Echo Thresholds for a 3-D Loudspeaker Configuration

Echo thresholds were examined with differing stimuli, lag sound directions, and decision criteria in a 3D loudspeaker reproduction environment. Two tests were undertaken to examine two different criteria: echo threshold with fusion and echo threshold with complete separation, each with three stimuli (orchestral, pink noise burst, and speech) and six lag sound directions in total. An adapted method of adjustment was used by subjects to control the delay between the lead and lag loudspeakers. Results showed that there were significant differences in echo threshold when the decision criteria differed. The orchestral stimulus was found to be significantly different from the pink noise burst and speech in both criteria. Few significant differences were noted between angles. In general, echo thresholds were higher with lag sources located in the median plane.