The Theory of Binaural Beats - An Experimental Contribution

The experiments here reported were performed in order to secure evidence concerning the cause of the additional maxima which occur in binaural heats. (See G. W. Stewart, Physical Review, Series 2, 3, p. 146, 1914, for a description of the phenomena.) These additional maxima occur at certain phase differences, and the change in these phase differences should depend upon the frequency of the tones, but not upon the frequency of the beats. If the additional maxima are caused by interaural conduction then, as it can be shown, the phase differences should vary as the frequencies. In the accompanying curve the phase differences, shown as fractions of π, are the ordinates and the frequencies, abscissae. Instead of a straight line which should obtain in the case of interaural conduction, we have a curve which is far from a straight line. (See Plate III.) The numbers in parentheses indicate the number of observations used in obtaining the position of the point. Five frequencies were used. After much consideration of theories involving interaural conduction, none seems to be in agreement with the evidence here shown