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Noise Canceling Headphones...switch to noise adding?

Discussion in 'Electronic Design' started by mike, Feb 16, 2010.

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  1. mike

    mike Guest

    I like to listen to music while riding the motorcycle.
    'Cause I don't want to get dead, I can't use tightly
    acoustically coupled phones that give good bass response
    but block out traffic sounds.
    So, I'm thinking I can just reverse the phase of
    noise canceling headphones and add the traffic noise
    back in. I'm guessing there's some low-pass filter
    on the cancel that I'd have to remove???

    Staying alive is more important than quiet
    Anybody tried this?
    Thanks, mike
  2. Sylvia Else

    Sylvia Else Guest

    Noise cancelling headphones must be measuring the sound inside the ear
    cup, subtracting what should be there - the music - and then playing the
    rest in antiphase.

    Or equivalently, measuring the sound outside the cup, applying a known
    transform representing the effect the cup has on sound, and then playing
    the result in antiphase.

    In neither case is reversing the phase going to give you sound inside
    the cup that corresponds to the sound outside.

  3. No, but I've never had to.

    I use moulded plugs with air tubes leading to acoustic drivers. I have
    the volume quite low, because the plugs block most of the noise anyway.

    The plugs are not absolutely quite, and as long as the volume isn't
    loud, I can still get some road noise. Certainly horns and truck engines.

    I really don't see the point of it, why use noise-cancelling ears if
    you're just going to re-introduce said noise back in again? Do you have
    any control over the cancelling circuitry? If so, I suppose you could
    reduce the cancelling signal a bit, so it doesn't cancel as much as it
    otherwise would.

    I'd be wary of filtering here though, the filter would destroy the
    validity of the feedback signal making it useless.
    If you *really* want filtering, then you could filter the environment,
    and feed that back in (separate to the cancelling portion), though, as
    above I really don't see that proving useful.
  4. Don't forget the wind noise. I used to travel about 1.5 hours on
    regular basis, most of that on a freeway. I could barely hear my own
    engine that was located between my legs uninsulated, let alone the car
    next to me that you wouldn't hear standing next to it.

    Basically, I had choice, I could get to my destination hearing all the
    noise, perhaps a bit of traffic in built up areas, and result in a
    screaming headache when I get there, or not.

    Also, I'm half deaf as well. (a neurological issue). This makes it
    difficult for me to descern a valid signal from background noise. The
    plugs allow me able to hear the headphones at a civilised volume,
    wereas, normal headphones (noise cancelling or not) the volume would
    have to be so loud it would make things worse.
  5. Sylvia Else

    Sylvia Else Guest

    Depend? No. But the more information you receive about the goings-on in
    your driving environment, the better it must be. And a motorcyclist is
    particularly vulnerable if there is an accident.

  6. Ban

    Ban Guest

    In Europe it's illegal to use headphones when driving a bike
    ciao Ban
  7. legg

    legg Guest

    I agree, although my bike has no engine on it.

    The volume on my 'noise' source is low enough to be wiped out entirely
    by local traffic - can't hear it within 100 feet of a truck engine. I
    also only use one ear for this, not both.

    I suspect that the actual problem is the noise from the motorcycle.

  8. Neither do four of mine. :)
    Bicycle noise is very very different from motorcycle noise. You get to
    hear every little bit of traffic noise. Wind noise is mostly a
    non-issue, and even when you *think* it's loud, it probably isn't.

    Then there's motorcycle noise. You're travelling a LOT faster. Yes,
    yes, I've done around 55mph on my bicycle, but that's the exception to
    the rule, it's not a routine thing.

    It's a far cry from spending hours on the freeway at ~70mph.
    THAT'S noise.
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