simple extension to any exact Approximation. An increase in hearing aid achieved accuracy with which an individual does the same Loudness perception is like the norm, can be seen on Fig. 5 in that basically the scaling curves through several regression lines in the sense of one Regression polygons are approximated piece by piece.

The procedure described with reference to FIGS. 4 to 6 is based on essential to the respective individual or standard scaling curve N or I as a first approximation only by a pair Regression lines, namely for low sound pressure levels and for high sound pressure levels, approximate.

This also corresponds to the approximation with which the simulation model according to (1) the respective scaling curves in the critical Frequency bands considered.

The model according to (1) which is preferably used becomes arbitrarily more precise (1 *) by using α _k (S _k ) instead of the level-independent parameters α _k . In (1), α _{k is} replaced by α _k (S _k ).

This expanded on the basis of the explanations for FIGS. 4 to 6 Procedure will be explained with reference to FIGS. 7 and 8.

7 are analogous to the functional blocks of FIG. 4 Function blocks with the same item numbers Mistake.

8 shows the scaling curve N of the norm and of an individual I in analogy to FIG. 5. In contrast to the approximation of FIG. 5, the scaling curve N is sound pressure level-dependent slope parameter α _N (S _k) is approximated, ie by a polygon of support values S _k of the curve N. This sound pressure level dependent parameter α _N (S _k) are assumed to be known by they can be easily determined from the known scaling curves N of the standard at the given support values S _kx .

In analogy to the considerations of FIG. 5, the arrangement according to FIG. 7, taking into account the individual hearing threshold T _kI for the time being, assumes that the curve N 'offset by the individual hearing threshold _value T _kI , on which the sound pressure level-dependent values continue to be formed Standard parameters α _N (S _k ) apply. The latter are changed until the curve N 'conforms to the scaling curve I of the individual with the required accuracy. At least as many level values S _{kx are} to be evaluated on the individual as the desired number of approximation tangents used for the approximation indicates.

From the respective necessary changes in the parameters α _N (S _k ), which are now dependent on the sound pressure level, the more precise course of the sound pressure level-dependent amplifications to be set on the hearing device on a channel-specific basis is determined with reference to FIG. 6b.

7, in addition to the bandwidths of the critical frequency bands CB _kN , a set of sound pressure level-dependent slope parameters α _N (S _k ) is stored in the memory unit 9. The individual I is again presented with normacoustic, narrow-band signals lying in the respective critical bands, but, in contrast to the procedure according to FIG. 4, per critical frequency band at different sound pressure levels S _kx .

The individual loudness ratings for these norm acoustic Signals of different sound pressure levels are preferred stored in a buffer unit 6. By is this filed loudness perception values, with a view on Fig. 8, the scaling curve I of the individual by Basic values recorded.

The storage unit 9 supplies the bandwidth CB _{kN associated} with the critical frequency band under consideration and the set of α parameters dependent on sound pressure level to the computing unit 11, in addition to the previously determined, individual, band-specific hearing threshold T _kI .

As already explained with reference to FIG. 4 and shown here only in a simplified manner, the frequency of the norm acoustic signal determines the critical frequency band k under consideration, and the values relevant for this are retrieved from the memory unit 9 accordingly. The sequence F of the following sound pressure level _values S _kx is preferably further stored in a memory device 10. As soon as the individual loudness perception values are recorded and stored in the storage unit 6, the sequence of the stored sound pressure level _values S _kx is also _fed from the storage unit 10 to the computing unit 11, with which the latter, according to FIG. 8, calculates the scaling _curve N 'from the hearing threshold _value T _kI , the bandwidth CB _kN and the sound pressure level-dependent steepness values α _N (S _kx ), and thus determined which loudness values would be expected according to curve N 'in FIG. 8 at the sound pressure levels S _{kx used} .

8, all sound pressure level-dependent difference values Δ are now determined on the comparison unit 15 and, if necessary, different incremental adjustment of the sound pressure level-dependent standard parameters α _N (S _kx ) by the incrementing unit 17 and on the superimposition unit 19, as indicated by Δ ' α is shown, the sound pressure level-dependent coefficients are changed and thus the course of the calculated curve N 'until a sufficient approximation of the curve N' to the curve I is achieved.

To this end, the difference appearing on the output side of the comparison unit 15, here in the sense of a difference in sound pressure level dependent between the curves S and the modified curve N 'according to FIG. 4, on the one hand the optimization or incrementation process is interrupted, on the other hand the sound pressure level-dependent α parameters that are present at the computing unit 11 are output, which correspond to the tangent slope values on the individual scaling _curve I, _i.e. α _kI (S _kx ) or the Δ'α _kI (S _kx ).

By analogy, these values are dependent on the sound pressure level to Fig. 6b and 6c, the specific critical frequency band assigned nonlinear gain function on Hearing aid determined and adjusted.

It was shown how with any accuracy the necessary Sound pressure level dependent, nonlinear amplification the hearing aid transmission in a channel corresponding to the particular one under consideration critical frequency band corresponds, determined and is used to set this channel.

It was assumed in a first approximation that for the individual perception of a narrowband signal Irrelevant width of the respective critical frequency band is, which, as can be seen from (1), is only approximate.

However, the width of the critical bands CB _k becomes relevant for the loudness perception of the individual if the presented normacoustic signals have spectra that lie in two or more critical frequency bands, because loudness summation according to (1) or (1 *) then occurs ,

So far it has been found that deviations from the band-specific Parameters α and T of an individual from the norm by digits the nonlinear level-dependent gain at the critical Channels of a hearing aid assigned to frequency bands can be compensated. As has been mentioned, the Width of the critical frequency bands individually, in particular in the case of hearing impaired people, the critical ones Frequency bands of the hearing impaired are usually wider than the corresponding to the norm.

A simple measurement method for the location or the limits of the critical frequency bands is described by P. Bonding et al., "Estimation of the Critical Bandwidth from Loudness Summation Data ", Scandinavian Audiolog, Vol. 7, No. 2, 1978. For this purpose, the range of norm acoustic presented Test signals steadily enlarged, and an individual scales, as described, the perceived loudness. The middle one The sound pressure level is kept constant. There where the individual perceives a noticeable increase in loudness, is the boundary between two critical frequency bands, because then loudness summation occurs.

It is therefore essential to determine the width of the critical frequency bands CB _{k I} for individual loudness perception correction based on broadband acoustic signals, ie when loudness summation occurs. From the knowledge of the frequency band limits deviating from the norm, the nonlinear amplification G of FIG. 6b in the respective hearing aid channels assigned to the critical bands is changed, depending on the frequency, in particular in frequency ranges which do not belong to the same critical band on the individual as in the norm are.

Simplified and heuristically, this should be based on FIG. 9a and 9b are explained.

In FIG. 9a, frequency bands CB _k and CB _{k + 1} , for example critical frequencies for the standard N, are drawn in over the frequency axis f. Below, in the same representation, the partially broadened, corresponding bands are entered for an individual I.

The nonlinear reinforcements found so far have been channel-specific or band-specific with reference to the critical ones Bandwidths of the standard determined. With consideration the critical bandwidths of the individual is from Fig. 9a it can be seen that, for example, the hatched area Δf in the individual falls within the broadened critical band k, while in the norm it falls in the band k + 1. This means but that, with the previous reference to the critical bandwidths the standard, signals e.g. in the hatched frequency range Δf in the individual must be corrected for gain.

