Role of Intensity and Time Differences in Localizing Low-Frequency Tones

Abstract

Subjects matched the position of a 500-cps tone by adjusting the interaural delay for a wide-band noise. The stimuli were presented alternately by means of earphones, using a gate having a rise and decay time of 10 msec. The tonal signal was adjusted by the experimenter to have a certain combination of interaural time difference (phase) and intensity difference. In some cases these were in accord and in some, in opposition. The subject attempted to match the localization of the tone by adjusting the interaural time difference for the noise stimulus by means of a variable lag-line. Under some of the extreme conditions these matches were hard to make, but for most combinations the subjects experienced no great difficulty. Data will be presented for four subjects. They show the combinations of time and intensity differences which yield equivalent localizations. The responses of all of the subjects can be fitted reasonably well by a single equation, but the constants of the equation differ markedly among the subjects. The data show further that the localizational effects of time and intensity are not simply additive. (This work was performed under Bureau of Ships Contracts NObsr-52267 and NObsr-72627.)