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Aug 2005

Volume 118, Issue 2, pp. 555-1220

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Optical and tomographic imaging of a middle ear malformation in the bullfrog (Rana catesbeiana)

Seth S. Horowitz, Andrea Megela Simmons, and Darlene R. Ketten

J. Acoust. Soc. Am. Volume 118, Issue 2, pp. 1166-1171 (2005); (6 pages)

Online Publication Date: 04 Aug 2005

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Using a combination of in vivo computerized tomography and histological staining, a middle ear anomaly in two wild-caught American bullfrogs (Rana catesbeiana) is characterized. In these animals, the tympanic membrane, extrastapes, and pars media (shaft) of the stapes are absent on one side of the head, with the other side exhibiting normal morphology. The pars interna (footplate) of the stapes and the operculum are present in their normal positions at the entrance of the otic capsule on both the affected and unaffected sides. The pattern of deformity suggests a partial failure of development of tympanic pathway tissues, but with a preservation of the opercularis pathway. While a definitive proximate cause of the condition could not be determined, the anomalies show similarities to developmental defects in mammalian middle ear formation.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing

Receiving beam patterns in the horizontal plane of a harbor porpoise (Phocoena phocoena)

Ronald A. Kastelein, Mirjam Janssen, Willem C. Verboom, and Dick de Haan

J. Acoust. Soc. Am. Volume 118, Issue 2, pp. 1172-1179 (2005); (8 pages) | Cited 14 times

Online Publication Date: 04 Aug 2005

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Receiving beam patterns of a harbor porpoise were measured in the horizontal plane, using narrow-band frequency modulated signals with center frequencies of 16, 64, and 100 kHz. Total signal duration was 1000 ms, including a 200 ms rise time and 300 ms fall time. The harbor porpoise was trained to participate in a psychophysical test and stationed itself horizontally in a specific direction in the center of a 16‐m-diameter circle consisting of 16 equally-spaced underwater transducers. The animal’s head and the transducers were in the same horizontal plane, 1.5 m below the water surface. The go∕no-go response paradigm was used; the animal left the listening station when it heard a sound signal. The method of constants was applied. For each transducer the 50% detection threshold amplitude was determined in 16 trials per amplitude, for each of the three frequencies. The beam patterns were not symmetrical with respect to the midline of the animal’s body, but had a deflection of 3–7° to the right. The receiving beam pattern narrowed with increasing frequency. Assuming that the pattern is rotation-symmetrical according to an average of the horizontal beam pattern halves, the receiving directivity indices are 4.3 at 16 kHz, 6.0 at 64 kHz, and 11.7 dB at 100 kHz. The receiving directivity indices of the porpoise were lower than those measured for bottlenose dolphins. This means that harbor porpoises have wider receiving beam patterns than bottlenose dolphins for the same frequencies. Directivity of hearing improves the signal-to-noise ratio and thus is a tool for a better detection of certain signals in a given ambient noise condition.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.66.Gf Detection and discrimination of sound by animals

A passive acoustic monitoring method applied to observation and group size estimation of finless porpoises

Kexiong Wang, Ding Wang, Tomonari Akamatsu, Songhai Li, and Jianqiang Xiao

J. Acoust. Soc. Am. Volume 118, Issue 2, pp. 1180-1185 (2005); (6 pages) | Cited 17 times

Online Publication Date: 04 Aug 2005

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The present study aimed at determining the detection capabilities of an acoustic observation system to recognize porpoises under local riverine conditions and compare the results with sighting observations. Arrays of three to five acoustic data loggers were stationed across the main channel of the Tian-e-zhou Oxbow of China’s Yangtze River at intervals of 100–150 m to record sonar signals of free-ranging finless porpoises (Neophocaena phocaenoides). Acoustic observations, concurrent with visual observations, were conducted at two occasions on 20–22 October 2003 and 17–19 October 2004. During a total of 42 h of observation, 316 finless porpoises were sighted and 7041 sonar signals were recorded by loggers. The acoustic data loggers recorded ultrasonic signals of porpoises clearly, and detected the presence of porpoises with a correct detection level of 77.6% and a false alarm level of 5.8% within an effective distance of 150 m. Results indicated that the stationed passive acoustic observation method was effective in detecting the presence of porpoises and showed potential in estimating the group size. A positive linear correlation between the number of recorded signals and the group size of sighted porpoises was indicated, although it is faced with some uncertainty and requires further investigation.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
43.80.Jz Use of acoustic energy (with or without other forms) in studies of structure and function of biological systems
43.66.Gf Detection and discrimination of sound by animals

