ACCURACY VERSUS CHOICE RESPONSE-TIME IN SOUND LOCALIZATION

An experiment was conducted to further explore sound localization for frontal sound incidence. The question of interest was whether two resp onse measures, accuracy in loudspeaker identification and choice respo nse time would be differentially affected by variation in three parame ters. These were the number Of loudspeakers (three, five and seven), t he separation between speakers (15 degrees versus 30 degrees), and sti mulus frequency (500 versus 4000 Hz). Twelve normal-hearing subjects w ere tested in a semi-reverberant room that modelled real-world listeni ng. Each was presented 12 blocks of listening trials, across ,which th e 12 conditions were presented in random order. A block comprised 20 r andom presentations of a 300-ms one-third octave noise band from each speaker. Subjects responded using a set of microswitches in the same c onfiguration as the loudspeaker array. Accuracy decreased as the numbe r of speakers increased and their separation decreased. Response time increased with number but was unaffected by separation. The effect of frequency was relatively small. A two-stage conceptual model, consisti ng of sensory encoding and non-sensory decision-making, provided a rea sonable framework for the results. (C) 1997 Elsevier Science Ltd.