Individual differences and left/right asymmetries in auditory space perception. I. Localization of low-frequency sounds in free field.

The number of subjects in studies on human spatial hearing is generally small. Therefore, individual differences and the factors underlying variability are unknown. In this study, we investigated across-listener variability in auditory localization abilities in a group of 50 naïve adults with normal hearing. Targets were trains of low-frequency noise bursts presented to 1 of 12 hidden speakers in the azimuthal plane. We observed less across-listener variability in the variance of individual responses but more in the root-mean-square and signed errors, which tended to increase with target angle. One third of the listeners demonstrated systematically smaller signed errors with left-sided targets than with right-sided ones. These asymmetries were observed less frequently in left-handers and females than in right-handers and males. Performance was not correlated with age. About 4 of 6 listeners trained with sensory feedback showed no reduction of asymmetries with training but rather showed a reduction in errors on their "best" side. Across-listener variability in the asymmetry of brain organization, notably linked to handedness or gender, is discussed.