CA2428908A1

CA2428908A1 - Diotic presentation of second order gradient directional hearing aid signals

Info

Publication number: CA2428908A1
Application number: CA002428908A
Authority: CA
Inventors: Lawrence T. Hagen; Mark A. Bren; Randall W. Roberts; Timothy S. Peterson; David A. Preves
Original assignee: Micro Ear Technology
Current assignee: Micro Ear Technology
Priority date: 2002-05-15
Filing date: 2003-05-14
Publication date: 2003-11-15
Also published as: EP1365628B1; DK1365628T4; EP1365628A3; EP1365628A2; ATE537666T1; US20080273727A1; US7822217B2; US7369669B2; EP1365628B2; US20030215106A1; DK1365628T3

Abstract

Systems, devices and methods are provided for diotically presenting second-order gradient directional hearing aid signals. The present subject matter provides an improved signal-to-noise ratio, and presents a desired directional signal to each ear. One aspect is a hearing aid system. In one embodiment, the system includes a first microphone system in a first device and a second microphone system in a second device. The first microphone system has a first output signal, and the second microphone system has a second output signal. Each output signal includes a first order directional signal. The system further includes a first receiver circuit and a second receiver circuit. The combination of the first output signal and the second output signal provides a diotic presentation of a second-order gradient signal to both the first receiver circuit and the second receiver circuit. Other aspects are provided herein.

Description

SLwK 1346.036LTS1 DIUTIC PRESEhITATIiDN ~71F SEC(3ND-~RDER G>rADIEI~1T
DIRECTIONAL ~RI~TG AID SIGNALS
TechW cal held This application relates generally to hearing aid systems and, more particularly, to systems, devices and methods for providing hearing aid signals with more directionality.
Bacl~gro~znd A non-directional hearing aid system allows a wearer to pickup sounds from any direction. When a hearing aid wearer is trying to carry' on a conversation within a crowded room, a non-directional hearing aid system does not allow the wearer to easily differentiate between the voice of the person to whom the wearer is talking and background or crowd noise.
A directional hearing aid helps the. wearer to hear the voice of the person with whom the wearer is talking, while reducing flee miscellaneous crowd noise present within the room. ~ne directional hearing aid system is implemented with a single microphone having inlets to cavities located in front and back of a diaphragm.
An acoustic resistor pieced across a hole in the back inlet of the microphone, in combination with the compliance formed by the volume of air behind the diaphragm, provides the single microphone with directionality. This directional hearing aid system is termed a first order pressure gradient directional microphone.
'The term gradient refers to the differential pressure across the diaphragm. A
first-~ ~ ' :
. order pressure gradient directional microphone relates to a microphone system that produces a signal based on the pressure differential across a single diaphragm.
Une measure of the amount of directivity of a directional hearing aid system uses a polar directivity pattern, which shows the amount of pickup at a specific frequency (in terms of attenuation in dB) of a directional hearing aid system as a function of azimuth angle of sound incidence. A directivity index is the ratio of I

SLWK i346.U36LTSi energy arriving from in front of the hearing aid wearer to the random energy incident .
from all directions around an imaginary sphere with the hearing aid at its center:
A first order pressure gradient directional hearing aid microphone is capable of producing both a cardioid polar pattern and a super cardioid polar pattern.
A
cardioid polar pattern produces a directivity index of about 3-4 dB. A super cardioid ;
polar pattern produces a directivity index of about 5-6 dB.
Persons with an unaidable unilateral hearing loss or persons having one ear that cannot be aided with a hearing aid (laiown as a dead ear) and one ear with some aidable hearing loss often have great difficulty communicating in high noise levels.
These persons lose their auditory system's normal ability to suppress noise.
Wth respect to a normal auditory system, the brain uses the balanced, fused, binaurau~
processed inputs from the two normal cochleas of a normal hearing person, and cross-correlates these inputs to. s~rppress noise.
Contralateral Routing Of Signals (CROS) and Bilateral Routing Of Signals (BI CROS) hearing aids, respectively, are o$en employed for such persons since they often have great difficulty wearing only one hearing aid. CROS and BI-CROS
system take sound from the bad ear, process it, then send the processed souad via hard wire, RF, or induction transmission to a receiver in the other ear.
CROS systems are used for individua3s with on unaidable ear and one ear with normal hearing or a meld hearing loss. CROS systems includes a microphone and a receiver. A microphone is worn on the unaidable ear, and the receiver is warn on the better ear. BI CROS systems are used. for individuals having one unaidable ear and one ear needing amplification. ~ BI-CROS systems include twa microphones and a receiver. In the Bi-CROS systeua, a microphone is worn on each ear, and the receiver is worn on the better ear. CROS and BI-CROS heating aids overcome the loss of about 6 dB caused by the head blocking and diffracting sounds incident to one ear (tbe dead side) as they cross over to the better ear.
There is a need in the art to provide improved systems, devices and methods SLWK 1346.035US1 for providing hearing aid signals with more directionality to improve .
communications in high noise levels. ' The above mentioned problems are addressed by the present subject matter and will be understood by rending and studying the follo~tring specification.
The present subject matter provides improved systems, devices and methods fbr providing hearing aid signals with more directionality to improve communications in high noise levels. _ .
The hearing aid system provides a directional microphone system and a receiver ax each ear. Ouiput signals from the directional microphone systems are combined to provide a second-order gradient directional signal, vrhi~h is presented .
.. to both receivers. The second-order gradient directional signal provides an improved signal-to-noise ratio due to a greater reduction of ambient noise from the sides and back of the hearing aid wearer Present data indicates that a dir~tivity index of about 9 dB is capable of being obtained throughout most of the frequency range with the second-order gradient dire~ional microphone scheme. Improved communication in high noise levels is achieved due to the increase in directivity index from about 6 to 9 dB, and the presentation of the desired signal to both ears.
One aspect of the present subject matter is a hearing aid system. According to one embodiment, the system includes a first microphone system, a second microphone system, a'first receiver circuit and a second raceiver circuit. The first microphone system and the first receiver circuit are positioned in a first device, and the second microphone system and the second receiver circuit are positioned in a . 25 second device. The first microphone system receives sound and has a first output signal representative of the sound received. The second microphone system receives .
sound and has a second output signal representative of the sound received.
Both the first output signal and the second output signal include a first-order gradient SLWK 1346.036US1 directional hearing aid signal. The first receiver circuit is connected to the first microphone system to receive the first output signal and is connected to the second microphone system to receive the second output signal. The second receiver circuit is connected to the first microphone system to receive the first output signal and is connected to the second microphone system to receive the second output signal.
The combination ofthe first output signal and the second output signal provide a diotic presentation of a second-order gradient signal to.the first receiver circuit and the second receiver circuit.
In one embodiment, the hearing aid system includes a first hearing aid device .
and a secand hearing device. Each hearing device includes a microphone system for receiving a sound and providing a signal representative of flee sound. lEach hearing device further includes a switch for selecting a made of operation to provide a selected signal. Each hearing device further includes signal processing circuitry for receiving and processing the selected signal into a processed signal representative of the sound. Each hearing device further includes a receiver far receiving the processed signal to produce a processed sound that aids hearing. The microphone system includes a directional microphone system for providing a first-artier pressure gradient directional signal representative of the sound, and an omnidirectional microphone system far providing an omnidirectional signal representative of the sound.. In one embodiment, the directional microphone system includes a set of .
omnidirectional microphone systems. When an omnidireetional mode of operation .
is selected, the selected signal includes the omnidirectional signal representative of ' ' the sound. When a first-order gradienf~directional mode of operation is selected, the selected signal includes the first-order pressure gradient directional signal.
When a - 25 second-order gradient directional made of operation is selected, the selected signal includes a sum of the first-order pressure gradient directional signals from the microphone system for both the first and the second hearing aid devices.. .

SLWK 1346.036US1 ~e aspect is a method for diotically presenting second-order gradient directional signals to a wearer of hearing aids. 1n one embodiment of the method, a sound is received both at a first microphone system in a first hearing aid device and a second microphone system in a second hearing aid device. Both the first . _ microphone systean and the second microphone system provide a first-order gradient directional signal representative of the sound received. The first-order gradient signals provided by the first microphone system and the second microphone system are summed to provide a second-order gradient directional signal. The second-order gradient directional signal is pzesented to a first rv~ i~a the first hearing aid device and to a second receiver in the second hearing aid device.
One aspect is a method for aiding hearing for a user wearing a frost hearing aid unit and a second hearing aid wait, A sound is received at a first microphone system in the first hearing aid unit and at a second microphone system in the second hearing aid unit. For a first mode of operation, a first omnidirectional signat representative of the sound from the first microphone syst~ is provided to a first receiver in the first hearing aid unit. A second omnidirectional signal representative ofthe sound frora the second microphone system is provided to a second receiver in the second hearing aid unit. For a second mode of operation, a fast dired~ional signal representative of the sound from the first microphone system is provided to 24 the first receiver in the first hearing aid unit. A second directional signal representative of the sound from the second microphone system is provided to the second receiver in the second hearing aid unit. For a third mode of operation, the ' $rst directional signal from the first microphone system is summed with the second directional signal from the second microphone system to form a second-order - 25 gradient directional signal representative of the sound. The second-order gradient directional signal is diotically presented to the first receiver in the first hearing aid unit and to the second receiver in the second hearing aid unit.

