Demonstrations

Speaker and Baffle

Code Number :	3B55.30
Disclaimer:	Reprinted by permission of Dick Berg, University of Maryland, for use on this website. The demonstrations contained and referenced herein are listed for the purposes of cataloging and describing physics demonstrations which should be conducted only under the direction of a trained instructional support professional or physicist. These demonstrations are not presented for the purpose of being conducted by persons unconnected to this Facility and/or persons not consulting with or being supervised by the recognized instructional support professional or physicist and his/her staff. The University is responsible only for those demonstrations carried out using its own equipment using established safety and scheduling policies, and bears no responsibility for those choosing to use this source material for their own purposes. All demonstrations described and contained herein are public domain, and can also be found in reference materials in libraries, bookstores, and electronic sources. Further information regarding legal liability in use of demonstrations and labs will be found on the web site Injuries in School/College Laboratories in USA. The University of Iowa Disclaimers: University of Iowa Disclaimer All Rights Reserved..
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

Rhett Herman, "As Simple as Possible", TPT, Vol. 40, # 2, Feb. 2002, p. 182.

Molly Johnson, "Sound Science - A Simple and Robust Hands-on Loudspeaker Activity," TPT, Vol. 37, # 6, p. 350, (Sept. 1999).

Allen Keeney and Brant Hershey, "Making Your Own Dynamic Loudspeaker," TPT, Vol. 35, # 5, p. 297- 299, (May 1997).

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.

W- 425: "Bite-a-Phone", DICK and RAE, Physics Demo Notebook.

11.1: Robert Ehrlich, "Speaker in a Board," Why Toast Lands Jelly-Side Down.

"Interference of Sound Waves," PIRA Newsletter. Vol. 3, No. 17, (Jan. 1990).

"Loudspeaker," The New Illustrated Science of Invention Encyclopedia: "How it Works," p. 1482.

Ron Hipschman, "Ear Piece," Exploratorium Cookbook II, p. 113.1 - 113.2.

Mail Questions and Comments to: Dale Stille