bluuebunny/crossref_metadata_2025 huggingface dataset:
Phoneme contrasts with two, same-talker speakers
Authors: Ericson Mark , Mishler Pamela
Published: October 2013

People often have difficulty hearing speech in the presence of concurrent conversations. This well-known cocktail-party effect can be parsed into energetic and informational masking effects. The purpose of this study was to measure and model the effects of energetic and informational masking that occur when two words, spoken by the same talker are heard at the same time. The word identification test used in the experiments was the Modified Rhyme Test (MRT). The MRT was used as both the stimulus and the masker, which afforded a multitude of consonant contrasts. The phrases were presented monaurally at 75 dB SPL over Sennheiser HD-520 headphones to four normal hearing listeners. The independent variables included 30 pairs of MRT word lists spoken by three male and three female talkers. The dependent variable was the percent correct identifications of the two consonants. Listeners performed at 94% correct for the first word choice and 72% correct for the second word choice. The distribution of errors was analyzed by place of articulation, manner of articulation, and speech-to-speech-ratio of the phoneme pairs and compared to articulation index predictions for speech intelligibility.
Cancelled harmonics—How high does the effect go?
Authors: Goupell Matthew J. , Zhang Peter Xinya , Hartmann William M.
Published: October 2013

Demonstration Number 1 in the IPO-NIU-ASA collection of auditory demonstrations (compact disk) periodically cancels and reinserts a harmonic of a complex tone having a 200-Hz fundamental and 20 equal-amplitude harmonics. This procedure causes a listener to hear out the manipulated harmonic as a separate tone. In this way, the demonstration exposes harmonics 1 through 10. The following question arises: What is the highest harmonic that can be made audible, and what is responsible for the limitation? Listening experiments, using random harmonic phases, fundamental frequencies (f0) from 50 to 2000 Hz, and a maximum harmonic frequency of 20 kHz, show that for high fundamental frequencies (f0>200 Hz) the highest audible harmonic frequency is insensitive to f0 and is only about 10 percent less than the highest audible sine frequency in quiet. For lower fundamental frequencies, the highest audible harmonic number tends to be insensitive to f0 and is 50–70 for normal hearing listeners. In this region the highest audible harmonic number can be predicted from noise-masked threshold data, but with a large uncertainty. [Work supported by NIDCD.]
Vibration of fluid-loaded hemi-prolate spheroidal shells
Authors: Boisvert Jeffrey E. , Hayek Sabih I.
Published: October 2013

The equations of motion for nonaxisymmetric vibration of hemi-prolate spheroidal shells of constant thickness were derived using Hamilton’s principle. The shell is clamped at the equator and is excited by mechanical surface force fields. The shell theory used in this derivation includes shear deformations and rotatory inertias. The displacements and rotations were expanded in an infinite series of comparison functions. The shell is fluid-filled and is submerged in an infinite fluid medium. The external and internal fluid loading impedances were computed using expansions of prolate spheroidal wavefunctions in each domain. The dynamic response of the fluid-loaded shell was determined using an axisymmetric normal surface force as the excitation input. Numerical results were obtained for the driving and transfer mobilities for several shell thickness-to-length ratios ranging from 0.005 to 0.1, and for various shape parameters, ‘‘a,’’ ranging from an elongated hemi-spheroidal shell (a=1.01) to a hemispherical shell (a=100). Results are presented for various combinations of external and internal fluid loading, and comparisons are made to the in-vacuo shell vibration. [Work supported by ONR and the Navy/ASEE Summer Faculty Program.]
How can one tell if noisy frequency response data contain a modal contribution?
Authors: Moloney Christopher W. , Ginsberg Jerry H.
Published: October 2013

A key question that arises in some techniques for experimental modal analysis is whether coherent modal information is buried within a frequency band of complex frequency response data. This question is especially problematic if the data are contaminated by a substantial level of noise. Furthermore, some identification algorithms introduce small anomalies to the data in the course of processing. To explore techniques for resolving this issue frequency response data for a one-degree-of-freedom system is generated analytically and contaminated with various levels of white noise. Five statistical measures are computed for a sequence of bands that are obtained by forming overlapping halves of the previous frequency bands. The five measures are the expected value, mean-square, and variance of the frequency response in each band, as well as eigen-analysis of the autocorrelation matrix and wavelet decomposition. Graphical results are presented and discussed, and an analytical assessment method is proposed.
Buried target detection with a synthetic aperture sonar
Authors: Piper John
Published: October 2013

