Estimated source intensity and active space of the American alligator (Alligator Mississippiensis) vocal display.
In this article the results are reported of a study to measure the intensity of the vocal displays of a population of American alligators (Alligator mississippiensis). It was found that the dominant frequencies in air range between 20 and 250 Hz with a source sound pressure level (SPL) of 91-94 dB at 1 m. The active space for the air-borne component is defined by the background and was estimated to be in a range up to 159 m in the 125-200 Hz band. For the water-borne component the dominant frequency range was 20-100 Hz with a source SPL of 121-125 dB at 1 m. The active space in water is defined by hearing thresholds and was estimated to range up to 1.5 km in the 63-100 Hz band. In the lowest frequency bands, i.e., 16-50 Hz, the estimated active space for otolith detection of near-field particle motion in water ranged to 80 m, which compared significantly with far-field detection for these frequencies. It is suggested that alligator vocal communication may involve two distinct sensory mechanisms which may subserve the functions of scene analysis and reproduction, respectively.
Todd
Neil P McAngus
NP
Faculty of Life Science, Jackson's Mill, University of Manchester, Manchester M60 1QD, United Kingdom. neil.todd@manchester.ac.uk
D000388:Air; D000489:Alligators and Crocodiles; D000818:Animals; D001309:Auditory Threshold; D008297:Male; D008962:Models, Theoretical; D009622:Noise; D013018:Sound Spectrography; D014828:Vocalization, Animal; D014867:Water
D014867:Water