ASA 127th Meeting M.I.T. 1994 June 6-10

3aPP14. Response measures used in free-field localization.

Mark A. Ericson

William D

Richard McKinley

AL/CFBA Bldg. 441, 2610 Seventh St., Wright-Patterson AFB, Dayton, OH 45433-7901

Two response measures, verbal spherical angles, and manual pointing, were compared in a free-field localization task. Verbal spherical angles refers to speaking the stimulus' azimuth and elevation angles with respect to the center of one's head. Manual pointing refers to pointing the stylus tip of an electromagnetic position digitizer onto a 12-in.-diam sphere and recording the azimuth and elevation of the tip with respect to the center of the sphere. Continuous visual and aural stimuli were presented from 272 directions around each of the five subjects, whose head motions were unrestrained. The accuracy and reaction times of the subjects were measured and compared. Pointing was more accurate than the verbal response, 10 and 22 deg, respectively. Pointing was about three times faster than the verbal response. The manual pointing technique is being used in other experiments to compare free-field and headphone localization performance.