The Function of Phase Difference in the Binaural Location of Pure Tones

Auditory Spatial Perception: Auditory Localization

“…The first suggestion that the position of a sound source can be localized on the basis of the difference in the time of arrival of the sound wave to the two ears was made by Mallock (1908) and shortly later corroborated by Aggazzotti (1911), Hornbostel and Wertheimer (1920), and Klemm (1920). The above phase/time localization mechanism has been shown to work well at low frequencies, but for sounds at frequencies exceeding about 1.2 kHz (Middlebrooks and Green, 1991), the wavelengths become shorter than the distance between the ears of the listener and phase differences become an ambiguous cue (Hartley, 1919;More and Fry, 1907;Strutt [Lord Rayleigh], 1907;Wilson and Myers, 1908). This observation prompted Strutt to propose the duplex theory of localization, in which phase differences and intensity differences are two complementary localization mechanisms allowing humans to localize low and high frequency 8 sound sources, respectively (Strutt [Lord Rayleigh], 1907).…”

Hearing.

“…Hartley (6) reports a striking agreement between the theoretical location of a pure tone in terms of its phase-difference at the two ears, and actual tests of localization with a moving source of sound. Accurate judgment extended, in his experiments, only to tones of about 600 v.d.…”

Recent acoustic research.

“…Hartley and Fry (36,37,38) question the importance of phase difference in binaural localization of tones and indicate that in all experiments in which the tones are separately led to the two ears the factor of distance is lacking. There are normally three cues to localization: the vertical angle, the horizontal angle, and the distance.…”