If, according to FIG. 9b, signals that are transmitted on a hearing aid channel that corresponds to the critical frequency band k of the standard are amplified with the nonlinear level-dependent gain function G _k (S _k ) previously explained with reference to FIG. 6b, then Signals in the superimposition range Δf, that is to say frequency-dependent, are additionally raised or possibly reduced.

Knowing the channel-specific, non-linear level-dependent gains G _k (S _k ) in the respective critical frequency bands determined as shown and knowledge of the deviations of the critical frequency bands CB _{kI of} the individual from those CB _{kN of} the standard, it is possible to make these deviations frequency-dependent through the gains G _k (S _k , f) to compensate for the hearing aid channels.

Of course it is easily possible to do all of that Model according to (1) defining parameters α, T and CB for the Norm and to determine experimentally for an individual and directly from deviations of these coefficients on correction point interventions to close the hearing aid. However, conditionally such a procedure the channel-specific measurement of the individual, which, as has been mentioned, is hardly for clinical applications it is a possibility.

Starting from the procedure according to FIGS. 4 and 7, FIG. 10 shows a further development as a function block signal flow diagram in which the parameters α _k and CB _k can be determined using a single method. Not only is one critical band after the other examined in accordance with FIGS. 4 and 7, but also, with broadband acoustic signals, the loudness summation is recorded and the width of the individual critical bands is thus also determined as a variable by optimization.

The simulation model parameters of the standard, namely α _N , CB _kN , are stored in a memory unit 41 and, in a preferred embodiment, not the hearing thresholds T _{kN of} the standard, but rather the hearing thresholds T _{kI of} the individual to be examined, determined beforehand by audiometry and taken from a memory unit 43.

An individual is acoustically presented with signals A _Δk by a generator that is no longer shown here. The electrical signals corresponding to them in FIG. 10, also designated A _Δk , are fed to a frequency-selective power measurement unit 45. The channel-specific average powers are determined on the unit 45 in accordance with the critical frequency bands of the standard, frequency-selective, and a set of such power values S _{Δk is} output on the output side. These signals are stored in a memory unit 47 in a channel-specific manner and specifically for the signal A _Δk (A No.) that is presented in each case. At presentation in each case one of the signals A _.DELTA.k all stored in the storage unit 41 coefficients are initially unchanged, supplied through a still to be described unit 49 to the arithmetic unit 51, a computing module 53, as are the predominant signal A _.DELTA.k corresponding power signals S _.DELTA.k. The computing module 53 calculates the loudness L 'according to (1) from the norm parameters α _N , CB _kN and the individual hearing threshold _values T _kI , taking into account the loudness _summation , which would result for the norm if the latter had hearing thresholds (T _kI ) such as the individual.

For each signal A _{Δk presented} , assigned to the signal, the calculated value L ' _{N is} stored in a storage unit 55 on the output side of the computing module 53. Each of the presented broadband (Δk) signals A _Δk , as described with reference to FIGS. 4 and 7, is assessed or categorized by the individual in terms of loudness perception, the evaluation signal L _I , again assigned to the respective presented acoustic signals A _Δk , stored in a storage unit 57. Both when determining L ' _N and when determining L _I , the loudness _{summation is} taken into account arithmetically or by the individual due to the broadbandness Δk of the signals A _Δk presented.

After the presentation of a given number of signals A _Δk , the corresponding number of values L ' _{N is} stored in the storage unit 55, as is the corresponding number L _I values in the storage unit 57.

Now the presentation of acoustic signals is stopped, the individual is no longer burdened. All assigned L ' _N and L _I values, which, depending on the numbers of the previously presented acoustic signals A _Δk , each form a course, are fed to a comparison unit 59 on the computing device 51, which compares the difference course Δ (L' _N , L _I ) determined. This difference profile is fed to the parameter modification unit 49, in principle similar to the control difference signal in a following control loop.

The parameter modification unit 49 varies the start values α _N , CB _kN , but not the T _kI values, for all critical frequency bands, while simultaneously recalculating the updated L ' _N value until the difference signal Δ (L' _N , L _I ) runs within a predeterminable minimum course, which is checked on the unit 61.

If the termination criterion ΔR is not yet reached, further acoustic signals A _Δk must be processed.

Thus, on the simulation model according to (1) with the individual hearing thresholds T _kI, the standard parameters α _N and CB _kN entered as start values, taking into account the signals S _Δk corresponding to the channel-specific sound pressure values retrieved from memory 47, are varied according to predetermined search algorithms until a maximum permissible deviation between the L ' _N and the L _I course has been reached.

If the achievement of a predetermined maximum deviation criterion ΔR by the difference Δ (L ' _N , L _I ) occurring on the output side of the unit 59 is registered on a comparator unit 61, the search process is terminated; The α and CB values on the output side of the modification unit 49 correspond to those which, used in (1), result in loudness values corresponding optimally with the individually perceived values L _I for the acoustic signals A _Δk presented: by varying the standard parameters, the individual values in turn became individual determined.

Control variables are determined from the parameter values present on the output side of the modification unit 49 when the search is terminated and their difference from the start values α _N and CB _{kN in} order to set the amplification functions on the frequency-selective channels of the hearing aid corresponding to the critical frequency bands.

As can be seen, it is the described The procedure is actually to find a minimum position of one multi-variable function. In most cases you will be there several sets of changed parameters to meet the with ΔR specified minimum criterion. The described The method can therefore be used to obtain several such solution parameter sets lead, then to physical places of the hearing aid, those sentences are used which make sense physically and for example the easiest let it be realized.

Solution parameter sets excluded from the outset can be, for example, only extremely difficult or unrealizable gain curves on the respective Channels of the hearing aid could lead through appropriate Specifications on the modification unit 49 from the outset be excluded.

A shortening of the search process can also be achieved, for example for hearing-impaired individuals, by replacing the standard parameters α _N or CB _{kN with} the α _kI or CB _kI values estimated from the individual hearing thresholds T _kI for hearing _{impaired people} as search _starting values in the Storage unit 41 are stored, especially if the hearing loss of the individual is determined from the outset.

Of course, the arithmetic unit 51 can also do the mentioned Include storage devices integrated in terms of hardware; is its delimitation shown in dashed lines in FIG. 10 to understand, for example, including in particular the computing module 53 and the coefficient modification unit 49.

The previously described procedure according to FIGS. 4, 7 and 10 are primarily suitable for the setting of a hearing aid ex situ. The determined manipulated variables may well be direct electronically transmitted to a hearing aid in situ, whereby but the real benefit of in situ adjustment, namely the consideration of the fundamental hearing impairment through a hearing aid, is not considered: First all manipulated variables are determined without a hearing aid, and then, without further acoustic signal presentation, its Setting made.

However, if you consider the basic considerations in context 4, 7 and 10 is rethinking, so it can be seen that in connection with the ex Considerations made in situ setting of a hearing aid readily on the "on-line" setting of a hearing aid let be transferred in situ. Instead of that, as before described, corresponding to a given loudness model the simulation model with predefined parameters of an individual or, if applicable, vice versa and finally from it, manipulated variables for the hearing aid are determined, it is readily possible to use the hearing aid to be adjusted in situ until the one perceived by the individual Loudness complies with the norm.

