An electroacoustic transducer, primarily in the form of a capacitive microphone, for incorporation into a semiconductor substrate. The vibrating element comprises a largely nontensioned diaphragm, such as an epitaxial layer formed on the semiconductor substrate, so as to greatly reduce its mechanical...http://www.google.com.au/patents/US4533795?utm_source=gb-gplus-sharePatent US4533795 - Integrated electroacoustic transducer
