bluuebunny/crossref_metadata_2025 huggingface dataset:
Space-frequency sound field distribution in the neighborhood of a temperature front
Authors: Katsnelson Boris , Tshoidze Alexander , Lynch James , Wang Ta-Wei
Published: October 2013

In this paper, the properties of the sound field in the area close to a temperature front (TF) in shallow water are studied. It is shown that for a realistic temperature front providing the variation of the sound speed profile, interesting effects due to horizontal refraction can be observed if the source/receiver are placed at distances of several hundred meters (up to 1 km) from the TF. It is shown that strong interferences in the sound field take place both in the range (horizontal plane) and frequency domains (resonance-like spectra of received signals). Effects of mode separation due to horizontal refraction can be experimentally observed (in principle) as well as the aforementioned intensity gain. These effects are similar to observed horizontal refraction phenomena in the presence in internal solitons. Numerical modeling is carried out, and an experimental setup is discussed for typical conditions in shallow water areas. [Work supported by RFBR (03-05-64568) and CRDF (REC 010-0)].
Additional evidence of nuclear emissions during acoustic cavitation
Authors: Taleyarkhan Rusi , West Colin , Cho JaeSeon , Lahey Richard
Published: October 2013

Time spectra of neutron and sonoluminescence emissions were measured in cavitation experiments with chilled deuterated acetone. Statistically significant neutron and gamma ray emissions (with more than 25 standard deviation accuracy) were measured with a calibrated liquid-scintillation detector. The neutron and sonoluminescence emissions were found to be time correlated over the time of significant bubble cluster dynamics. The neutron emission energy was at and below 2.45 MeV and the neutron emission rate was up to ∼400000 n/s. Measurements of tritium production were also performed and these data implied a neutron emission rate due to D-D fusion which agreed with what was measured. In contrast, control experiments using normal acetone did not result in statistically significant tritium activity, or neutron or gamma ray emissions. The talk will highlight significant details of the acoustic chamber design, characterization and qualification along with the nuclear data obtained.
The temperatures of single-bubble sonoluminescence
Authors: Suslick Kenneth S. , Flannigan David J.
Published: October 2013

We observe extraordinarily intense single-bubble sonoluminescence (SBSL) from concentrated sulfuric acid (H2SO4) containing noble gases. Strong atomic Ar emission and extensive vibronic progressions from sulfur monoxide (SO) are also present in the SBSL spectra. The Ar atom excited states observed are too high in energy to be thermally populated and must be excited by high energy particle impact, consistent with Ar atom SBSL from an emissive shell surrounding an optically opaque plasma core, just as in a star or thermonuclear explosion. From relative intensities of Ar lines, we find that the observed effective emission temperature during SBSL is 15200±1900 K. SBSL emission temperatures can be systematically controlled over the range from ∼1500 to ∼20000 K by changing the applied acoustic pressure or the thermal conductivity of the dissolved gas.
Development of film bulk acoustic wave resonators based on piezoelectric aluminum nitride
Authors: Matsumoto Hisanori , Asai Kengo , Hikita Mitsutaka
Published: October 2013

Film bulk acoustic wave resonators (FBARs) have high quality factors (Q) and are smaller than conventional surface acoustic wave devices, so they are particularly suitable for constructing the bandpass filters of mobile phones. This report covers the simulation and fabrication of FBARs consisting of an aluminum nitride (AlN) piezoelectric layer sandwiched between molybdenum (Mo) electrode layers. The simulation was based on Mason’s equivalent circuit model. Other than material Q, the AlN material constants for the FBAR model were those reported by Tsubouchi and Mikoshiba [K. Tsubouchi and N. Mikoshiba, IEEE Trans. Sonics Ultrason. 32, 634–644 (1985)]. The material Q of AlN was assumed to be 1000. Thickness values for the AlN and Mo films were determined by simulation, after which the FBARs were fabricated. Reactive radio-frequency sputtering and direct-current sputtering were adopted for deposition of the AlN and Mo films, respectively. In terms of frequency properties, our FBARs achieved Q of 800 and an effective electromechanical coupling coefficient of 5.7%. The transmission loss was greater than that calculated through simulation. This result suggests that the material Q of AlN is less than 1000. This may be due to suboptimal film quality.
Fibrous proteins and tensile elasticity of the human vocal fold
Authors: Chan Roger W. , Tirunagari Neeraj , Fu Min
Published: October 2013

