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Helium pitch-shifter

Jul 30, 2007


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Would this work?

pitchshifter.png

Maybe the tank needs to be upright and filled with helium and some other gas half and half, so there’s a difference in gas density, which compresses the sound waves making the pitch higher. Like this:

pitch2.png

Of course, some other gases could be used for different effects. I think using a combination that would make the pitch lower would result in clean shifting, a situation where there tends to be a lot of phasing. Then again the acoustics of the tank would have to be perfect. But let me think I invented something really clever at least for a while, OK?

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6 responses to "Helium pitch-shifter"

  • Jochen says:

    1

    Hey man – that _will_ work, at least the upper one. Putting two different gases into your soundpitcher would result in a homegueneous mixture of the gases with a pitch-change according to the resulting density.

    Ever heard a transmission from deep seas divers working for offshore oil exploration and drilling? They stay at 500 meter depth and more for some days and their gas for aspiration is a mixture of oxygen and helium preventing the bends by substituting the “dangerous” nitrogen by helium. They sound like Mickey Mouse – and it’s perfectly the situation described by your pitchshifter.png. So it’s all not that stupid nonsense as you may have thought of before:-)
    Greets
    Jochen

  • kometbomb says:

    2

    Thanks for confirming this, I have to start looking for free balloons so I get some helium to test this. ;)

  • poorsod says:

    3

    Not entirely sure. I remember reading somewhere that inhaling helium actually acts as a high-pass filter, so you wouldn’t pitch-shift it upwards, just filter out all the low-frequency energy.

    I think. Probably best just to try it.

  • Hamilton Lovecraft says:

    4

    I believe it *won’t* work.

    My understanding is that helium makes the pitch of your voice rise because the vocal cords vibrate faster in light helium than in dense air. You might change the frequency response of the speaker a little, but the speaker’s being driven by an external electrical signal that isn’t affected by helium.

  • Dan says:

    5

    Yeah, if it was the sound waves travelling through the helium that made your voice higher, then you wouldn’t hear the higher pitch unless all of the air was helium, in which case you would die from a lack of oxygen. I’m pretty sure the helium sound is because of an effect of the helium on your body, not the sound waves.

  • Phill says:

    6

    It won’t work. Helium changes voice pitch because the vocal cords behave essentially like a resonant chamber. The speaker has no such mechanism, so the frequency generated by the diaphragm in the speaker will be the same as that recieved by the diaphragm in the mic.

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