SLWK I346.436~3SI
These and other aspects, embodiments, advantages, and features will become apparent from the following description and the referenced drawings.
Brief Description of the Drawings S Figure 1 illustrates a cardioid polar directivity pattexn of a hearing aid that provides a directional signal representative of a received sound.
Figure 2 illustrates a super cardioid polar direetivity pattean of a hearing aid that provides a directional signal representative of a received sound.
Figure 3 ~lustrates a pave view of one embodiment of an in-the-ear ' hearing device. _ .
Figure 4 i3lustrat~ a polar directivity pattern of a second-order gradient diredianal signal provided by a combination of two directional signals.
. Figure 5 illustrates one embodiment of a heating aid system that diotically presents second-order gradient directional hearing aid signals.
Figure 6 illustrates another ~nbodixneut of a hearing aid system that diotically presents second-order gradient directional hearing aid signals.
Figure 7 illustrates one embodiment of suannning circuitry that provides part of the amplifier and hearing aid circuitry illustrated in the embodiment of Figure 6.
Figure 8 illustrates another embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals.
Figure 9 ilhzstrates another embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid sigz~ais.
. Figure 10 illustrates another embodiment of a hearing aid system that diotically preseats second-order gradient directional hearing aid signals.
- 25 Figure 11 illustrates another embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals.
Figure 12 illustrates another embodiment of a hearing aid ~ that diotically presents second-order gradient directional hearing aid signals.

_ . , . . __~_ ....._. ~_ :. ".. . _ .... _.._ _,..~_ :~. __. ._ . _. ..___.
._r.. . m. . .__ SLWK 1346.~35US1 Figure 13 illustrates another embodiment of a hearang aid system that diotically presents second-order gradient directional hearing aid signals.
Figure 14 illustrates afwther embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals. . .
Figure 15 illustrates another t~xnbodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals..
Figure I 6 illustrates a block diagram of one embodiment of a swxt~3h-selectable directional-omxudirectional microphone system for the bearing aid systeun.
Figure 17 illustrates a schematic diagram of one embodiment of a switch ' selectable directional-omnadirectaiional a~aicrophone system for the bearing aid syst~.
.. Figure I8 illustrates a diagram of one embodiment of a hard wired hearing aid system that dioticalIy presents second-order gradi~t directional hearing aid signals.
Figure I 9 illustrates a diagram of one embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals, wherein the system includes a removable cord between two hearing aids.
Figure 20 illustrates a diagram of one embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals, wherein the system includes a wireless transmission between two hearing aids.
. ' ' Detailed Descriptioa~
The following detailed description of the present subject math refers to the - ' 25 accompa~xying drawings which show, by way of illustration, specific aspects and embodiments in which the present subject matter may be practiced. In the drawings, h7ce numerals descn'be substantially similar components throughout the several views. These embodiments are described in sufficient detail to enable those skilled SLwK 134b.036US1 ' in the art to practice the present subject knaatter Other embodiments may be utilized f and structiuul, Logical, and electrical changes may be made without departing from the scope of the present subject matter. The following detailed description is, therefore, not to be takea~ in a limiting sense, and the scope of the present subject .
matter is defined only by the appended claims, along with the full scope of equivalents to which such claims are entitled.
Figure 1 illustrates a eardioid polar directivity pattern of a hearing aid that provides a directional signal representative of a received sound. '.fhe polar directivity pattern provides one measure of the amount of diredivity of a directional hearing aid system. The polar directivity pattern l OP shows the amount of pickup at a specific frequency {in terms of attenuation in Db) of a directional hearing aid system as a function of azimuth angle of sound incidence. Accurate measurement of .. a polar direcfivity pattern requires an anechoie chamber. ,!fin anechoic chamber is an enclosed room that reduces sound ref ection from its inner wall surfaces and that attenuates ambient sounds entering from the outside. Thus, inside an anechoic chamber, the direction of arrival of sound can be controlled so that it comes from . only on specific angle of incidence. A cardioid or heart shaped polar pattern 101 pFOduces a diredivity index of aboeit 3-~ dB. The dsn~xivity index is the ratio of energy arriving fiom in front of the hearing aid wearer to the random energy incident from all directions around and imaginary sphere with the hearing aid at its center.
Figure 2 illustrates a super cardioid polar direcrivity pattern of a hearing aid:
that provides a directional signal representative of a received sound. ~ A
super ' cardioid polar pattern 201, which cau also be obtained with a first ~rd~ ~
gradient directional hearing aid microphone, produces a 5-b dB direetivity index. ' - 25 Figure 3 illustrates a perspective view of one embodiment of an in-the-ear hearing device. The in the-ear hearing aid 302 includes a housing 304 having a face plate 306 and a molded shell 308. The molded shell 3t18 is adhered to the face plate 306, indicated along line 310. The molded shell 308 is custom molded to fit each SLWK I346.03fsUS1 individual hearing aid wearer by known processes, such as making an, impression of .

the individual hearing aid wearer's ear and forming the molded shell based an that impression. The face plate 306 is coupled to a circuit board {not shown) locate inside the in the-ear bearing aid 308, which contains the circuitry for the heating aid s device.

Extending through the in the-ear hearing aid 308 and specifically face plate 306, is a battery door 312, a volume control 314, a switch 316, and at leasl'one microphone 318 and 320. The battery door 312 allows the hearing aid wearer access to change the battery (not shown). The volume control 3 i4 allows the hearing aid wearer to adjust the volume or amplification level of the hearing aid. Switch 3I6 extends through tile housing 304 and specifically face plate 306.
Switch 316 allows the hearing aid wearer to manually switch the in the-ear hearing aid among two or more modes of operation. Switch 316 is electronically couple to the circuit contained within the in the-ear hearing aid, which will be describe in further detail later in the specificafion. In one ~bodi~nent, which will be descnbed in further detail below, a hearing aid system according to the present subject Znatter can be switched among an omnidirectional (or non-direcrional) hearing aid mode to hear sounds from all directions, a frst-order directional hearing aid mode, such as for .

reducing background noise when carrying on a conversation in a crowded or noisy room,.and a second-order directional hearing aid mode, such as far further reducing background noise when carrying on a conversation in a noisier room.

Figure 4 illustrates a polar directivity pattern of a second-ordez gradient - directional signal provided by a combination of two directional signals. The polar direetivity pattern 401 shows the amount of pickup at a specific frequency (in this case,1K) of a hearing aid system as a function of azimuth angle of sound incidence.

In the illustrated pattern, the l3irectivity Index (DI - the ratio of sounds incident straight ahead to those incident all around an imaginary sphere) was 10.1 dB and the Unidirectional index (UDI - the ratio of sounds incident on an imaginary front SLWK 1346.U36US1 hemisphere to those from an imaginary mix' hemisphere) was 5.0 dB. This polar pattern I I O indicates that sounds incident from the sides and rear will. be . ' ' significantly attenuated. The DI predicts up to a 10 dB improvement in signal-to-noise ratio, depending upon the amount of reverberation in the listening ' environment.

Figure 5 illustrates one embodiment of a hearing aid system that diotically '.

presents secand-order gradient directional hearing aid signals.
. The illustx~ted system 522 includes a first hearing aid device 524 (such as may be located to aid a Ieft ear of a wearer) and a second hearing aid device 526 (such as may be located to aid a right ear of the wearer). The illustrated f rst hearing aid device 524 includes a first microphone system 528 and a first receiver circuit 530;
and the illustrated second hearing aid device 526 includes a second microphone system 532 and a .. second receiver circuit 534. The first microphone systea0 528 receives sound, and provides a first output signal representative of the sound received on line 536. The I S second microphone system 532 receives sound, and provides a second output signal representative of the sound received on line 538. Both the first and the second microphone systems include a directional microphone system. As such, both the f rst and the second output signals are capable of including a first-order gradi~t directional hearing aid signal. .

As will be discussed in more detail below with respect to Figures 8 and 9, various embodiments of the first and the second microphone systeDns are also capable of producing omnidireetional (or non directional) signals.
In these ~nbodiments, the wearer of the hearing aid system is able to select a dire~onal mode of operation and an omnidixectional mode of operation as desired for the wearer's listening situation and environment.

