Dr. Ross on Hearing Loss
Listening to Music Through a Cochlear Implant: Part 2
by Mark Ross, Ph.D.
For the last few months, I’ve been giving myself a “musical auditory training program” by listening to various kinds of music for thirty to forty minutes a day. My musical selections have ranged from the classics to operatic arias, Chassidic music, country and folk, pop, Broadway musicals, etc. It’s been an enlightening, frustrating, disappointing, but occasionally rewarding experience. It’s important to note at the outset that my conclusions fully apply only to me. If there is one generalization that can be made regarding the outcome with a cochlear implant (CI), whether for speech or music, it is that individual variations are the rule and not the exception. Still, I hope that some of my personal experiences and insights may be applicable to other implant users.
At first, I directly connected the implant to a CD player using the supplied patch cord. While this worked very well, it did mean listening only with the implant and not utilizing the residual hearing in my contralateral ear. Although I have about a 95 dB hearing loss in that ear, it is still functional and it made no sense for me to ignore it. Indeed, the bimodal condition (CI plus HA) is being supported by more and more objective evidence as generally superior to the implant alone (at least in terms of speech perception). So now I listen to music using both ears in two ways. One method is to use my computer, which comes with excellent speakers that I locate some 18 inches from me. This stimulates both ears naturally. I have found several sites which provide me with a wide sample of musical genres and selections from which to choose. I listen in my home office, away from the noise and distractions in the house.
Using the other method, I switch the hearing aid and the implant to the telecoil position, plug a neckloop into the output of the CD player, and listen with both ears using inductive coupling. Initially, I found that I had to situate the neckloop on top of my ears rather than around my neck, in order to increase the strength of the inductive connection. More recently, I have switched to using a pair of silhouette inductors which I place behind my ears. These are more convenient to use and provide both the HA and the CI with excellent inductive coupling to the CD player.
When listening, I explicitly focus my attention on the auditory sensations I am experiencing. Attention is a way of increasing the readiness of the central nervous system to receive and benefit from the auditory stimuli it is receiving. My goal is to recapture at least some of the pleasure I used to experience in listening to music. This requires that I focus on the signal that I’m listening to, trying to separate the various acoustical elements as well as to identify and experience the melodic themes. Every once in a while, however, I do stop myself when I’m listening to a piece that I can still enjoy, and shift my mind from a training mode and back to the simple pleasure of listening to music. Which, really, is the whole point of this exercise.
I have found that my auditory memory plays a crucial role in my training program. There have been a number of reports that have noted the contribution of memory to melody recognition and enjoyment; however, I do not think that this aspect has been sufficiently stressed. As I listen to the music, I find that I constantly engage my auditory memory in the listening process. I keep trying to discern a familiar pattern, one that I can then relate to my vivid memory of the same melody. In other words, the acoustic sensations, how they vary and change in time, are constantly being compared to my recollections of how they sounded in my pre-implant days. Without these stored memories, I would not be hearing a melody at all, only a cacophony of unrelated sound sequences. It seems that the stored memories of some musical selections serve as a kind of template to which the incoming sounds are compared. My ability to enjoy music depends, then, not only on what comes through the implant, but also on what my memory contributes to the listening experience.
After many hours of listening, I feel comfortable with some general conclusions. One of the primary ones is that any piece that I didn’t know or recognize before I got the implant, I find that I still don’t recognize or enjoy. I can easily follow the beat and rhythm of the selection; I feel that I can distinguish the unique timbre of many of the various instruments; I often understand most of the lyrics, perhaps even more than I did pre-implant; I can hear distinct pitches and pitch changes (the prerequisite for melody recognition); but even so, for an unfamiliar selection, I am unable to create a melodic experience out of all these auditory sensations. I’ve tried and tried, but any selection I didn’t already know - and this includes all the musical genres that I’ve listened to - still sounds rather flat and basically atonal. At this point, therefore, I do not think further efforts with this category to be a good use of my listening time, though I may continue to sample such selections (even if inadvertently, at social events, etc.).
Then there are a number of selections that I did know in the past, but didn’t particularly like. In listening to these, I usually find that I still don’t like them even though I can recognize the melody. So that leads to my second conclusion: If I didn’t like a selection pre-implant, it is unlikely that I’ll like it now. This shouldn’t be surprising. My musical tastes haven’t changed just because I now use a cochlear implant, and there is no reason to think that they will. My reactions reflect the fact that I’m an adult with a mature neurological system and formed listening preferences (unlike a child whose system is more readily modified by new sensations and experiences). So spending time listening to these selections also does not seem to be a good use of my listening time.
