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Silence Gun: Strange weapon of the future

  1. Mar 3, 2012 #1


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    I wonder if this is for real? I can see it being a popular item for married couples, and teachers.


  2. jcsd
  3. Mar 3, 2012 #2


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    I don't remember details, but delayed sound played through headphones is used in stuttering therapy - it is called delayed auditory feedback. It forces speaker to slow down. Perhaps it is all in the correct selection of delay, from what I remember correct delay is a personal thing has to be set up experimentally.

    Checked: according to wikipedia delays used are up to 200 ms - or 0.2 sec. So the device doesn't sound reliable to me (unless slowing someone down is already considered a success).
  4. Mar 3, 2012 #3

    D H

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    The underlying concept is certainly correct. My cellphone does this to me far too often. It echos on occasion. Sometimes the echo is intermittent and highly distorted. I've learned to continue on with the conversation despite these occasional interuptions. Other times, the echo is very persistent and very clear. This is so utterly confusing that I have to hang up and call again.
  5. Mar 3, 2012 #4

    Ivan Seeking

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    Radio talk show hosts have always had a problem with this affecting listeners calling in.

    "Please turn down your radio"
  6. Mar 3, 2012 #5
  7. Mar 3, 2012 #6
    Audio companies have been researching speakerless sound systems for years. Instead of speakers you can use tiny transducers working at frequencies the human ear can't hear. Aim two transducers at a target like a chair and mix their signals in mid air to produce audiable sound that seems to emerge out of thin air. One college student experimented with a similar effect by projecting his voice from the roof of his dorm into the ear of passing coeds. They'd look around, see nobody was there, and take off running.

    Think of the possibilities though! Movie theaters which automatically silence the jerk sitting behind you without anyone else ever noticing. Its also possible to use the transducers to turn windows and walls into speakers to project sound right where you want it.

    Last edited: Mar 3, 2012
  8. Mar 3, 2012 #7
    I would like to try this thing out.

    The science center where I live has a sound canceling room. It's basically a room that records and then plays back an interference pattern from various mics and speakers all over the room. The result, you can talk in the room, but nothing comes out! It's a really strange feeling, pure silence. Nothing like what you get with those "noise canceling" headphones.
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