It is quite possible to evaluate the loudness perception by using the individual to determine whether an incremental parameter change made on Hearing aid, in analogy to Fig. 4 and 7, a change in Loudness perception against the loudness of the norm or from surrenders her way. However, that should be avoided Individual through the hearing aid fitting in an unreasonable way is too heavily stressed in terms of time and concentration.

With a view to the procedure explained with reference to FIG. 10 but now it can be seen that this is optimal for the in situ hearing aid fitting. The preferred procedure is to be explained with reference to FIG. 11, in which function blocks, which correspond to those of Fig. 10, with the are provided with the same reference numerals. The procedure is the same with the differences described below of Fig. 10 explained.

The acoustic signals A _Δk are fed to the hearing aid system HG with transducers 63 and 65 on the input and output sides and individual I, the latter loading the perceived L _I values into the memory 57 with the evaluation unit 5.

Exactly the same as was explained with reference to FIG. 10, the L _I value is stored in the memory 57 for each presented standard-acoustic, broadband signal A _Δk . With the power _values S _Δk from the storage unit 47 according to FIG. 10 and the standard parameter values from the storage unit 41, the loudness values L ' _{N are} initially determined on the computing module 53 according to (1) or (1 *), as was explained with reference to FIG. 10 , calculated and, specifically assigned to the presented signals A _Δk , stored in the memory unit 55. Via the comparison unit 59 and the modification unit 49, the standard parameters from the memory unit 41 are then modified, as described, until they, when used in (1) or (1 *), give L ' _N values with predeterminable accuracy corresponding to the L _I values in memory 57.

The following then applies: α ' nk = α N ± Δ'α k 'CB' nk = CB nk ± Δ'CB k . and L ' N = L I for all A. .delta..sub.k ,

But this also applies: α ' nk = α Ik 'CB' nk = CB Ik ,

However, this also means that if the hearing aid transmits input signals with a correction loudness L _Kor = L _Kor (± Δα _k , ± ΔCB _k , ΔT _k ), with ΔT _k = T _kI -T _kN set, the entire system consists of the hearing aid and individual perceives a loudness according to the norm.

As has already been explained in principle with reference to FIG. 6c, the hearing aid HG has a number k _o frequency-selective transmission channels K between the converter 63 and converter 65. Actuators for the transmission behavior of the channels are connected to an actuating unit 70 via a corresponding interface. The latter are fed the initial manipulated variables SG _o previously determined as optimal.

Now that the changed parameters α ' _Nk , CB' _{Nk have been} determined for a predetermined number of presented normacoustic, broadband signals A _Δk by means of the computing module 53 and the modification unit 49, by means of which, according to FIG. 8, the Scaling curves N 'have been adapted to those of the individual I with a hearing aid HG that has not yet been adjusted, the parameter changes found act ± Δα _k , ± ΔCB _k , ± ΔT _k or the parameters α _N , T _kN , CB _kN and α _kI , T _kI , CB _kI via the manipulated variable control unit 70 in such a way that it controls the hearing aid in such a way that its channel-specific frequency and amplitude transmission behavior for the signals A _Δk , on the output side, produce the correction loudness L _Kor .

While in the procedure according to FIG. 10 and with a view of FIG. 8, the parameters of the standard were changed until the scaling curves N 'match the scaling curves I and the hearing thresholds T _{kN were} not required for this, but only for the determination of the amplifications 6b, the hearing thresholds of the individual, stored in memory 43, and the standard hearing thresholds, stored in memory 44, are also used according to FIG. 11.

From those determined in FIG. 11 in analogy to the procedure according to FIG. 10 Parameter changes to, according to FIG. 8, N 'in I transfer, as well as determined from the differences of the hearing thresholds, summarized, the tax quantity determination unit 70 according to FIG. 11 manipulated variable changes ΔSG for the channel-specific Frequency and amplitude transmission behavior of the hearing aid in such a way that the scaling curves of the individual I with the hearing aid HG with the desired accuracy the scaling curves N of the standard are introduced:

The loudness behavior of the hearing aid forms the intrinsic, i.e. "own" loudness perception of the individual that of the norm, the loudness perception of the individual with hearing aid becomes or is the same as that of the norm, based on that of the standard, can be specified.

Compared to an "ex situ" attitude of the transmission behavior of a hearing aid has the example based on Fig. 11 shown "in situ" setting the essential Advantage on that the physical "in situ" transmission behavior the hearing aid and e.g. the mechanical ear interference be taken into account by the hearing aid.

In Fig. 12a) and b) are two basic implementation variants of a hearing aid according to the invention, using simplified signal flow function block diagrams, which are "ex situ", but preferably "in situ" as described can be put.

The hearing aid, as shown in FIGS. 12 a) and b), should, when optimally set, transmit received acoustic signals with the correction loudness L _Kor to its output, so that the system hearing aid and individual has a perception that is equal to that of the standard or (ΔL in Fig. 12a) deviates from this by a predeterminable amount.

According to FIG. 12 a), channels 1 to k _{o are} provided on a hearing aid according to the invention, followed by an acoustic-electrical input converter 63, each assigned to a critical frequency band CB _kN . The entirety of these transmission channels forms the signal transmission unit of the hearing aid.

The frequency selectivity for channels 1 to k _o is implemented by filter 64. Each channel also has a signal processing unit 66, for example with multipliers or programmable amplifiers. The non-linear, band- or channel-specific amplifications described above are implemented on the units 66.

All signal processing units 66 act on the output side to a summation unit 68, which in turn is on the output side to the electrical-acoustic output transducer 65 of the hearing aid acts. Until then, the two versions are correct according to FIGS. 12a) and 12b).

In the embodiment variant according to FIG. 12a), the principle of which is hereinafter referred to as the “correction model”, the converted acoustic input signals present on the output side of the converter 63 are converted into their frequency spectrum at a unit 64a. This creates the basis for subjecting the acoustic signals, in the frequency domain, to the loudness model according to (1) or (1 *) on a computing unit 53 ', parameterized with the correction parameters Δα _k , ΔCB _k , ΔT _k found as described above, that is according to the correction loudness L _KOR . The aforementioned channel-specific correction parameters and the corresponding correction loudness L _{KOR are converted} into actuating signals SG ₆₆ on the computing unit 53 ', with which the units 66 are set.

The values .DELTA.SG supplied to the hearing aid according to FIG. 12a) according to FIG. 11 therefore essentially correspond to the channel-specific correction parameters in this embodiment variant. By controlling the transmission behavior of the hearing aid via the units 66, as a function of the acoustic input signals currently pending and the correspondingly valid correction parameters, it is achieved that the hearing aid transmits the input signals mentioned with the correction loudness L _KOR . The system individual with hearing aid thus perceives the required loudness, be it preferably the same as the standard or in this respect in a predetermined ratio.

In the embodiment variant according to FIG. 12b), which follows "Difference model" variant is mentioned by the converted acoustic input signals as well as the electrical Output signals of the hearing aid to units 64a Spectra formed. On a computing unit 53a are due of the input spectra as well as the loudness model parameters of the Norm N calculates the current loudness values which the Would perceive norm based on the input signals. Analogous on a computing unit 53b based on the output signal spectra the loudness values calculated by the individual without hearing aid, i.e. the intrinsic individual. For this purpose, the modeling computing unit 53b Model parameters of the individual fed, as before described, determined.

