A diagram showing four sinusoids of frequencies 1200, 1400, 1600 and 1800 hertz (green, purple, orange and red). Also shown is the summed signal (black) and the sinusoid with the same period as the beat frequency (<i>f</i><sub>0</sub>, 200 Hz). Above is the spectrum of the signals.
<a href="//commons.wikimedia.org/wiki/User:Inductiveload" title="User:Inductiveload">Inductiveload</a>
<span class="int-own-work" lang="en">Own work</span>