Underwater Hearing In Man: 3. An Investigation Of Underwater Sound Localization In Shallow And Noisy Water

Abstract

The ability of divers to discriminate the angular separation of two sound sources in the presence of high ambient noise in a reverberant environment was tested. In a first experiment it was found that divers could not discriminate directionality with separations as large as 90 degrees for low signal-to-noise ratios. However, when the signal-to-noise ratio was increased to about 19 dB, all four divers could discriminate a 30 degree angle with 100% accuracy. Two of the four divers could discriminate a 15 degree separation of sources. In a second experiment a procedure was used in which the angular separation between sound sources could be continuously varied between about 35 degrees and 1.4 degrees. Six divers were tested but the data for one diver was uninterpretable. For the remaining five divers the underwater minimum audible angle for a 46-Hz band of noise centered at 1 kHz varied between 2.7 degrees and 8.6 degrees over all trials. There was some suggestion in the data that experience in underwater listening enhances localization skills.