On the one hand, a controller 116 compares the loudness values L _N and L _I determined by standard and individual modeling and, channel-specifically, the parameters of the standard model and the individual model and, on the output side, sends control signals SG ₆₆ to the transmission units 66 in accordance with the determined differences, such that the modeled loudness L _I becomes equal to the currently required standard loudness L _N.

In contrast to the correction model variant of FIG. 12a), controller 116 first determines the necessary correction loudness L _{KOR in} accordance with FIG. 12b).

Also in the differential model variant according to FIG. 12b) Hearing aid transmission with the units 66 set so that the currently pending acoustic signals with the correction loudness be transferred, so that modeling the loudness on the output signals, according to the perception behavior of the individual (53b), a loudness results accordingly the perceived by the standard or in this regard in a definable relation.

• dass, wie anhand der Fig. 1 bis 11 erläutert, ausgehend von einem gegebenen mathematischen Norm-Lautheitsmodell, Parameteränderungen ermittelt werden, welche dem Lautheits-Empfindungsunterschied von Norm und Individuum entsprechen. Damit sind Modellunterschiede und Individuummodell bekannt.
• An einem Hörgerät wird dasselbe mathematische Modell vorgesehen.
• Das Lautheitsmodell am Hörgerät wird in Funktion der Parameterunterschiede (Δ) betrieben, welche das Lautheitsmodell des Individuums demjenigen der Norm angleichen, wozu die gefundenen Modell-Parameterunterschiede und/oder die Norm-Parameter und die Individuum-Parameter dem Hörgerät zugespiesen werden.
• Am Hörgerätemodell wird im letzterwähnten Fall laufend überprüft, ob die aus den momentanen Eingangssignalen nach dem Modell der Norm berechnete Lautheit auch der durch das Individuum-Modell aufgrund der Ausgangssignale errechneten entspricht. Aufgrund der Modell-Parameterunterschiede und gegebenenfalls der modellierten Lautheitsunterschiede wird die Uebertragung am Hörgerät in regelndem Sinne so geführt, dass modellierte Lautheiten L_I, L_N in vorgebbare Relation kommen, vorzugsweise gleich werden.

In summary, it can therefore be stated:

• that, as explained with reference to FIGS. 1 to 11, parameter changes are determined based on a given mathematical norm loudness model, which correspond to the loudness-sensation difference between norm and individual. Model differences and individual models are thus known.
• The same mathematical model is provided on a hearing aid.
• The loudness model on the hearing aid is operated as a function of the parameter differences (Δ) which match the loudness model of the individual to that of the standard, for which purpose the model parameter differences found and / or the standard parameters and the individual parameters are fed to the hearing aid.
• In the latter case, the hearing aid model continuously checks whether the loudness calculated from the current input signals according to the standard model also corresponds to the loudness calculated by the individual model based on the output signals. On the basis of the model parameter differences and, if applicable, the modeled loudness differences, the transmission on the hearing aid is carried out in a regulating sense in such a way that modeled loudnesses L _I , L _{N come} into a predefinable relation, preferably become the same.

In retrospect, for example in FIG. 10 or 11, it is readily apparent that the functions of those described there "ex situ" processing units, in particular the computing units 53, the modification units 49 and 70, can be perceived directly by the controller unit 71 on the hearing aid can. The combination of the procedure according to FIG. 11 with a hearing aid according to FIG. which both compute the same loudness model, time sequentially with other parameters.

An embodiment of a hearing aid according to the invention, combined from the procedure according to FIG. 11 and the structure 12a) is shown in FIG. It is for the same Function blocks have the same position symbols as in Fig. 11 and 12 used. For reasons of clarity, only one Channel X of the hearing aid shown. At the beginning one connects Switching unit 81 according to the storage unit (41, 43, 44) Fig. 11, shown here as a unit, with the unit 49. A switching unit 80 is in the position shown, i.e. is open, a switchover unit 84 is also initially effective in the position shown.

In these switching positions, the arrangement works exactly as shown in FIG. 11 and explained in this context. After the adjustment method explained with reference to FIG. 11 has been run through, the determined parameter changes Δα _k , ΔCB _k , ΔT _k , which convert the individual loudness model (I) into the standard loudness model (N), when the hearing aid is put into operation by switching over the switching unit 80 in the storage unit 41 ', 43', 44 'acting in the same way as the storage unit 41, 43, 44 is loaded. The switching unit 81 is switched to the output of the last-mentioned storage unit. At the same time, the modification unit 49 is deactivated (DIS), so that it directly supplies the data from the storage unit 41 'to 44' unmodified and permanently to the computing unit 53c.

The switchover unit 84 is switched over so that the output on the arithmetic unit 53c, now acting as arithmetic unit 53 'according to FIG. 12a), acts via the manipulated variable control unit 70a on the transmission path with the units 66 of the hearing aid. The ΔZ _k parameters Δα _k , ΔCB _k , ΔT _k , as shown in dashed lines, act together with L _KOR on the manipulated variable control unit 70a.

In this way, the loudness model arithmetic unit 53c integrated in the hearing aid is initially used to determine the model parameter changes Δα _k , ΔCB _k , ΔT _k required for correction and then, in operation, to guide the transmission manipulated variables of the hearing aid in a time-variable manner - in accordance with the current acoustic signals Relationships - used.

sound optimization

The determination of the correction loudness model parameters on the hearing aid and thus the necessary manipulated variables for generally non-linear channel-specific amplifications, e.g. for the hearing impaired, allows different target functions, or the loudness requirements can be used as a target function, as mentioned, with different sets of correction loudness model parameters and therefore manipulated variables ΔSG ₆₆ can be achieved.

In general, one tries to the deaf, to rehabilitate so that he is back like the norm feels. This goal was achieved according to the previous explanations achieved in terms of loudness. The goal, namely that the individual with the hearing aid feels the same loudness perceives as the norm, but does not necessarily have to the optimum of individual hearing needs, in particular sonic type.

One has to assume that individual deviations from the mentioned goal, i.e. to adjust the loudness to the isophones average normal hearing, in practice as be felt more optimal, if you have one at all taking into account fine adjustment, namely optimization of the hearing aid parameters also for optimal acoustic sound perception, want to consider.

Experience has shown that so-called sound parameters are mainly associated with the frequency response of the hearing aid. In the range of high, medium and low frequencies therefore the gain should sometimes be raised and / or can be lowered to influence the sound of the device, as is common with hi-fi systems.

But is on one as previously described regarding isophones the hearing aid optimally set the gain frequency selective, i.e. in certain transmission channels, raised, the correction loudness changes.

This creates the further task of a loudness-optimized Hearing aid the correction parameter set used for this to change so that on the one hand the sense of sound is changed, on the other hand the previously achieved goal, namely individual loudness perception with hearing aid like that Norm, is maintained.

Due to the multi-parameter optimization task, which for Compliance with the loudness requirement leads, as before mentioned, several parameter sets lead to the solution, i.e. it is entirely possible to target parameters of the correction loudness model to change and maintain the loudness requirement by changing other model parameters accordingly sure.

This will be explained with reference to FIG. 14, starting from FIG. 11 become.

FIG. 14 shows that in addition to the precautions of FIG. 11 measures to be taken; the same functional blocks which already listed in FIG. 11 and thus explained, have the same item numbers.

It goes without saying that the following explanations also apply to a system according to FIG. 13 and for the Set the hearing aids according to FIGS. 12a), b). For reasons of clarity however, the measures to be taken starting from Fig. 11.