Synthetic aperture sonar (SAS) systems can provide the high resolution and high signal-to-noise ratios that are important in detecting buried targets. Previous experiments with the Coastal Systems Station SAS have shown good results for above critical grazing angle targets and mixed results for below critical angle targets. Interest in characterizing the environmental conditions, which can allow detection at sub-critical angles, has prompted additional SAS testing. This paper describes a buried target experiment that included two 1.5-meter by 0.5-meter cylindrical targets, one 35-cm silicon-fluid-filled sphere, and two 58-cm air-filled spheres. These targets were buried under sandy sediment in 17 meters of water approximately 1 mile offshore from Panama City Beach, Florida. Above critical angle and below critical angle runs were made during November 2001 and June 2002. Environmental conditions and the seafloor ripple structure were reported by divers and, during the 2002 experiment, measured by the Applied Physics Laboratory/University of Washington with their second-generation in situ measurement of porosity (IMP2) instrumentation.
Teaching acoustics courses online
Authors: Burroughs Courtney B.
Published: October 2013

Three graduate-level courses in noise control engineering have been taught by the Graduate Program in Acoustics through the Penn State World Campus for more than four years. In each course, students receive (1) a study guide which gives an overview of the course, the software, and assignments, and (2) a CD which contains the content of the course with animations embedded in the text. Because all communications are online, students have been able to take these courses asynchronously on their own schedule with minimum disruptions in their home and work schedules. Students work on group projects, known as collaborative learning activities, and conduct simulated measurements using virtual instruments. Individual learning activities include study questions, written problems, computer coding, and interactive demonstrations. The first course has been offered four times and several students have completed all three courses. Overviews of the elements of these online courses that have been successful and the elements that have presented problems, along with a discussion of adjustments that we have been able to make and those that we would like to make to improve the courses, will be presented.
Localization of dolphin whistles through frequency domain beamforming using a narrow aperture audio/video array
Authors: Ball Keenan R. , Buck John R.
Published: October 2013

Correlating the acoustic and physical behavior of marine mammals is an ongoing challenge for scientists studying the links between acoustic communication and social behavior of these animals. This talk describes a system to record and correlate the physical and acoustical behavior of dolphins. A sparse, short baseline audio/video array consisting of 16 hydrophones and an underwater camera was constructed in a cross configuration to measure the acoustic signals of vocalizing dolphins. The bearings of vocalizing dolphins were estimated using the broadband frequency domain beamforming algorithm for sparse arrays to suppress grating lobes of Thode et al. [J. Acoust. Soc. Am. 107 (2000)]. The estimated bearings from the acoustic signals were then converted to video image coordinates and a marker was placed on the video image. The system was calibrated both at an indoor tank and from an outdoor dock at UMass Dartmouth prior to field tests in a natural lagoon at the Dolphin Connection on Duck Key, FL. These tests confirmed that the system worked well within the limits of underwater visibility by consistently placing the marker on or near the whistling or echolocating dolphin. [Work supported by NSF Ocean Sciences.]
Study of a scanning HIFU therapy protocol, Part I: Theory and simulations
Authors: Kargl Steven G. , Andrew Marilee A.
Published: October 2013

Over the last several years, many researchers have compared model predictions of isolated thermal lesions, caused by acoustic fields generated from (spherically) focused transducers, to thermal lesions created in tissue phantoms, in vitro soft tissue samples, and in vivo soft tissue samples. The models typically couple a nonlinear acoustic field from a focused transducer to the bio-heat transfer equation (BHTE). Recent experiments in polyacrylamide gel phantoms and excised bovine liver samples have demonstrated the possible deposition of thermal lesions in a scanning mode. An initial modeling effort to predict scanned thermal lesions will be discussed. The nonlinear acoustic field from a spherically focused transducer is predicted by a time–domain solution of the Khokhlov–Zabolotskaya–Kuznetsov equation. This field is then used as a heat source in the BHTE. The importance of scan rate, acoustic frequency, and time-averaged intensity will be investigated. [Work supported by USAMRMC.]
Fast calculations of the exact nearfield produced by a circular piston
Authors: McGough Robert J. , Samulski Thaddeus V.
Published: October 2013

The computation time and the numerical error are both reduced substantially with an improved technique that calculates the nearfield pressure produced by a circular piston. A comparison of simulation results shows that, once the errors for all results are normalized, this new technique is at least 3 to 4 times faster than the impulse response approach of Oberhettinger and Stepanishen. Further improvements are obtained when the computational grid is divided into sectors defined by the angle between the coordinates of each field point and the normal evaluated at the center of the circular piston. The sector number is then converted through a linear function to a value that specifies the sampling of the integrand. When continuous wave excitations are applied to a simulated piston with a radius of five wavelengths, the resulting computations verify that this sectoring scheme reduces the computation time by an additional factor of 2 without increasing the maximum error value. These fast calculations are especially useful in numerical simulations for thermal therapy, where pressure fields are computed in large volumes for arrays with multiple sources.
Estimating ‘‘true’’ HIFU-induced temperature changes using thermocouples
Authors: Yang Xinmai , Roy Ronald A. , Holt R. Glynn
Published: October 2013

