A quantitative study of combination tones.

Abstract

By use of the electrical responses of the cochlea in the guinea pig a study was made of the combination tones produced in the ear by two sinusoidal stimuli. A large number of components were found, all members of the series mh [plus or minus] nl, where h, l are the primary frequencies and m, n are whole numbers. Each component first rises as a power function of stimulus intensity, then attains a maximum and falls rapidly. For lower orders at least, the early part of the function is represented by the equation f (mh [plus or minus] nl)[alpha]PhmPln, in which f indicates the intensity function of the tone in parentheses, and Ph, Pl designate the stimulus intensities of the primaries. The results are considered in relation to the theories of origin of combination tones. The transformation theory is found correct in principle, though in need of alteration in detail. Evidence is presented that the summation tone is a component of equal status with the difference tone, and not a difference tone of higher order.