NLFC compared to CP in patients with and without cochlear dead regions
Research type
Research Study
Full title
A comparison of conventional hearing aid processing (CP) and non-linear frequency compression (NLFC) processing in adult patients with and without cochlear dead regions who have a moderate to severe sensorineural hearing loss.
IRAS ID
264352
Contact name
Kerri Millward
Contact email
Sponsor organisation
Manchester University NHS Foundation Trust
Duration of Study in the UK
0 years, 4 months, 6 days
Research summary
We are interested in an additional hearing aid feature called non-linear frequency compression (NLFC). This aims to improve audibility of high frequency sounds by converting them into lower frequencies and has been shown to benefit those with moderate-severe sensorineural hearing loss (SNHL). Cochlear dead regions (DRs) are areas of the inner hearing organ (the cochlea) where there is little or no function and are commonly found in regions responsible for detecting high pitched (frequency) sounds.
Not all people with hearing loss have DRs. We would like to investigate whether based on the presence or absence of DRs, patients with moderate-severe SNHL perform better or prefer their hearing aids programmed conventionally, or with NLFC activated. To do this, two participant groups will be created based on findings from the threshold equalising noise (TEN) test which identifies cochlear DRs. Two participant groups will be created; one group with DRs and one group without DRs.
All participants will receive two hearing aids and will wear these programmed conventionally for ~six weeks and with NLFC activated for ~six weeks in a counterbalanced manner. Following each condition, participants will complete a questionnaire and various speech tests will be performed. This involves participants repeating sentences, words or speech sounds they hear from a speaker in quiet and in the presence of background noise. Individuals’ scores will be calculated for each test and their performance when NLFC was activated and deactivated will be compared. This will be analysed alongside the questionnaire data to compare the ‘DR’ and ‘no DR’ group in both conditions. Findings may help to determine whether NLFC should be activated for all moderate-severe SNHL patients, or just those with DRs, helping clinicians to optimise hearing aid settings for patients.
Summary of Results:
What we wanted to know:
Do patients perform best when their hearing aids are set up in the traditional way (with conventional processing), or when an additional hearing aid feature called frequency compression is activated on their hearing aids?
Does patient’s performance with conventional processing and frequency compression differ depending on whether the cochlea (the inner hearing organ) has non-functional ‘dead regions?
Which settings do patients prefer?Cochlear dead regions
No participants tested positive for cochlear dead regions. This was likely due to the hearing levels of the participants recruited, who had moderate thresholds on average.Sentences in noise
At a group level, participants correctly identified more words correctly when frequency compression was activated, than when conventional hearing aid processing was used. This difference was not statistically significant.Words in quiet
At a group level, participants achieved a higher score when frequency compression was activated, compared to conventional hearing aid processing. This difference was not statistically significant.Sound discrimination
With conventional processing, no participants were able to identify the ‘V’/ ‘Z’ contrast. When frequency compression was activated, 7 out of 8 participants were able to consistently discriminate between these two speech sounds. This improvement was significant.Questionnaire
At a group level, participants rated the sound quality better when conventional hearing aid processing was used, compared to frequency compression.Final Choice
Half of all participants chose to keep their hearing aids with conventional processing and half chose to have frequency compression set as their main programme.Summary
Whilst frequency compression has shown to assist with the identification of high-frequency speech sounds, the differences were not statistically significant. Although the questionnaire results showed a preference towards conventional processing, participant’s final choice of programming was split equally.
Results show that for some patients, activating frequency compression may be beneficial. The findings have helped to consider the best method of how to programme frequency compression and confirmed that a patient-by patient, individualised approach is needed.REC name
West of Scotland REC 4
REC reference
19/WS/0162
Date of REC Opinion
1 Nov 2019
REC opinion
Further Information Favourable Opinion