We have shown that listeners can locate two sound sources producing simultaneous sounds when the sounds are independently generated wideband noise bursts. Listeners’ localization performance is better when the sound at one source is sinusoidally amplitude modulated (AM) 180 deg out-of-phase relative the AM of the other sound as opposed to conditions in which the envelope modulation phase is the same (in-phase) for the sound at both sources. This improved localization performance can be measured up to AM rates of 200 Hz. Listeners can discriminate out-of-phase from in-phase modulation between the two sounds up to AM rates of 500 Hz. In the current study, we use filtered noises (lowpass: 125–500 Hz, highpass: 1500–6000 Hz, and wideband: 125–6000 Hz) in an attempt to determine the role interaural time and level differences play in localizing the sources of two independently generated AM sounds. The results will be discussed in terms of the cues listeners might use in localizing multiple sound sources when the sounds occur simultaneously.

The pitch-shift of the residue has been used as an argument for the importance of temporal fine structure in pitch perception. Discrimination of a change in fundamental frequency (F0) for harmonic complexes was compared to discriminating a change in the shifted frequency (f) in pitch-shift of the residue stimuli. Patterson and Wightman [J. Acoust. Soc. Am. 59, (1976)] showed that a linear relationship exists between matched pitch and the frequency of the lowest spectral component for pitch shift of the residue stimuli (stimuli for which the spacing between adjacent spectral components is constant, but all components in the complex are shifted up or down in frequency). Obtaining pitch matches for pitch shift of the residue stimuli is a difficult task because of the ambiguous nature of the pitch shift of the residue in several conditions. Using the two discrimination experiments allows for an estimate of the slopes relating matched pitch to the frequency of the lowest component. Slopes estimated from the discrimination experiments will be compared to those obtained by the previous authors to determine if the discrimination experiments provide a valid way to predict the matched pitch of pitch-shift of the residue stimuli. [Research supported by NIDCD.]