System consisting of a microphone and a preamplifier
US6914992B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jul 1, 1999 |
| Grant date | Jul 5, 2005 |
| Priority date | — |
| Expiry date | Jul 1, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R25/604
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A system, more particularly a hearing aid, consisting of a microphone and a preamplifier, wherein the microphone comprises a housing having therein an opening to the surroundings, a diaphragm and a backplate, while the amplifier is coupled to the system consisting of the diaphragm and the backplate and has a field effect transistor as input element. In the housing, in a space which is bounded by, on the one hand, the diaphragm and, on the other, the housing wall, and which does not comprise the opening to the surroundings, a pressure equalization opening is present, which has a diameter such that in the audible audiospectrum it does not make an essential contribution to the suppression of low frequencies. In the input stage of the amplifier, at the output of the field effect transistor, a low-pass filter or a high-pass filter or a combination thereof is arranged. Through this measure, the frequency characteristic can be optimally influenced to suppress noise.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.