Role of expectancy in front-back confusions during sound source localization

Abstract

Front-back confusions (FBCs) often occur in laboratory experiments. Stimulus complexity, especially for high-frequency sounds, and head motion significantly reduce FBCs, so that in the everyday world FBCs probably do not often influence sound source localization. There is a small literature suggesting that listeners “expectancies” (based on experience or other sensory inputs) for where sound sources might be also affect FBCs. A low-pass noise that produces a large number of FBCs and a high-pass noise that does not were used. Listeners indicated the location of sound sources on the azimuth plane. The study aimed to investigate FBCs and not sound source localization accuracy. For one condition, listeners were told that the noises would all be coming from in front, that in another condition from in back, and in a third condition from the full 360° azimuth circle. In the first (front) and second (back) conditions, most of the sounds came from the front or back respectfully, but 20% did not. The expectancy that sounds would be in front or in back had a large influence on FBCs as compared to when sounds were presented from the entire azimuth circle. (Work supported by grants from NIDCD and Oculus VR, LLC.)