Factors influencing the minimum audible change in head orientation of a talker

Humans can detect changes in the head orientation (a.k.a. facing angle) of a talker using only auditory cues. Head orientation cues are beneficial for determining whether one is the intended recipient of an utterance and for segregating a target talker from background talkers. Because human talkers are directional sound sources, binaural cues and monoaural spectral cues can both contribute to talker head orientation perception. In this study, we assessed listeners’ sensitivity to talker head orientation changes using only monaural cues. We tested several factors that could influence the minimum audible change in head orientation: talker and gender (two male, two female), stimulus bandwidth (full-band versus low-pass filtered at 8 or 10 kHz), transducer (loudspeaker versus headphone), stimulus uncertainty (interleaved versus blocked presentation of four talkers), and vocal production mode (speech versus singing). Bandlimiting at 8 or 10 kHz led to worse performance, as did increasing stimulus uncertainty. The effect of transducer was very limited. Performance with speech was better than that with singing. The effect of talker was large and consistent, suggesting individual variability in speech directivity patterns may affect head orientation cues. Work supported by NIH grant R01DC019745.