Primary Beats and Combination Tones

When two sine waves of equal amplitudes but different frequencies are played simultaneously, several interesting sounds can be heard. 

Combinations of pure tones, from Rossing, Moore and Wheeler


 

Two tones are presented with equal amplitude.  One remains at the starting frequency.  The other starts at the same frequency and its frequency gradually increases.  Three frequency excursions of differing lengths are possible.

Starting frequency [Hz] (default is A above middle C)

MUTE       

Beats with constant frequency shift:     Df = 1 Hz     Df = 5 Hz     Df = 10 Hz

Two tones are presented with equal amplitude.  One remains at the starting frequency.  The OTHER starts at the same frequency and its frequency gradually increases.  Three frequency excursions of differing lengths are possible.

Short Ramp (Primary beats)     Medium Ramp (Roughness)     Wide Ramp (Combination tones)

This applet requires Java 1.1 and a sound card.  The highest frequency that can be produced without aliasing problems is ~3500Hz.   This demonstration was created by Dan Boye.