HEADPHONE LOCALIZATION OF SPEECH

Three-dimensional acoustic display systems have recently been develope d that synthesize virtual sound sources over headphones based on filte ring by head-related transfer functions (HRTFs), the direction-depende nt spectral changes caused primarily by the pinnae. In this study 11 i nexperienced subjects judged the apparent spatial location of headphon e-presented speech stimuli filtered with non-individualized HRTFs. Abo ut half of the subjects ''pulled'' their judgments toward either the m edian or the lateral-vertical planes, and estimates were almost always elevated. Individual differences were pronounced for the distance jud gments; 15% to 46% of stimuli were heard inside the head, with the sho rtest estimates near the median plane. The results suggest that most l isteners can obtain useful azimuth information from speech stimuli fil tered by nonindividualized HRTFs. Measurements of localization error a nd reversal rates are comparable with a previous study that used broad band noise stimuli.