While omitting unfamiliar musical selections and those I disliked from my training activity would appear to be quite a limiting condition, I haven’t found it so. I find that I still have a large repertoire of music fixed in my auditory memory that I can draw on, music that I liked in the past that I can now listen to and enjoy. This includes original recordings made in the l920s and l930s (“ragtime” piano included), operatic arias, many classical pieces, country and western music, and many pop singers from the 1930s through the l960s. In terms of modern tastes, however, I am probably a musical Neanderthal in that even when I was able to hear and enjoy music via my hearing aids, I rarely listened to any music composed after the 1970s; it simply never “spoke” to me. So my musical auditory memory encompasses a much earlier period than a younger implant user would have (or, perhaps, some older person more tolerant of modern “sounds” than I am!).
Still, whatever a person’s musical background and preferences, the task is the same: The implant user must determine if listening to music, in any genre selected, is or can be made pleasurable. For example, the fact that an implant user can usually still perceive beat and rhythm fairly normally will make rap music more accessible than another genre that depends more on the melodic component, particularly since the lyrics may now be more easily understood. People who have enjoyed and can relate to this musical genre before receiving an implant should still be able to find pleasure in listening to it. And this is exactly the way it should be since, as has already been pointed out, music appreciation entails very personal preferences.
Because I wasn’t able to discern a melody in any unfamiliar musical piece, I wondered if I possessed the necessary prerequisites for melody perception (the sensory capacity to discern pitch changes moving up and down a musical scale). So with the assistance of my very patient implant audiologist, we tested my ability to discriminate between various notes on a piano. I could reliably discriminate one note differences of all the piano keys at the midpoint on the keyboard, but did much poorer at the very low and very high pitches. Additionally, I was able to perceive a pitch sensation when each of my 22 electrodes was stimulated. Still, while I think I did quite well on these measures, it evidently was not good enough for me to hear or appreciate an unfamiliar melody. Something else, some other sensory capacity, must still be lacking. We also tried changing the stimulation rate of the processor and using a number of slightly different maps. None of these proved to be any better than the one I was already using.
So after four months, what kind observations and conclusions can I make regarding my “musical auditory training” program? In brief, I would say the results have been mixed. I have found that listening to many of the songs (but only the ones I already knew and liked) seems more pleasurable. It is also clear that I am adopting a lower standard of normalcy. I find myself overlooking some atonal passages, something I would not have tolerated years ago. I haven’t noticed any clear preference for any of the genres that I’ve listened to. In all of them, there are pieces that sound “not bad,” some few that actually sound “pretty good,” and many that seem to be simply tolerable. For some pop music, I find that if I sing along, it sounds much better. It is as if I’m blending what I hear and what I produce. However, I’m rarely sure than I’m on key with my own singing – I don’t really trust my self-monitoring - but my wife assures me that I usually am.
What seems to come through best in any of the genres is when there is a clear differentiation between some desired signal (vocals, a few instruments, etc.) and the background sounds or accompaniment (a positive signal-to-noise ratio). It is when there is too much sound, like a full orchestra, with or without vocals, that everything sounds dense and when the sound elements tend to blend together. This applies to choral music as well; it is the soloists that I most enjoy. Apparently, besides auditory memory, much depends upon the interaction of the acoustics of the input sound and the processor. For example, I’ve noticed that my appreciation of the same song sung by two different vocalists can vary significantly; I may enjoy one but not the other. The role of auditory memory still seems dominant, however: Even if I usually like a singer, if he or she is singing an unfamiliar song, I still don’t get it.
It seems to me that I’ve come close to what kind of music appreciation can be realized with a cochlear implant, at least for me. Even at its best, when I can recognize and enjoy listening to some piece, it is clear that some “flavor” of the music is missing. It is hard to define, but music simply does not move me the way it did before. A musical piece is a complex acoustic event, different from speech, and the current generation of implants is not designed to transmit a full-bodied musical signal. I understand that music appreciation is now a research priority for manufacturers and basic researchers; among the abstracts of papers delivered at a recent CI convention, there were a number that dealt with enhancing music appreciation. What’s clear to me is that we need changes in processing strategies, some that are explicitly devoted to music perception. The challenge, of course, is to determine exactly what these changes should be. I do believe that we will be seeing progress on this front in the not-too-distant future – hopefully soon enough so that I personally can take advantage of them.