An easy and economical way to measure temperature rises in tissue and tissue-mimicking phantoms is with imbedded thermocouples. However, a thermocouple undergoing HIFU exposure is subject to the formation of a viscous boundary layer, leading to an additional local temperature rise not experienced by the rest of the focal region. The resulting temperature measurement is then not indicative of the average undisturbed temperature in the region. This is the so-called thermocouple artifact (we will argue against the use of the word artifact). Motivated by our bubble-enhanced heating experiments, we present a simple method for estimating HIFU-induced temperature changes. The influence of the thermocouple is modeled by an effective increase in the local sound absorption coefficient. The effective absorption coefficient is estimated by measuring the increased rate of heating brought on by the thermocouple. The temperature rise in the medium adjacent to the thermocouple is then predicted by incorporating the effective local absorption into the acoustic source term in the 3D heat conduction equation. Comparisons between simulation and experiment and between the reported method and other methods for thermocouple-artifact correction are presented. [Work supported by the U.S. Army.]
Monitoring evolution of HIFU-induced lesions with backscattered ultrasound
Authors: Anand Ajay , Kaczkowski Peter J.
Published: October 2013

Backscattered radio frequency (rf) data from a modified commercial ultrasound scanner were collected in a series of in vitro experiments in which high intensity focused ultrasound (HIFU) was used to create lesions in freshly excised bovine liver tissue. Two signal processing approaches were used to visualize the temporal evolution of lesion formation. First, apparent tissue motion due to temperature rise was detected using cross-correlation techniques. Results indicate that differential processing of travel time can provide temperature change information throughout the therapy delivery phase and after HIFU has been turned off, over a relatively large spatial region. Second, changes in the frequency spectrum of rf echoes due to changes in the scattering properties of the heated region were observed well before the appearance of hyper-echogenic spots in the focal zone. Furthermore, the increase in attenuation in the lesion zone changes the measured backscatter spectrum from regions distal to it along the imaging beam. Both effects were visualized using spectral processing and display techniques that provide a color spatial map of these features for the clinician. Our results demonstrate potential for these ultrasound-based techniques in targeting and monitoring of HIFU therapy, and perhaps post-treatment visualization of HIFU-induced lesions.
Towards a laser-vibrometry technique for measuring railroad rail stress
Authors: Damljanović Vesna , L. Weaver Richard
Published: October 2013

There is a broad consensus on the need for cost-effective and reliable methods for measurement of axial stress in railroad rails. Constrained thermal expansions and contractions induce large forces which in turn lead to bucklings and rail breaks. We are developing a new method for such measurements, based on the decrease (increase) of effective dynamic flexural rigidity under the influence of compressive (tensile) loads. Scanned laser vibrometry measurements of vibration fields at a prescribed frequency, followed by a comparison with guided wave theory for the complex cross section of the rail, allows the extraction of flexural wavenumbers. These wavenumbers are in turn related to contained load and to the rail’s intrinsic rigidity. Here we report the ongoing status of this work, describing the results of extensive laboratory measurements on unloaded rail, and test-bay measurements on rails subjected to compressive loads to 100 kip.
Analysis of digitized on-site ultrasonic state measurements
Authors: Hailu Sissay , Hazony Dov , Hazony Yehonathan
Published: October 2013

Of concern is noninvasive gage-less monitoring fatigue experiments as well as detection and tracking of cracks, surface, and bulk. Accordingly, a digital signal decomposition method is developed for the analysis of sharp, time-limited ultrasonic pulses traveling through a tensile specimen on-site. The method extracts from the propagating pulses, respective elongation, and diameter reduction due to stress, associated with signal delays and changes in amplitude and shape. The analytical process is based on a nonlinear multivariate regression analysis. When applied to the current experiments, the method extracts delay variations accurate to the order of ±1 ps and quantified signal-deformation data. These results relate to a tensile-stress experiment under a five-cycle strain-cycle experiment, extending some of the cycles well into the plastic regime of a stainless steel specimen. The three-section cylindrical specimen consists of two gripper heads and a slender cylindrical section 6 mm in diameter and 20 mm long. Transducers are implanted on both specimen faces along the main axis [Mostafa et al., Int. J. Fract. 85, 99–109 (1997)]. [Work supported by NASA.]
Linear and nonlinear angle beam ultrasonic spectroscopy to evaluate adhesive layers
Authors: Adler Laszlo , Xie Bin , Iakovlev Vadim , Rokhlin Stanislav
Published: October 2013

A new technique for quantitative evaluation of adhesive bond integrity of metals and composites called angle beam ultrasonic spectroscopy was developed. The novelty of this approach is that it utilizes both normal and obliquely incident ultrasonic beams on the bond line simultaneously and measures the frequency response of the reflected ultrasonic signals. From the frequency dependence of the reflection coefficients, elastic moduli, attenuation coefficients, thickness and density of the adhesive layer can be measured. The method was further enhanced by adding a low-frequency dynamic load acting as a nonlinear (parametric) enhancement. The low-frequency excitation parameters are set to make the maximum stress distribution coincide with the bond line. In addition to the bond layer properties, interfacial spring constants are also obtained by using the nonlinear method. Experimental results on adhesive samples will be presented and discussed with model prediction.
Influence of acoustic memory on ultrasonic attenuation
Authors: McPherson Michael , Ostrovskii Igor , Breazeale M. A.
Published: October 2013

