Letter to Dr. Sacks

This is a letter I sent to Dr. Oliver Sacks, celebrated neurologist, about the history of my hearing impairment. If you find this interesting and/or useful, you probably also want to read Talking With the Hearing-Impaired.

Note that there's an update from early 2016 at the bottom, explaining how getting a second implant has vastly improved things for me.

Date: Fri, 28 Nov 2008 17:22:06 -0800
From: Aahz <aahz@pobox.com>
Subject: Cochlear implant vs amusia
Dear Dr. Sacks,

First, before you read the rest of this letter, please send a quick response so I know you received it -- I don't need a reply to the rest, but I would like to know that you at least got it. (Spam filters kill so much e-mail these days.)

The rest of this letter contains more background and detail, but the summary is that I'm writing to you because Musicophilia, chapter 8, footnote 5 contains an error that I find personally upsetting. That is, while I do indeed suffer from cochlear implant-induced amusia, it is almost entirely a result of the limited frequency range (with a lower cutoff of 250Hz) rather than because of lack of resolution within the available range. And it is upsetting because Advanced Bionics has not made it possible to fix that problem, even though it is well within in their capability to do so.

This is far longer than it needs to be, but it's the first time I've written down my history, so it's partly for myself; based on what I've read of your writings, you seem to find extensive case histories interesting, so I don't feel that I'm wasting your time, but do feel free to skim as you wish.

Family lore claims that my hearing loss started at about a year old, as a result either of the infection that I had or the antibiotics (probably one of the -mycin class) used to treat it. What is known is that I lost my sense of balance and had to learn to walk all over again. (I never have regained a sense of balance; until I made a concerted effort in my teenage years, I couldn't even walk a straight line. I now have a fairly good purely visual/kinesthetic sense of balance.)

Shortly afterward, my parents noticed that I was having more trouble hearing, but the doctor would jingle keys, watch me turn my head, and say, "He's just ignoring you." When my parents finally took me to an audiologist (because they performed experiments proving to their satisfaction that I couldn't hear well), they learned that I had an unusual hearing loss that left much of my high-frequency hearing intact, which I credit with the fact that nobody can detect that I'm lifelong hearing-impaired from my diction.

I had a hearing aid in my right ear in kindergarten and in my left ear in second grade. I was entirely mainstreamed in school. My hearing continued to decline, but after I dropped out of college (for reasons at most tangentially related to my hearing), I was able to do phone-based technical support from the early 1990s through the mid-1990s.

In the late 1990s, after I had already stopped doing phone support, I discovered that my right ear was functionally deaf and I stopped using a hearing aid (getting useful amplification exceeded my pain threshold). August 2001 was when I discovered that although I still had useful hearing in my left ear, my pain threshold was dropping and I could wear a hearing aid at most a couple of hours per day without excruciating pain. Even now, I still wear an earplug in my left ear when I'm in any situation noisier than one-on-one conversation in a quiet room.

After doing some research, I decided to get an implant from Advanced Bionics.

I had my cochlear implant surgery at UCSF in 1/2002 and was activated four weeks later. Although I had been in many ways living as a functionally deaf person since August (including starting to learn sign language, something I had refused to do previously), I was still using my hearing aid as much as I could. With the cochlear implant, I finally stopped using my hearing aid, and I was astonished to learn from its absence just how much chronic pain I'd been living with for the past few years. Although I am overall not satisfied with the implant, I have to say that it did give me my life back.

With one-on-one conversations, I sometimes hear better than people with normal hearing, even in noisy environments. My lack of satisfaction with the implant comes from two specific complaints:

* The frequency range is limited, particularly at the lower end (stopping at 250Hz -- I'm missing almost half the piano!)

* It takes a good two or three seconds for me to "lock on" to a new speaker in a multi-person conversation (which means that three-person conversations are difficult at best, and anything more is nearly impossible unless people make a point of catering to me)

My suspicion is that the second issue is related to the first: I have done some testing with my hearing aid since getting the implant, and the hearing aid gives me a wider frequency range (especially at the lower end) and I don't have the problem locking on to multiple speakers. I think that the lower frequency sounds have some kind of vocal signature I use to identify speakers. But, of course, I cannot test this without the cooperation of Advanced Bionics.

