Minimum audible angle and minimum audible movement angle in the median sagittal plane as a function of stimulus spectrum and reference elevation

Abstract

Minimum audible angle (MAA) and minimum audible movement angle (MAMA) were measured employing a pseudo-virtual method of stimulus presentation. All stimuli were digitally recorded through KEMAR’s two ears while he was positioned in an anechoic chamber with fixed and moving loudspeakers presenting sounds in his median sagittal plane; these recorded binaural stimuli were subsequently played through insert earphones to subjects seated in a darkened sound-insulated room. For the measurement of MAA, subjects had to say which of two stationary 300-ms sounds was higher in elevation; for the measurement of MAMA, subjects had to say whether a single moving sound moved up or down. Velocities in the MAMA experiment ranged from 20°/s to 150°/s. Stimuli were Gaussian noise bursts that were either wide band, 4-kHz low passed, or 4-kHz high passed. Reference elevation was either 0° or 45° elevation. Results will be discussed in terms of static and dynamic pinna cues that underlie elevation discrimination for high-frequency stimuli and the possible shoulder-bounce cue that may enable elevation discrimination for low-frequency stimuli. [Work supported by NIDCD 00185.]