Viscoelastic response of the human vocal fold under tension has been reported previously, demonstrating nonlinearity and hysteresis of stress–strain curves. However, the importance of various matrix molecules for tensile elasticity of the vocal fold is not well understood. It is important to correlate the biomechanical behavior of the vocal fold with its histological microstructure, so as to examine the relative contributions of the matrix proteins such that cultured tissue constructs for repairing voice disorders may be engineered accordingly. This study attempted to test the hypothesis that collagen and elastin play a major role in determining the tensile elasticity of the vocal fold. Uniaxial tensile elastic properties of the vocal cover and vocal ligament were quantified using a servo-control lever system. The specimens were also studied histologically with elastin van Gieson stain. Digital image analysis of the vocal fold cover showed that a more profoundly nonlinear stress–strain curve and a higher elastic modulus (tangent Young’s modulus) were associated with higher densities of collagen and elastin in the specimens. These findings suggested that both collagen and elastin fibers likely contribute significantly to elasticity of the vocal fold under tension, thereby regulating vocal fold length changes and fundamental frequency control. [Work supported by NIH.]
Optimized multistatic sonobuoy array patterns
Authors: DelBalzo Donald R. , Kierstead David P. , Rike Erik R.
Published: October 2013

Standard patterns for monostatic sonobuoy fields were developed during the Cold War for deep, uniform underwater environments, where a simple median detection range defined a fixed spacing between sonobuoys (usually along staggered lines). Oceanographic and acoustic conditions in littoral environments are so complex and dynamic that spatial and temporal variability of low-frequency signal and noise fields destroys the basic homogeneous assumption associated with standard tactical search concepts. Genetic algorithms (GAs) have been applied to this problem to produce near-optimal, nonstandard search tracks for monostatic mobile sensors that maximize probability of detection in such inhomogeneous environments. For the present work, a new capability, SCOUT (sensor coordination for optimal utilization and tactics) was developed to simulate multistatic distributed-sensor geometries and to optimize the locations of multistatic active sonobuoys in a complex, littoral environment. Both standard and SCOUT-derived tactics were evaluated for cumulative detection probability and compared. The results show (a) that the standard pattern is not optimal even for a homogeneous environment and (b) that standard patterns are grossly ineffective in inhomogeneous environments. [Work was sponsored by NAVAIR.]
Coupled perturbed modes for a wedge waveguide
Authors: Higham Chris J. , Tindle Chris T.
Published: October 2013

A transformation of the normal modes is described to accommodate the density jump found in range-dependent penetrable bottom problems. The transformation is necessary for the application of perturbation theory to a coupled mode model of a wedge waveguide. The combination of conventional coupled modes and perturbation theory yields an efficient modal theory for shallow water acoustics of range dependence. The method is applied to upslope propagation in the ASA benchmark 2 wedge [J. Acoust. Soc. Am. 87, 1499–1510 (1990)].
Modeling the acoustical focusing properties of shoaling surf
Authors: Deane Grant , Tindle Chris
Published: October 2013

Shoaling surf focuses sound, creating high intensity caustics that impact the performance of underwater communications systems and sonars in the very near shore region. Simple expressions for the time-varying caustic locus and amplitude can be derived from the Kirchhoff–Helmholtz scattering integral. The analysis shows that a focus is formed at a range equal to one-half the crests radius of curvature when the wave is directly over a shallow water source, and moves toward the crest and decreases in intensity as the wave shoals shoreward. The analysis is compared with numerical scattering calculations based on measured surface gravity wave profiles, and also with experimental data in which 10-kHz, single cycle pulses were transmitted over a 40 m path in 6 m of water just north of Scripps Pier. The impact of the caustics on sonar performance will be discussed. [Work supported by ONR.]
Measurement and subjective evaluation of the spatial modulation of late reverberation
Authors: Begault Durand R.
Published: October 2013