Recently a new physical phenomenon of acoustic memory has been described [Phys. Rev. Lett., 89, 155506-1/3 (2002)]. In this lecture, we show for the first time the connection between acoustic memory and ultrasonic attenuation. Different results are given showing attenuation as a function of temperature, of ultrasound amplitude, and of frequency. We used [001] LiNbO3 single-crystal samples and longitudinal acoustic waves over the frequency range from 10 to 32 MHz. Strong correlation exists between acoustic memory amplitude and the measured coefficient of ultrasonic attenuation. Acoustic memory causes strong variation in attenuation measurements. In this light, we discuss the known difficulties in practical attenuation measurements in ferroelectrics. We mention an unusual temperature dependence, including a strong hysteresis effect. The frequency and amplitude dependence of attenuation are also discussed.
Equations for direct numerical simulation of sound propagation in a moving atmosphere
Authors: Ostashev Vladimir E. , Liu Lanbo , Wilson D. Keith , Moran Mark L. , Aldridge David F. , Marlin David
Published: October 2013

Most previous analytical and numerical studies of sound propagation in a moving atmosphere have been based on wave equations for the sound pressure and on various parabolic approximations to the wave equations. However, these equations cannot be used as starting equations for recently proposed direct numerical simulation (DNS) of sound propagation outdoor since such starting equations should be first-order differential equations with respect to time. In the present paper, we derive two closed sets of the first-order differential equations for the sound pressure and fluctuations in medium velocity and density due to a propagating sound wave. These sets can be used as starting equations for DNS of sound propagation in a moving atmosphere. The ranges of applicability of these sets are studied by comparing them with the equations for the sound pressure used previously. Note that both sets can also be employed for analytical studies of sound propagation in a moving atmosphere. Examples of the use of these sets for DNS and analytical studies of sound propagation in a moving atmosphere are presented. [Work partially supported by a DoD High-Performance Computing Modernization Office grant and U.S. Army Research Office Grant No. DAAG19-01-1-0640.]
An analytic model for acoustic scattering from an impedance cylinder placed normal to an impedance plane
Authors: Swearingen Michelle E. , Swanson David C.
Published: October 2013

An analytic model for the scattering of a spherical wave off an infinite right cylinder embedded perpendicularly in a ground surface is developed in cylindrical coordinates. The model is developed to simulate a single tree and is developed as a first piece to creating a model for estimating attenuation in a forest based on scattering from individual tree trunks. Comparisons are made to the plane wave case, the transparent cylinder case, the transparent ground case, and the rigid ground case as a method of theoretically verifying the model. Agreement is excellent for all benchmark cases. Model sensitivity to five parameters is determined, which aids in error analysis, particularly when comparing the model results to experimental data, and offers insight into the inner workings of the model. An experiment was performed to collect real-world data on scattering from a cylinder normal to a ground surface. The data from the experiment is analyzed with a transfer function method into frequency and impulse responses. The model results are compared to the experimental data. Agreement is good below 1500 Hz, and poor for higher frequencies.
Coordinate determination of the low-flying object by the acoustical method
Authors: Oboznenko Igor L. , Dat Tran H.
Published: October 2013

The acoustical method of passive sonar is proposed for determination of the object flying at low altitudes. The method is based on sound refraction into the lower relatively to the object medium. The Rayleigh waves are used with the speed far higher than the low-flying noisy target. Besides the spherical wave, the side wave with attenuation in depth is reflected to the receiver. The latter can be clearly detected on the depth of the surface half-wave that in reality for the infralow frequency amounts up to hundreds of meters. The location finding of the object is obtained via creation of the static fan of the polar pattern with the specified angular resolution of each radar view. At the horizontal range (100 km), depth of immersion multiple of N receivers (horizontal collinear equidistant antenna) and the height of the flying object 3–10 m, in the wave field the correction to the ray acoustics, which is very significant in its amplitude, is done. To count horizontal range to the object, a vectorial (three components) displacement (or vibrating speed) receiver, placed into the center of the radar array is used. The model experiments in water match the calculations.
Analysis of the radiation from the violin f-holes using patch near field acoustical holography
Authors: Williams Earl G. , Bissinger George
Published: October 2013

