Median plane localization: dependence on spectral content

Abstract

Subjects were asked to report the elevation of noise stimuli differing in their spectral content. Some stimuli contained a single frequency band differing in center frequency and bandwidth; others contained multiple equal-amplitude frequency bands. All of the stimulus frequencies were in the range between 1 kHz and 16 kHz. Speakers were located in the median-sagittal plane at six frontal locations (−30, −15, 0, 15, 30, 45), as well as above (90) and behind (180) the listener. The experiments were conducted in a sound-treated room with the speakers concealed from view. Stimuli were 200 ms in duration and presented from only one speaker at a time. On each trial subjects used a pen to mark the perceived stimulus location(s) on a pre-printed coordinate diagram; subjects could indicate the perception of multiple sources and accurately represent auditory image widths and/or ambiguities. Preliminary data confirm historical results showing that localization of single noise bands depends on center frequency and bandwidth. When localizing multiple-band stimuli, responses depended on band density: with a few sparse bands, most subjects heard multiple source locations; for high band densities, subjects heard a single source at or near the true speaker location. [Work supported by NIDCD (R01 00100).]