- Clive Greated
A sound that may be heard when two loud musical tones are sounded together but is not present when either of the tones is sounded separately. If the frequencies of two pure tones are f1 and f2, the frequencies of the combination tones are f1+f2, f1–f2, 2f1+f2, 2f1–f2, f1+2f2, f1–2f2, 2f1+2f2, 2f1–2f2 etc. They are usually attributed to non-linearities in the system through which the sound is being transmitted or reproduced. If the only system involved is the ear, they are sometimes described as ‘subjective tones’; the most prominent are the ‘simple’ difference tone, with frequency f2–f1, and the ‘cubic’ difference tone, with frequency 2f1–f2, where f1...