Although differential pressure measurements offer a direct means to understand the energy flow from the f-holes of the violin they have been performed only at discrete frequencies over relatively limited portions of the acoustic field, and none have ever covered an entire f-hole over a broad frequency region. Application of recently developed near field acoustical holography (NAH) patch processing techniques to 108-node planar rectangular grid microphone data provides a powerful tool to understand the flow of acoustic energy from the f-holes up to 4 kHz. The grid covered each f-hole as well as a small portion of the violin top-plate and provided the necessary spatial resolution to allow isolation of only f-hole aperture radiation in the NAH processing. The projected radiativity in the far field at 1.2 m from just the f-holes was compared with prior microphone measurements in an anechoic chamber over an entire sphere around the violin. As expected the lowest cavity mode A0 was the major radiator at the frequencies below all the corpus modes. Surprisingly the first corpus bending modes appear to radiate strongly through the f-holes also. [Work supported by ONR and NSF.]
A structural dynamics and experimental investigation of the American five-string banjo
Authors: Dickey Joe , Wakland Ray
Published: October 2013

The American five-string banjo is unique among musical instruments in that many significant parameters that effect tone are easily adjusted. This is probably why so many banjo players fiddle with their banjo. The instrument is a combination of canonical vibrating systems, i.e., plucked strings that drive a circular, radiating, membrane. A structural dynamics model and experiment are used to characterize the sound and relate changes in sound to setup parameters. Three figures-of-merit, FOMs, are defined; they are loudness, brightness, and decay rate of the sound. The effects of a number of parameters on the FOMs are investigated analytically and experimentally. Among these are the loss factor and tension of the membrane, mass of the bridge, and the location on the string of the excitation. It is noted that the calculated effects of the changes agree with generally accepted setup practices.
Modal analysis and sound radiation from Caribbean steelpans
Authors: Morrison Andrew
Published: October 2013

The Caribbean steelpan is one of the most interesting acoustic musical instruments invented in the last century. Although simple in design, the acoustic properties of the steelpan are surprisingly complicated. Holographic interferometry was used to determine the modes of vibration of a double second and a low tenor steelpan. Sound intensity measurements were taken to explore the relationship between the modes of vibration and the radiated sound field. The pan was placed in an anechoic chamber, and selected notes were excited electromagnetically with a swept sinusoid signal. A two-microphone probe was used to gather sound intensity measurements. Sound intensity maps and animations were constructed for the first three harmonics.
The effects of bell vibrations on the acoustic spectrum of the trumpet
Authors: Moore Thomas R.
Published: October 2013

The acoustic spectrum of a modern trumpet with the bell section heavily damped has been compared to the spectrum of the same instrument with the bell section left free to vibrate. The amplitude of vibration of the metal was measured in both cases and was shown to be significantly different between the two sets of measurements. Artificial lips were used to ensure consistency between trials. A significant change in the acoustic spectrum between the two cases is found, with the variation being largest in the lower harmonics where the relative power may change by as much as a factor of 2. It is shown that the changes can be explained by a variation in the viscous boundary layer that is attributable to the vibrating walls of the bell. [Work supported by a grant from the Jessie Ball duPont Fund.]
Merit-based funding at the National Science Foundation
Authors: Harper Mary P.
Published: October 2013

National Science Foundation (NSF) invests in the best ideas from the most capable people as determined by competitive merit review. This talk will first summarize how NSF evaluates proposals for research and education projects in speech communication. The review timeline, as well as the merit review criteria of intellectual merit and broader impacts, will be discussed. Finally, a summary of current and future NSF funding opportunities will be provided.
Training camp: The quest to become a new National Institutes of Health (NIH)-funded independent investigator
Authors: Sklare Daniel A.
Published: October 2013

This presentation will provide information on the research training and career development programs of the National Institute on Deafness and Other Communication Disorders (NIDCD). The predoctoral and postdoctoral fellowship (F30, F31, F32) programs and the research career development awards for clinically trained individuals (K08/K23) and for individuals trained in the quantitative sciences and in engineering (K25) will be highlighted. In addition, the role of the NIDCD Small Grant (R03) in transitioning postdoctoral-level investigators to research independence will be underscored.
Development of an impedance tube technique for in-situ classification of marine sediments
Authors: Wilson Preston S. , Roy Ronald A. , Carey William M.
Published: October 2013

The removal of samples or the insertion of measuring devices into the ocean bottom can alter the acoustic behavior of these sedimentary materials. A less invasive method for the acoustic characterization of marine sediments in the 1 to 10 kHz frequency range has been investigated. A water-filled impedance tube has been used to measure the complex reflection coefficient at the surface of a sediment layer at the bottom of a water tank. The acoustic properties of the sediment were obtained as a function of frequency by an inversion process. The system is modeled numerically and an effective fluid description of the sediment is used. The difference between the measured and predicted complex reflection coefficient is minimized through variation of the sediment sound speed and attenuation in the model. Results will be presented for different sediments. [Work supported by U. S. Navy ONR.]
Use of a buried array to characterize sediment volume scattering
Authors: Jackson Darrell R. , Williams Kevin L. , Ivakin Anatoliy N. , Thorsos Eric I.
Published: October 2013

