Ear defenders employing active noise control
US5600729A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 22, 1995 |
| Grant date | Feb 4, 1997 |
| Priority date | — |
| Expiry date | Aug 22, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG10K2210/506
- WIPO fieldOther consumer goods
- WIPO sectorOther fields
Abstract
An ear defender having one or more microphones (1) for detecting the sound level in the proximity of the wearer's ear, one or more speakers (4) for generating a noise reduction signal within the earshell, and a digital feedback controller (W) for generating a feedback signal derived from the output of the microphones and for applying said feedback signal to the speaker inputs, and estimation means (F') for providing an estimation of the earshell transfer function and subtracting from the input to the feedback controller a signal representing the estimated electroacoustic transfer function of the system. The operation of the digital feedback controller may be controllable by the output of a computational circuit (C) operable on the difference between the microphone output and the feedback controller input modified by a model (F") of the electroacoustic transfer function. A second, analogue or digital, feedback controller (W') may be included to provide an approximate feedback signal to the speakers and to improve the impulse response of the system.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.