Beat Notes

What happens when two sinusoids that are not harmonically related are added?

**Figure 1:** Beat Note made by adding sinusoids at frequencies 218 Hz and 222 Hz.
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The resulting waveform shows a periodic, low frequency amplitude envelope superimposed on a higher frequency sinusoid.

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The beat note comes about by adding two sinusoids that are very close in frequency.

``Music 270a: Modulation'' by Tamara Smyth, Department of Music, University of California, San Diego (UCSD).