The iilus#rated first receiver ramuit 530 includes a first receiver 540 for providing sound to aid hearing, and a signal pxooessing cwt 542 for receiving the first output signal from the first microphone system 528, and providing a first i0 . --._~, SLWK 1346.o36US!
prod signal representative of the sound received to the first receiver 540.
The illustrated second receiver circuit 534 inch~des a second receiver S44 for providing sound to aid hearing, and a signal processing circuit 546 for receiving the second .
output signal from the second microphone system 532, and providing a second .
processed signal representative of the sound received to the second receiver 544.
One embodiment of the processing circuitry 542 includes conventional amplifier and hearing aid circuitry for processing heating aid signals for a receive In the illustrated hearing aid system 522, the output of the first microphone system 528 is connected to the output of the second microphone system 532 via line 548, which foams a summing node for the first output signal and the second output signal. In one embodiment, line 548 is a physical conductor or cable that extends from the first hearing aid device to the second hearing aid device.
.. The first-order gradient directional hearing aid signals provided as the output signals from the frst and the second microphone systems are summed together to provide a second-order gradient directional signal. This seco~-ordex gradient directional signal is simultaneously presented to the first receiver circuit 530 and the second receive circuit 534. This results in a simultaneous presentation of the same sound to each ear (l, e, a diotic presentation). Thus, the illustrated hearing aid system 522 is capable of dioticalPy presenting a second-order gradient directional hearing aid signal that has an expected diredivity index of about 9 dB. _ Figure 6 illustrates another embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals. The illustrated system 622 includes a first hearing aid device 624 (sack as may be .
Iocated to aid a Ie$ ear of a wearer) and a second hearing aid device 626 (such as may be located to aid a right ear of the wearea~). The illustrated first hearing aid device 624~includes a first microphone system 628 and a first receiver circuit 630;
and the illustrated second hearing aid device 626 includes a second microphone .
f system 632 and a second receiver circuit 634. The first microphone system 628 1i SLWK 1346.03bUS1 receives sound, and provides a first output sig~tal r~resentative of the sound received on line 636. The second microphone system receives sound, and provides a second output signal representative of the sound received on Line 638. Both the first and the second microphone systems include a directional microphone systean.
As such, both the first and the second output signals are capable of including a first-order gradient directional hearing aid signal.
The illustrated first receiver circuit 630 includes a first receiver 64tj for providing sound to aid hearing, and a signal processing circuit 642 for receiving the first output signal from the first microphone system 628, and providing a first processed signal representative of the sound received to the first receiver 640. The illustrated second receiver cizcuit 634 include a second receiver 644 for providing sound to aid hearing, and a signal processing circuit 646 for receiving the second output signal from the second microphone system 632, and providing a second gro~essed signal representative of the sound received to the second receiver 644.
In the illustrated system, the first signal pzocessing circuit 642 includes a ' first summing module 652; and the second signal procxssing circuit 646 includes a second summing module 654. The first sumnning module 652 combines the first directional output signal on line 636 and the second directional output signal on line 650. The second summing module 654 combines the first directional output signal on line 649 and the second directional output signal on line 638. The sum7ming modules 652 and 654 provide the ability to appropriately ruatch the first and second directional output signals and/or to perform other signal processing. One embodiment of summing circuitry is shown and descn'bed with respect to Figure 7.
In one embodiment, lines 649 and 650 form at least one physical conductor that extends from the first hearing aid device to the second hearing aid device.
Various embodim~ts include analog and digital transmission systems.
Figare 7 illustrates one embodiment of sumnning circuitry that provides part of the amplifier and hearing aid circuitry illustrated in the embodiment of Figure 6.

SLWK 1346.036US1 One eonbodim~t of the summing circuitry 752 includes a phase delay module 756 and a gain module 758. One embodiment of the summing circuitry includes an adjustable phase delay module and an adjustable gain module. These modules function to adjust the phase and gain of at least one of the directional output signals, after which the directional output signals are combined at smn~ming node 760 and presented to the remaf nder of the processing circuitry 742 of the receiver circuit.
Thus, these modules 756 and 758 function to compensate for slightly mismatched directional signals to achieve a desired second-order polar pattern"
Figure 8 dlusrrates another embodiment of a hearing aid system that 1 fl diotically presents second-order gradient direcfional hearing aid signals. The illustrated system 822 includes a first hearing aid device 824 (such as may be located to aid a left ear of a wearer) and a.second heW ng aid device 826 (such as may be located to aid a right ear of the wearer). The illustrated farst hearing aid device 824 includes a brst microphone system 828 and a first receiver circuit 830;
I5 and the illustrated second hearing aid device 826 includes a second microphone system 832 and a second receiver circuit 834. The first microphone system 824 receives sound, and provides a first output signal r~resve of the sound received on line 836. The second microphone system 832 receives sound, and provides a second output signal representative of the sound received. on line 838.
20 The frost microphone system 828 includes a directional microphone system 862 and an omnidirectional microphone system 854; and the second microphone .
.
system 832 includes a directional microphone system 866 and an omnidirectionaI
' microphone system 868. In one embodiment, both the first and the second microphone systems 828 and 832 include a switch-selectable directionat-25 omnidirectional microphone system for providing a directional mode of operation in which the first-order gradient directional hearing aid signal is produced, and an omnidirectional mode of operation in which an omnidirectional signal is produced.
In this embodiment, the switch selectable directional-omnidirectionai microphone i3 SLwK 1346.fl36US1 system effectively forms the illustrated omnidirectional nucrophone systean and the directional microphone system 864 and. 868 for the first and the second hearing aid devices 824 and 826, respectively: The wearer of the hearing aid system is able to select a directional mode of operation and an omnidirectional mode of operation as desired far the wearer's listening situation and environment.
In the illustrated hearing aid system, the output afthe first microphone system 828 is connected to the output of the second microphone system 832 via line 848, which farms a surciming node for the first output signal and the second output signal. The illustrated switches 870 and 872 are. positioned bctweea the line and the microphone systems such that both omnidirectional and diredaionat signals are capable of being summed and diotically presented to the receiver circuits and 834 in the first and the second hearing aid devices 824 and 826, ~spectively In one embodiment, line 848 is a physical conductor or cable that extends from the first hearing aid device to the second hearing aid device. Other eDnboanments include wireless communication. When the switches are positioned to select a directional mode of operation, the first-order gradient directional hearing aid signals provided as the output signals from the first and the second directional microphone systems 862 and 866 are summed tog~h~ to provide a second-order gradient directional signal that is diotically presented to the receiver circuits 830 and 834 in the first and the second hearing aid devices 824 and 826, respectively:
Figure 9 illustrates another ernbodim~rt of a hearing aid system that diotically presents second-order gradient directional hearing aid signals. The illustrated systeaa 922 includes a first hearing aid device 924 {such as may be located. to aid a left ear of a wearer) and a second hearing aid device 926 (such as may be located to aid a right ear of the wearer). The illustrated first hearing aid device 924 includes a first microphone system 928 and a first receiver circuit 930;
and the illustrated second hearing aid device 926 inchzdes a second microphone system 932 and a second receiver circuit 934. The fit~t microphone system 928 SLwK 1346.03bUS1 receives sound, and provides a first output signal representative of the sound received on line 93b. The second microphone system 932 receives sound, and provides a second output signal representative of the sound received on line 938.
The first microphone system 928 includes a directional microphone system S 962 and an omnidirectional microphone system 964; and the second nuc~ophone system 932 includes a directional rniarophone system 966 and an omnidirectional f microphone system 968. In one embodim~t, 'both the first and the second microphone systems 928 and 932 include a switch selectable dir~ional- , omnidirectiorial microphone system for providing a directional mode of operation in 10, which the first-order gradient directional hearing aid signal is produced, and an omnidirectional mode ofoperation in which an omnidirectional signal is produced.
In this embodiment, the switch-selectable directional-omnidirectional nucrophone system effectively forms the illustrated omnidirectional microphone system 964 and 968 and the directional microphone system 962 and 966 for the first and the second 1S . hearing aid devices 924 and 926, respectively The wearer' of the heating aid syst~n is able to select a directional mode of operation and an omnidirectional mode of .
operation as d~irad for the wearer's listening situation and envirounment In the illustrated hearing aid system 922, the output of the first directional microphone system 962 is ooianected to the output of the second directional 20 microphone system 966 via line 948, which fom~s a summing node for the first output signal and the second output signal. T"he illustrated switches 970 and 972 are positioned such that only the directional signals from the first and the second directional microphone systems 962 and 966 are capable of being summed and diotically presented to the receiver qrcuits 930 and 934 m the first and the second 25 hearing aid devices 924 and 926, respectively. in one e~mbodimenty line 948 is a physical conductor or cable that ext~ds from the first hearing aid device 924 to the second hearing aid device 926. Other embodiments include wireless communication.
IS
_. .. . _~-__. . ____..._ I ~_._ _ ..._ _~.,N.~ ~> ~~_~.~~ ~-,. _ .~s-~~. ~
..~,.,~~.-~ _ ..:..:. . __~_... . .. . .... .. _.....

