Dolphin hearing: Relative sensitivity as a function of point of application of a contact sound source in the jaw and head region

The auditory input area of the dolphin head was investigated in an unrestra ined animal trained to beach itself and to accept noninvasive electroenceph alograph (EEG) electrodes for the recording of the auditory brain-stem resp onse (ABR). The stimulus was a synthetic dolphin click, transmitted from a piezo-electric transducer and coupled to the skin via a small volume of wat er. The results conform with earlier experiments on acute preparations that show best auditory sensitivity at the middle of the lower jaw. Minimum lat ency was found at the rear of the lower jaw. A shaded receiver configuratio n for the dolphin ear is proposed. (C) 1999 Acoustical Society of America. [S0001-4966(99)05606-4].