The acoustical characterization of a large rectangular space with uniformly distributed absorption is facilitated by a predictably linear reverberant decay of decibel sound pressure level. By contrast, large spaces with irregular shapes yield correspondingly irregular reverberant decays. A contributing factor is coupled space effects where the several reverberant decays occur simultaneously. When the mean free path for reflections is relatively large, as in a cathedral, temporal thresholds can be exceeded to the point where it is possible to hear spatially separated decays. The phenomenon of a slow amplitude modulation between separate locations can be described as moving late reverberation, which is audible, e.g., in a cathedral when an organ note is stopped. Measurements of this phenomenon were made in San Franciscos Grace Cathedral, a French Gothic-style Episcopal church, using multiple calibrated microphone impulse response recordings. Data on the temporal-spatial diffusion of reverberation from various spatial perspectives are presented, along with sound examples. Preliminary listening test data involving subjective evaluation of late reverberation movement is presented, where the temporal and spatial components of a synthetic impulse response is manipulated in a manner characteristic of similar large spaces.
Evoked potential measurements of the West Indian manatee modulation rate transfer function
Authors: Mann David , Casper Brandon , Cook Mandy , Colbert Debborah , Gaspard Joseph , Reep Roger , Bauer Gordon
Published: October 2013

Evoked potential measurements of two Florida manatees (Trichechus manatus latirostris) suggest that these herbivores have evolved an auditory system with high temporal resolution. The manatee modulation rate transfer function (MRTF) is maximally sensitive to a 600-Hz amplitude modulation (AM) rate. This modulation rate is midway between the AM sensitivities of terrestrial mammals (chinchillas, gerbils, and humans) (80–150 Hz) and dolphins (1000–1200 Hz). We also demonstrate evoked potential responses to carrier frequencies up to 40 kHz. These results suggest that manatees may have reasonable underwater localization abilities despite the high speed of sound underwater, which could be important in enabling them to localize oncoming boats.
Range-dependent inversion for ocean and bottom properties from modal dispersion curves
Authors: Potty Gopu , Rajan Subramaniam , Miller James
Published: October 2013

Range-dependent sediment acoustic properties estimated from modal dispersion data will be presented. Rajan et al. [J. Acoust. Soc. Am. 82, 998–1017 (1987)] have developed a linear perturbation technique to determine the bottom acoustic properties using group velocity dispersion relation for range-independent environments. This method has been now extended to cover range-dependent inversions for the sediment acoustic properties. Results of inversions performed using synthetic data show that the range-dependent properties can be retrieved using data from multiple source-receiver combinations. If only one source-receiver combination is used, the inversion procedure determines the range averaged sediment properties. A range-dependent inversion technique will be applied to field data from ASIAEX East China Sea (ECS) Experiment. Broad band acoustic data from Wide Band Sources (WBSs) collected on a vertical line array in frequency range 10–400 Hz will be used for the inversion. Over 200 such WBSs were deployed during the experiment and many source–receiver combinations among these will be used to investigate the range variability of compressional wave speed profiles in the ECS experiment location. Results will be compared with core data, geophysical surveys and nonlinear inversions. [Work supported by ONR.]
Inversions for attenuation profiles using modal amplitude ratios
Authors: Potty Gopu , Miller James
Published: October 2013

