Localization of frequency-separated bands of noise in the median plane

Abstract

Six subjects reported the perceived location of two sets of noise stimuli presented through speakers in the median-sagittal plane. Two sets of stimuli were generated by passing flat (1 to 16 kHz) Gaussian noise through multiple, equal-amplitude bandpass filters. The control stimulus included all frequencies between 1 and 16 kHz. The first set contained two to six equally spaced, 1/3-octave-wide noise bands. The second set contained five equally spaced noise bands that varied in common bandwidth. Loudspeakers in the medial-sagittal plane were located at six frontal locations (−30, −15, 0, 15, 30, 45, with 0 directly in front) and two rear locations (120, 180). The experiments were conducted in a sound-treated room with the speakers concealed from view. Stimuli were 200 ms in duration and presented from one speaker per trial. Subjects used a pen to mark perceived stimulus locations on preprinted coordinate diagrams. Despite noticeable intersubject differences, most subjects localized stimuli with five or six 1/3-octave-wide bands as well as control stimuli. Many subjects showed steady decreases in accuracy as the bandwidths of five bands were reduced. HRTFs were recorded for each listener, and several model algorithms are being evaluated. [Work supported by NIDCD: Grants R01 DC00100 and P30 DC04663.]