Preferred delay and phase-frequency response of open-canal hearing aids with music at low insertion gain

Abstract

Objective: Preferences between low delays and phase-frequency responses of behind-the-ear, open-canal hearing aids were investigated with acoustic conditions deemed sensitive to delay effects by normal-hearing listeners. Design: Hearing aids with the following selectable delay and phase response options were fitted at low insertion gain: (1) 1.4 ms delay, minimum phase; (2) 3.4 ms delay, minimum phase; and (3) 3.4 ms delay, linear phase. Blind paired comparisons were made between processing options and between each option and a muted hearing-aid output with two music stimuli. The three alternative forced choice responses were “Slightly prefer”, “Prefer”, or “Strongly prefer”. Study sample: Twelve hearing-impaired musicians. Results: At the 3.4-ms delay, the minimum-phase response was significantly preferred to the linear-phase response for one music sample and vice-versa for the other sample with a sign test (p < 0.04) but not a Wilcoxon signed rank test that accounted for the low preference strength. Preferences between all other processing conditions were not significant. Conclusions: In acoustic conditions sensitive to delay effects, delays of 1.4 or 3.4 ms were either not detected or no less preferable than no delayed aided signal. It is unclear whether different phase-frequency responses may be preferred with different music stimuli.

Key Words::

• Hearing aid
• open canal
• delay
• phase
• music

Acknowledgements

We wish to thank the many musicians who assisted in this study and Prof. Peter Blamey (The Bionics Institute) for his advice regarding the experimental design. This study was conducted under Project 08/831H approved by the Royal Victorian Eye and Ear Hospital Human Research and Ethics Committee. Parts of this paper were presented in a poster at The International Hearing Aid Research Conference, Lake Tahoe, California, USA, 11–15 August 2010.

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