“Frequency compression hearing aids; benefit, acclimatization, and candidature”

Contact Name: Dr Kathryn Hopkins

Contact Email: kathryn.hopkins-2@manchester.ac.uk

Dr Kathryn Hopkins graduated from the University of Cambridge with a BA in Natural Sciences (specialising in Physiology) in 2005. She stayed in Cambridge to complete her PhD and one-year post-doctoral project  with Prof. Brian Moore on the subject of temporal processing deficits in hearing-impaired listeners. In April 2010 she was appointed as a Lecturer in Audiology at the University of Manchester. Her research focuses on understanding the mechanisms underlying hearing difficulties due to aging and noise exposure.

Frequency compression hearing aids are now commonly fitted in the NHS. However, most previous research studies demonstrating their effectiveness used different fitting procedures to those typically used in the clinic, where clinicians do not usually alter the frequency compression parameters from those recommended by the manufacturer. We examined the possible benefits of frequency compression when used with the manufacturers recommended parameters for adults with mild-severe hearing loss.  We also investigated whether benefit from frequency compression was related to the duration of frequency compression use, as might be expected if a long acclimatization period is necessary to gain full benefit.

Fifty-two adults were tested. All were fitted with Phonak frequency compression  hearing aids as part of their standard clinical care and had been using frequency compression for between two weeks and two years at the time of testing. Speech recognition thresholds in noise and consonant recognition in quiet were measured with and without frequency compression enabled.  Overall, consonant recognition was significantly better with frequency compression enabled, although the effect was small (three percentage points).  There was no significant difference in speech reception thresholds with frequency compression enabled or disabled.

There was no significant correlation between duration of frequency compression experience and benefit from frequency compression for either outcome measure, suggesting that a long period of acclimatisation is not necessary to gain the full benefits from frequency compression.  Frequency compression benefit was correlated with mean audiometric threshold at 2 and 3 kHz, with more benefit for individuals with better thresholds at these frequencies. Analysis of high frequency speech audibility suggested that for participants with a substantial hearing loss at 2 and 3 kHz, high frequency speech information was inaudible irrespective of whether frequency compression was enabled; this might explain the correlation between benefit and audiometric thresholds at these frequencies.

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