This project is aimed primarily at an understanding of the mechanisms of binaural hearing. Most specifically, we have examined sensitivity to interaural differences of time and intensity. Detection of such time differences, presented in the high frequency domain, has been studied using amplitude modulated (AM) tones, delayed to one ear. In the past we confirmed that this ability is based on information in the higher frequencies by showing that low frequency masking noise had little or no effect on performance and that lateralization could not be obtained when the signal to one ear was AM while the signal to the other was a tone of the modulation frequency. By varying: 1) the frequencies of the carriers, interaurally, 2) the modulator, diotically, and 3) the depth of modulation, we have now been able to show that the limits of temporal information, extracted from AM, are set by the monaural critical band. At low frequencies, we studied the ability to lateralize in a situation where there were no signal onsets or offsets; the transients in this case were masked by noise. We have found that lateralization of signals of at least 100 msec is unaffected by the absence of onset information. This has led to the development of a neural model which incorporates both phasic and tonic activity to account for the effects of duration on lateralization. BIBLIOGRAPHIC REFERENCES: Nuetzel, J. & Hafter, E. "Frequency bands for binaural interaction," J. Acoust. Soc. Amer., (1975) 58, S54. Hafter, E.R., Gilkey, R.H. & Dye, R.H. "Lateralization of signals without onsets," J. Acoust. Soc. Amer., (1976) 59,S22.