The effects of frequency lowering on speech perception in noise with adult hearing-aid users

Abstract

Objective: Frequency lowering (FL) strategies move high frequency sound into a lower frequency range. This study determined if speech perception differences are observed between some of the different frequency lowering strategies that are available. Design: A cross-sectional, repeated-measures design was used to compare three hearing aids that used wide-dynamic range compression (WDRC) and either non-linear frequency compression (NFC), linear frequency transposition (LFT), or frequency translation (FT). The hearing aids were matched to prescriptive real ear targets for WDRC. The settings for each FL strategy were adjusted to provide audibility for a 6300 Hz filtered speech signal. Sentence recognition in noise, subjective measures of sound quality, and a modified version of the speech intelligibility index (SII) were measured. Study sample: Ten adults between the ages of 63 to 82 years with bilateral, high frequency hearing loss. Results: LFT and FT led to poorer sentence recognition compared to WDRC for most individuals. No difference in sentence recognition occurred with and without NFC. The quality questionnaire and SII showed few differences between conditions. Conclusion: Under similar fitting and testing conditions of this study, FL techniques may not provide speech understanding benefit in certain background noise situations.

Key Words:

• Frequency lowering
• hearing aids
• speech perception

Acknowledgements

Portions of this research was presented at the American Acoustical Society meeting in Scottsdale, Arizona, March 4–6, 2015, in a poster titled The effects of frequency lowering on speech perception in noise. Special thanks to C.J. Brodie, Kelley Trapp, and Erin Stewart for their assistance with data collection, and to Lauren Kawaguchi and Keito Omokawa for their assistance with data analysis. This research was supported in part by the National Institutes of Health (P20 GM109023 and P30 DC004661).

Declaration of interest

The authors report no conflicts of interest.