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Beat Notes

What happens when we add two frequencies that are not harmonically related?

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

Figure 6: Beat Note made by adding sinusoids at frequencies 218 Hz and 222 Hz.
\scalebox{0.8}{\includegraphics{eps/beatspec.eps}}

The resulting waveform shows that there is a periodic, low frequency amplitude envelope superimposed on a higher frequency sinusoid.

Figure 7: Waveform of a Beat Note.
\scalebox{0.9}{\includegraphics{eps/beatwav.eps}}

What is going on?


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``CMPT 468: Additive Synthesis'' by Tamara Smyth, Computing Science, Simon Fraser University.
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Copyright © 2012 by Tamara Smyth.
Please email errata, comments, and suggestions to Tamara Smyth<tamaras@cs.sfu.edu>