April 2020 The Hearing Journal
Cochlear implants (CIs) have helped many people with hearing loss regain their ability to understand speech. Unfortunately, the same cannot be said for music appreciation, which holds the key to not only higher quality of life but also better speech understanding for CI users.
One reason for this deficiency is that music perception poses auditory challenges that can exceed those of language perception during CI-mediated listening. While CIs capture rhythm—one of the acoustic features of music—reasonably well, significant work remains to improve the two other critically important aspects of music perception: pitch and timbre. Researchers who tested the recognition of 12 familiar melodies in CI users with and without rhythmic cues found that the average performance was 58 percent correct when rhythmic cues were preserved but only 29 percent correct when those cues were removed. Rhythm, however, is far from enough for music appreciation, the importance of which is underpinned by the fact that CI users rank music as the second most important acoustic stimulus in their lives next to understanding speech. Music appreciation is closely tied to quality of life for those with CIs, said Raymond Goldsworthy, PhD, an associate professor of research otolaryngology-head and neck surgery at the Keck School of Medicine of the University of Southern California who is a CI user himself. “We have to be able to improve music appreciation for cochlear implant users because to do so, we can impact their quality of life across a number of important domains, including how well they feel about their social interactions and their ability to do different kinds of community engagement and community enrichment,” he said.
Music appreciation is also crucial to CI users because improving music perception in implant recipients has been shown to confer benefit on other practical tasks such as speech recognition in quiet and in noise. More specifically, a study has offered strong preliminary support for the idea that better perception of voice pitch can aid in separating voices in a background of other talkers and help CI users hear better in a multitalker environment. Characterising that relationship between music and pitch perception and speech recognition is one of Goldsworthy's goals for his five-year study on music appreciation after cochlear implantation, which is funded by a $2 million grant from the National Institutes of Health. “One of the things that I found is that implant users who have better pitch perception tend to do better in noisy situations,” he said. “I really want to strengthen the evidence and to clearly show just how true that is, how important it is that implant users with good pitch perception will affect their speech recognition outcomes.”
Goldsworthy's research examines everything from basic psychophysics in changing the signal processing in CIs to the psychology of hearing loss. “There have been a number of studies that looked at the psychology of hearing loss and how that has affected music appreciation, and then there have been the focused studies that really looked at signal processing and trying to show that certain signal processing elements can improve outcomes for implant users,” he said. “But we are really taking a comprehensive approach, and we are trying to look across all of those to the very basic building blocks of signal processing, how we can improve speech perception for CI users, all the way up to the higher psychological and sociological factors that are affecting how much they are simply enjoying music.”
First and foremost, what Goldsworthy hopes audiologists will take away from his research is the understanding that it's important to recommend music listening to CI users. “I remember back when I got an implant, and that was a long time ago, that was 30 years ago, there was this idea that cochlear implant users can't enjoy music or that music appreciation would be poor,” he said. “And that's a horrible thing to say; that's kind of a self-fulfilling prophecy. And I think that's the most important thing that would come out is to solidify this idea, which is certainly gaining momentum over the past 10, 15 years, that music listening is good for the cochlear implant users to do as a way of rediscovering how things sound and it's really good for helping to train them on their new way of hearing.”
Goldsworthy, who lost his hearing at age 13 after contracting spinal meningitis, has always been naturally motivated to understand CIs and improve music appreciation for CI users. More recently, what has really motivated him to focus on music appreciation itself is the realisation that it is about a lot more than signal processing, he said. “We can talk about how well a hearing aid or cochlear implant works, and they work really well,” said Goldsworthy. “But even though they work really well, they are different. With any kind of hearing loss or restoration, there's some kind of difference in the way that we hear. Understanding that can help some people reconcile how music sounds to them now with how it used to sound, so I want to make a focused effort in trying to help people appreciate music more with whatever level of hearing that they have.”