The long‐range echolocation detection capability of an Atlantic Bottlenose dolphin, Tursiopstruncatus, in a noise‐limited environment was determined using a 7.62‐cm diam water‐filled sphere as the target. The 50% target detection threshold range was found to be 113 m. Using the transient form of the sonar equation, it was found that the results obtained with the 7.62‐cm sphere matched previous results obtained with a 2.54‐cm solid sphere and the same animal, to within 1.5 dB in terms of signal levels or within 5.4% in terms of ranges. The sonar equation was also used to obtain an estimate of the animal’s detection threshold, which was determined to be between 3.8–5.3 dB. The animal was found to perform like a Neyman–Pearson detector, limiting his false alarm rate to 23% and below.

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