SLWK 1346.t336iTS1 When the switches are positioned to select a directional mode of operation, ' the first-order gradient directional healing aid signals provided as the output signals from the first and the second directional microphone systems 962 and 966 are summed together to provide a second-order gradient directional signal that is dio6cally presented to the receiver circuits 930 and 934 in the first and the second hearing aid devices 924 and 926. When the switches are positioned to select an omnidirectional mode of operation, the omnidirectional signal faom the fii~t omnidirectional microphone system 964 is presented to the first receiver chit 930, and the omnidirectional signal from the second amnidirectionat unicrophone system . ' 968 is presented to the second receiver circuit 934.
Figure 10 illustrates another embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals. The illustrated hearing aid system 1022 is similar to that earlier shown and descn'bed with respect to Figure 5. This embodiment of the hearing aid system includes a removable cord 1048 that extends between the first hearing aid system 1024 and the second hearing aid system 1026. In the allus~ated embodiment, both the first and the second the second hearing aid devices have sockets 1074 into which fibs removable cord 1048 is plugged.
~Vh~a both hearing aid devices 1024 and 1026 are functioning in a .
directional mode of operation to produce a first order gradient directional signal, and when the cord 1048 is attached between the hearing aid devices 1024 and 1026,.
the output signals from the first and the second directional microphone systems are ' ' summed together to provide a second-order gradient directional signal that is diotically presented to the receiver circuits 1030 and 1034 in the first and the second hearing aid devices 1024 and 1026, respectively. When the cord 1048 is.removed and both hearing aid devices 1024 and 1026 are functioning in a directional mode of operation, the first microphone system 1028 presents one first-order gradient signal to the first receiver circuit 1030, and the second microphone system 1032 SLWK 1346.o36US 1 indepeandenfly presen#s another first-order gradient signal to the second receiver circuit 1034.
In one dent, each of the illustrated hearing aid devices 1024 and 1026 is capable of functioning in an omnidirectional mode of operation. When both hearing aid devices 1024 and 1026 are fuanctioning in an omnidirectional mode of operation to produce an omnidirectional signal and when the cord 1048 is attached between the hearing aid devices, the output signals firom the first and seared microphone system are summed togethe,~ and are diotically pres~.ted to the first and the second receiver circuits 1030 and 1034. When both hearing aid devices 1024 ' and 1026 are functioning in an omnidiredional mode of operation and when the _ cord 1048 is not attached between the hearing aid devices, the :first microphone system 1028 presents one omnidirectional signal to the first receivei circuit and the second microphone system 1032 independently presents another omnidirectional signal to the second receiver circuit 1034.
1 S Figure 11 illustrates another ~t of a hearing aid system that diotieally presents second-order gradient directional hearing aid signals. The illustrated hearing aid system 1122 is similar to that earlier shown and described v with respect to Figure 5. This embodiment of the hearing aid system includes a switch 1 I76 that disconnects the first hearing aid device i 124 fiom the second hearing aid device 1126.
When both hearing aid devices 1124 and I 126 are functioning. in a direcxional mode of operation to produce a first-order gradient directional signal, ~ ' and when the switch 1176 is closed to provide an electrical uxinnecfiton-between the .
hearing aid devices through line 1148, the output signals from the first and the second microphone systems 1128 and 1 i32 are summed together to provide a second-order gradient directional signal that is dioticalLy presented to the receiver circuits l I30 and 1134 in the first and the second hearing aid devices 1124 and 1126, respectively. When the switch 1176 is opened. to disconnect the first hearing SLWK 1346.036US1 aid device from the second hearing aid device 112b and bath hearing aid devices are functioning in a directional mode of operation, the :Crst microphone system presents one first-order gradient signal to the first receives circuit 1130, and the s second microphone system 1 I32 independently presents another first-order gradient signal to the second receiver circuit 1134.
in one embodiment, each of the illustrated hearing aid devices 1124 and 1 i26 is capable of functioning in an omnidirectional mode of operation. When both t hearing aid devices are functioning in an omnidirectional :mode of operation to f K
pzoduce an omnidir~fiional signal and when the switch 1176 is closed, the output I O signals frnm the first and second microphone systems 1128 and 1 I32 are summed together and a resultant signal is dioticatly presented to the first and the second.
receiver circuits. The resultant signal has an improved signal-to-noise ratio as compared to one of the omnidirectional signals. Summing the omnidirecfiional output signals together increases the signal by about b dB, and only increases the noise by about 3 dB. When both hearing aid devices are functioning in an omnidirectfonal mode of operation and when the switch 1 I76 is_opened, the first microphone system I 128 presents one omnidirectional signal to the first receiver .
circuit 1130 and the second microphone system 1132 independently presents another omnidirectional signal to the second receiver circuft 1134.
Figure I2 illustrates another embodiment of a hearing aid system that diotically presents second-order gradi~t directional hearing aid signals. The illustrated hearing aid system 1222 is similar to that earlier shown and described ~ . -with respect to Figure S. 1n this embodiment of the heating aid system, the first hearing aid device 1224 includes a first transceiver ('TxlRx) 1278 connected to the - 25 output of the first microphone system through switch 1280., and the second hearing aid device 1226 includes a second transceiver (TxlRx) 1282 connected to the output of the second microphone system through switch 1284. The first and the second SLWK 1346.036US1 transceivers are used to provide two-way wireless communication, as illustrated by line 1248, between the first and the second hearing aid devices.
When both hearing aid devices 1224 and 1226 are functioning in a directional mode of operation to produce a first order gradient directional signal, and when the switches 1280 and 1284 are closed to provide an electrical connection to the transceivers, the output signals from the first and the second microphone systems are summed together at nodes 1236 and 1238 to provide a second-order gradient directional signal that is diatically presented to the receiver circuits 1230 and 1234 in the first and the second hearing aid devices 1224 and 1226, respectively.
i0 When the switches 1280 and 1284 are opex~sd to disconnect the transceivers and both hearing aid devices.are functioning in a directional mode of operation, the fast microphone system 1228 presents one first-order gradient sigaal to the first receiver circuit 1230, and the second microphone system 1232 independently presents another first-order gradient signal to the second receiver circuit 1234.
. In one embodiment, each of the illustrated hearing aid devices is capable of functioning in an omnidirectional mode of operation. When both hearing aid devices are functioning in an omnidirectional mode of operation to produce an omnidirectional signal and when the switches 1280 and.1284 are closed, the output signals from the first and second microphone system are smnmed together at nodes 1236 and 1238, and the resultant signal is diotically presented to the first and the second receiver circuits 1230 and 1234. The resultant signal has an improved signal to--noise ratio as compared to one of the omnidixeetional signals.
Suznming the omnidirectional output signals tog~her increases the signal by about 6dB, and only increases the noise by about 3 dB. When both hearing aid devices are - 25 funetiomng in an omnidirectional mode of operation and when the switches and 1284 are opened, the first microphone system 1228 presengs one omnidirectional signal to the first receiver circuit 1230 and the second microphone system 1232 independently presents another amnidirectional signal to the second SLwK 1345.035US1 receiver circuit 1234. According to various embodiments, the wireless communication includes, but is not limited to, inductance and 1tF
transmissions.
According to various embodiments, the wireless communication involves analog and digital signal prace<ssing.
Figure 13 illustrates another embodiment of a hearing aid system that diotically presents second.-order gradient directional hearing aid signals.
The illustcaxed hearing aid system 1322 is similar to that earlier shown and described with respect to Figure 12. In this embodiment of the hearing aid systean, the first hearing aid device 1324 includes a first transmitter (T~c) 1386 and a f rst receiver I O (Rx) 1387 both connected to the output of the first microphone system 1328 through switch 1380, and the second hearing aid device 1326 includes a second transmitter (Tx) 1388 and a second receiver (ltx) 1389 botli connected to the output of the second microphone system 1332 through switch 1384. The illustrated transmitters and receivers are used to provide two one-way wireless coxnmunicafiion, as illustrated by line 1349 and 1350, between the first and the second hearing aid devices. In one embodiment, a one-way wireless liadc is provided using inductive tra~mission with a relatively simple tuned circuit on the transmitting side and an off the-shelf amplitude modulated receiver in the receiving hearing aid side.
One example of am off the-shelf amplitude modulated receiver is the Ferranti receiver. Two one-way wireless links operating at different frequencies are capable of being employed as a two-way wireless linl~. Digital signal processing also can be used to code each ona~-way signal in a two-way wireless linl~.
' Figure 14 illustrates another embodimeant of a hearing aid system that diotically presents second-order gradient directional hearing aid signals. The - 25 illustrated hearing aid system 1422 is similar to that earlier shown and described with respect to Figure 13. In this eanboditnent of the hearing aid system, the first hearing aid device 1424 includes a first transmitter (Tx) 1486 connected to the ou~ut of the first micaaphone system through switch 1490, and a first receiver (Rx) SLWK 134&.o3bUS1 1487 connected to the output of the fixst microphone system 1428 through switch 1491. The second hearing aid device 1426 includes a second traesmitter (Tx) connected to the output of the second microphone s1432 through switch 1492, and a second receiver (Rx) 1489 connected to the output of the second microphone system 1432 through switch 1493. The illustrated transmitters and receivers are used to pmvide two one-way wireless communication, as illustrated by line 1449 and 1450, between the f rst and the second hearing aid devices. In one e~c~dime~nt, a ono-way wireless link is provided using inductive transmission with a relatively simple tuned circuit on the teansmitting side and an off tla~-shelf amplitude modulated receiver in the receiving hearing aid side. One exempla of an off the-shelf amplitude modulated receiver is the Ferranti ZN414Z receiver. The-switches provide a user with additional control to proeide a second-order gcadi~t directional .~ signal to o~ae of the two hearing aid devices, for example. Two one-way wireless links operating at different frequencies are capable of being employed as a two-vvay wireless link. Digital signal processing also can be used to code each one-way .
signal in a two-way wireless Iinh Figcare 15 illustrates another embodiment of a hearing aid system that diotically presents second-order gradient directional hearing aid signals. The illustrated hearing aid system 1522 is similar to that earlier shown and described with respect to Figure 14. In this embodiment of the hearing aid system, the first hearing aid device 1524 includes a furst transmitter ( Tx) 158b connected to the . ' output of the first microphone system 1528 through switch 159U, and a first receiver (Rx) 1587 connected to a fast summing module 1552 in the f rat receiver circuit 1530 through switch 1591. The second hearing aid device 1526 includes a second -- 25 transmitter ( Tx) 1588 connected to the output of the second microphone system 1532 through switch 1593, ~d a second receiver (Rx) I589 connected to a second sunnmiag module 1554 in the second receiver. circuit 1534 through switch 1593.
In one ~xnbodiment, the first and the second summing module 1552 and 1554 include .