There are assessment criteria regarding sound perception, as described by Nielsen, for example sharp, shrill, dull, clear, reverberant, to just a few call.

In analogy to the quantification of loudness perception or to loudness scaling, as was explained with reference to FIG. 1, a sound sensation structured according to specific categories can also be numerically scaled, for example according to the criteria known from Nielsen. 14 and 11, after hearing device HG has been set by finding a correction parameter set (Δα _k , ΔCB _k , ΔT _k ) such that the individual with the hearing device has at least approximately the same loudness perception as the norm, the individual states: for example, in the case of the same broadband norm-acoustic signals A _{Δk presented} , on a sound scaling unit 90. A numerical value is assigned to each sound category on the unit 90. On a differential unit 92, the individually quantified sound sensation KL _{I is} compared with the sound sensation KL _{N of} the norm, for example, which is statistically determined for the same acoustic signals A _Δk . These are stored in a memory unit 94 so that they can be called up.

Now, however, are from the sound sensation statement of the individual with regard to the spectral composition of what he perceives Signals direct conclusions possible. For example, is that Sound sensation of the individual with the loudness-balanced Hearing aid, for example, too shrill, so it is readily apparent that the gain on at least one of the listening frequencies Channels of the hearing aid HG is to be withdrawn. The resulting loudness change must however by intervention on channels involved in loudness formation, namely with corresponding reinforcement changes, undone in order not to give up the previously achieved goal. So gives way to the sound sensation of the individual loudness-matched hearing aid from that of the standard, 14 becomes a sound characterization unit according to FIG 96, for example between comparison unit 59 and parameter modification incrementing unit 49, activated, which the parameter modification on the unit 49 in limited in their degree of freedom, i.e. one or more of the mentioned parameters, regardless of the minimum at unit 59 received difference, changed and constant.

Now the error criterion ΔR, which is no longer shown in FIGS. 11 and 14, has to be fulfilled recently as an abort criterion according to FIG. 10; if the mentioned parameter is kept, the still free parameters are changed via unit 59 until loudness is again felt according to the standard - L _I = L ' _N - but now with a changed sound.

The sound characterization unit 96 is preferably connected to an expert database, shown schematically at 98 in FIG. 14, to which the information relating to individual sound sensitivity deviation from the norm is supplied. Information, for example, is stored in the expert database 98
"shrill at A _Δk is the result of too much amplification in channels No. ...."

If "shrill" is felt, it is based on the expert database and the sound characterization unit 96 which Reinforcement in one or more of the higher frequency hearing aid channels withdrawn, with what at the comparison unit 59 no longer meets the termination criterion ΔR according to FIG. 10 and a new search cycle for the correction model parameters uses, but with the prescribed by the expert system Withdrawal of amplification in higher-frequency hearing aid channels.

A specific constellation of simultaneously prevailing correction _coefficients Δα _k , ΔCB _k and ΔT _k in a critical frequency band k can be regarded as a band-specific state vector Z _k (Δα _k , ΔCB _k , ΔT _k ) of the correction loudness model. The entirety of all band-specific state vectors Z _k forms the band-specific state space, which is three-dimensional in the case considered here. Band-specific state vectors Z _{k are} primarily responsible for every sound feature that can occur during sound scaling, with "shrill" and "muffled" in high-frequency critical bands. This expert knowledge must be stored as rules in the sound characterization unit 96 or the expert system 98.

If the band-specific correction state vectors Z _k , which give the individual a sense of loudness with the hearing aid essentially the same as that of the standard, as described above, have been found, then a changed state vector Z ' _{k must be} sought in at least one of the critical bands to change the sound. When changing the one band-specific state vector, it must either be changed further so that the loudness remains the same, or at least one other band-specific state vector must also be changed. The parameters of the correction loudness model on the hearing device thus result, based on the parameters of the standard, from a first incremental change “Δ” for conforming loudness adjustment and from second incremental changes δ for sound matching.

The correction loudness model on the hearing aid, for example according to FIG. 12 a), therefore uses parameters of the type α KOR = ± Δα k ± δα k ; CB KOR = ± ΔCB k ± δCB k ; T KOR = ± δT k ,

With each newly found or controlled band-specific state vector on the hearing device model, Z ' _k , which is intended to impart a new timbre to the individual, the corresponding manipulated variables according to FIGS. 12a), 12b) or 13 are switched to the actuators on the hearing device channels and the hearing device thereby readjusted, whereupon the individual continues to assess the sound quality while continuing to comply with the norm of loudness perception and accordingly inputs it at the unit 90 according to FIG. 14. This process is repeated until new δα _k , δCB _k and δT _{k are} searched for with the correct sign, until the individual equipped with the hearing aid perceives the presented acoustic signals satisfactorily, for example also evaluates their sound quality the same as the norm.

Instead of an absolute statement regarding sound quality, which the interactive procedure described above oriented towards the statement of normal hearing (memory 94) different iterative comparative, relative test methods, for example after Neuman and Levitt, for whom Proven sound sensation optimization. So it is entirely possible a variety of related channel-specific state vector sets, which each meet the loudness criteria, as explained, by calculating each time that Termination criterion ΔR according to FIG. 10 is reached, a new one Computing cycle is triggered, for example with a changed channel-specific state vector. The individual can again for example in a systematic selection process from the found, all the loudness requirements fulfilling sets of channel-specific state vectors determine the sentence that optimally satisfies it.

In Fig. 15, again in functional block representation, is Hearing aid according to the invention according to FIG. 12b) (model difference variant) presented in a form as is preferred is realized. To make the overview easier the same reference numerals used as for the hearing aid according to FIG. 12b) were used.

The output signal of the input converter 63 of the hearing aid is subjected to a time / frequency transformation at a transformation unit TFT 110. The resulting signal, in the frequency domain, is transmitted in the multi-channel time-variant loudness filter unit 112 with the channels 66 to the frequency / time domain FTT transformation unit 114 and from there, in the time domain, to the output converter 65, for example a loudspeaker or another stimulus transducer for the Individual. On a computing part 53a, the standard loudness L _{N is} calculated from the input signal in the frequency domain and the standard model parameters in accordance with Z _kN .

The individual loudness L _{I is} calculated analogously on the output side of the loudness filter 112. The loudness values L _N and L _I are supplied to the controller unit 116. The controller unit 116 provides the actuators, such as the multipliers 66a or programmable amplifiers, on the loudness filter 112 such that L I = L N becomes.

With this hearing aid according to the invention, the individual Loudness corrected to the standard loudness by the isophones of an individual are brought into line with those of the norm.

Loudness-corrected frequency masking

Even if with the hearing aid according to the invention, such as 15, the objective function "standard loudness" and possibly also achieved sound perception optimization language is understandable not yet optimal. This is due to the masking behavior of human hearing, which in a damaged individual hearing is different from the norm. The frequency masking phenomenon states that soft tones in close frequency neighborhood of loud tones faded out will not contribute to loudness perception.

If the intelligibility is to be further increased, then it must ensure that those spectral components, that are unmasked in the standard, i.e. perceived, also if individual hearing is damaged are perceived, the latter mostly through a distinguishes widened masking behavior. With the injured Hearing components were usually masked, which are unmasked in the standard hearing.

