ADAPTING TO SUPERNORMAL AUDITORY LOCALIZATION CUES - I - BIAS AND RESOLUTION

Head-related transfer functions (HRTFs) were used to create spatialize d stimuli for presentation through earphones. Subjects performed force d-choice, identification tests during which allowed response direction s were indicated visually. In each experimental session, subjects were first presented with auditory stimuli in which the stimulus HRTFs cor responded to the allowed response directions. The correspondence betwe en the HRTFs used to generate the stimuli and the directions was then changed so that response directions no longer corresponded to the HRTF s in the natural way. Feedback was used to train subjects as to which spatial cues corresponded to which of the allowed responses. Finally, the normal correspondence between direction and HRTFs was reinstated. This basic experimental paradigm was used to explore the effects of th e type of feedback provided, the complexity of the simulated acoustic scene, the number of allowed response positions, and the magnitude of the HRTF transformation subjects had to learn. Data showed that (1) al though subjects may not adapt completely to a new relationship between physical stimuli and direction, response bias decreases substantially with training, and (2) the ability to resolve different HRTFs depends both on the stimuli presented and on the state of adaptation of the s ubject. (C) 1998 Acoustical Society of America.