Auditory search asymmetry between pure tone and temporal fluctuating sounds distributed on the frontal-horizontal plane

Search asymmetry is useful for consideration of the primary features of the human cognitive system and has been intensively investigated in the visual domain. In this paper, search asymmetry in the auditory domain was examined for sound sources spatially distributed in the frontal-horizontal plane. The results clearly showed the existence of search asymmetry between pure tones and temporal fluctuating sounds such as narrow band noises, AM tones and FM tones. The reaction time required to detect a temporal fluctuating sound among distracting pure tones was less dependent on the number of components than the reaction time required to detect a pure tone among distracting temporally fluctuating sounds. These results suggest that the human auditory system utilizes temporal changes in amplitude and frequency of sound as a basic feature for the detection of target sounds in the presence of other sounds.