16 shows, starting from the representation of what has been described so far 15 hearing aid according to the invention, a Further development, in addition to the loudness correction of the Individual also a masking correction for a hearing impaired Individual, hence frequency demasking becomes. It should be noted in advance that through change the masking behavior of the hearing aid and therefore its frequency transmission behavior also the loudness transmission changes, each time after changing the frequency masking behavior The loudness transmission is also iterative must be recreated.

16, the input signal of the hearing aid is in the frequency range supplied to a standard masking model unit 118a, where the input signal is masked as with the Standard. How the masking model is determined will be shown later explained.

The output signal of the hearing aid in the frequency domain is analog, supplied to the individual masking model unit 118b, whereupon the output signal of the hearing aid the masking model of the intrinsic individual. The input and output signals masked with the N and I models are supplied to the masking controller 122 and compared it. In function of the comparison results Controller 122 accesses a masking filter in a regulatory sense 124 until the mask "hearing aid transmission and individual "are aligned with those of the norm is.

The multichannel time-variable loudness filter 112 is followed by the likewise multichannel time-variable masking filter 124, which, as mentioned, is set in function of the difference determined at the masking controller 122 such that the norm-masked input signal at unit 118a equals the "individual + hearing aid" -masked output signal at unit 118b will. If the transmission behavior of the hearing aid has now been changed via the masking controller 122 and the masking filter unit 124, the correction loudness L _{KOR of} the transmission no longer corresponds to the required one, and the loudness controller 116 adjusts the manipulated variables on the multi-channel time-variable loudness filter 112, that the controller 116 again determines the same loudness L _I , L _N.

Masking correction via controller 122 and loudness tracking via controller 116 are thus carried out iteratively, the loudness model used, defined by the state vectors Z _LN , Z _LI , remaining unchanged. It is only when both the loudness controller 116 and the masking controller 122 that the iterative matching of the filters 112 and 124 achieves the same within narrow tolerances, is the transmitted signal at the frequency / time transformation unit 114 converted back into the time domain and to the individual transfer.

Analogous to the loudness model, the frequency _{masking model is} parameterized by state vectors Z _FMN or Z _FMI .

17, starting from the example shown Masking behavior of normal hearing N, that hearing impaired individuals I are explained and, by the latter going backwards, the masking correction in a greatly simplified Representation to be explained.

If, according to the representation N of FIG. 17, a static acoustic signal is presented to the human ear, for example with the three frequency components f ₁ -f _{3 shown} , a masking curve F _{fx is} assigned to each frequency component in accordance with its loudness. Only the level components that exceed the masking limits, corresponding to the F _f functions, contribute to the sound and loudness perception of the broadband signal presented, for example with the frequency components f ₁ -f ₃ . In the constellation shown, the norm perceives a loudness to which the _unmasked components L _f1N -L _f3N contribute. The slopes m _unN and m _{obN of} the masking _curves F _f are essentially _independent of frequency and level if, as shown, the frequency scaling takes place in "bark", according to E. Zwicker (in critical bands).

In the case of a hearing-impaired individual I, the masking curves F _f are broadened as far as the gradients m are concerned, and they are also raised. This can be seen from the illustration for a hearing-impaired individual I at the bottom in FIG. 17, according to which, with the same acoustic signals presented with the frequency components f ₁ -f _3, the component on the frequency f _{2 is} not perceived and thus does not contribute to the perceived loudness , The frequency masking behavior of the standard N is again shown in dashed lines in characteristic I of FIG. 17.

It is now a question of realizing a filter characteristic by "frequency demasking filtering" on a hearing aid for the individual I, which corrects the masking behavior of the individual to that of the norm. As is shown in principle in FIG. 17 at 126, this is preferably implemented in each channel of the hearing aid assigned to a critical frequency band, which together with frequency-dependent amplification G ', in particular raises the frequency components masked out in the damaged individual so that the same frequency components as with the norm, contribute equally to the sound perception and loudness perception of the individual. The correction of the L _f1I , L _f3I components to the L _f1N , L _f3N values is achieved by the loudness _correction - different T _kI , T _kN .

In the case of non-stationary signals, i.e. if the frequency components of the presented acoustic signal vary in time, the total masking limit FMG formed by all frequency-specific masking characteristic curves F _f naturally also varies over the entire frequency spectrum, with which the filter 126 or the channel-specific filter must be guided in a time-variable manner.

The frequency masking model for the standard is known from E. Zwicker or from ISO / MPEG according to the literature reference below. However, the applicable individual frequency masking model with FMG _I must first be determined in order to be able to carry out the individually necessary correction, as shown schematically with the unmasking filter 126 in FIG. 17.

Furthermore, frequency components, which according to the frequency masking model of the norm be masked, so don't contribute to loudness at all not taken into account, i.e. not broadcast.

18 how the individual masking model FMG _{I is} determined on an individual.

Narrow band noise R _o , preferably centered with respect to the center frequency f _{o of} a critical frequency band CB _{k of} the standard or, if already determined as described above, the individual, is presented to the individual via headphones or, and preferably, via the already loudness-optimized hearing aid. A sinusoidal signal, preferably at the center frequency f _o , is added to the noise R _o , as are sinusoidal signals at f _un and f _ob above and below the noise spectrum. These test sinus signals are added sequentially in time. By varying the amplitude of the signals to f _un , f _o and f _ob , it is determined when the individual to whom the noise R _{o is} presented perceives a change in this noise. The corresponding perception _limits, designated A _Wx in FIG. 18, determine three points of the frequency _{masking behavior} F _{foI of} the individual. In this case, certain estimates are preferably used in advance in order to shorten the investigation process. The masking at the center frequency f _o is initially estimated to be -6dB for the hearing impaired. The frequencies f _un and f _ob are chosen to be offset by one to three critical bandwidths with respect to f _o . This procedure is preferably carried out at two to three different center frequencies f _o , distributed over the hearing range of the individual, in order to determine FMG _I , the frequency _{masking model of} the individual or its parameters, such as in particular m _obf , m _unf .

FIG. 19 schematically shows the experimental setup for determining the frequency masking behavior of an individual according to FIG. 18. At a noise generator 128, noise center frequency f _o . Noise bandwidth B and the average noise power A _{N are} set. The output signal of the noise generator 128 is superimposed on a superposition unit 130 with the respective test sinusoidal signals, which are set on a sine generator 132. Amplitude A _S , frequency f _{S can be} set on the test sine generator 132. As will be explained with reference to FIG. 20, the test sine generator 132 is preferably operated in a clocked manner, for which purpose it is activated cyclically, for example via a clock generator 134. The superimposition signal is fed to the individual via an amplifier 136 via calibrated headphones or, and preferably, directly via the hearing aid according to FIG. 16, which is still to be optimized with regard to frequency masking.

According to FIG. 20, the noise signals R _{o are} presented to the individual, for example every second, and the respective test sinusoidal signal TS is added to one of the noise packets. The individual is asked whether and, if so, which of the noise packages sounds different from the others. If all noise packets sound the same to the individual, the amplitude of the test signal TS is increased until the corresponding noise packet is perceived differently from the others, then the associated point A _{W is found} on the frequency masking characteristic FMG _I according to FIG. 18. The unmasking model according to block 126 of FIG. 17 can be determined from the masking model of the individual determined in this way and the known standard.

