Michael Seufer’s Web Site

Michael Seufer was one of the original Acclaim trial patients. He has an excellent description of his progress well worth reading. This post is a response to a question I received from a reader and I though it would be more useful to make a complete post on the issue.

 I have seen Michael Seufer’s website and have read about his experience with the implant. His story is quite remarkable in that the time it took for him to adapt to the implant was very quick – which I imagine is atypical. He states in his story:

“The first individual words began surfacing within thirty minutes of leaving the parking garage. Four hours later, by the time Michael was somewhere in Iowa, every word he spoke or sang was crystal clear. Four days later, back home in Columbus, all distortion was gone. Voices, music, environmental sound, all natural. The hearing aid stayed in a drawer.”

Do you think “natural” in this case is relative?

Before I signed up for the Acclaim clinical trial I had alrady had the opportunity to research implants for 6 or 7 years. Most of that time was spent looking at the Advanced Bionics device as we lived near their headquarters in Santa Clarita, CA at the time. We went to some presentations, read their literature and talked to a few of their patients.

Some patients were very happy with the results, some said that music sounded so bad they never wanted to listen to music again. Everyone emphasised how important it is to retrain your brain with comprehension / word recognition exercises.

I don’t think I can comment on what Michael considers “natural” but for me, my implant does not sound “natural”. It does sound more “natural” than when it was first turned on but I think there are too many technological limitations for a cochlear implant to sound truly natural. Below are some of the reasons I believe an implant, on its own, cannot sound natural

Technology

From a technological standpoint, the cochlear implant has significant disadvantages to natural hearing which include, among others

• A pressure sensitive device, like the ear drum, that is nowhere near as flexible and responsive as an eardrum
• Software that is, compared to natural hearing, quite limited in its ability to turn the mechanical movement into an electrical impulse – all you have to do is listen to music recorded with the most expensive studio microphones to know this, and the above, to be true
• A cochlear implant replaces thousands of stereocilia with somewhere between 19 and 32 electrodes (probes)
• The ear is designed to receive sound waves with the higher frequencies received at the wider / outer part of the cochlear and the bass sound closer to the inside of the cochlear.

From the point of view of the placement of the electrodes / probes, the surgeon has a limited ability to place the electrodes where he wants them, compared to the natural cilia. Between the reduction in number of sound receptors / translators in the ear and the limits on where they are placed, there is a significant loss in the ability to replicate the root frequencies your brain has already spent 1, 10, or 50 years learning to recognize.

Then add the loss of harmonics. Everything you hear, from a note on a piano, to the sound produced by a bird, or a hammer on a nail, has a ‘root’, or ‘base’ / primary frequency. Take the note ‘A’ on a concert tuned piano, it vibrates at 440 cycles per second. At least, that’s the primary frequency produced by the string. However, that isn’t the only frequency the string produces. It also produces sound waves that are multiples and divisions of that value, plus some, at lower volumes, that are not multiples. These other sounds are referred to as harmonics (they play at the same time).

So the ‘A’ note you hear on the piano, with natural hearing, is not just a sound wave pulsing at 440hz. It has a lot of additional frequencies which provide the “tone” of the note (piano in this case), or the “natural” sound of the piano. Now, listen to that tone without any harmonics and it’s pretty bland and “unnatural” sounding.

So, now that you have an implant with no natural hearing left in the implant ear, the implant cannot produce all those harmonics to your brain so there is no way it’s going to sound “natural”. A lot is going to depend on how the implant is programmed, but it is also going to be limited to how well placed the electrodes are, how well / accurately they convert the 440hz sound wave to electrical energy and what your brain now does with this signal that has no harmonics.

This is different for someone who still has some natural hearing left in the implanted ear, or whose other ear can provide a lot of that harmonic information to your brain. Your brain combines the information from each ear into a “whole” sound field. That’s why when you are talking to one individual standing to your left, you hear them speaking as a single voice with little reverberation or echo, even though your left ear is receiving the sound sooner than your right, and your brain is turning the delay information into localization (the sound is coming from the left).

In addition, one has to consider that the electronics typically don’t provide any sound below 200hz – 250hz. Think about the lower octaves on the piano, or a bass guitar, or perhaps a drum. I play bass guitar in a worship team. If I remove my left hearing aid and plug my left ear, I cannot hear any notes from the bass at all because the implant is not translating the sound waves into electrical energy at all, never mind “that my brain can understand”. So my brain is not receiving any representation of those notes, or frequencies, because the implant isn’t reproducing them and I have no natural hearing in my right ear. If the implant is turned off, I’m deaf my right ear. This cut-off point varies a little, but not by much.

This is a very simplistic explanation of why I don’t believe, unless you have some significant natural hearing left in your implanted ear, that what you are hearing in the implanted ear can sound truly natural.

I am experimenting with my implant, listening to pure sine waves generated by my computer at various frequencies and volumes to see what I can hear with my implant. If I discover anything interesting I will let you know.