Physics Demo Number: 056

Approximate Run Time: 5 min

Removal of Bare Radio Speaker Phase Cancellation With A Simple Cardboard-Sheet Baffle

Demo Description

A bare speaker is placed behind a cardboard-sheet baffle with a hole in it. When set against the hole, the volume and quality of the sound is distinctly better.

Scientific Principles

  • Sound Wave Generation by Speakers

  • Phase Cancellation

 

Equipment

  • Radio and Bare Speaker

  • Cardboard sheet


Equipment Location

  • The radio [with external bare speaker] are in Kit (056) on [D-1-4 ].

  • The cardboard sheet [with speaker-sized hole] lives in [D-1-4].

Instructions

The radio [with external bare speaker] and cardboard sheet [with speaker-sized hole] are used with a radio (tuned to an appropriate station) so that one can vividly hear a big difference in volume and quality of the sound depending on whether or not the speaker is placed against the cardboard at the hole.

Of necessity, when a condensation leaves one side of the speaker, a rarefaction leaves the other side of the speaker.
 
Writeup created by David A. Burba
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