Curved Reflectors - Whispering Gallery

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 Code Number :   3B35.39

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 :   Good  
Principle :   Group & Phase Velocity 
Area of Study :  Acoustics   
Equipment :   Parabolic reflectors, tape player.
Procedure :   Attach the tape player to the focal point of one of the reflectors.  Align the reflectors so that they are parallel and some long distance apart (greater than 25 ft.).  When the reflectors are aligned properly the tape player can be turned down to a volume that cannot be heard when standing near the other reflector unless you hold your ear to the focal point of that reflector.
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   References

Thomas B. Greenslade, Jr., "Whispering Galleries", TPT, Vol. 18, # 1, Jan 1980, p. 52.

Thomas B. Greenslade, Jr., "19th Century Textbook Illustrations IV", TPT, Vol. 13, # 9, Dec. 1975, p. 522.

Robert H. Johns, "Parabolic Reflectors for Sound", TPT, Vol. 11, # 9, Dec. 1973, p. 567.

 

Jearl Walker, "Some Whispering Galleries Are Simply Sound Reflectors, But Others Are More Mysterious", The Amateur Scientist, Oct. 1978.

 

Ron Hipschman,  "Focused Sound,"  Exploratorium Cookbook II, p. 115.1.



Mail Questions and Comments to:  Dale Stille