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Acoustic Resonance Chamber Design- Wine glass shattering

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  1. May 7, 2013 #1

    taylaron

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    Gold Member

    Greetings PFers,

    I'm designing a demonstration unit for use in grade schools demonstrating the principle of resonance upon wine glasses (shattering them). I intend to put a wine glass into an acrylic chamber of some geometry, hand the student a microphone and see if they can generate the glass' resonant frequency. Their voice will be amplified through an audio amplifier and projected through a medium size (8-12'' diameter) speaker

    Device requirements:
    1. Demonstrate phenomenon of acoustic resonance using wine glasses
    2. Utilize a speaker and amplifier to generate the sound waves
    3. Device should be able to fit on a desktop
    4. Sound outside of the device shouldn't be unbearably loud (enclosed container for sound isolation)
    5. Capable of handling input from frequency generator or a microphone
    6. Protective shroud to isolate observers from flying glass
    7. Wine glass should be observable through the top and around most of the wine glass
    8. Able to handle varying sizes of wine glasses (varying pedestal height)
    9. User should be able to see the wine glass vibrating (likely via strobe light)
    10. Built-in canister for broken glass and a lid to insert another wine glass

    I have three primary concerns in designing this demonstration unit
    1. Geometry of the container causes as little deconstructive interference within the chamber as possible
    design chamber so node length corresponds with typical radial distance to glass surface​
    2. The sound outside* the device shouldn't be deafening, with the demonstrator able to speak over the noise
    single or double acrylic walls for sound isolation. Vacuum between walls? Sound cancellation with another speaker? ​
    3. Geometry of the speaker orifice

    Some good examples of this principle are the following videos:




    I'm not worried about the electronics-that's relatively simple. But I do need help designing the container. I presume a cylindrical container with a hole in one side where the sound enters would make the most physical sense because the glass would be the same distance from the chamber at any angle. Wine glasses resonate typically between 450 and 650 Hz. How do I make a chamber that can handle this wide range of frequencies? I want the chamber to be a resonance chamber so the speaker amplitude doesn't have to be really loud (or soft for a long period of time...) The videos show a simple straight hole as the orifice. Should the hole be parabolic in shape to aid dispersion? I'm thinking that I should test the geometry in a water chamber to see if deconstructive interference is an issue.

    I have access to Solidworks 2012 student edition with simulator,but I don't think it does acoustic simulation. Does anyone know of a free acoustic simulator?

    Thanks for your time!
    -Taylaron
     
    Last edited by a moderator: Sep 25, 2014
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