3B55.30 - Speaker and Baffle

Code Number:
3B55.30
Demo Title:
Speaker and Baffle
Condition:
Fair
Principle:
Speaker Construction, Constructive & Destructive Interference
Area of Study:
Acoustics
Equipment:
Plexiglas plate with hole, Homemade Paper Speaker in Plexiglas Frame, Magnet, Tape Deck, and Amplifier.
Procedure:

Plug the homemade speaker into the amplifier and start it playing.  The difference in sound quality with and without the Plexiglas plate should be apparent.  The amplifier will have to be turned up quite far for the homemade speaker. This speaker will also move back and forth on the magnet, at times rather violently.

References:
  • Peter Heller,  "Drinking-Cup Loudspeaker - A Surprise Demo",  TPT, Vol. 35, # 6, p. 334, Sept. 1997.
  • Chris Chiaverina, "Softspeakers", TPT, Vol. 24, # 1, Jan. 1986, p. 55.
  • W- 335:  "Cheap Speaker Cabinet",  DICK and RAE, Physics Demo Notebook.
  • Robert Ehrlich, "11.1 - Speaker in a Board", Why Toast Lands Jelly-Side Down, p. 171.
  • "Interference of Sound Waves",  PIRA Newsletter.  Vol. 3, No. 17, Jan. 1990.
  • Ron Hipschman, "Ear Piece", Exploratorium Cookbook II, p. 113.1 - 113.2.




Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.