Psychoacoustical Investigations in Binaural Sound Localization

Three major binaural localization tests have been conducted with subjects using individual head-related transfer functions (HRTFs) as well as subjects using non-individual HRTFs. In the case of non-individual HRTFs the interaural time difference (ITD) was approximated using different models.

The tests I and II yielded a diminution of the lateralization of stimuli in the presence of reverberation. Test III investigated the localization of speech in the presence of two different distracting speech signals. Pure reverberation of voices other than the target serving as distracters did not have any influence on localization. Pure direct sound of those voices degraded the localization performance at the lowest target-to-distracter ratio of -12dB.

Except for a slightly lower localization accuracy of subjects using non-individual HRTFs no systematic difference has been found between the two groups of subjects. The discrepancies in the results of test I and test II are assumed to be caused by the different testing conditions (subjects were blindfolded in test II but not in test I).