Beats - Oscillators, Speakers And Oscilloscope
To hear audio beats and see their wave form on an oscilloscope.
Pasco Dual Function Generator, loudspeaker, and four-trace scope.
Two oscillators (in a Pasco Dual Function Generator) create sine waves which are displayed on the oscilloscope. The sum is also created by the Dual Function Generator and output to the third trace of the oscilloscope as well as to a loudspeaker. The beats can be seen and heard as the frequency of one of the sine waves is varied, producing slow changes in amplitude (small frequency differences) or the wave packet effect (larger frequency differences).
H. J. Janssen and E. L. Flerackers, Beats: An Interference Phenomenon, TPT 17, 188-189, (1979).