With reference to FIG. 16, the TARGET masking is actually at block 118a calculated according to the acoustic signal presented and, via masking controller 122, filter 124 in FIG Signal transmission path adjusted until the masking on it and on the individual - model on 118b - the same Result delivers, as from the leadership masking model in block 118a required. As mentioned, changes with frequency masking correction generally also the loudness transmission, so that loudness control and frequency masking control alternately until both are made Only then will criteria be met with the required accuracy via block 114, the "quasi currently" acoustic signal is present Signal converted back into the time domain and the individual transmitted.

At this point it must be noted that it is quite possible instead of the actual measurement the individual frequency masking behavior of the latter Audiogram measurements and / or loudness scaling according to Fig. 3 at least to be estimated. Becomes model identification of the individual based on approximate estimates, so the identification process (Fig. 18 to 20) becomes essential shortened.

Loudness corrected time masking

Even if the loudness an individual has with the hearing aid perceives with the loudness perceived by the norm agrees and also, as has been described, the frequency masking behavior of the hearing aid system with the individual Frequency masking behavior is what the norm is also achieved with the measures described above, speech intelligibility is not yet optimal. This, because human hearing as another psycho-acoustic Perception also has a masking behavior in time, that differs from the time masking behavior in the norm Individual, especially a hearing impaired individual, different.

While the frequency masking behavior says that, at Presence of a spectral component of an acoustic signal high level, simultaneously applied spectral components with low Levels and in close frequency neighborhood of the high level component under certain circumstances nothing about the perceived loudness contribute, results from the masking behavior in the Time that timed after the presence of a loud acoustic Signals may not be perceived quietly. That is why slower speaking is also for the temporal Unmasking a deaf person is helpful.

In analogy to the problems identified and solved above regarding loudness, sound optimization and frequency masking, it is therefore a further increase in intelligibility therefore, signal sections which are time unmasked in the standard are, with the help of a hearing aid according to the invention to be perceived unmasked by the individual.

Taking into account or correcting the time masking behavior on a hearing aid designed as previously described it is important to remember that what has been described so far Procedure on processing individual spectra based. Interactions of temporally following spectra were not to be considered. In contrast, the Consideration of the time masking effect a causal relationship to establish between currently pending acoustic Signals and future pending acoustic signals. M.a.W. is a further developed, also the time masking behavior hearing aid in principle equipped with time-variable delay arrangements, about the effects of a past acoustic signal to be able to take into account and control a subsequent one. But this also means that the loudness correction and Frequency masking correction, as mentioned on individual spectra based on the fact that they belong to the time Input and output spectra for the formation of loudness and frequency masking corrections stay synchronized.

Again, a change or correction of the temporal signal sequence leading to a time masking correction is necessary, the current loudness changes, with which the loudness correction, as already in connection with the frequency masking correction was carried out must become.

21, starting from the above-described hearing aid structure, in particular according to FIG. 16, shows its modification to take time masking corrections into account. After the time / frequency transformation at the unit 110, signal spectra accumulated sequentially in time are stored in a spectrum / time buffer 140 (waterfall spectrum display). Optionally, the spectrum-over-time representation can also be calculated with the Wigner transformation (see Ref. 13, 14). A plurality of input spectra obtained and stored sequentially in time are processed on the standard loudness computing device 53 ' _a - acting for the individual spectra in frequency analogously to the computing device 53a of FIG. 16 - and the L _{N time} image is fed to the controller unit 116a.

The frequency / time inverse transformation unit 114 (Wigner inverse transformation or Wigner synthesis) is an analog to Buffer 140 acting spectrum / time buffer 142 upstream.

Analogously, a further computing device 53 ′ _{b determines} the time image of the L _I values determined on the basis of the spectra. This time image is compared with the time image of the L _N values at controller 116a, and the comparison result is used to control a multi-channel loudness filter unit 112a with controlled, time-variable dispersion (phase shift, time delay). The filter 112a thus ensures that the temporal correction loudness image of the transmission with the loudness image of the individual corresponds to that of the norm.

The 142 respectively stored spectra in the buffers 140, the total of signals over a predetermined time period, for example from 20 to 100 msec depict, time and frequency masking model computers for the standard 118 _'a and the individual 118' are further _b supplied to the are parameterized with the norm and individual parameters or state vectors, Z _FM , Z _TM . Both frequency masking model F _N , analogous to FIG. 16, and time masking model T _{M are} implemented therein. The outputs of the computers 118 ' _a , 118' _b act on a masking controller unit 122a, the latter acting on the multi-channel unmasking filter 124a, which can now also be used to control the dispersion in a time-variable manner in addition to 124 from FIG. 16. By modeling computer 118 _'a, 118' _b, and the controller unit 122 is the filter unit 124 so as to frequency transfer and time response controlled so that the frequency and time corrected masked temporal Eingangsspektralbild with the individually modeled (118 _'b) of the output Zeitspektralbildes matches.

Driving the loudness filter 112a and the masking correction filter 124a is preferably carried out alternately until both assigned controllers 116a and 122a Detect predetermined minimum deviation criteria. First then the spectra in the buffer unit 142 are correct Time sequence on unit 114 converted back into the time domain and transmitted to the individual wearing the hearing aid.

21 shows a hearing device structure in the case of loudness correction, Frequency masking correction and time masking correction on signals converted into the frequency range.

A technically possibly simpler design variant 22 consistently takes time phenomena in signals into account in the time domain and phenomena related to frequency response Signals in the frequency domain. This is done before the time / frequency transformation unit 110, which according to the execution 16 preferably shows an instantaneous spectrum transformation executes a time mask correction unit, as shown schematically 141 upstream or, if necessary also as a supplement or replacement, between reverse transformation unit 114 and output transducer 65, such as speakers, Stimulator, e.g. an electrode stimulated cochlear Implant.

This takes place between the transformation units 110 and 114 Signal processing in block 117 according to the processing between 110 and 114 of FIG. 16.

The time mask correction unit designated 140 in FIG. 22 is shown in more detail in FIG. it includes a time-loudness model unit 142 on which, preferably as a performance integral, the course of the loudness over the Time of the acoustic input signal is tracked. Analogous is in another time-loudness model unit 142 instantaneous loudness of the signal in the time range before it Conversion determined at the time / frequency transformation unit 110. The loudness curves in the time of the input signal mentioned and the output signal mentioned are on compared to a (simplified) time-loudness controller 144, and on a filter unit 146, namely essentially a gain control unit GK, the loudness of the output signal, considered over time, that of the input signal equalized.

The input signal is used to carry out the time masking correction fed to a time buffer unit 148, according to which W. Verhelst, M. Roelands, "An overlap-add technique based on waveform similarity ... ", ICASSP 93, pp. 554-557, 1993, WSOLA algorithms or, according to E. Moulines, F. Charpentier, "Pitch Synchronous Waveform Processing Techniques for Text to Speech Synthesis Using Diphones ", Speech Communication Vol. 9 (5/6), pp. 453-467, 1990, PSOLA algorithms used become.

On a standard time masking model unit 150 _N , the standard time masking to be described is modeled on the input signals, on the further unit 150 _I , on the output signals of the time buffer unit 148, the individual time masking. The time maskings modeled on the signals on the input and output sides of the time buffer unit 148 are compared on a time masking control unit 152, and in accordance with the comparison result, the signal output on the time buffer unit 148 is time-controlled via the algorithms mentioned, preferably used, ie the transmission via the time buffer 148 controlled time-variable expansion factor or delay.

The time masking behavior of the standard is again from E. Zwicker known. The time masking behavior of an individual is to be explained with reference to FIG. 24.

