Liveblogging again, this time from Hearing Aids II with 8 audiology grad students in their 2nd year. Our final project this semester will involve interviewing a hearing aid company representative. I'm looking forward to that one; I wonder if I can get to talk with the folks who designed mine. And skimming the list of lecture topics for the term, I'm excited.
- Introduction to digital hearing aids / High Fidelity in hearing aids
- DSP in hearing aids
- Processing delay and digital filtering
- Digital noise reduction
- Compression: Perceptual consequences
- Digital Feedback Suppression
- Open Canal Fittings
- Automatic/adaptive directionality
- Bandwidth enhancement & frequency lowering
- Wireless connectivity
There's room at the end of term for special topics, and I hope we get to cover music, and/or maybe language. But that's my own selfish wishing; I'm not an audiologist-to-be, I'm a hearing aid user and an engineer and a musician and someone who's attempting to become a polyglot.
Dr. Alexander relays some breaking news from this summer. Apparently, here's what's up on the cutting edge of hearing aid technology developments.
ExSilent released AirTAP, a technology that lets hearing aids remove their buttons; users control the settings by tapping their ear, and the hearing aid registers the change in pressure and switches mode accordingly. ("It doesn't do that when another object gets near your ear?" one audiology student asked. "We'll assume they worked the kinks out.")
While all this development happens, I note, thousands of people in the developing world cope with varying degrees of deafness without any hearing aids at all, unable to afford even the most basic pair. It's a thought that's never very far from my mind. Dr. Alexander also reminds us that many people who do have hearing aids live in rural areas and need to drive for hours, miss a day of work, stay in a hotel, etc. -- for just the most basic of adjustments. We don't all live in a world of convenient plenty.
Apple filed a patent (US 2012/0183165 A1) in July describing how the iPhone could be used as a remote control accessory for hearing aids, or even as a way to enable audiologists to program a patient's hearing aids remotely -- in certain states. (Others require the audiologist to see the patient in person.) This brings up the controversy about outsourcing of audiology; could I someday have my hearing aids adjusted cheaply by someone in China who I never see? For that matter, is this a step in the direction of allowing me to adjust my hearing aids myself -- and would I want to? Even if I'm a hacker whose first impulse is to say "duh, yes!" I also know there's tons of complexity I don't know, and that I could hurt my hearing more if I did something wrong; you can't simply reboot your cochlea after an inexperienced mistake.
There's also a new iPad app (ClearPath) for explaining hearing loss to people; it includes a hearing loss simulator ("what does the world sound like with this kind of hearing loss?") and other little things, and came advertised in a typically audiology-shiny PDF. I grit my teeth whenever I see audiology-shiny, though I understand its purpose; most people don't want to be overwhelmed.
Newstime is over. Dr. Alexander passes around the insides of a hearing aid, stripped of plastic and sans battery; they're tiny electrical components (chips and microphones and such) held together by flexible electrical tape. Tiny. Most of the hearing aid consists of battery, really. I pull off one of my own hearing aids and stare at it; next to that thing, my hearing aid is huge. But then again, when I hold my hearing aid next to an early version of a digital hearing aid, it's tiny; the first wearable digital hearing aids were wired to a processor that clips to the waist and is about the size of a cell phone. Tradeoffs from changing times.
Now we go through a timeline of hearing aid technology developments:
- 1950s: first behind-the-ear hearing aids, instead of the clunky belt-worn units with a wire running to your ear (like a permanent walkman).
- 1960s: smaller transducers dramatically shrink the size of hearing aids. First in-the-ear hearing aid appears (1961), though it won't be popular until 1975.
- 1970s: zinc-air battery appears (1971); it's smaller, cheaper, and longer-lasting than the previous technology of zinc-air batteries.
- 1980s: first in-the-canal hearing aid appears. President Ronald Reagan wears a hearing aid (1983) and suddenly, so do a lot of other people. I lose my hearing at age 2 (1988), the first prototype wearable digital hearing aid is developed (1989).
- 1990s: first completely-in-the-canal aids, my parents discover my deafness and I get my first hearing aids (1991, an analog pair), first digitally programmable hearing aids (1996 -- they still control analog signal processing components, but those components are digitally adjusted), I refuse to wear my hearing aids and FM unit any longer and successfully petition parents and teachers to let me stop wearing them to school (1996), the first commercial digital hearing aids appear (1996, but nobody wants to use them because they're larger than analog hearing aids).
- 2000s: Digital hearing aids start outselling analog ones. I go to high school and get my second pair of hearing aids (2002; I never consistently wear them).
I start having weird flashbacks to my first two pairs of hearing aids (age 4 and age 16) as Dr. Alexander starts stepping through the part of the timeline I've existed for. I remember seeing those devices; I remember seeing graphics of curves sweeping through decibels surrounded by letters that corresponded to the button someone needed to push to get that curve into the filter in my ear. It's strange listening to the march of technological progress, thinking about what I was doing at the time (piano competitions, etc) and thinking about whether any of the cutting-edge developments would have helped. (Usually the answer is no.) And whether I could have gotten hold of them. (Also usually no.)
And apparently there is a "hierarchy of hearing needs" (from Taylor & Mueller, 2011) -- it makes perfect sense to me. This is, in order, the things a hearing aid needs to do well; in other words, it's more important to get the stuff early in the list right. Helps with prioritizing features.
- Audibility & comfort in quiet
- Comfort in noise (Walking into my elementary school's lunchroom, the din always became unbearable; my first mealtime act was usually to slip my hearing aids into my pocket and chow down in silence.)
- Speech intelligibility in noise (Because of those experiences, I'd thought it was impossible for me to pick out conversations in a place with background noise. One of the tiny amazing moments that happened on the first day of my current hearing aids was driving to dinner with Jen and Seb and realizing I could hear them above the engine, and then that I could hear them in the restaurant. I could go out to dinner and have a conversation with someone. Crazy.)
- Convenience, ease of use, simplicity (While hiking through England, part of my daily routine was tending to my hearing aids; I disassembled and packed them in a dehumidifier just as religiously as I applied blisterstick to my feet.)
And then there's more stuff I'll write about tomorrow, because I need to read up on some more of it for next week's quiz. But already: DUDE. Where has this class been all my life? I wish this class was available to all interested geeky people with a hearing loss they are (or are interested in) technologically dealing with. I need to tell the hearing aid hacking community about this.