SLwK 1346:036US1 an adjustable phase delay module and an adjustable gain module as shown and , described earlier with respect to Fig~rre 7. The illustrated transmitters and receivers are used to provide two one-way wireless conununication, as illustrated by line 1 S49 and 1 SSO, between the first and the second hearing aid devices. ~dhen both hearing S aid devices are functioning in a directional mode of operation to produce a f rst order gradient directional signal, and when the switches 1590, 1591, IS92,1593 are closed to provide an electrical connection to the transmitters and receivers;
the output signals from the first and the second directional microphone systems are summed together in the first and the second summing modules 1SS2 and 1SS3 to provide a second-order gradient directional signal that is diotically presented to the xeceivers 1 S40 and 1 S44 in the f rst and the second hearing aid devices 1 S24 and 1526, respectively In one embodiment, a one-way wireless link is provided using inductive transmission with a relatively simple tuned circuit on the transmitting side and an off the-shelf amplitude modulated receiver in the receiving hearing aid side.
1 S One example of an off the-shelf amplitude modulated receiver is the Ferranti ZN414Z receiver. The switches provide a user with additional control to provide a second-order gradient direciaonal signal to one of the two hearing aid devices, for example. Two one-way wireless links operating at different frequencies are capable of being employed as a two-way wireless ialc. Digital signal processing also can be used to code each one-way signal in a tvcro-way wireless link.
One of ordinary skill in the art will understand, upon reading and comprehending this disclosure, that various embodiments ofthe present subject matter include various elements form one or more of the em eats shown and described with respect to Figures S-IS.
2S According to various embodiments, the microphone systems illustrated in Figures S-G and 8-1 S include an omnidireetional microphone system for producing an omnidirectional output signal representative of a sound received by the omnidirectional microphone system, and a directional microphone system for stwx i34s.o3sus~ _ producing a directional output signal representative of a sound received by the directional micaophone system. According to various embodiments, these microphone systems include a switch selectable directional-omnidirectional microphone that provides the functions of the directional and the omnidirectional microphone systems. One example of a switch selectable directional-omnidirectional, microphone is a singlo-cart<idge acoustic directional-omnidirectional microphone such as the Microtronic 6903. Another example of a switclrselectable directional-omnidirectional microphone is a switch selectable, electrically-summed dual-omnidirectional directional microphone system, such as that provided in 'CT.S. Patent No. 5,757,933 and LT.S. Patent Application Serial No.
09/452,631, filed on March 31,1998, both of which are assigned to Applicants' assignee and are hereby incorporated by reference their entirety. Embodiments for a switch seIe~able, electrically summed dual-omnidirectional directional microphone system are provided below with respect to Figures 16 and 17.
1 S Figure 16 illustrates a block diagram of one e~iabodiment of a switch-selectable directional-omnidirectional microphone system for the hearing aid system. The directional microphone system 1611 utilizes two non-directional microphone circuits to achieve a directional nucrophone signal. The directional microphone system 1611 includes a first non-directional microphone. system and a second non-directional microphone systean 1615.
The position of the first and the second microphone syst~ns in one . -embodiment of a hearing aid system is illustrated in Figure 3. Microphone 318 and microphone 320 include inlet tubes, which protrude through the xn-the-ear hearing aid face plate 360. The microphones 31 S and 320 are spaced a relatively short - 25 distance apart, preferably less than'h inch. In. one embodianent, the microphones .
318 and 320 are preferably 1J3 of an inch apart.
The axis of directionality is defined by a line drawn through the inlet tubes, indicated at 319. 'The in the-ear hearing aid is of a molded design such that the axis SLwK I346.036USi of directionality 319 is relatively horizontal to the floor when the in-the-ear hearing aid is positioned within the hearing aid wearer's ear and the wearer is in an upright sitting ar standing position. This design achieves desirable directional perfomsance of the in-the ear hearing aid.

S Refernng again to Figure 16, in one embodiment, the output signals from the second non dnrectional microphone system 1615 {indicated by signal 1621) is' .

.
eiedricalIy coupled through switch-1623, and summed at node 1625 with-the first non-directional microphone system 1613 (indicated by signal 1627).
The resulting ~. .

output signal is indicated at 1629. The output signal 1629 is electrically coupled to a hearing aid circuit 1631. For example, various ~nbodiments of the hearing aid circuit 1631 include a linear circuit, a compression circuit, an adaptive higlrpass filter, and a high power output stage. ' .

.. ~ In one embodiment, the output signal 1625 from the first non directional microphone system 1613 and second non-directional microph~aae system 1615 is amplified by passing it through an amplifier 1133. The resulting output signal of amplifier 163, indicated at 1635, is coupled to the hearing and circuit 1631. The amplifier 1633 and the hearing aid circuit 1131 forma processing circuit in a receiver circuit as described previously ~ .

The in-the-ear hearing aid 16 is switched between a non-directional mode and a directional made through the operation of switch 1623.
In the non-directional mode, switch 1623 is open {as shown), and non-directional microphone 161 g feeds:

directly in hearing aid t i63 i. For operation in a directional mode, switch 1623 is closed, and the first non-directional microphone system 13 i I and second .

non-directional microphone system 1615 output signals 1627 and 1621 are sumnned at suanming node 1625, with the resulting output signal 1627 being coupled to hearing aid circuit 1631.