During the SAX99 experiment, a buried array was used to measure the sound field due to sources placed in the water column. Measurements were made over the frequency range 11–50 kHz. The sound field at the array showed a ‘‘coda’’ that was longer than suggested by simulations of rough-interface scattering. Simulations have been used to show that scattering by sediment volume heterogeneities is the likely cause of the coda. The volume scattering strength has been estimated by fitting a point scatterer model to the data, and the strongest discrete scatterers have been located and characterized by means of backpropagation. When the measured properties of the volume scatterers are inserted in backscattering models, the predicted backscattering strengths fall somewhat below measured values, indicating that roughness scattering is dominant at this (sandy) site. [Work supported by ONR.]
Porosity and grain size dependence of the longitudinal wave velocity of water-saturated beach sand
Authors: Kimura Masao , Noguchi Masahiro
Published: October 2013

The longitudinal wave velocity of water-saturated sand is dependent on the porosity. The data which show the relationship between the velocity and the porosity are dispersed [E. L. Hamilton and R. T. Bachman, J. Acoust. Soc. Am. 72, 1891–1904 (1982)]. It seems that this dispersion is due to the grain size, the standard deviation of the grain size, and the grain shape. In this study, to investigate the dispersion, the longitudinal wave velocities, the porosities, and the grain sizes of many kinds of water-saturated beach sands are measured. The relationships between the velocity, the porosity, and the grain size are obtained. From these results, it is seen that the velocity of the water-saturated beach sand with the same porosity varies with the grain size. That is, the velocity of the water-saturated beach sand with the same porosity increases, as the grain size increases. It is considered that the frame bulk modulus of the water-saturated beach sand with the same porosity varies with the grain size.
High frequency scattering, attenuation and permeability in sands
Authors: Yamamoto Tokuo , Sakakibara Junichi , Mohri Yoshiyuki
Published: October 2013

Imaging the permeability within sediments is one of the important problems that is not well investigated in geoacoustics. Acoustic wave energy scattered from velocity and density fluctuations within sediments increases the attenuation. However, only the intrinsic attenuation due to the Biot mechanism is related to permeability. We investigate this problem using the crosswell acoustic tomography and simple propagation measurements in water saturated sands in a large tank and a pond. The range of frequency is from 10 to 100 kHz. The sands used in the experiments are of uniform grain sizes of 0.05 to 0.5 mm. We find that the wave propagation data follows the Biot theory. The apparent attenuation due to scattering is proportional to the velocity fluctuations and can be significant. For accurate imaging of permeability in sand volume, the removal of the apparent attenuation due to volume scattering from total attenuation is very important. [Work supported by ONR Code 321OA, NIRE, and MEST.]
Models of discrete scattering in marine sediments
Authors: Ivakin Anatoliy N.
Published: October 2013

Acoustic scattering in marine sediments with discrete inclusions, such as shell fragments and rocks, is described in terms of the scattering cross section per unit sediment volume and the scattering cross section per unit seabed area. These cross sections are expressed through the individual scattering functions of discrete targets and statistical distributions of their parameters (size, shape, orientation, material, etc). Some simplified approaches for description of the individual scattering from irregular inclusions are considered. Rigorously, individual scattering functions should take into account the influence of the water–sediment interface. Effects which result from this influence are discussed. The role of the size distribution function is analyzed. Two types of distributions are considered. The first one is a narrow distribution with one dominating scale. The second type is a wide or multiscale distribution, for example, described by a power-law function. The frequency-angular dependencies of the seabed scattering strength for various models of discrete scattering are calculated and discussed. [Work supported by ONR, Ocean Acoustics.]
Ambient noise analysis of underwater acoustic data
Authors: Snyder Mark A. , Orlin Pete , Schulte Annette , Newcomb Joal
Published: October 2013

The Littoral Acoustic Demonstration Center (LADC) deployed three Environmental Acoustic Recording System (EARS) buoys in the northern Gulf of Mexico during the summers of 2001 and 2002. The buoys recorded frequencies up to 5859 Hz continuously for 36 days in 2001 and for 72 days in 2002. The acoustic signals recorded include sperm whale vocalizations, seismic airguns, and shipping traffic. The variability of the ambient noise is analyzed using spectrograms, time series, and statistical measurements. Variations in ambient noise before, during, and after tropical storm/hurricane passage are also investigated.
High-frequency characterization of tissue phantoms using a scanning acoustic microscope (SAM)
Authors: Farny Caleb H. , Chklovski Tara C. , Szabo T. L. , Roy Ron A. , Cleveland Robin O.
Published: October 2013