According to FIG. 24, if an acoustic signal A _{1 is} presented to the standard over time t, a second acoustic signal A ₂ , which is subsequently presented, is only perceived if its level is above the time masking limit TMG _{N shown} in broken lines. The course of this masking limit on decay is primarily given by the level of the acoustic signal currently being presented. If signals with different loudness follow, an enveloping TMG results from all TMGs triggered individually by the signals.

FIG. 24 shows the time masking limit profile ZMG of, for example, a hearing-impaired individual under representation I with the same, schematically represented acoustic signals A ₁ and A ₂ . It can be seen that the second in the time signal A ₂ is not perceptible when the hearing impaired may. The dot-time masking behavior TMG _N , assumed for example, of the curve N is again shown in dash-dotted lines in the course of I. From the difference it can be seen that a time masking correction basically involves either delaying the second signal A ₂ on the individual - using the hearing aid - until his individual time masking limit has dropped sufficiently, or the signal A ₂ to be strengthened in such a way that the individual is also above his time masking limit.

If the perceived area of the signal A ₂ is designated L in the course of N, the last-mentioned procedure on the individual reveals that A ₂ must be amplified so that, in the best case, the same perceived area L is above the individual's time masking limit.

In any case, as can be seen from the explanations 21 to 23 results from current acoustic Waveforms, shifted in time, correction interventions be made, the future acoustic signals affect.

The decay time T _at the time masking TMG limit _N to the standard is essentially independent of the level or loudness of the time masking triggering signal, as shown in FIG. 24 of A _1. This also applies to hearing impaired people, so that in most cases it is sufficient to determine the decay time T _{AI of} the time masking limit TMG _I regardless of the level.

25, to determine the individual time masking limit decay time T _AI, the individual is presented with a click-free and click-free narrow-band noise signal R _o . After exposure of the noise signal R _o a test sinusoidal signal with Gaussian wrap-around him will be presented after a set interval T _Paus. A point corresponding to A _{ZM of} the individual time masking limit TMG _{I is} determined by varying the envelope amplitude and / or the pause time T _Paus . Further changes in the pause time and / or the envelope amplitude of the test signal determine two or more points of the individual time masking limit.

This is done, for example, with a test arrangement as shown in FIG. 19, but using a test sine generator 132 which emits a Gauss-encased sine signal. The individual is asked at which pair of values T _Paus and amplitude of the Gauss envelope the test signal after the noise signal is currently being perceived.

Here, too, the individual masking behavior can also be estimated from diagnostic data, which results in a significant reduction in the time for the identification of the individual time masking model TMG _I. As mentioned, the essential parameter of this model is the decay time T _AN or T _AI .

Literature:

1) E. Zwicker, Psychoacoustics, Springer Verlag Berlin, University text, 1982

2) O. Heller, audiometric audiometry using the method of dividing categories, Psychological contributions 26, 1985

3) A. Leijon, Hearing Aid Gain for Loudness-Density Normalization in Cochlear Hearing Losses with Impaired Frequency Resolution, Ear and Hearing, Vol. 12, No. 4, 1990

4) ANSI, American National Standard Institute, American National Standard Methods for the Calculation of the Articulation Index, draft WG S3.79; May 1992, V2.1

5) B.R. Glasberg & B.C.J. Moore, Derivation of the auditory filter shapes from notched-noise data, hearing research, 47, 1990

6) P. Bonding et al., Estimation of the Critical Bandwidth from Loudness Summation Data, Scandinavian Audiolog, Vol. 7, No. 2, 1978

7) V. Hohmann, dynamic compression for hearing aids, psychoacoustic Fundamentals and algorithms, dissertation UNI Göttingen, VDI-Verlag, row 17, No. 93

8) A.C. Neuman & H. Levitt, The Application of Adaptive Test Strategies to Hearing Aid Selection, Chapter 7 of Acoustical Factors Affecting Hearing Aid Performance, Allyn and Bacon, Needham Heights, 1993

9) ISO / MPEG standards, ISO / IEC 11172, 1993-08-01

10) PSOLA, E. Moulines, F. Charpentier, Pitch Synchronous Waveform Processing Techniques for Text to Speech Synthesis Using Diphones, Speech Communication Vol. 9 (5/6), pp. 453-467, 1990

11) WSOLA, W. Verhelst, M. Roelands, An overlap-add technique based on waveform similarity ..., ICASSP 93, p. 554-557, 1993

12) Lars Bramslw Nielsen, Objective Scaling of Sound Quality for Normal-Hearing and Hearing-Impaired Listeners, The Acoustics Laboratory, Technical University of Denmark, Report No. 54, 1993

13) B.V.K. Vijaya Kumar, Charles P. Neuman and Keith J. DeVos, Discrete Wigner Synthesis, Signal Processing 11 (1986) 277-304, Elsevier Science Publishers B.V. (North-Holland)

14) Francoise Peyrin and Rémy Prost, A Unified Definition for the Discrete-Time, Discrete-Frequency, and Discrete-Time / Frequency Wigner Distributions, p. 858 ff., IEEE Transactions on Acoustics, Speech, and Signal Processing, Vol. ASSP-34, No. August 4, 1986

Claims (8)

Method for producing a hearing aid adapted to an individual, characterized in that depending on the output signal of an acoustic / electrical transducer (63) on the input side on the hearing device according to a predefined model (L _N ) implemented on the hearing device, a psycho-acoustic perception target value is modeled, depending on the input signal of an output-side electrical / mechanical output transducer (65) on the hearing aid according to the predefined model (L _I ), the psycho-acoustic perception size, as it is perceived by the individual, is modeled, as a function of the modeling result difference (116) provides the signal transmission (64, 66, 66a) from said output to said input (SG ₆₆ ). Method according to Claim 1, characterized in that the model is implemented twice on the hearing aid (L _N , L _I ), with one (L _N ) the target size and the other with which the individual's perception is modeled at the same time. Method according to one of Claims 1 or 2, characterized in that the signal transmission between the output and the input is carried out via frequency-selective, parallel channels (64, 66) and this is set (66a). Method according to one of claims 1 to 3, characterized in that the signal transmission is not linear. Hearing aid with an acoustic / electrical input converter (63), an electrical / mechanical output converter (65), a signal transmission unit (64, 66, 66a, 68), which is connected between the output of the input converter (63) and the input of the output converter (65) and has the control inputs, characterized in that the hearing aid has a computing arrangement (64a, 53a, 53b, 116), on which inputs are operatively connected on the one hand to the output of the input converter (63), on the other hand to the input of the output converter (65), and on the output side is operatively connected to the control inputs (66a). Hearing aid according to claim 5, characterized in that the computing arrangement has a first modeling computer (53a) which, based on a given model (L) and a first set of parameters (Z _kN ) as a function of signals at the output of the input converter (63), has a first modeling result determined, and a second modeling computer (L _I ), which determines a second modeling result according to the given model (L) and a second set of parameters (Z _kI ) as a function of signals at the input of the output converter (65) and a signal in on the output side of the computer _arrangement Dependency of the modeling result difference is generated. Hearing aid according to one of claims 5 or 6, characterized in that the signal transmission unit has frequency-selective, parallel channels (64, 66, 66a) and control inputs are provided on the channels (66a). Hearing aid according to claim 7, characterized in that at least some of the channels have non-linear amplification units (66a), on which the control inputs act.

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