That the strike tone is in some sense aural perception is no longer doubted : the most likely explanation is that it is a perceptual effect, possibly a difference tone created subjectively by the ear from two objectively existing partials ."
12.
Cymbals, bells, and, I've always thought, pipe organs, get a lot of their zing out of having a mass of high frequency inharmonic partialsa all interfering with one another and producing difference tones and all manner of other complex interactions.
13.
There are two types of combination tones : "'sum tones "'whose frequencies are found by adding the frequencies of the real tones and "'difference tones "'whose frequencies are the difference between the frequencies of the real tones . " Combination tones are heard when two pure tones ( i . e ., tones produced by simple harmonic sound waves having no overtones ), differing in frequency by about 50 cycles per second or more, sound together at sufficient intensity ."
