title: Estimated source intensity and active space of the American alligator (Alligator Mississippiensis) vocal display.
abstract: 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.
authors.affiliation: Faculty of Life Science, Jackson's Mill, University of Manchester, Manchester M60 1QD, United Kingdom. neil.todd@manchester.ac.uk
authors.forename: Neil P McAngus
authors.initials: NP
authors.lastname: Todd
mesh_terms: 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
chemical_list: D014867:Water