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Journal of the Acoustical Society of America

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May 2010

Volume 127, Issue 5, pp. EL179-3296

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Time and frequency parameters of bottlenose dolphin whistles as predictors of surface behavior in the Mississippi Sound

Erica N. Hernandez, Moby Solangi, and Stan A. Kuczaj, II

J. Acoust. Soc. Am. Volume 127, Issue 5, pp. 3232-3238 (2010); (7 pages)

Online Publication Date: 12 May 2010

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Acoustic characteristics related to contour of the whistle (such as highest and lowest frequency, beginning and ending frequency, whistle duration, and number of turns) of bottlenose dolphin (Tursiops truncatus) whistles were measured to test whether any of the measurements were related to the behavioral state of the dolphins when the whistle was recorded (coded as mill, travel, mill/travel, feed, or social). Objective measures of time and frequency were obtained using Raven, while number of turns in a whistle was determined by human raters. In all a series of discriminant function analyses using the acoustic characteristics to predict the behavioral state, the highest standardized canonical discriminant function coefficients were: lowest frequency, number of turns, and duration. The models that incorporated these variables performed significantly better than chance at correctly assigning the whistles into the surface behavior category in which they were recorded. The rate of whistling was related to group size, surface behavior and season via a series of two-way ANOVAs (analysis of variance).
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar

Measuring inter-pulse intervals in sperm whale clicks: Consistency of automatic estimation methods

Ricardo Antunes, Luke Rendell, and Jonathan Gordon

J. Acoust. Soc. Am. Volume 127, Issue 5, pp. 3239-3247 (2010); (9 pages)

Online Publication Date: 12 May 2010

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Sperm whale clicks are characterized by a multi-pulsed structure. The time lag between consecutive pulses, i.e., the inter-pulse interval (IPI), is related to the size of the sound production organ such that its measurement provides a means to acoustically estimate the size of individual whales. Due to off-axis effects the identification of pulses is, however, not always straightforward, and automatic measurement methods provide not only more objective estimation, but may also facilitate IPI estimation in cases where single click measurements are ambiguous. In particular, averaging measurements over a time series of clicks from the same whale could enhance the discrimination of time invariant pulses. The authors developed two automatic methods of automatic IPI measurement based on waveform and autocorrelation averaging and compared their accuracy and consistency with other previously used methods. Manual measurement by an experienced operator provided the most self-consistent estimates. The autocorrelation averaging technique had the best overall performance of the automated methods achieving a very similar performance to manual measurement. On some recordings cepstrum averaging methods converged when autocorrelation did not. Therefore, applying both of these automated methods and choosing the best of the two are recommended.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
43.80.Ev Acoustical measurement methods in biological systems and media
43.30.Sf Acoustical detection of marine life; passive and active

A description of sounds recorded from melon-headed whales (Peponocephala electra) off Hawai‘i

Adam S. Frankel and Suzanne Yin

J. Acoust. Soc. Am. Volume 127, Issue 5, pp. 3248-3255 (2010); (8 pages)

Online Publication Date: 12 May 2010

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Between 2004 and 2006, large groups of melon-headed whales were recorded off the Big Island of Hawai‘i. No other odontocete species were sighted in these groups. Recordings contained echolocation clicks, burst-pulse sounds, and whistles. Echolocation clicks typically contained energy beginning at 13 kHz and continued strongly to the frequency cutoff of the recording system, suggesting that the frequency content of the clicks continued well beyond 24 kHz. Burst-pulse sounds were typically short, with a mean duration of 586 ms with a mean inter-pulse interval of 2.47 ms. The distribution of numbers of pulses was skewed toward fewer pulses, with a mean of 46.7 pulses. Overall, whistles were relatively simple frequency-modulated downsweeps, upsweeps, and sinusoidal signals. Fundamental frequencies ranged from 890 Hz to 23.5 kHz. Most whistles had smooth contours, although frequency steps were observed. Whistles were generally short, with a mean duration of 586 ms. The acoustic characteristics of these whistles were similar to those in the only previously published descriptions of melon-headed whale vocalizations [ Watkins et al. (1997). Caribbean J. Sci. 33, 34–40 ; Janik and Curran (2007). 17th Biennial Conference on the Biology of Marine Mammals, Capetown, South Africa ] and were shown to be distinguishable from whistles of other odontocete species.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
43.30.Nb Noise in water; generation mechanisms and characteristics of the field

Growth and recovery of temporary threshold shift at 3 kHz in bottlenose dolphins: Experimental data and mathematical models

James J. Finneran, Donald A. Carder, Carolyn E. Schlundt, and Randall L. Dear

J. Acoust. Soc. Am. Volume 127, Issue 5, pp. 3256-3266 (2010); (11 pages) | Cited 9 times

Online Publication Date: 12 May 2010

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Measurements of temporary threshold shift (TTS) in marine mammals have become important components in developing safe exposure guidelines for animals exposed to intense human-generated underwater noise; however, existing marine mammal TTS data are somewhat limited in that they have typically induced small amounts of TTS. This paper presents experimental data for the growth and recovery of larger amounts of TTS (up to 23 dB) in two bottlenose dolphins (Tursiops truncatus). Exposures consisted of 3-kHz tones with durations from 4 to 128 s and sound pressure levels from 100 to 200 dB re 1 μPa. The resulting TTS data were combined with existing data from two additional dolphins to develop mathematical models for the growth and recovery of TTS. TTS growth was modeled as the product of functions of exposure duration and sound pressure level. TTS recovery was modeled using a double exponential function of the TTS at 4-min post-exposure and the recovery time.
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43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing

Temporary threshold shift in a bottlenose dolphin (Tursiops truncatus) exposed to intermittent tones

James J. Finneran, Donald A. Carder, Carolyn E. Schlundt, and Randall L. Dear

J. Acoust. Soc. Am. Volume 127, Issue 5, pp. 3267-3272 (2010); (6 pages) | Cited 4 times

Online Publication Date: 12 May 2010

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Temporary threshold shift (TTS) was measured in a bottlenose dolphin exposed to a sequence of four 3-kHz tones with durations of 16 s and sound pressure levels (SPLs) of 192 dB re 1 μPa. The tones were separated by 224 s of silence, resulting in duty cycle of approximately 7%. The resulting growth and recovery of TTS were compared to experimentally measured TTS in the same subject exposed to single, continuous tones with similar SPLs. The data confirm the potential for accumulation of TTS across multiple exposures and for recovery of hearing during the quiet intervals between exposures. The degree to which various models could predict the growth of TTS across multiple exposures was also examined.
Show PACS
43.80.Nd Effects of noise on animals and associated behavior, protective mechanisms
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
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