Data from the ASIAEX East China Sea (ECS) experiment is used to estimate sediment attenuation coefficients as a function of frequency and depth. Modal amplitude ratios for modes in the frequency range 10 to 300 Hz are used to obtain the attenuation profiles. These inversions use broad-band data from wide band sources (WBSs) deployed in the area. The modes are detected, identified and their amplitudes measured using a time-frequency wavelet analysis. A joint inversion for attenuation coefficient profile, water depth, source and receiver depths, range and empirical orthogonal functions in the water column is performed. This inversion differs from our earlier technique in that instead of modal attenuation coefficients we treat the attenuation coefficient profile as the primary unknown. This enables us to reduce the number of unknowns and hence allows us to use higher modes in the inversion. Data from many WBS charges will be used to estimate an average value for attenuation and its standard deviation. The results will be compared with core data and frequency and depth dependence will be examined. [Work supported by ONR.]
Validation of the rapid geoacoustic characterization (RGC) algorithm
Authors: Heaney Kevin D. , Murray James
Published: October 2013

The rapid geoacoustic characterization (RGC) algorithm was developed to perform near-real time geoacoustic inversion in shallow water using the striations of passing surface ships of opportunity. It has been applied to inversion workshop data [Heaney, IEEE J. Ocean Eng. 2004 (1)] and measured surface ship data [Heaney, IEEE J. Ocean Eng. 2004 (1)]. It is currently under review for inclusion in the Navy’s Ocean Atmospheric Media Library (OAML). As part of the OAML approval process a set of seven test cases was generated for the independent validation and verification of the code. These cases span the range of simulated to measured data, and range-independent to range-dependent environments. The method as well as results of the application of this algorithm to these test cases will be presented. The limitations of the algorithm will be addressed.
Synthetic data inversion of porous ocean sediment based on Biot model
Authors: Lee Keunhwa , Seong Woojae
Published: October 2013

Geoacoustic inversion usually estimates parameters by modeling the ocean sediment as either acoustic or elastic media. Treating the sediment as porous medium and partial inversion for sediment moduli has been performed [N.P. Chotiros, J. Acoust. Soc. Am. 112, 1853–1868 (2002)]. In this study, synthetic data inversion based on the full Biot model consisting of 13 unknown parameters is performed. At first, sensitivity tests are done to figure out how much a parameter affects the acoustic fields. Then, iterative inversions using synthetic data are performed based on the parameter’s sensitivities. Sensitive parameters are searched first, while other insensitive ones are fixed at their representative values. Finally, the insensitive parameters are optimized with the previous found sensitive parameter values fixed. In addition to the full Biot model, the equivalent fluid model utilizing complex wave speed and density is used for the inversion to test if the Biot parameters can be retrieved from these inverted complex wave speed and density.
Geoacoustic inversion and subbottom profiling with ambient noise
Authors: Harrison Chris H.
Published: October 2013

A total of six experiments using a drifting vertical array have been carried out between 2002 and 2004. The purpose was to investigate the bottom reflection properties by inversion of ambient noise (GAIN=GeoAcoustic Inversion of Noise) and to investigate subbottom layering (SUPRA-GAIN=SUb-bottom PRofiling using Ambient noise) at frequencies from a few hundred Hz to 5000 Hz. Areas covered include the fairly flat, layered sediments of the Malta Plateau and the rocky outcrops of the Ragusa Ridge in the Mediterranean south of Sicily. Interesting comparisons can be made with other surveying techniques such as the boomer and chirp sonar. Fourier theory states that the depth limit for such subbottom profiling is set by the frequency resolution of the deduced reflection loss. There are other factors that degrade the deeper returns and some pragmatic limitations have been established. Comparisons of results with models suggest that as far as acoustic reflection properties are concerned, in rocky localities the roughness of the rock is more important than the shear.
Respiratory smooth muscle relaxation using vibrations
Authors: Du Youhua , Al-Jumaily Ahmed
Published: October 2013

