Beat Frequency of Sound Waves
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Adjust the sliders to explore the relationship between the difference in frequencies of the two component waveforms (shown dashed) and the resulting beat frequency seen in the upper plot. The red region in the upper plot is projected in the lower plot: move the "zoomed view" slider to view where the component waveforms are in phase, so that their sum reaches maximum amplitude, and where the waveforms are out of phase, so that their sum reaches minimum amplitude. The frequencies permitted by the "mean frequency" slider are audible to humans: click the "play tones" button to hear the resulting beating effect.
Contributed by: Christopher Engberg (May 2009)
After work by: Jon McLoone
Open content licensed under CC BY-NC-SA
Note that each stereo channel plays a tone of a single frequency, so that beating effect is the inteference of the soundwaves and not the speakers playing the mathematical summation of the two waveforms.
"Beat Frequency of Sound Waves"
Wolfram Demonstrations Project
Published: May 29 2009