Simultaneous production of two pure tones with frequenciesf1andf2is associated both with auditory beats (rapid fluctuations in loudness) and with audible difference tones. Since the same frequencyf1−f2is encountered in both cases, students tend to think a difference tone is nothing more than a beat phenomenon whose frequency is high enough to be in the audible range. But, in fact, these are two entirely distinct effects. This article discusses how to convincingly present this difference at three levels: (1) simple theory of added and multiplied waveforms; (2) visual demonstration with electronic Fourier analyzer; and (3) audible demonstration. These show that our ears can literally hear and distinguish two separate phenomena.