At one point shortly after getting implanted, I went to a concert with a cello/violin/piano trio, and I could hear only overtones from the cello with my implant (I cross-checked against my hearing aid).

This is purely a software limitation. I know this because Advanced Bionics invited me to visit and be a guinea pig for an upgrade to the processor programming. I whined so much about the frequency limitation that they gave in and let me try a program that went down to 100Hz. But I only had it for about fifteen minutes, just long enough for me to go out to my car and test the expanded range on my crappy car stereo, just long enough for me to get confirmation that my lack of enjoyment of music really was largely due to the constricted frequency range. (I do still enjoy music, but not as much as I used to before getting implanted.)

My guinea pig visit was in September 2002. As of my last visit to an audiologist (May 2007), the software used to program the implant processor still did not permit any frequency range lower limit less than 250Hz.

I also have some other issues, such as the 25dB threshold (the processor does not transmit sounds quieter than 25dB), the need to constantly swap batteries (supposedly ameliorated to a full day with a newer processor, but I used to get almost a week of battery life when I had hearing aids), and the fact that the processor falls off too easily during vigorous physical activity. These issues aren't the ones that make me curse the implant, though.

On the other hand, I would say that aside from the frequency range limitation, having a cochlear implant has actually reduced my amusia a bit (and my partner agrees with me, at least in terms of my ability to correctly sing musical sounds that I hear). I think that it is primarily because the analog amplification of my hearing aids introduced more distortion than the digital pulsing from the implant. I also suspect that it's partly because my own voice now uses the same auditory pathway (that is, I now only hear my voice through the implant and not through internal resonance in my head going directly to the ear).

At this point, unlike Michael Chorost, I do not have enough time and energy to battle a company that doesn't care about helping me. Overall, despite my lack of satisfaction, I have a technology fix for my hearing that works well enough. I'm certainly not asking you to do anything, but if you felt like using your prestige to shame Advanced Bionics, I wouldn't complain.

I'm mainly writing to you to correct your error in declaring that cochlear implants cause amusia and to remind you (and anyone else who you happen to forward this to) that as far as I can tell, nobody really understands how cochlear implants work and that individual responses to implants vary widely.


Footnote 5) Someone with a cochlear implant, which is only capable of reproducing a limited range of tones, has, in effect, a technologically induced amusia, as Mrs. L has a neurologically based one. Cochlear implants replace the 3,500 inner hair cells of a normal ear with just 16 or 24 electrodes. While speech is understandable with such poor frequency resolution, music suffers. In 1995, with his cochlear implants, Michael Chorost compared his experience of music to "walking colorblind in an art museum." It is difficult to add more electrodes, because they short each other out if placed too close together in the wet environment of the body. However, software programming can be used to create virtual electrodes in between the physical ones, giving a 16-electrode implant the equivalent of 121 electrodes. With new software, Chorost reported that he went from being able to distinguish between tones 70 hertz apart -- equivalent to three or four semitones in the middle frequency range -- to tones 30 hertz apart. While this is still poorer than the resolution of a normal ear, it significantly improved his ability to enjoy music. Technological amusia can therefore be addressed by uniquely technological means. (See Chorost's fascinating memoir, Rebuilt: How Becoming Part Computer Made Me More Human, and an article he wrote for Wired, "My Bionic Quest for Bolero.")
Update 1/2016: I received a left-ear Nucleus implant from Cochlear Ltd. in 3/2014. It goes down to 63Hz, giving me two full octaves of additional hearing on the bottom. As a result, I've been able to continue my career as a square dance caller.

The reason I got the second implant was partly because of the frequency limitation but more because the pain threshold in my left ear had been dropping (i.e. I was wearing the earplug more often and getting less benefit from it). I hoped that similar to most people who have tinnitus, getting the implant would improve the pain situation. I got lucky: my pain went to nearly zero. As part of the process of ramping up to the second implant, I figured out that the pain was due to neurological leakage from my right ear. Go figure.

Also as of 1/2016, the 250Hz limit still exists in my right ear. In fact, my hearing is now worse because of some stupid decisions made by Advanced Bionics. I could fix those problems by reverting to an earlier version of the processor (I currently have a Naida Q70), but because the Nucleus gives me significantly better speech comprehension and because I get some other functional improvements from the Naida and because the old version of the processor is out of support, I'm stuck with it.


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