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Room reverberation effects in hearing aid feedback cancellation
1AudioLogic, A Cirrus Logic Company, Boulder, Colorado 80301, USA. jkates@audiologic.cirrus.com
The Journal of the Acoustical Society of America
|February 24, 2001
Summary
Room reverberation significantly impacts hearing aid feedback cancellation. Adapting filters struggle with acoustic variations, limiting maximum stable gain and headroom increase in real-world environments.
Area of Science:
- Acoustics
- Hearing Aid Technology
Background:
- Room reverberation affects hearing aid feedback cancellation.
- The strength of these effects depends on acoustic conditions.
Purpose of the Study:
- Investigate the impact of room reverberation on hearing aid feedback cancellation.
- Evaluate the effectiveness of adaptive feedback cancellation filters in varying acoustic environments.
Main Methods:
- Used a behind-the-ear (BTE) hearing aid on a dummy head with an open fitting.
- Measured hearing aid impulse responses at multiple locations in an office.
- Adapted feedback cancellation filters to measured feedback paths and estimated maximum stable gain.
Main Results:
- A low-order ARMA model with an adaptive FIR filter effectively modeled the feedback path excluding reverberation.
- Increasing adaptive filter length provided minimal improvement due to inability to model reverberation.
- Mismatch between modeled and actual feedback paths limited headroom increase, varying by location.
Conclusions:
- Room reverberation poses a challenge for hearing aid feedback cancellation systems.
- Adaptive filters have limitations in modeling complex acoustic environments, impacting performance.
- Location-dependent acoustic variations restrict the achievable benefits of feedback cancellation technology.
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