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Journal of the Acoustical Society of America

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May 2008

Volume 123, Issue 5, pp. 2443-EL120

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Suppression of shocked-bubble expansion due to tissue confinement with application to shock-wave lithotripsy

Jonathan B. Freund

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2867-2874 (2008); (8 pages) | Cited 6 times

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Estimates are made of the effect of tissue confinement on the response of small bubbles subjected to lithotriptor shock pressures. To do this the Rayleigh–Plesset equation, which governs the dynamics of spherical bubbles, is generalized to treat a bubble in a liquid region (blood), which is in turn encased within an elastic membrane (like a vessel’s basement membrane), beyond which a Voigt viscoelastic material models the exterior tissue. Material properties are estimated from a range of measurements available for kidneys and similar soft tissues. Special attention is given to the constitutive modeling of the basement membranes because of their expected importance due to their proximity to the bubble and their toughness. It is found that the highest expected values for the elasticity of the membrane and surrounding tissue are insufficient to suppress bubble growth. The reduced confinement of a cylindrical vessel should not alter this conclusion. Tissue viscosities taken from ultrasound measurements suppress bubble growth somewhat, though not to a degree expected to resist injury. However, the higher reported viscosities measured by other means, which are arguably more relevant to the deformations caused by growing bubbles, do indeed significantly suppress bubble expansion.
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43.80.Gx Mechanisms of action of acoustic energy on biological systems: physical processes, sites of action
43.35.Wa Biological effects of ultrasound, ultrasonic tomography
43.40.Ng Effects of vibration and shock on biological systems, including man

Mathematics of pulsed vocalizations with application to killer whale biphonation

Judith C. Brown

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2875-2883 (2008); (9 pages) | Cited 3 times

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Formulas for the spectra of pulsed vocalizations for both the continuous and discrete cases are rigorously derived from basic formulas for Fourier analysis, a topic discussed qualitatively in Watkins’ classic paper on “the harmonic interval” [“The harmonic interval: Fact or artifact in spectral analysis of pulse trains,” in Marine Bioacoustics 2, edited by W. N. Tavogla (Pergamon, New York, 1967), pp. 15–43] . These formulas are summarized in a table for easy reference, along with most of the corresponding graphs. The case of a “pulse tone” is shown to involve multiplication of two temporal wave forms, corresponding to convolution in the frequency domain. This operation is discussed in detail and shown to be equivalent to a simpler approach using a trigonometric formula giving sum and difference frequencies. The presence of a dc component in the temporal wave form, which implies physically that there is a net positive pressure at the source, is discussed, and examples of the corresponding spectra are calculated and shown graphically. These have application to biphonation (two source signals) observed for some killer whale calls and implications for a source mechanism. A MATLAB program for synthesis of a similar signal is discussed and made available online.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar

Broadband backscatter from individual Hawaiian mesopelagic boundary community animals with implications for spinner dolphin foraging

Whitlow W. L. Au and Kelly J. Benoit-Bird

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2884-2894 (2008); (11 pages) | Cited 3 times

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Broadband simulated dolphin echolocation signals were used to measure the ex situ backscatter properties of mesopelagic boundary community (MBC) in order to gain a better understanding of the echolocation process of spinner dolphins foraging on the MBC. Subjects were captured by trawling with a 2-m-opening Isaacs-Kidd Midwater Trawl. Backscatter measurements were conducted on the ship in a 2000 L seawater tank with the transducer placed on the bottom pointed upwards. Backscatter measurements were obtained in both the dorsal and lateral aspects for seven myctophids and only in the dorsal aspect for 16 more myctophids, six shrimps, and three squids. The echoes from the myctophids and shrimps usually had two highlights, one from the surface of the animal nearest the transducer and a second probably from the signal propagating through body of the subject and reflecting off the opposite surface of the animal. The squid echoes consisted mainly of a single highlight but sometimes had a low amplitude secondary highlight. The backscatter results were used to estimate the echolocation detection range for spinner dolphins foraging on the mesopelagic boundary community. The results were also compared with multi-frequency volume backscatter of the mesopelagic boundary community sound scattering layer.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
43.30.Sf Acoustical detection of marine life; passive and active
43.30.Ft Volume scattering
43.20.Fn Scattering of acoustic waves

The structure of vocal sounds produced with the mouth closed or with the mouth open in treefrogs

Marcos Gridi-Papp

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2895-2902 (2008); (8 pages)

