Adult hearing-aid users with cochlear dead regions restricted to high frequencies: Implications for amplification

Abstract

Objectives: Cochlear dead regions (DR) are common in adult hearing-aid users, but are usually restricted to high frequencies. The aim was to determine the benefit of high-frequency amplification for ears with and without high-frequency DRs. Design: Participants were fitted with the study hearing aid and tested under four conditions: unfiltered (NAL-NL2 prescription), and low-pass filtered at 1.5, 2, and 3 kHz. VCV stimuli were presented at 65 dB (A) in quiet and in 20-talker babble at a signal-to-babble ratio of 0 dB. Study sample: Experienced adult hearing-aid users: one group of 18 with a DR edge frequency above 1.5 kHz, and a group of 18 matched controls. Results: Overall performance was best in the unfiltered condition. There was no significant difference in mean performance between the two groups when tested in quiet. However, the DR group obtained less benefit from high-frequency amplification when tested in babble: the mean difference between the unfiltered and 3-kHz filtered condition was 6% and 13% for the DR group and controls, respectively. Conclusions: In adults with a moderate hearing loss and a restricted DR, speech recognition was always best in the unfiltered condition, although mean performance in babble was lower for the DR group.

Key Words:

• Adults
• cochlear dead regions
• speech recognition
• hearing aids
• benefit

Acknowledgements

This paper presents independent research funded by the National Institute for Health Research (NIHR) under its Research for Patient Benefit (RfPB) programme (Grant reference number PB-PG-0408-15055). The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR, or the Department of Health. This research was facilitated by the Manchester Biomedical Research Centre. The authors would like to thank Professor B.C.J. Moore and one anonymous reviewer for helpful comments on earlier versions of this manuscript.

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