Tuesday, February 24, 2009

Caveat Emptor

Cochlear implants apparently can do a fantastic job of restoring the world of sound. However, your mileage may vary. I've been reading testimonials, blogs, forums, and anything I can find about cochlear implants. There are some who think that it sounds natural and are able to hear again from the moment of activation. There are others who find the sound foreign, alien, and otherwordly, and struggle to interpret the signals as recognizable sounds and speech.

Most often, people find voices to be cartoonish and high pitched in tone. This is a result of the insertion depth. The hair cells at the end of the spiral of the shell-like cochlea are for the lowest frequencies, while the hair cells at the opening of the shell are for the highest frequencies. The deeper an implant is inserted, the deeper the pitch that is stimulated. Most people will experience a bias to higher pitch. Some people will experience almost normal or lower pitch, but the majority state that voices are higher and more cartoonish. Think Mickey Mouse. Alvin and the Chipmunks.

There apparently isn't much of a method to inserting an implant for accurate pitch reproduction. Every ear is different, and there's just no way for the surgeon to know how far to insert an implant. There is one implant producer, Med-El, that boasts of a longer implant than competitors have, which is intended to insert deeper and reach those lower frequencies more reliably. However, Med-El was just recently approved by the FDA for use in the US, and there is virtually no presence here yet. Also, their sound processing algorithms don't seem as advanced as AB's. Although in their favor, they have the smallest BTE (Behind The Ear) units.

People will get post-CI audiograms indicating nearly normal hearing response to frequencies from 250 Hz to 8000 Hz. The world is awash in sound, and speech can be deciphered without lip-reading in social settings and on the phone. So CIs promise to help me hear everything, but only in the pitches that the implanted device can stimulate. Hopefully I get a normal insertion, but most likely, I will get cartoon voices on activation day. I have mixed feelings about that. I'll be able to hear everything, but through a high-pitched filter.

Programming the implant is another consideration. Taking electrodes and immersing them in a salty, wet environment, one cannot expect reliable and repeatable sparks every time. The sound processor program's settings, or the map, as it is called, has to be fine-tuned to your ear and your preferences. Unfortunately, the neurological response to electrical stimulation can change over time, causing, literally, static to be heard, along with other undesired effects. That indicates that it's time for a new mapping appointment. So I'll be constantly looking for that sweet spot of optimum performance from the implant.

Also, there's the matter of the surgery. Once I go under that knife, I am committing to a life of surgery. If I have complications, I'll need surgery. If the implant fails, I'll need surgery. If I want an upgrade, I'll need surgery. If it has a limit on how long it should be in my head, I'll need surgery. Surgery has all sorts of risks, medical, financial, and otherwise. Definitely not one of the high points of going the bionic route.

But I'll be able to hear everything. Through a squawky box. Maybe.

I've always de-emphasized low frequencies in my right hearing aid, because that ear has a good level of high frequency hearing, although it is now fading. I've had good success using a strategy with crispy whispers, clinks and beeps in my right ear, and booming, rumbly bass in my left ear. I found that amplifying the lows muddied up the high frequencies, so my high-frequency ear developed a preference for quiet low frequency amplification. So when I turn off my left boomy aid, and only listen to the crispy whispers in my right ear, is that what a CI might sound like? Maybe I've already sort of trained my brain to listen to CI sound?

In other news, the old Oticon Sumo DM is back in my ear. I just don't like the Phonak. I gave it a week, almost, but found myself frustrated and hating the sound from it. Maybe modifying the Phonak's programming will help, but I have generally not had much luck with that brand. The Sumo DM seems awfully loud after wearing the Phonak, so I am wearing it low. But everything seems so much more detailed and clear with this hearing aid.

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