In one embodiment, the second non-directional microphone system includes nom-directional microphone 1620, an inverter 1637, an adjustable poise SLwK 1346.036USI
delay module 1639, and an adjustable gain module 1641. °The output signal of microphone 1620 is coupled to inverter 1637, indicated at 1643. The output signal of inverter 1637 is coupled to the adjustable pulse delay anodule.1639, indicated at 1645. The output of adjustable phase delay module ib39 is coupled bo the adjustable gain modude~ 1641, indicated at l 647. The output of the adjustable gain module 1641 is coupled to switch 1623, indiarted at 1649_ The output signal. l b43 of microphone 1620 is inverted by inverter 1637.
Further, in one embodim~t, when switch 1623 is .closed, the phase delay of the output of mieraphone 1620 may be adjusted relative to the output of microphone 1618. Similarly, adjustable gain module 1641 adjusts the amplitude of the output signal received from microphone 1620 relative to the output signal 1627 from microphone 1618. By providing such adjustment, the hearing aid manufacturer - andlor the hearing aid dispenser is able to vary the polar directivity pattern of the in-the-ear hearing aid The adjustable nonYdirectional microphone system 1615 allows the polar pattern to be adjusted to compensate for small ears which do no allow Larger inlet spacing. Further, the adjustable non-direcfiional microphone system 1615 allows for adjustments to compensate for the differ~ces in manufacturing tolerances between non-directional microphone 16I S and non-directional microphone 1620.
Figure 17 illustrates a schematic diagram of one embodiment ofa switch-selectable directional-omnidirectional microphone system 1711 for the hearing aid system. Non-directional microphone 1718 has a coupling capacitor C 1 coupled to its output. Resistor Rl is electrically coupled between coupling c~paeitor C l and summing node 1725. Non-directional microphone 1720 has a coupling capacitor C2 - 25 coupled to its output_ Coupled to the output of C2 is inverter 1737 with adjustable phase delay 1739. The adjustable phase delay is an adjustable low pass filter.
The inverter 1737 is an operational amplifier OPAMi, shown in an inverting.
configuration. Coupled between capacitor C2 and the input node of OPAMP 1 and s~.wK. ms.o3scrsl the output node of OPAII~fP 1 is resistor R3. Similarly, coupled between input node of OP~MP I and the output node of OPAMP 1 is a capacitor C3.
~'he gain between the input of OPT I and the output of OP.AMP 1 is indicated by the relationship R31R2. In one preferred embodiment, R3 equals R2, resulting in a unity gain output signal from OPAMI' 1.
In one ~nbodim:ent, the low pass capacitor C3 for the phase delay 1739 is adjustable. By adjusting capacitor C3, andJor resistor R3, the phase delay"of the nondirectional microphone 1720 output relative to the non-directional microphone 1718 is adjusted. Coupled to the output node of OPAMP 1 is resistor RS in series ' with an adjustable resistor or potentiometer R6. Further, coupled to output signal 1727 is an inverting operational amplifier, OPA.1V1P 2 having an input node and an output node. Coupled between the input node and the output node is resistor R.~.
Also coupled between the input node and the output node is a capacitor C4. Tn one embodiment, capacitor C4 and resistor R3 and R4 are adjustable.
I S When switch 1723 is open, the resulting amplification or gain from the output from non-directional microphone 1718 is the rafio of resistors R4lRl.
When switch 1723 is closed, the output gain contn'bution from microphone 1720 is determined by the ratio ofR4/(RS plus R6}. 13y adjusting the adjustable potentiometer Rb, the amplitude of non-dizectional microphone 1720 of the output sigaal. relative to the output signal amplitude of non-directional microphone may be adjusted. By adjusting both capacitor C3 and resistor R6, the hearing aid is adjusted to vary the polar directivity pattern of the in-the-ear hearing.aid from ~ .
' cardioid to super cardioid as desired. In one embodiment, the values for the circuit components shown in Figure 17 are as follows: Cl = O.O1~F, C2 = O.OIy,F, C3 =
0.Q22yaF; C~ =1 l OpF, Rl = l OK, R2 = IOK, k3 =10K, R4 =11V1, RS =10K, and R6 = 2.2K.
Tn one embodimezet, non-directional microphone 17 a 8 and non-directional microphone 1720 are non-dirrectional microphones as produrxd by Knowles I~lo.

SLWK I346.036US1 BM5346. In one embodim~t, operational amplifiers OPAMP 1 and OPAMP 2 are inverting Gennum gIearing Aid Amplifiers No. 1i4 IrX509.
The illustrated hearing aid allows a wearer to switch between a non-directional mode and a directional mode by simple operafion of switch 1721 located on the in-the-ear hearing aid.. The circuit components which make up the directional microphone system and the hearing aid circuit are alI located within the hearing aid housing and coupled to the inside of face plate. Further, by adjustment ' of the adjustable phase delay and adjustable gain, the directional microphone system is adjusted to vary the polar diredivity pattern to account for manufacturing =
differences. It may be desirable to adjust the polar directivity pattern between cardioid and super cardioid for various reasons, such as to compensate for limited inlet spacing due to small ears or to compensate for the manufacturing tolerances between the non-direckionai microphones. It is also rerognazed that capacitor and resistor R4 are able to be adjusted to compensate for each individual's hearing loss situation.
The associated circuitry allows the two non directional microphones to be positioned very close together and still produce a directional microphone system having a sager cardioid polar directivity pattern. Further, the directional .
microphone system is able to space the two microphones less than one inch apart in order for the directional microphone system to be incorporated into an in-the-ear hearing aid device. In one embodiment, the two microphones are spaced about 0.33 inches apart In one embodiment, the two microphones are spaced about 0.2 inches .
apart. The in-the.-ear hearing aid circuitry, including the directional microphone system circuitry and the hearing aid circuit circuitry, utilize microcomponents and ~ .
. 25 may further utilize printed circuit board technology to allow the directional microphone system and hearing aid circuit to be located within a single in the-ear heating std.
z7 sLwK i3~s.o3susi Figure 18 illustrates a diagram of one embodiment of a hard-wired hearing aid system that diotically presents second-order gradient directional hearing aid signals. The illustrated embodiment of the system 1822 includes a first hearing aid device 1824 that includes a first microphone system 1828 and a first receiver circuit 1830; and further includes a second hearing aid device 1826 that includes a second microphone system 1832 and a second receiver circuit 1834. The microphone systems 1828 and 1832 are switchselectable omaidarectional-directional microphone systems. The first receiver circuit 1830 includes a first receiver and a first processing circuit 1842; and the second receive- circuit 1834 includes a second receiver 1844 and a second processing circuit 1846.
In the illustrated embodiment, the switch selectable omnidirectional-directional microphone systems include a single~caxtxidge acoustic directional-omnidireetional microphone. One of ordinary slkill in. the art will understand, upon reading and comprehending this disclosure, how to incorporate a switch selectable, eleetEically summed dual-omnidirectional directional microphone system as illustrated in Figures 16 and 17, for example, in the switch-selectable omnidirectional-directional microphone systems.
The first and the second hearing aid devices 1824 and 1826 include a first switch 1861 and a second switch 1863, respectively. The switches are connected to selectively provide either an omnidireetional signal on line 1865 and 1867 from the . ' omnidirectional microphone system or a directional signal on lane 1869 and 1871 ' from the directional microphone system as the output signal on Iine 1873 and to the processing circuit 1842 aad 184$. The output 1869 of the directional microphone systean for the fast hearing aid device is coupled to the output 1871 of' - 2S the directional microphone syst~n far the second hearing aid device via line 1877 such that the directional hearing aid signals are summed at the nodes represented by lines 1869 and 1871. Thus, when the switches 1861 and 1863 are positioned to select a direcfiional mode of operation, the sum of the directional hearing aid signals ' SLwK 1346.03bUS1 .
is presented. as a second-order gradient directional signal to both the first processing .
circuit 1842 and the second processing circuit 1846. in one embodiment, a capacitor CAP 1 is used to AC couple the directional microphones.
A first battery for providing power to the first hearing aid device 1824 is ' shown at 1879, and a second battery far providing power to the second hearing aid device 1826 is shown at 1881. The negative terminal of the batteries are connected together to provide a conunon reference voltage between the two hearing aid devices. The negative terminal of the batteries are appropriately connected to the microphone systems, the processing circuits and the receivers. The positive terminal . of the batteries are also appropriately connected to the microphone system, the pmg t ~ ~e receivers (although not shown). .
Figure i9 illustrates a diagram of one embodiment of a hearing aid system .e that diotically presents second-order gradient directional healing aid signals, .
wherein the system includes a removable cord between two healing aids. This embodiment is similar to the embodiment previously shown and described with respect to Figure 18. This embodiment includes a first switch 1961 and a second _ switch 1963 to selectively provide an omnidirectianal signal on Line 1965 and from the omnidirectional microphone system or a directional signal on line 1969 and -1971 from the directional microphone system as the output signal on line 1973 and I97S to the processing circuit 1942 and 1946. This embodiment includes a first socket 1983 for the first hearing aid device 1924 and a second socket 1985 for the .
second hearing aid device 1926. The output signal and the common ground reference signal for each hearing device are appropriately connected to their respective sockets. A removable cord, such as that previously shown and descn'bed - 25 with respect to the system of Figure 10, is attached to the sockets.
When. the cord is attached and both microphone systems are providing a fast-order directional signal as an output signal on lines 1973 and 1975, the cord allows the two first order ' directional output signals to be summed to form a second-order gradient directional SLWR 134G.036I,TS1 .
signal at the nodes represented by lines 196 and 1971. The second-order gradient directional signal is pt~l to both the first processing circuit 1942 and the second processing circuit 1946 on lines 1973 and 1975, respectively Figure 20. illustrates a diagram of one embodiment of a hearing ad system that diotically presents second-order gradient directional hearing aid signals, wherein the system includes a wireless transmission between two hearing aids.
This embodiment includes a first switch 2061 and a second switch 2063 to selectively provide an omnidirectionai signal on line 2065 and 2067 from the omnidirectional microphone systenn or a directional signal on line 2069 and 2071 frnm the ~ ' directional microphone system as fhe output signal on line 2073 and 2075 to the processing circuit 2042 and 2046. This embodiment is similar to the embodiments previously shown and descn'bed with respect to Figures I8 and 19. Iii this embodiment,~the first hearing aid device 2024 zncludes a first transceiver block 2078 coupled to the output of the first directional microphone system, and the second hearing aid device 2026 includes a second transceiver block 2082 coupled to the , output of the second directional microphone system. In one embodiment, capacitors are used to AC couple the directional microphone systems to the transceivers, respectively In one embodiment, switches 2080 and 2084 are used to selectively .
disconnect the transceivers from the output of the directional microphone.
Disconnecting the switches 2080 and 2084 allows the two hearing aid devices and 2026 to operate as two individual first-order gradient directional instruments. .
This embodiment of the hearing aid system uses wireless communication ' between the hearing aid devices. Examples of wireless communication include, but are not limited to, induction and RF h~ansmission.
' 25 The present subject matter has disclosed switches. These switches ate not limited to a particular type switch, For example, the present subject matter is capable of using various switches, including but not limited to mechanical swatches, inductive reed switches, electronic switches and programmable so#tware switches.

