Perception of spatial information in a multiple object auditory space

Auditory space produced by means of a Continuous Transmission Frequency Modulated (CTFM) wide beam wide band sonar has been used in a sensory aid for the blind for some time. Underwater sonar using this auditory space has also shown its increasing promise in fish finding applications. Yet, laboratory measurements on the perception of spatial information produced by this auditory display were conducted under stationary conditions only, and showed a poor resolution capability of subjects which is entirely unmatched with the observed performance of either the sensory aid user or the fishing sonar operator in his mobility or shoal tracking task. In this thesis, laboratory experiments using realistic system simulation are described which determine the ability of subjects to detect and resolve objects in space by auditory means under both static and dynamic conditions. Step by step investigation on the auditory perception of spatial information is approached from the very simple situation of two single stationary tones to the extremely complicated situation of two multiple component tones varying with respect to time in a noise contaminated auditory space. It is shown that the auditory resolution and detectability are significantly improved in the dynamic case, when the inputs to the subjects' ears are very rich in information. In addition to these experiments, theoretical study on the auditory display, the sonar system and several related factors are also extensively developed in this thesis