BINAURAL DETECTION OF SONAR SIGNALS

Standard methods of presentation of sonar signals to operators have not maximized the capabilities of the auditory system. A dichotic method of sonar signal presentation to operators is described which is based on the masking-level-difference (MLD) principle in hearing. Twenty-six listeners of varied experience detected recorded broadband sonar targets and low-frequency pure tones that were embedded in 100 Hz - 4 kHz recorded and synthesized backgrounds. The signals were either homophasic or antiphasic and the backgrounds were always homophasic. Average detection thresholds for the antiphasic sonar signals were 5 - 7 dB better than their homophasic counterparts. Pure tone antiphasic detection thresholds were also 6 - 11 dB better than in the homophasic presentation. The sonar signals show similar MLD's as those found with speech signals.