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FM stereo hearing aid question.

Discussion in 'Electronic Design' started by [email protected], Nov 22, 2005.

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  1. Guest

    A pair of FM 'bug' transmitters could send left/right signals to a pair
    of separate FM ear phones that would be helpful to the hard of hearing.

    AFAIK an MP3 FM transmitter takes the MP3 audio out of the headphone
    jack and modulates it in FM stereo for transmission to an FM receiver.

    Assume a pair of FM stereo headphones, how could one integrate the
    signals from left/right FM 'bugs' for transmission to the FM

    Perhaps a multiplex arrangement of separate FM transmitter/receivers,
    one for each ear, and tuned to 2 different frequencies would be
    possible and desireable.

    As 'Bluetooth' style ear receivers become more common, hearing aids in
    the same shape will be easily hidden in plain sight.

    Using DSP for noise cansellation, directivity, etc, combined with an FM
    system, fabulous 'bionic' hearing would be possible.

    All help would be greatly appreciated.
  2. Ken Taylor

    Ken Taylor Guest

    Why on earth use FM in this process? Hearing aids are essentially
    amplifiers, albeit very selectively frequency dependant. Noise suppression
    and so forth using DSP is already built in to modern units. A 'bionic'
    hearing aid, for the profoundly deaf, actually 'decodes' the audio and
    stimulates nerve endings in the ear itself rather than sending sound into
    the ear.

    If you are just after a transmitter to get audio from an electronic device
    (TV, stereo, whatever) to a person some distance away, this is already done
    in stereo (my mother-in-law has one) using a stereo FM transmitter and

    If you have a stereo FM headphone you need a (single) stereo headphone
    transmitter - you can't 'multiplex' two mono FM transmitters and receive
    them on your stereo receiver.


  3. Guest

    I've had a similar idea as a method for overcoming the mono sound for
    the FM systems used in hearing aids. I use the TelCom from Phonak
    which takes the stereo connectors from my home receiver, but then
    broadcasts the audio over FM in mono since both ears pickup the same
    signal. There isn't a right and left on the FM receivers for my
    hearing aids. I'm pretty sure there is a way to set the receivers on
    the hearing aids to receive a different frequency. Now I would just
    need the TelCom or some other FM transmitter to broadcast Left to one
    frequency, and Right to another. Having FM is great, but not having
    Stereo for music and movies is a bummer. (And yes, I realize that I'm
    probably trying to make these things do more than they were originally
    intended, and that I could just go and use my regular headphones if I
    really wanted.)

    I haven't spent enough time on the matter, but do know that you can buy
    small transmitters for pretty cheap and tune them yourselves.

    Dane Ashworth
  4. Jim Thompson

    Jim Thompson Guest

    I have a Sony headset that is "wireless" stereo. It uses IR to
    transmit from source to phones.

    ...Jim Thompson
  5. Guest

    Here's one cheap way for FM stereo.

    2 Lobeman FM earclip receivers. $14.95 ea
    2 FM bugs sold on Ebay for about $20 ea.

    Tune Left for one freq and the Right for another freq.

    Certainly under $100
  6. Seinheiser (I've spelled that wrong) had an IR system decades ago,
    and I think it's their system (at least what they make nowadays)
    that is often sold as an aid to the deaf.

    But they use a separate receiver, and then feed the signal into
    the hearing aids via inductive coupling. Most hearing aids have
    an inductive pickup as standard, for use with telephones, so basically
    placing a flat coil betweeen the aid and the head couples signal into

    The IR receiver has just a standard headphone jack on it, so it can
    be used with headphones or the coupler.

    Use a stereo IR system with two couplers, and you get stereo.

    I wonder what is in the original poster's hearing aid. I find it
    hard to believe that there's an actual radio receiver, so likely
    the "wireless transmitter" is an audio amplifier feeding a loop,
    which allows inductive pickup in the hearing aid. That will never
    be stereo, since there's no way of differentiating between the
    audio loop on the left channel and the audio loop on the right channel.

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