In this study, we describe the results of two experiments that help clarify the conditions under which interaural time delays can facilitate the identification of simultaneously-presented vowel sounds. In one experiment we measured the intelligibility of simultaneously-presented natural speech and speech that had been degraded in a manner that precluded the use of pitch information. In a second experiment we measured the identification accuracy gained by adding pitch and amplitude information to whispered vowel-like sounds. The major results of these experiments are twofold. First, interaural time delays can indeed facilitate the identification of simultaneously-presented speech-like sounds, even when cues based on common fundamental frequency are not available. Second, the ease with which the very potent contribution of interaural timing information can be exploited is strongly facilitated in turn by the presence of dynamic variations in the stimuli (such as the monaural amplitude and frequency fluctuations that are characteristic of natural speech sounds).