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Frogs and toads mostly call with their mouths shut, unlike many other vertebrates. Sound is generated when air crosses the larynx, but there is no direct airflow to the external environment and radiation occurs at the skin. This study directly compares the acoustic output obtained from euthanized frogs with the mouth open against the output obtained with the mouth closed during activation of the larynx by airflow. With the mouth closed, the vocal sac was inflated and the acoustic energy was concentrated in the same harmonics as in the advertisement call, whereas with the mouth open, energy was spread in a wide range of harmonics. The acoustic output at the dominant frequency was more intense with the mouth closed than with the mouth open. More sound was radiated through the vocal sac and head than through the rest of the body. The spectral differences between open and closed mouth treatments matched the differences observed between natural advertisement calls, produced with the mouth closed, and distress calls, produced with the mouth open. By calling with the mouth closed, treefrogs can potentially produce advertisement calls with the energy concentrated in a narrower frequency range than with the mouth open.
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43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
43.64.Tk Physiology of sound generation and detection by animals

Human listeners attend to size information in domestic dog growls

Anna M. Taylor, David Reby, and Karen McComb

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2903-2909 (2008); (7 pages) | Cited 1 time

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The acoustic features of vocalizations have the potential to transmit information about the size of callers. Most acoustic studies have focused on intraspecific perceptual abilities, but here, the ability of humans to use growls to assess the size of adult domestic dogs was tested. In a first experiment, the formants of growls were shifted to create playback stimuli with different formant dispersions (Δf), simulating different vocal tract lengths within the natural range of variation. Mean fundamental frequency (F0) was left unchanged and treated as a covariate. In a second experiment, F0 was resynthesized and Δf was left unchanged. In both experiments Δf and F0 influenced how participants rated the size of stimuli. Lower formant and fundamental frequencies were rated as belonging to larger dogs. Crucially, when F0 was manipulated and Δf was natural, ratings were strongly correlated with the actual weight of the dogs, while when Δf was varied and F0 was natural, ratings were not related to the actual weight. Taken together, this suggests that participants relied more heavily on Δf, in accordance with the fact that formants are better predictors of body size than F0.
Show PACS
43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar
43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.71.Bp Perception of voice and talker characteristics

Carrier-dependent temporal processing in an auditory interneuron

Patrick Sabourin, Heather Gottlieb, and Gerald S. Pollack

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2910-2917 (2008); (8 pages)

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Signal processing in the auditory interneuron Omega Neuron 1 (ON1) of the cricket Teleogryllus oceanicus was compared at high- and low-carrier frequencies in three different experimental paradigms. First, integration time, which corresponds to the time it takes for a neuron to reach threshold when stimulated at the minimum effective intensity, was found to be significantly shorter at high-carrier frequency than at low-carrier frequency. Second, phase locking to sinusoidally amplitude modulated signals was more efficient at high frequency, especially at high modulation rates and low modulation depths. Finally, we examined the efficiency with which ON1 detects gaps in a constant tone. As reflected by the decrease in firing rate in the vicinity of the gap, ON1 is better at detecting gaps at low-carrier frequency. Following a gap, firing rate increases beyond the pre-gap level. This “rebound” phenomenon is similar for low- and high-carrier frequencies.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing

The frequency response of rat vibrissae to sound

Lisa F. Shatz and Craig W. Christensen

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2918-2927 (2008); (10 pages)

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The motion of isolated rat vibrissae due to low frequency sound has been modeled and measured with good agreement (within a factor of 2) between the data and the model’s predictions. As had been done in previous studies on the response of rat vibrissae to tactile stimulation [ Hartmann, M. J., Johnson, N. J., Towal, R. B., and Assad, C., J. Neurosci 23, 6510–6519 (2003) and Neimark, M. A., Andermann, A. L., Hopfield, J. J., and Moore, C. I., J. Neurosci 23, 6449–6509 (2003) ] the vibrissae were modeled as thin conical beams. The force of the vibrating air on a vibrissa was modeled using the exact solution for a vibrating infinite cylinder in linear fluid. A finite element method was used to model the motion of a single vibrissa fixed at its base, using the aforementioned fluid force. Values for Young’s modulus and vibrissa mass density were taken from a previous study [Neimark et al. (above)]. The model had no freely fitted parameters. Motion of isolated vibrissae was measured using a video camera with microscope. The sound stimulation was created using a stereo speaker connected to a signal generator. The tuning was found to be sharp, with quality factors that varied between 3 and 7, much sharper than the motion of cricket cercal hairs or in vitro inner ear hair bundles.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.20.Ks Standing waves, resonance, normal modes
43.40.Cw Vibrations of strings, rods, and beams
43.20.Tb Interaction of vibrating structures with surrounding medium

