Validating a rapid psychophysical procedure for estimating interaural time difference thresholds

The detection and discrimination of interaural time differences (ITDs) underpin many binaural abilities. Obtaining precise "threshold"-ITDs is, however, often quite time consuming. This study investigated the use of a rapid, descending series procedure to estimate threshold-ITDs. The procedure involves beginning with a suprathreshold ITD and then decreasing the ITD over sequential trials independent of response accuracy, ending with subthreshold ITDs. Normal hearing participants were tested using both an adaptive and descending series procedure. The results from the two procedures were comparable, while the descending series procedure required approximately half the time to complete as did the adaptive procedure. A function was determined for estimating ITD thresholds from the number of correct responses obtained with the descending series procedure. The results indicate that a descending series procedure is an efficient approach for estimating threshold-ITDs.