SLWK 1346.0~6~JS1 According to various embodiments, programmable memories are used to cause the hearing aid devices to operate in various modes of operations.
One embodiment of the present subj ect matter provides a hearing aid systean that has at least three modes of operation. A sound is received at a first microphone S system in a first hearing aid unit and at a second microphone system{ in a second hearing aid unit. For a first mode of operation, a first onmidiredional signal representative of the sound from the first microphone system is provided t~5 a first receiver in the first hearing aid unit. A second onuudixectional signal representative of the sound from the second microphone system is provided to a second receiver in the second hearing aid unit. This first mode is beneficial in situations where there is little noise and the user desires to listen to sounds in all directions. For a second mode of operation, a first directional signal representative of the sound from the first microphone system is provided to the first x~eiver in the first hearing aid u~nftt. A
second directional signal representative of the sound from the second microphone 1.5 system is provided to the second receiver in the second hearing aid unit.
This second mode is beneficial in situation where there is more noise. The user is able to detect a conversation, for example, in front ofhim but loses ability to hear sounds to the back or to the sides. For a third mode of operation, the first directional signal from the first microphone system is summed with the second directional signal from the second microphone system to form a second-order gradient directional signal representative of the sound. The second-order gradient directional signal is .
' diotically presented to the first receiver in the first hearing aid unit and to the second . ' receiver in the second hearing aid unit. This third mode is t~eneficial in even noisier situation as it provides more directionality. There is some loss of iow-fi~equency . 25 response an the third mode, and there is additional loss in the ability to'hear sounds .
to the back or to the sides.
As has been provided above, the present subject matter provides improved systemis, devices and methods for providing hearing aid signals with more .

S1LWK 1346.o36~7S1 directionality to improve communications in high noise levels. The hearing aid system includes a directional microphone system and a receiver at each ear.
Output signals from the directional microphone systems are combined to px'ovide a second-order gradient directional signal, which is presented to the receiver at both ears. The second-order gradi~t tonal signal provides an improved signal-to-noise ratio, and an expected directivity index of about 9 dB throughout most of the frequency range. The Biotic prrtation of the second-order gradient signal improves conimunieation in high noise levels.
One of ordinary skill in the art will understand, upcin reading and comprehending this disclosure, that the present subject matter is capable of being incorporated in a variety of hearing aids. For example, the present subject mater is capable of being used in custom hearing aids such as in the-ear, half'shell and in-tha.canal styles of hearing aids, as well as for behind-the-ear hearing aids.
Furthermore, one of ordinary skill in the art will understand, upon reading and comprehending this disclosure, the method aspects of the present subject matter using the figures presented and described in detail above.
Although specific embodiments have been illustrated and des~ed herein, it will be appreciated by those of ordinary skill in the art that any arrangement which is calculated to achieve the same purpose may tae substituted for the specific embodiment shown. This application is intended to cover adaptations or variations of the present subject matter. It is to be understood that the above description is .
intended #o be illustrative, and not restrictive. Combinations of the above embodiments, and other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the.present subject matter should be determined with reference to the appended claims, along with the full scope of equivalents to which such ciaizns are entitled.

Claims

1. A hearing aid system, comprising:.
a first microphone system positioned in a first device for receiving sound and having a first output signal representative of the sound received, wherein the first output signal includes a first-order gradient directional hearing aid signal;
a second microphone system positioned in a second device for receiving sound and having a first output signal representative of the sound received, wherein the second output signal includes a first-order pressure gradient directional hearing aid signal;
a first receiver circuit positioned in the first device for aiding hearing in a first ear of a wearer, the first receiver circuit being connected to the first microphone system to receive the first output signal and connected to the second microphone system to receive the second output signal; and a second receiver circuit positioned in the second device for aiding hearing in a second ear of a wearer, the second receiver circuit being connected to the first microphone system to receive the first output signet and connected to the second microphone system to receive the second output signal, wherein the first output signal and the second output signal provide a diotic presentation of a second-order gradient signal to the first receiver circuit and the second receiver circuit.

2. The system of claim 1, wherein each of the first and second microphone systems includes a switch-selectable directional-omnidirectional microphone system for providing a directional mode of operation in which the first-order gradient directional hearing aid signal is produced and an omnidirectional mode of operation in which an omnidirectional signal is product.

3. ~The system of claim 2, wherein the switch-selectable directional-omnidirectional microphone system includes a directional microphone for providing the directional mode of operation and an omnidirectional microphone for providing the omnidirectional mode of operation.

4. ~The system of claim 2, wherein the switch-selectable directional-omnidirectional microphone system includes:
a first omnidirectional microphone system having a first omnidirectional output signal representative of the sound received; and a second omnidirectional microphone system having a second omnidirectional output signal representative of the sound received, wherein the first omnidirectional output signal and the second omnidirectional output signal are summed in the directional mode of operation to provide the first-order gradient directional hearing aid signal, and wherein one of the first and the second omnidirectional signals provides the omnidirectional signal in the omnidirectional mode of operation.

5. ~The system of claim 1, wherein:
the first receiver circuit includes a first receiver and a first signal processing circuit for receiving the first output signal and providing a first processed signal representative of the sound received to the first receiver, and the second receiver circuit includes a second receiver and a second signal processing circuit for receiving the second output signal and providing a second processed signal representative of the sound received to the second receiver.

6. ~The system of claim 5, wherein:

the first signal processing circuit includes an adjust phase module and an adjust gain module for adjusting a phase and a gain of the second output signal and summing the first output signal and the second output signal; and the second signal processing circuit includes an adjust phase module and an adjust gain module for adjusting a phase and a gain of the first output signal and summing the first output signal and the second output signal.

7. A hearing aid system, comprising:
a first instrument for aiding hearing in a first ear of a wearer, including:
a first microphone system for receiving sound and having a first output signal representative of the sound received, wherein the first output signal includes a first-order directional signal;
and a first receiver circuit connected to the first microphone system to receive the first output signal; and a second instrument for aiding hearing in a second ear of a wearer, including:
a second microphone system for receiving sound and having a second output signal representative of the sound received, wherein the second output signal includes a first-order directional signal; and a second receiver circuit connected to the second microphone system to receive the second output signal, wherein the first-order directional signals from the first microphone system and the second microphone system are combined to provide a second-order directional signal that is diotically presented to the first receiver circuit and the second receiver circuit.

8. The system of claim 7, further comprising at least one electrical conductor between the first instrument and the second instrument for transmitting the first output signal from the first microphone system to the second receiver circuit, and the second output signal from the second microphone system to the first receiver circuit.

9. The system of claim 8, wherein the at least one electrical conductor includes a removable cord for removable attachment to sockets in the first instrument and the second instrument.

10. The system of claim 7, further comprising a wireless link between the first instrument and the second instrument for transmitting the first output signal from the first microphone system to the second receiver circuit, and the second output signal from the second microphone system to the first receiver circuit.