The dependencies of phase velocity and dispersion on trabecular thickness and spacing in trabecular bone-mimicking phantoms

Keith A. Wear

J. Acoust. Soc. Am. Volume 118, Issue 2, pp. 1186-1192 (2005); (7 pages) | Cited 16 times

Online Publication Date: 04 Aug 2005

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Frequency-dependent phase velocity was measured in trabecular-bone-mimicking phantoms consisting of two-dimensional arrays of parallel nylon wires (simulating trabeculae) with thicknesses ranging from 152 to 305 μm and spacings ranging from 700 to 1000 μm. Phase velocity varied approximately linearly with frequency over the range from 400 to 750 kHz. Dispersion was characterized by the slope of a linear least-squares regression fit to phase velocity versus frequency data. The increase in phase velocity (compared with that in water) at 500 kHz was approximately proportional to the (1) square of trabecular thickness, (2) inverse square of trabecular spacing, and (3) volume fraction occupied by nylon wires. The first derivative of phase velocity with respect to frequency was negative and exhibited nonlinear, monotonically decreasing dependencies on trabecular thickness and volume fraction. The dependencies of phase velocity and its first derivative on volume fraction in the phantoms were consistent with those reported in trabecular bone.
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43.80.Qf Medical diagnosis with acoustics

Acoustic radiation from a fluid-filled, subsurface vascular tube with internal turbulent flow due to a constriction

Yigit Yazicioglu, Thomas J. Royston, Todd Spohnholtz, Bryn Martin, Francis Loth, and Hisham S. Bassiouny

J. Acoust. Soc. Am. Volume 118, Issue 2, pp. 1193-1209 (2005); (17 pages) | Cited 6 times

Online Publication Date: 04 Aug 2005

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The vibration of a thin-walled cylindrical, compliant viscoelastic tube with internal turbulent flow due to an axisymmetric constriction is studied theoretically and experimentally. Vibration of the tube is considered with internal fluid coupling only, and with coupling to internal-flowing fluid and external stagnant fluid or external tissue-like viscoelastic material. The theoretical analysis includes the adaptation of a model for turbulence in the internal fluid and its vibratory excitation of and interaction with the tube wall and surrounding viscoelastic medium. Analytical predictions are compared with experimental measurements conducted on a flow model system using laser Doppler vibrometry to measure tube vibration and the vibration of the surrounding viscoelastic medium. Fluid pressure within the tube was measured with miniature hydrophones. Discrepancies between theory and experiment, as well as the coupled nature of the fluid–structure interaction, are described. This study is relevant to and may lead to further insight into the patency and mechanisms of vascular failure, as well as diagnostic techniques utilizing noninvasive acoustic measurements.
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43.80.Qf Medical diagnosis with acoustics
43.40.Yq Instrumentation and techniques for tests and measurement relating to shock and vibration, including vibration pickups, indicators, and generators, mechanical impedance
43.40.Ey Vibrations of shells
43.20.Mv Waveguides, wave propagation in tubes and ducts

A model for estimating ultrasound attenuation along the propagation path to the fetus from backscattered waveforms

Timothy A. Bigelow and William D. O’Brien, Jr.

J. Acoust. Soc. Am. Volume 118, Issue 2, pp. 1210-1220 (2005); (11 pages) | Cited 3 times

Online Publication Date: 04 Aug 2005

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Accurate estimates of the ultrasound pressure and/or intensity incident on the developing fetus on a patient-specific basis could improve the diagnostic potential of medical ultrasound by allowing the clinician to increase the transmit power while still avoiding the potential for harmful bioeffects. Neglecting nonlinear effects, the pressure/intensity can be estimated if an accurate estimate of the attenuation along the propagation path (i.e., total attenuation) can be obtained. Herein, a method for determining the total attenuation from the backscattered power spectrum from the developing fetus is proposed. The boundaries between amnion and either the fetus’ skull or soft tissue are each modeled as planar impedance boundaries at an unknown orientation with respect to the sound beam. A mathematical analysis demonstrates that the normalized returned voltage spectrum from this model is independent of the planes orientation. Hence, the total attenuation can be estimated by comparing the location of the spectral peak in the reflection from the fetus to the location of the spectral peak in a reflection obtained from a rigid plane in a water bath. The independence of the attenuation estimate and plane orientation is then demonstrated experimentally using a Plexiglas plate, a rat’s skull, and a tissue-mimicking phantom.
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43.80.Ev Acoustical measurement methods in biological systems and media
43.80.Qf Medical diagnosis with acoustics
43.20.El Reflection, refraction, diffraction of acoustic waves
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