Abstract:

A line array of three hydrophones with a video camera attached to the array was used to measure the echo location signals of wild Atlantic Spotted Dolphins. The separation distance between hydrophones in the array was 30 cm. The array was attached to a float that supported an amplifier--line driver assembly with the signals sent via a 76-m multi-conductor cable back to the support boat. The float and array assembly was oriented by a swimmer. The echo location signals from the hydrophone were digitized simultaneously at a sample rate of 500 kHz. Twenty files of echo location click trains were collected with the quality of the data varying from poor (files with lots of whistles and off-axis signals) to very good. The on-axis signals typically had a bimodal spectrum with a low-frequency peak at 45--60 Hz and a high-frequency peak at 120--140 kHz. Peak-to-peak source levels up to 210 dB re: 1 (mu)Pa were measured. The rms bandwidth varied between 32 and 46 kHz, with a cluster around 40 kHz.