| ??? 03/20/06 22:22 Read: times |
#112631 - bah Responding to: ???'s previous message |
Kai Klaas said:
Well, a 23bit ADC, a dynamic range of 138dB, a DSP with 150 millions operations per second and this powered by a 1.4V battery indeed looks like alien hamster technology... Bah, Kai, you are trying to tell me this is something you won't be able to do singlehandedly with a mid-range 8051 and a handful of well-chosen transistors? :-))) Of course, if I would manufacture the hearing aids wanting to squeeze out $$$$s from the pacient and his health insurance company, I'd try to take their breath with the technology I use - or at least with my techtalk. I won't say a hi-end aid could be stitched together from a handful of TL082's but I believe a fair try is not beyond the reach of a skilled engineer attending here. But let's translate some of the techtalk from the site you mentioned: The circuit samples the raw output of the microphone at a million samples per second and then processes those samples 32 thousand times a second in three separate frequency bands. The digital signal processor statistically analyses the signals to automatically regulate each channel to maximize the user's listening experience. The system compensates in each of the channels for the differences in loudness perception, known as "recruitment," experienced by most hearing impaired people ("I can't hear you ... stop shouting"). This loudness mapping involves a large number of compressors and varying time windows to avoid any sudden audible changes or distortion. After the signal processing is complete, the circuits convert the 20 bit wide data stream into a single pulse, direction-coded (+ or -) signal that is presented directly to the output transducer without any digital to analog conversion. The noise frequencies are above 200 k Hertz and are ignored by the output transducer. etc.etc. Oh yeah, and there are also nice examples of the "overperfections" of the "digital technology" (this term being a nasty techtalk in itself) documented there: Long time hearing aid wearers sometimes object to the lack of distortion and noise in the environment that they remember from their old aids, but they usually can hear and understand much better with these aids. One user reported that the background noise of the airplane he was riding in almost completely disappeared (which gave him quite a scare) when the signal processor circuit turned on. OK now I am exagerrating. But I believe you see my point. Jan Waclawek |
| Topic | Author | Date |
| Digital Hearing Aids | 01/01/70 00:00 | |
| What do you want to know? | 01/01/70 00:00 | |
| Custom | 01/01/70 00:00 | |
| Tell me more | 01/01/70 00:00 | |
| Sorry | 01/01/70 00:00 | |
| try? | 01/01/70 00:00 | |
| VALVES | 01/01/70 00:00 | |
| ...and the earphones... | 01/01/70 00:00 | |
| Here we go | 01/01/70 00:00 | |
| Thank you | 01/01/70 00:00 | |
| How does it work | 01/01/70 00:00 | |
| HYbrid | 01/01/70 00:00 | |
| my dads aid | 01/01/70 00:00 | |
| Sorry | 01/01/70 00:00 | |
| Hearing aid chips | 01/01/70 00:00 | |
| Grant, I saw your location | 01/01/70 00:00 | |
| Swallows | 01/01/70 00:00 | |
| not the cacti, it is wildflowers | 01/01/70 00:00 | |
| Link moved Zarlink | 01/01/70 00:00 | |
| Digital Hearing Aids | 01/01/70 00:00 | |
| Thats right | 01/01/70 00:00 | |
| Ahem | 01/01/70 00:00 | |
| My point! | 01/01/70 00:00 | |
| Power | 01/01/70 00:00 | |
| I don't think so | 01/01/70 00:00 | |
| Really ? | 01/01/70 00:00 | |
| Maybe | 01/01/70 00:00 | |
| NOT ear mounted | 01/01/70 00:00 | |
| There goes the plan | 01/01/70 00:00 | |
| As expensive as gold... | 01/01/70 00:00 | |
| On Hold | 01/01/70 00:00 | |
| don't scare him | 01/01/70 00:00 | |
| as so often before the one thing not men | 01/01/70 00:00 | |
| I thought he wants to make it for himsel | 01/01/70 00:00 | |
| I do not think so | 01/01/70 00:00 | |
| Cosmic technology | 01/01/70 00:00 | |
| bah | 01/01/70 00:00 | |
| Exactly! | 01/01/70 00:00 | |
| That would be trying to kill an elephant | 01/01/70 00:00 | |
| How about | 01/01/70 00:00 | |
| Phoning | 01/01/70 00:00 | |
| Affirmative | 01/01/70 00:00 | |
| Alternative | 01/01/70 00:00 | |
| phone "adapter" | 01/01/70 00:00 | |
| comfort noise | 01/01/70 00:00 | |
Noise reduction | 01/01/70 00:00 | |
| Digital hearing aids | 01/01/70 00:00 | |
| Phones | 01/01/70 00:00 |