A SAM has been developed to measure the acoustic properties of samples. The SAM consists of a wideband (35–75 MHz) ultrasound transducer operating in pulse-echo mode. Waveforms measured from the front and back surfaces of a uniform sample are used to determine the impedance, sound-speed, and attenuation of the sample as a function of frequency. The principle of causality is used to ensure that the sound-speed dispersion and attenuation measurements are consistent. The transducer is scanned over the surface of the sample in a raster scan and a two-dimensional map of the acoustic properties averaged over depth can be obtained. Scans of high-density polyethylene show agreement with previously published properties. The SAM was used to evaluate the high-frequency acoustic properties of a tissue phantom composed of agar, gelatin and silica. The silica content was varied from 2% to 10% and the impact of the silica scattering particles on the acoustic properties was evaluated. The sound-speed showed almost no dependence on silica content but the attenuation at 30 MHz increased from 8.4 to 23.8 dB/cm. This phantom has the potential to be used to mimic the walls of blood vessels. [Work supported by the NSF through the Center for Subsurface Sensing and Imaging Systems.]
An avoidance behavior model for migrating whale populations
Authors: Buck John R. , Tyack Peter L.
Published: October 2013

A new model is presented for the avoidance behavior of migrating marine mammals in the presence of a noise stimulus. This model assumes that each whale will adjust its movement pattern near a sound source to maintain its exposure below its own individually specific maximum received sound-pressure level, called its avoidance threshold. The probability distribution function (PDF) of this avoidance threshold across individuals characterizes the migrating population. The avoidance threshold PDF may be estimated by comparing the distribution of migrating whales during playback and control conditions at their closest point of approach to the sound source. The proposed model was applied to the January 1998 experiment which placed a single acoustic source from the U.S. Navy SURTASS-LFA system in the migration corridor of grey whales off the California coast. This analysis found that the median avoidance threshold for this migrating grey whale population was 135 dB, with 90% confidence that the median threshold was within ±3 dB of this value. This value is less than the 141 dB value for 50% avoidance obtained when the 1984 ‘‘Probability of Avoidance’’ model of Malme et al.’s was applied to the same data. [Work supported by ONR.]
Phylogenetic perspectives on noise-induced fear and annoyance
Authors: Bowles Ann
Published: October 2013

Negative human responses to noise are typically interpreted in terms of human psychological, cognitive, or social processes. However, it may be useful to frame hypotheses about human responses in terms of evolutionary history, during which negative responses have been part of a suite of adaptions to a variable sound environment. By comparing the responses of a range of nonhuman animals to various types of noise, it is possible to develop hypotheses about the ecology of human responses. Examples of noise-related phenomena that could be explained usefully from this perspective include the Schulz curve, noise-induced physical stress, acute fear responses induced by transient noise, and the relationship between temperament and noise-induced annoyance. Responses of animals from a range of taxa will be described and their behavior interpreted in terms of their life-history strategies. With this perspective, some testable hypotheses about noise-induced fear and annoyance will be suggested.
Identifying the sources of environmental sounds with a varying number of spectral channels
Authors: Shafiro Valeriy , Jenkins James J. , Strange Winifred
Published: October 2013

Normally hearing adult listeners were asked to identify the sources of 60 familiar environmental sounds processed through a vocoder simulation of a cochlear implant with a varying number of frequency channels. Using a Latin square design, listeners heard 10 different sounds in one of the six channel conditions (2, 4, 8, 16, 24, 32) followed by all 60 unprocessed sounds. For each sound, listeners selected one of 60 response options that best described the sound’s source. Preliminary results indicate that (1) source identification accuracy markedly improves up to 16 channels, but does not continue to improve with further increases in the number of channels; (2) individual sounds vary in the number of channels needed for accurate source perception; (3) increasing the number of channels positively affects source identification of some sounds, while it negatively affects others; (4) listeners show different response biases when listening to low versus high number-of-channels stimuli; (5) systematic confusion can be found in listeners’ erroneous responses to stimuli. These findings highlight differences among spectral and temporal factors important for source identification and suggest ways of classifying environmental sounds based on spectral resolution required for source identification. [Work supported by NIDCD.]
Difference limens for vocal aperiodicities
Authors: Kreiman Jody , Gerratt Bruce R.
Published: October 2013

Although jitter, shimmer, and noise characterize all voice signals, recent data from a method of adjustment task suggest that these acoustic attributes do not all have equal perceptual importance. Listeners did not agree well with one another when asked to match the amounts of jitter or shimmer in a voice, although they did agree well in their matching responses to noise. Several explanations for this finding are possible. Listeners may be insensitive to differences in amounts of jitter and shimmer in a voice, so that difference limens are large relative to customary measurement resolution; or listeners may have difficulty separating jitter and shimmer perceptually from the composite noise component. To investigate these issues, we synthesized several series of stimuli with and without noise, and differing by steps in the amounts of jitter or shimmer present. Listeners heard pairs of these stimuli and were asked to respond whether stimuli were the same or different. Receiver operating characteristic analysis was applied to determine how listener sensitivity to jitter and shimmer varies. [Research supported by NIDCD.]
Perceptual differences in source–filter characteristics of racially affiliated dialects of American English
Authors: Purnell Thomas , Kopplin Laura
Published: October 2013

