Interaural discrimination of phase and level differences of spectral sections of low‐frequency noise

Abstract

A 2000‐Hz, low‐passed noise was generated with a band of frequencies either interaurally phase shifted or presented with an interaural level difference. When an interaural level difference was generated, the level of all components at one ear was the same and a band of the noise was reduced in level at the other ear. The level of all the components was the same when an interaural phase shift was introduced for a band of the noise. When a band of frequencies are interaurally phase shifted, a pitch (sometimes referred to as the Huggins pitch) is produced. The just discriminable differences of interaural phase or level were measured as a function of the band width of the interaurally changed frequencies and the spectral location of the band. Listeners were more sensitive to interaural phase differences than to interaural level differences. These discriminations appear to be made on the basis of the pitch produced by the stimuli. The listeners report that when these pitches occur, the pitch is lateralized toward one side of the head while the noise timbre is lateralized on the opposite side. The results will be discussed in relation to the concept of a central spectrum and the mechanisms responsible for pitches similar to the Huggins pitch. [Research supported by grants from the NIH (NINCDS) and the AFOSR).]