Frequency and level dependent masking of the multiple auditory steady-state response in the bottlenose dolphin (Tursiops truncatus)

Brian K. Branstetter, James J. Finneran, and Dorian S. Houser

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2928-2935 (2008); (8 pages)

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The potential for interactions between steady-state evoked responses to simultaneous auditory stimuli was investigated in two bottlenose dolphins (Tursiops truncatus). Three experiments were conducted using either a probe stimulus (probe condition) or a probe in the presence of a masker (probe-plus-masker condition). In the first experiment, the probe and masker were sinusoidal amplitude-modulated (SAM) tones. Probe and masker frequencies and masker level were manipulated to provide variable masking conditions. Probe frequencies were 31.7, 63.5, 100.8, and 127.0 kHz. The second experiment was identical to the first except only the 63.5 kHz probe was used and maskers were pure tones. For the third experiment, thresholds were measured for the probe and probe-plus-masker conditions using two techniques, one based on the lowest detectable response and the other based on a regression analysis. Results demonstrated localized masking effects where lower frequency maskers suppressed higher frequency probes and higher amplitude maskers produced a greater masking effect. The pattern of pure tone masking was nearly identical to SAM tone masking. The two threshold estimates were similar in low masking conditions, but in high masking conditions the lowest detectable response tended to overestimate thresholds while the regression-based analysis tended to underestimate thresholds.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.64.Ri Evoked responses to sounds
43.66.Dc Masking
43.66.Gf Detection and discrimination of sound by animals

Effect of combined source (F0) and filter (formant) variation on red deer hind responses to male roars

Benjamin D. Charlton, David Reby, and Karen McComb

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2936-2943 (2008); (8 pages)

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Studying female response to variation in single acoustic components has provided important insights into how sexual selection operates on male acoustic signals. However, since vocal signals are typically composed of independent components, it is important to account for possible interactions between the studied parameter and other relevant acoustic features of vocal signals. Here, two key components of the male red deer roar, the fundamental frequency and the formant frequencies (an acoustic cue to body size), are independently manipulated in order to examine female response to calls characterized by different combinations of these acoustic components. The results revealed that red deer hinds showed greater overall attention and had lower response latencies to playbacks of roars where lower formants simulated larger males. Furthermore, female response to male roars simulating different size callers was unaffected by the fundamental frequency of the male roar when it was varied within the natural range. Finally, the fundamental frequency of the male roar had no significant separate effect on any of the female behavioral response categories. Taken together these findings indicate that directional intersexual selection pressures have contributed to the evolution of the highly mobile and descended larynx of red deer stags and suggest that the fundamental frequency of the male roar does not affect female perception of size-related formant information.
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43.80.Lb Sound reception by animals: anatomy, physiology, auditory capacities, processing
43.80.Ka Sound production by animals: mechanisms, characteristics, populations, biosonar

Shape-based ultrasound tomography using a Born model with application to high intensity focused ultrasound therapy

Başak Ülker Karbeyaz, Eric L. Miller, and Robin O. Cleveland

J. Acoust. Soc. Am. Volume 123, Issue 5, pp. 2944-2956 (2008); (13 pages)

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A shaped-based ultrasound tomography method is proposed to reconstruct ellipsoidal objects using a linearized scattering model. The method is motivated by the desire to detect the presence of lesions created by high intensity focused ultrasound (HIFU) in applications of cancer therapy. The computational size and limited view nature of the relevant three-dimensional inverse problem renders impractical the use of traditional pixel-based reconstruction methods. However, by employing a shape-based parametrization it is only necessary to estimate a small number of unknowns describing the geometry of the lesion, in this paper assumed to be ellipsoidal. The details of the shape-based nonlinear inversion method are provided. Results obtained from a commercial ultrasound scanner and a tissue phantom containing a HIFU-like lesion demonstrate the feasibility of the approach where a 20 mm×5 mm×6 mm ellipsoidal inclusion was detected with an accuracy of around 5%.
Show PACS
43.80.Sh Medical use of ultrasonics for tissue modification (permanent and temporary)
43.20.Fn Scattering of acoustic waves
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Bi Mathematical theory of wave propagation
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