Hearing aid, especially of the in-the-ear type
US5033090A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 4, 1990 |
| Grant date | Jul 16, 1991 |
| Priority date | — |
| Expiry date | Sep 4, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04R2460/11
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a hearing aid with a microphone, an amplifier and a receiver supplying amplified sound to the user, a second signal path is provided comprising a second, feedback-suppressing microphone, placed at a location to receive feedback-causing sound from the receiver. The output of second provided microphone is suitably attenuated and delayed by an amount .DELTA.t corresponding to the effective acoustical distance a+b between the second microphone and the main microphone and supplied to a difference amplifier in opposition to the signal from the main microphone. Thus, the component of the signal from the main microphone likely to cause positive feedback or "howling" is substantially cancelled out. In another embodiment, the feedback-suppressing signal path is an acoustical path comprising a tube leading to a rear cavity in a microphone of the directional or differential type.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.