11. The system of claim 10, wherein the wireless link includes a two-way wireless link.

12. The system of claim 10, wherein. the wireless link includes two one-way wireless links.

13. The system of claim 7, wherein the first and second microphone systems each include a switch-selectable directional-omnidirectional microphone for providing a directional mode of operation in which the first-order directional signal is produced and an omnidirectional mode of operation in which an omnidirectional signal is produced.

14. The system of claim 7, further comprising a switch for disconnecting the second microphone system from the first receiver circuit and disconnecting the second receiver circuit from the first microphone system to move from a mode of operation that provides a diotic presentation of the second-order directional signal to a mode of operation that provides first-order directional signals to the first and second receiver circuits.

15. The system of claim 7, wherein:
the first microphone system has a directional mode of operation in which a first directional signal is produced as the first output signal and an omnidirectional mode of operation in which a first omnidirectional signal is produced as the first output signal;
the second microphone system has a directional mode of operation in which a second directional signal is produced as the second output signal and an omnidirectional mode of operation in which a second omnidirectional signal is produced as the second output signal;
the system further comprises a user-wearable switch for selecting a desired mode of operation from an omnidirectional mode of operation in which the first receiver circuit receives the first omnidirectional signal and the second receiver circuit receives the second omnidirectional signal, a first-order gradient mode of operation in which the first receiver circuit receives the first directional signal and the second receiver circuit receives the second directional signal, and a summed second-order gradient mode of operation in which a second-order directional signal is diotically presented to the first and second receivers.

16. The system of claim 7, wherein:

the first receiver circuit includes a first receiver and a first signal processing circuit for receiving the first output signet and providing a first processed.
signal representative of the sound received to the first receiver; and the second receiver circuit includes a second receiver and a second signal processing circuit for receiving the second output signal and providing a second processed signal representative of the sound received to the second receiver.

17. The system of claim 16, wherein:
the first signal processing circuit includes an adjust phase module and an adjust gain module for adjusting a phase and a gain of the second output signal and summing the first output signal and the ascend output signal; and the second signal processing circuit includes an adjust phase module and an adjust gain module for adjusting a phase and a gain of the first output signal and summing the first output signal and the second output signal.

18. A hearing aid system, comprising a first hearing aid device and a second hearing device, each hearing device including:
a microphone system for receiving a sound and providing a signal representative of the sound, the microphone system including:
a directional microphone system for providing a first-order pressure gradient-directional signal representative of the sound; and an omnidirectional microphone system for providing an omnidirectional signal representative of the sound;
a switch for selecting a anode of operation to provide a selected signal, wherein:
when an omnidirectional mode of operation is selected, the selected signal includes the omnidirectional signal representative of the sound;

when a first-order gradient directional mode of operation is selected, the selected signal includes the first-order pressure gradient directional signal; and when a second-order gradient directional mode of operation is selected, the selected signal includes a sum of the first-order pressure gradient directional signals from the microphone system for both the first and the second hearing aid devices;
signal processing circuitry for receiving and processing the selected signal into a processed signal representative of the sound; and a receiver for receiving the processed signal to produce a processed sound that aids hearing.

19. The system of claim 18, when a diotic omnidirectional mode is selected, the selected signal includes a sum of the omnidirectional signals from the microphone system for both the first and the second hearing aid devices.

20. The system of claim 18, wherein the microphone system includes a switch-selectable directional-omnidirectional microphone for providing the directional microphone system when either the first-order or second-order gradient directional mode of operation is selected and for providing the omnidirectional microphone system when an omnidirectional mode of operation is selected.

21. The system of claim 18, wherein the microphone system includes:
a first omnidirectional microphone system having a first omnidirectional output signal representative of the sound; and a second omnidirectional microphone system having a second omnidirectional output signal representative of the sound, wherein the first omnidirectional output signal and the second omnidirectional output signal are summed in either the first-order or second-order gradient directional mode of operation to provide the first-order gradient directional signal, and wherein one of the first and the second omnidirectional signals provides the omnidirectional signal in the omnidirectional mode of operation.

22. The system of claim 18, further comprising a cable removably attached between the first hearing aid device and the second hearing aid device, wherein the first-order pressure gradient directional signals are transmitted through the cable and, when the cable is removed, both the first hearing aid device and the second hearing aid device function as an individual first-order gradient directional hearing aid device.

23. A method for diotically presenting second-order gradient directional signals to a wearer of hearing aids, comprising:
receiving a sound both at a first microphone system in a first hearing aid device to provide a first-order gradient directional signal representative of the sound received and at a second microphone system in a second hearing aid device to provide a first-order gradient directional signal representative of the sound received;
summing the first-order gradient signals provided by the first microphone system and the second microphone system to provide a second-order gradient directional signal; and presenting the second-order gradient directional signal to a first receiver in the first hearing aid device and to a second receiver in the second hearing aid device.

24. The method of claim 23, further comprising adjusting a gain for at least one of the first-order gradient signals prior to summing the first order gradient signal.

25. The method of claim 23, further comprising adjusting a phase delay for at least one of the first-order gradient signals prior to summing the first-order gradient signal.

26. The method of claim 23, further comprising adjusting a gain and a phase delay for at least one of the first-order gradient signals prior to summing the first-order gradient signal.

27. The method of claim 23, further comprising, for a first directional mode of operation:
operating a first switch to prevent the first-order gradient signals from being summed;
presenting the first-order gradient signal provided by the first microphone system to the first receiver; and presenting the first-order gradient signal provided by the second microphone system to the second receiver.

28. The method of claim 27, further comprising, for a second directional mode of operation:
operating a second switch such that the first microphone system provides an omnidirectional signal representative of the sound received in the first hearing aid rather than the first-order gradient directional signal;
operating a third switch such that the second microphone system provides an omnidirectional signal representative of the sound received in the second hearing aid rather than the first-order gradient directional signal;
presenting the omnidirectional signal provided by the first microphone system to the first receiver, and presenting the omnidirectional signal provided by the second microphone system to the second receiver.

29. The method of claim 23, wherein summing the first-order gradient signals provided by the first microphone system and the second microphone system to provide a second-order gradient directional signal includes transmitting the first-order gradient signals between the first microphone system and the second microphone system through at least one conductor.

30. The method of claim 23, wherein summing the first-order gradient signals provided by the first microphone system and the second microphone system to provide a second-order gradient directional signal includes transmitting the first-order gradient signals between the first microphone system and the second microphone system through a wireless link.

31. The method of claim 30, wherein transmitting the first-order gradient signals between the first microphone system and the second microphone system through a wireless link includes transmitting the first-order gradient signals through a two-way wireless link.

32. The method of claim 30, wherein transmitting the first-order gradient signals between the first microphone system and the second microphone system through a wireless link includes transmitting the first-order gradient signals through a two one-way wireless links.

33. A method for aiding hearing for a user wearing a first hearing aid unit and a second hearing aid unit, comprising:

receiving a sound at a first microphone system in the first hearing aid unit and at a second microphone system in the second hearing aid unit;
for a first mode of operation, providing a first omnidirectional signal representative of the sound from the first microphone system to a first receiver in the first hearing aid unit and a second omnidirectional signal representative of the sound from the second microphone system to a second receiver in the second hearing aid unit;
for a second mode of operation, providing a first directional signal native of the sound from the first microphone system to the first receiver in the first hearing aid unit and a second directional signal representative of the sound from the second microphone system to the second receiver in the second hearing aid unit; and for a third mode of operation, summing the first directional signal from the first microphone system to the second directional signal from the second microphone system to form a second-order gradient directional signal representative of the sound, and diotically presenting the second-order gradient directional signal to the first receiver in the first hearing aid unit and to the second receiver in the second hearing aid unit.

34. The method of claim 33, further comprising operating a switch to select a mode of operation from the first, second and third modes of operation.

35. The method of claim 33, wherein operating a switch includes manually operating a switch.

36. The method of claim 33, wherein operating a switch includes magnetically operating a reed switch.

37. The method of claim 33, wherein operating a switch includes operating a programmable memory switch.

38. The method of claim 33, wherein summing the first directional signal from the first microphone system to the second directional signal from the second microphone system includes electrically connecting an output of the first microphone system to an output of the second microphone system.

39. The method of claim 38, wherein summing the first directional signal from the first microphone system to the second directional signal from the second microphone system further includes adjusting a gain and a phase delay for at least one of the first directional signal and the second directional signal.

40. The method of claim 33, wherein summing the first directional signal from the first microphone system to the second directional signal from the second microphone system includes transmitting the first directional signal from the first microphone system to the second receiver through a first wireless link and transmitting the second directional signal from the second microphone system to the first receiver through a second wireless link.

41. The method of claim 40, wherein summing the first directional signal from the first microphone system to the second directional signal from the second microphone system further includes adjusting a gain and a phase delay for at least one of the first directional signal and the second directional signal.