Musicians have an advantage on a spatial-hearing task only when they are highly trained, start training early, and...

Musicians perform better than non-musicians on a variety of non-musical sound-perception tasks. Whether that musicians' advantage extends to spatial hearing is a topic of increasing interest. Here we investigated one facet of that topic by assessing musicians' and non-musicians' sensitivity to the two primary cues to sound-source location on the horizontal plane: interaural-level-differences (ILDs) and interaural-time-differences (ITDs). Specifically, we measured discrimination thresholds for ILDs at 4 kHz (n =246) and ITDs at 0.5 kHz (n = 137) in participants whose musical-training histories covered a wide range of lengths, onsets, and offsets. For ILD discrimination, when only musical-training length was considered in the analysis, no musicians' advantage was apparent. However, when thresholds were compared between subgroups of non-musicians (<2 years of training) and extreme musicians (≥10 years of training, started ≤ age 7, still playing) a musicians' advantage emerged. Threshold comparisons between the extreme musicians and other subgroups of highly trained musicians (≥10 years of training) further indicated that the advantage required both starting young and continuing to play. In addition, the advantage was larger in males than in females, by some measures, and was not evident in an assessment of learning. For ITD discrimination, in contrast to ILD discrimination, parallel analyses revealed no apparent musicians' advantage. The results suggest that musicianship is associated with greater sensitivity to ILDs, a fundamental sound-localization cue, even though that sensitivity is not central to music, that this musicians' advantage arises, at least in part, from nurture, and that it is governed by a neural substrate where ILDs are processed separately from, and more malleably than, ITDs.