Dr.-Ing. Steven C. Marcrum Au. D., Regensburg
Video 13 
2018
“A clinical assessment of feedback reduction systems in open-fit hearing aids”
The primary purpose of this study was to update existing data on additional gain before feedback (AGBF) and maximum stable gain (MSG) in commercially available, open-fit hearing instruments. A secondary purpose was to evaluate ratings of sound quality with feedback reduction systems active.
AGBF and MSG were evaluated in six premium-level, commercially available hearing instruments. Subjective ratings of sound quality were obtained for each hearing aid in response to speech and music stimuli via subjective listening tests.
Twenty adults with normal hearing participated in gain measurement testing, while thirty adults with normal hearing provided ratings of sound quality with feedback reduction systems active. Mean AGBF for 2000 to 4000 Hz ranged from 5 to 16 dB across manufacturers.
Mean MSG in the same frequency region ranged from 25 to 35 dB across manufacturers. Statistical analysis revealed significant variability across hearing instrument manufacturers that was not attributable to the type of feedback reduction system used. Meaningful AGBF and MSG differences between participants within each given manufacturer were also identified. Finally, sound quality ratings were not related to the type of feedback reduction algorithm.