Three forced-choice experiments are described investigating perceptual cues of tokens simulating three racially-affiliated varieties of American English, namely African American English (AE), Chicano English (CE), and General American English (GE). These experiments test whether the locus of the conceptual assignment of pseudo-tokens to specific socially constructed groups resides primarily in either source or filter characteristics of the tokens. In the first experiment, responses to real tokens matched the implied dialect better than chance. The subsequent experiments used synthetic versions of the token with the greatest percent match for each group. For the second experiment the source and filter were separated using LPC filtering, then swapped across groups. Two mirror sets of tokens were produced where F0 was fixed and F0 was absent (whispered). Findings provide evidence that cues for token identification are primarily filter oriented, although for CE and GE source cues also play a minor perceptual role. To test the finding that the filter plays a greater perceptual role than the source, the same three sets of tokens were pass band masked by noise. Tokens pass band filtered for the 400 Hz to 2,000 Hz frequency range were perceived less well than other filtered tokens.
Effects of speaking rate on the vowel length distinction in Japanese nonsense words
Authors: Hirata Yukari
Published: October 2013

This study examined how speaking rate affected the durations of phonemic short and long vowels in Japanese. Four native Japanese speakers produced five triplets of disyllabic nonsense words: CV́CV, CV́VCV, and CV́CVV (C=/m/; V=/i/, /e/, /a/, /o/, and /u/), e.g., /máma/, /má:ma/, and /máma:/. Speakers read these words in a carrier sentence at slow, normal, and fast rates three times each. Durations of accented and unaccented short vowels in CV́CV, and contrasting accented long vowels in CV́VCV and unaccented long vowels in CV́CVV, as well as word durations, were measured from spectrograms. There was a significant amount of overlap between the durations of short and long vowels across the three rates. Rate changes affected the duration of long vowels more than short vowels, showing asymmetry of distribution, consistent with Port et al. [Phonetica 37, 235–252 (1980)]. In contrast with the absolute durations, the ratios of long to short vowels, three-mora (CV́VCV or CV́CVV) to two-mora (CV́CV) words, and vowel (short or long) to word durations were little affected by rate changes. These results are consistent with the view that a relational invariance exists in temporal dimensions of speech [Pickett et al., Phonetica 56, 135–157 (1999)].
Sensitivity of spectral moments to Swedish dental versus American English alveolar word-initial /t/ bursts
Authors: Buder Eugene H. , Parham Douglas F. , Stoel-Gammon Carol
Published: October 2013

Previous investigations comparing Swedish dental versus American English alveolar /t/ production found many acoustic differences in both adults and 30-month-old children [C. Stoel-Gammon, K. Williams, and E. H. Buder, ‘‘Cross-language differences in phonological acquisition: Swedish and American /t/,’’ Phonetica 51, 146–158 (1994)]. The primary differences in the word initial consonants included the second spectral moment (‘‘spectral SD’’), VOT, and burst intensity. However, subsequent studies demonstrated that spectral SD and other moments measures were sensitive to recording environment and correlated with other production characteristics. Moreover, measurements of spectral SD differed across these languages in other stop bursts such as /p/ and /k/. These observations raised questions regarding the true sensitivity of this measure in place of articulation for /t/. To examine these questions, the current work examines stop burst characteristics of two adult male native speakers of Swedish and American English recorded in an anechoic chamber with digital equipment. Results suggest that the primary variation of spectral SD in /t/ bursts is attributable to the dental versus the alveolar place of articulation. However, the results indicate that spectral moment measures are also generally sensitive to burst intensity, which may be unrelated to place but still language-specific. [Work supported by NICHD R01-HD32065.]
Perception of English palatal codas by Korean speakers of English
Authors: Yeon Sang-Hee
Published: October 2013

This study aimed at looking at perception of English palatal codas by Korean speakers of English to determine if perception problems are the source of production problems. In particular, first, this study looked at the possible first language effect on the perception of English palatal codas. Second, a possible perceptual source of vowel epenthesis after English palatal codas was investigated. In addition, individual factors, such as length of residence, TOEFL score, gender and academic status, were compared to determine if those affected the varying degree of the perception accuracy. Eleven adult Korean speakers of English as well as three native speakers of English participated in the study. Three sets of a perception test including identification of minimally different English pseudo- or real words were carried out. The results showed that, first, the Korean speakers perceived the English codas significantly worse than the Americans. Second, the study supported the idea that Koreans perceived an extra /i/ after the final affricates due to final release. Finally, none of the individual factors explained the varying degree of the perceptional accuracy. In particular, TOEFL scores and the perception test scores did not have any statistically significant association.