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A technical comparison of digital frequency-lowering algorithms available in two current hearing aids
1The Bionic Ear Institute and The Department of Otolaryngology, The University of Melbourne, Victoria, Australia. hmcdermott@bionicear.org
Plos One
|July 27, 2011
Summary
Two new hearing aid frequency-lowering schemes improve audibility of high-frequency sounds but also distort signals. Different fitting approaches are needed for Widex Audibility Extender and Phonak SoundRecover to suit individual hearing loss.
Area of Science:
- Audiology
- Acoustics
- Signal Processing
Background:
- Two distinct frequency-lowering techniques, Widex Audibility Extender (linear transposition) and Phonak SoundRecover (nonlinear compression), were introduced for high-frequency hearing impairments.
- Both techniques aim to compensate for perceptual effects of high-frequency hearing loss and have shown perceptual benefits in studies.
- Detailed technical descriptions and comparisons of the signal modifications by these schemes were lacking.
Purpose of the Study:
- To technically analyze and compare the performance of Widex Audibility Extender and Phonak SoundRecover frequency-lowering schemes.
- To evaluate the modifications these hearing aid technologies apply to sound signals.
Main Methods:
- Measured hearing aid outputs with frequency-lowering functions enabled and disabled.
- Utilized input signals including sinusoids, flute sounds, and speech material.
- Performed spectral analyses on the output signals from each hearing aid condition.
Main Results:
- Both Widex Audibility Extender and Phonak SoundRecover effectively lowered high-frequency acoustic signals.
- Both frequency-lowering techniques introduced some distortion to the processed signals.
- Significant differences in perceptual effects are expected from each scheme despite similar audiometric fitting.
Conclusions:
- Frequency-lowering schemes can improve audibility of high-frequency sounds in hearing aids.
- The distinct processing methods of Widex Audibility Extender and Phonak SoundRecover lead to different perceptual outcomes.
- Appropriate selection and fitting of these advanced hearing aid schemes are crucial for individual listener needs and preferences.
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