Moving sound source discrimination in humans: Mismatch negativity and psychophysics

The ability to discriminate moving sounds sources with different dynamic properties was studied in humans. Mismatch negativity was studied in an experiment on dichotic stimulation, with deviant stimuli simulating the instantaneous movement of the auditory image to the right or left of the head midline in the horizontal plane. Standard stimuli simulated continuous movement of the sound source to the right or to the left to the same angular distances. It was also established that both deviant stimuli caused mismatch negativity, its parameters being independent on the direction of sound movement. Psychophysical testing of the same group of subjects showed that discrimination between the stimuli was below the psychophysical threshold. The results obtained are discussed from the point of view of current theories of moving sound localization. The correlation between the objective and subjective levels of discrimination of moving auditory images are discussed.