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Acoustic feedback margin improvements in hearing instruments using a prototype DFS (digital feedback suppression)
1Technical-Audiological Department, Fredericiaskolen, School for Deaf and Profoundly Hard-of-Hearing Children, Fredericia, Denmark.
Scandinavian Audiology
|January 1, 1991
Summary
A digital feedback suppression (DFS) system significantly improves hearing instrument performance. The DFS system enhanced acoustic feedback margins by up to 16.3 dB in behind-the-ear and in-the-ear hearing instruments.
Area of Science:
- Audiology
- Acoustics
- Biomedical Engineering
Background:
- Acoustic feedback is a common problem in hearing instruments.
- Digital feedback suppression (DFS) systems aim to mitigate feedback.
- Understanding the efficacy of DFS systems is crucial for hearing aid development.
Purpose of the Study:
- To investigate the properties of a prototype digital feedback suppression (DFS) system.
- To quantify the improvements in acoustic feedback margin provided by the DFS system.
- To assess the impact of the DFS system on sound quality.
Main Methods:
- Complex loop gain measurements were performed in an anechoic room.
- The study involved 21 ears with behind-the-ear (BTE) hearing instruments and 4 ears with in-the-ear (ITE) hearing instruments.
- Measurements were taken under normal and 180-degree phase shift conditions.
Main Results:
- For BTE instruments, median improvements in acoustic feedback margin were 13.1 dB and 10.0 dB.
- For ITE instruments, improvements ranged from 9.8 to 16.1 dB (normal) and 13.7 to 16.3 dB (180-degree phase shift).
- The DFS system significantly reduced amplitude distortion caused by external feedback signals.
Conclusions:
- The prototype DFS system effectively increases the acoustic feedback margin for both BTE and ITE hearing instruments.
- DFS technology offers substantial improvements in hearing instrument performance.
- The system also enhances sound quality by minimizing amplitude distortion.