Evaluation of the effects of nonlinear frequency compression on speech recognition and sound quality for adults with mild to moderate hearing loss

Abstract

Objective: While potentially improving audibility for listeners with considerable high frequency hearing loss, the effects of implementing nonlinear frequency compression (NFC) for listeners with moderate high frequency hearing loss are unclear. The purpose of this study was to investigate the effects of activating NFC for listeners who are not traditionally considered candidates for this technology. Design: Participants wore study hearing aids with NFC activated for a 3–4 week trial period. After the trial period, they were tested with NFC and with conventional processing on measures of consonant discrimination threshold in quiet, consonant recognition in quiet, sentence recognition in noise, and acceptableness of sound quality of speech and music. Study sample: Seventeen adult listeners with symmetrical, mild to moderate sensorineural hearing loss participated. Better ear, high frequency pure-tone averages (4, 6, and 8 kHz) were 60 dB HL or better. Results: Activating NFC resulted in lower (better) thresholds for discrimination of /s/, whose spectral center was 9 kHz. There were no other significant effects of NFC compared to conventional processing. Conclusion: These data suggest that the benefits, and detriments, of activating NFC may be limited for this population.

Key Words::

• Nonlinear frequency compression
• sound quality
• sentence recognition
• consonant recognition

Acknowledgements

Portions of this project were completed as a degree requirement for the second author. The authors would like to thank Jodi Rokuson, Jeremy Federman, and Elizabeth Harland for their assistance with participant recruitment and data collection. In addition, the authors would like to thank Michael Boretzki, Christine Jones, and Myriel Nyffeler for their insights and expertise during the development stages of this project. This project was funded by Phonak AG and the Dan Maddox Hearing Foundation.

Declaration of interest: The authors report no conflicts of interest.