Hearing aid music-listening programs and sound quality: A recent research project at the University of Tennessee

In my last post, I discussed the conversations that I had with the journalist Gary Parks about music and hearing loss. Just after writing this post, I received a copy of a poster about music and hearing aids that was presented at the Association for Research in Otolaryngology (ARO) meeting in Baltimore Maryland U.S.A. in February 2019. This work was conducted at the University of Tennessee in Knoxville by Patti Johnstone, Ph.D., Associate Professor and Director of Clinical Education in Audiology, along with her colleagues in engineering and music. One of the authors was Marshall Chasin, AuD whom I have personally collaborated with over the last 10 years. He was the one who passed this poster on to me.

The goal of this investigation was to determine, using blinded listening tests, if child and adult musicians:

1. prefer live music recordings of individual musical instruments with a dedicated music program (DMP) activated or deactivated;
2. prefer one signal processing scheme over another when listening to recordings of live musical instruments;
3. can correctly identify a musical instrument when listening to recordings of live music.

The authors used live music recordings of musical instruments recorded through 5 different hearing aids. The musical instruments were the bassoon, cello, marimba, trumpet, tuba, xylophone, and violin. The live music recordings included a C major scale and a short musical excerpt. The hearing aids were all programmed using NAL NL2 for a 50dB HL flat hearing loss. The DMP was activated and deactivated in each hearing aid. The hearing aids used in this study included a Bernafon ChannelFree^™ instrument.

There were 60 normal hearing subjects – all musicians – who participated in the experiment, 30 children and 30 adults. The subjects listened to the recordings via headphones that were randomly presented using a custom MATLAB interface. The subjects were blind as to the make of the hearing aid, if the DMP was activated or not, and which musical instrument they were listening to.

One of the most interesting results of this study, especially for me, was that the Bernafon Juna ChannelFree^™ hearing aid was ranked significantly higher than the other hearing aids when the musical instrument had a bass fundamental frequency or more bass harmonics (e.g., a tuba) regardless of whether the DMP was activated or not.

The authors discussed several interesting conclusions. The first three are listed below:

1. child and adult musicians with normal hearing prefer music recorded through a hearing instrument with the DMP activated;
2. compression systems like Bernafon’s ChannelFree^™ may enhance the perception of music for instruments with a bass fundamental frequency and harmonics;
3. music fidelity, richness, circuit noise, and pitch distortion are factors that may affect a musician’s willingness to use a hearing aid.

This multidisciplinary study is impressive given the number of subjects who are musicians - 60 subjects - and the number of stimuli - 126. The authors also made the effort to record the musical instruments live rather than use commercially available sound samples. This work adds to our knowledge about how music is perceived by musicians and potentially hearing aid users via hearing aids and gives some further insight into how future devices should be designed. It was also very interesting to me that both adults and children were included in this study.

Music is an important part of many individual’s lives, regardless of age, whether they are musicians or music lovers. It is therefore a good idea to find out about an individual hearing-impaired person’s experience with music and then encourage them to use their music program whenever they play or listen to music. It is always interesting to hear what they think and learn from their experiences.

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