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Build Your Own Bluetooth Hearing Aid
CloudShape writes "I've been trying to find a way to make a mobile phone work with my hearing aids for some years now, and I finally managed it a few days ago. Although the procedure itself is pretty simple, the surrounding issues are good for quite a bit of discussion."
That you RTFA. This is /. after all. But if you did you would have seen:
No amount of extension cable will make a wired hands-free usable - the wire always conducts enough RFI to cause trouble, regardless of any filters that might be in place.
So connecting the phone directly to the hearing aid via a wire isn't an option.
SteveM
edit:
Seems as if Phonak has their own deal called SmartLink. No sign of a Widex version like I said earlier, but again, it's planned but may not exist.
I'm going to be looking into this since I have a Phonak Claro hearing aid that I bought a year ago. Finally can use those cellphones now!
For those of you who are wondering, hearing aid users experience an extremely loud crackling sound when using the cell phone normally. If we use the telephone switch which make use of built in telecoils in some cell phones, a loud buzzing sound overpowers the voice coming out of the phone. It's very annoying indeed. Some phones, amazingly, do not have these problems. I once tried my friends phone made by Samsung, and it was amazingly clear! Just a bit of advice, in case, anyone was wondering :)
I once worked for a cell phone company in Phoenix. I'm not a cellular engineer, so the theory and such is a bit over my head, but I was offered a simplified explaination on how the CDMA system worked, and how it differed from other forms of cellular access. This was several years ago, so hopefully I remembered it correctly.
Analog cellular works much like standard radio. A signal is broadcast on a particular channel and your phone negotiates with the cell towers to broadcast on a that channel; each user has a distinct access path. Analog signals also have to broadcast above the noise floor in order to be heard by the tower. I think the FCC limits the maximum power of analog to 4 watts.
Each analog call has to use a single analog phone line. This is somewhat limiting for the cell companies as they need a single POTS voice channel for each cellular connection. This gets very expensive as the number of calls go up.
TDMA is a multiplex scheme. It stands for Time Division Multiple Access. Each phone under TDMA is given a specific "slice" of a channel to communicate on. This allows multiple phones to operate on the same channel at the same time, allowing the carrier to expand the capacities of the cell towers without adding extra land-lines.
CDMA stands for Code Division Multiple Access. Under the CDMA system, each phone communicates with the cell tower and agrees upon a particular part of the spectrum to use, a particular channel in the spectrum, and a compression method. Depending on the compression used, you can squish more calls per channel. CDMA also operates below the noise floor, so a typical CDMA broadcast is in the milliwatt (or lower) range. The power is adjusted several times per second to keep multiple phone signals on the channel from stepping all over each other.
I've probably got some of the particulars wrong, as about 25% of what the engineer said to me was over my head.
There's so little difference between politics and jihad lately...
I use a Kyocera 2035 without any problems. I'm profoundly deaf (HA model escapes me at the moment).
The phone itself is a "brick" according to my friends that have new ones smaller then my thumb, but I'm hesitant to upgrade because it simply WORKS. I've used friends' fancy new Nokias and they just don't do the job. Crappy telecoils or something? I don't know, but my 3.5 yr old Kyocera keeps working for me...
--Dave
maybe he wants to hear when he's not using the phone? That's probably why he did it, as a switch,also, bluetooth has less human audible interference than the straight normal cellphone transmission carries, the wire propogates and interferes with the hearing aid circuitry and operation.
It's in the article, unless I am reading this wrong.
RTFA - "No amount of extension cable will make a wired hands-free usable - the wire always conducts enough RFI to cause trouble, regardless of any filters that might be in place." Wires really transmit. I used some spare wire to wrap around my wireless to boast the signal.
For the hearing who wonder what exactly we are talking about, telecoil is a magnetic link with the speaker of the item you are listening to. The microphone is shut off. Most cell phones crank out a lot of magnetic noise. I have this problem with my $2,000 (each!) digital Interra AV MM's and my Nokia phone. I simply use the included headset that comes with the phone and loop the small speaker behind my ear close to the hearing aid, then switch to telecoil. The sound I get is so good, I prefer to use my cell phone over any other phone.
Crushing my karma one post at a time.
You know, the thought had never even crossed my mind... thank you for that, it made me laugh!
As mboverload says, I wrote the disclaimer in capitals because everyone seems to do it that way. I'm not sure why, although I suspect it might be so that people can't claim that a disclaimer was "hidden in the surrounding text" or somesuch. If someone could claim that the disclaimer was hidden so they wouldn't notice it, they might just be able to sidestep it on the basis that it hadn't been made clear, and demand damages anyway.
The reason my page doesn't have a clickable contents list with in-page link targets is so that people are forced to start at the top where the disclaimer will be presented to them up front. Mind you, I can't help feeling that it's a shame we live in a day and age where this kind of legal paranoia is necessary...