Acuity of spatial stream segregation along the horizontal azimuth with non-individualized head-related transfer functions

Auditory spatial cues help the nervous system segregate features of a soundwave into distinct streams. To study this process, we must allot for changes in auditory spatial acuity along the horizontal azimuth, and some evidence suggests that this relationship differs for concurrent versus consecutive sounds. Here, we developed a paradigm to measure the change in spatial stream segregation along the horizontal azimuth and validate the effectiveness of non-individualized head-related transfer functions, the most easily-accessed form of auditory spatialization, in this procedure. We tested 18 normal-hearing adults using anthropometrically-matched non-individualized head-related transfer functions. We applied a spatial stream segregation task where participants identified the rhythm of a target stream presented with a spatially-separated masker. Spatial separation varied according to an adaptive staircase procedure, and thresholds were calculated both near the midline and in the far left periphery. This work will assist neuroscientists and others in the design of stimuli for eliciting brain activity related to spatial stream segregation.