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Re: [regsaudioforum] Re: (OT) Noise cancellation in cars

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  • Uli Brueggemann
    IMO the noise cancellation does not necessarily use a feedback loop. I guess it uses some filter and then it simply adds the inverted mic signal to the music
    Message 1 of 46 , May 1, 2008
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      IMO the noise cancellation does not necessarily use a feedback loop. I guess it uses some filter and then it simply adds the inverted mic signal to the music signal.. A feedback loop always makes a system slower.

      And I can report that the noise cancellation headphone I'm using always in an airplane (Philip xxx..) does not remove low frequencies as well as high frequencies. So it seems to work the other way round compared to Robert's guess.

      Uli

      On Thu, May 1, 2008 at 6:16 AM, Robert Greene <regonaudio@...> wrote:

      This would depend on how it works, it seems.
      I think systems like this are likely to be feedback loops
      in effect. This would seem the logical way to make such a thing work.
      And if it got out of whack, it could just feedback more and more,
      like microphone howl and the like, up to the upper limit of its
      absolute SPL capacity.
      I would surely not want such a thing unless it had a definite upper
      SPL limit(which of course it could, since as TM says it does not
      need to put out too much power acoustically to do its job).

      REG

      PS The idea that this is related to room correction is quite right.
      And it will have the same problem as room correction: inability to
      deal with high frequencies over broad areas. But of course much of
      the noise in cars is low frequency. And there it ought to work.


    • Fred
      Aha! I perceive your cunning plot to goad me to ampliation - and don t get me started about motor cyclists! Fred. ...
      Message 46 of 46 , May 6, 2008
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        Aha!
        I perceive your cunning plot to goad me to ampliation
        - and don't get me started about motor cyclists!

        Fred.

        --- David Fagan <david.fagan@...> wrote:

        > Hi Fred,
        >
        > Don't hold back - what do you really think about
        > cyclists? :-)
        >
        > Dave.
        >
        > -----Original Message-----
        > From: regsaudioforum@yahoogroups.com
        > [mailto:regsaudioforum@yahoogroups.com]
        > On Behalf Of Fred
        > Sent: 06 May 2008 02:31
        > To: regsaudioforum@yahoogroups.com
        > Subject: RE: [regsaudioforum] Re: (OT) Noise
        > cancellation in cars
        >
        >
        > My earlier comments aside, I number cycists among
        > they
        > who think they have special rights on the road.
        >
        > To - Position themselves on the road so as to hold
        > back dozens of cars at barely more than walking
        > speed.
        > Rarely signal, look behind or even manoeuvre safely
        > before turning.
        > Emerge from nowhere in blinkered faith of clear ways
        > ahead.
        > Interweave and wobble among traffic expecting always
        > to be seen and avoided.
        > Jeopardise pedestrians on footpaths, walkways and
        > pavements.
        > Treat traffic lights as things to ride through or
        > weave round.
        > Find cars convenient to lean on but may scratch them
        > in passing.
        > Regard vehicles as totally responsible for accidents
        > and rarely rarely think to insure themselves.
        > Have a can't pay, can't stay attitude to damage they
        > cause.
        > Ride at night without lights, reflectors or bright
        > clothing.
        > Consider the rules of the road a matter for powered
        > vehicles.
        > Cause embarrassment by wiggling their admirably
        > shapely lycra tight posteriors - only discovered to
        > be
        > male when overtaking.
        >
        > Arrive at the office stinking from their exertions,
        > expecting everyone to "understand" until they've
        > changed and freshened up.
        > And at weekends those very same blighters could be
        > driving the aforementioned BMWs and SUVs their wives
        > used during the week!
        >
        > Grrrr!
        >
        > :-)
        >
        > Fred.
        >
        >



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