Many respiratory disorders (asthma in particular) are associated with the shortening of the smooth muscles within the airway walls. This could be attributed to an allergic response that results in airway constrictions. Physically, the shortening of smooth muscles is caused by cross-bridges (the heads of myosin molecules attached to the actins). Muscle relaxation is normally achieved by special bio-chemically driven medications. This work has demonstrated that muscle relaxation can be achieved by mechanical excitation. The dynamic response of contracted tracheal smooth muscles to vibrations under isometric conditions is investigated. This is achieved using two-dimensional finite element modeling as well as experimental investigation. The main algorithm of the finite element modeling is to determine the variation in the muscles’ stiffness caused by external excitation. However, the experimentation focused on using an electric field to stimulate the contraction and using mechanical vibration to produce the relaxation. The main outcome from this work is that smooth muscle relaxation can be achieved by contact mechanical vibration. The question that remains to be answered is can contracted smooth muscles be relaxed by noncontact oscillation? Answering this will definitely add to the body of knowledge for developing a drug-free methodology of relieving airway constrictions.
Vector Doppler ultrasound for the detection of internal bleeding
Authors: Cunitz Bryan , Kaczkowski Peter , Crum Lawrence
Published: October 2013

A vector Doppler (VD) ultrasound system has four advantages over color-flow Doppler (CFD) in identifying internal bleeding: (1) measures instantaneous velocity more accurately, (2) measures flows perpendicular to the transmitter, (3) distinguishes between flows at different depths, and (4) detects the 3-D direction of the flow. A real-time vector Doppler system has been built and tested in vitro. The system consists of one focused transmitting/receiving transducer (10 mm diameter, 50 mm curvature, 5 MHz frequency) and four receiver transducers (5 mm diameter, flat discs, 5 MHz frequency). The signals are passed through analog filters and preamplifiers and then digitized at 20 MHz to obtain a Doppler signal. A digital signal processing algorithm is implemented to calculate flow direction from a combination of the five received signals as well as remove error from systematic phase shifts inherent in the instrumentation. The software was also designed to decrease the time it takes a user to locate arterial flow vessels. The system was tested using two flow phantoms: a moving string to verify accuracy and precision of the velocity, and cornstarch flowing through a tube to simulate blood flow. For both phantoms, device accuracy was tested over a range of angles and velocities.
Echogenicity from disturbed blood flow by an eccentric stenosis under pulsatile flow
Authors: Paeng Dong-Guk , Choi Min Joo , Yoon Suk Wang , Shung K. Kirk
Published: October 2013

In order to investigate echogenicity from blood flow disturbance, a severe eccentric stenosis (∼70%) was constructed in a polystyrene tube (9.5-mm inner diameter) of a mock flow loop. A GE LOGIQ 700 Expert system was used to collect longitudinal and cross-sectional B-mode images from porcine whole blood. Harmonic, power, and color Doppler, and B-flow modes were also collected as references. Flow speed and stroke rate were controlled under pulsatile flow. The ‘‘black hole,’’ a hypoechoic zone at the center stream, was observed upstream of the stenosis during systole, while an expanding ‘‘bright ring’’ appeared during diastole in cross-sectional images. These rings looked like eddies due to backflow during diastole in longitudinal images. A bright stream line appeared from the orifice of the stenosis along the higher flow-speed zone during systole. A hyperechoic parabolic profile appeared once during a pulsatile cycle in longitudinal images showing the periodic spatial variation further downstream under some flow conditions. The parabolic profiles seemed to be a bright ring in cross-sectional images. Both longitudinal and cross-sectional images were helpful to understand 3D structures of echogenicity from disturbed blood flow by an eccentric stenosis under pulsatile flow.
3D mesh design to evaluate sense of place in closed spaces
Authors: Serafin Stefania , Fontana Federico
Published: October 2013

The waveguide mesh defines ideal numerical schemes for the simulation of acoustic linear pressure wave fields, characterized by having constant parameters along the propagation domain. Using the waveguide mesh it is possible to accurately simulate closed spaces of arbitrary size and dimensions. We propose a real-time implementation of the 3D waveguide mesh which runs under the Pure data platform. The parameters the user can control, in real-time, are the mesh dimensions, the damping characteristics of the surfaces and the listening point and sound source positions. In previous experiments, we tested the listeners’ ability to evaluate distance, by placing different sound sources inside an acoustic tube simulated by using the 3D mesh. In this paper we are interested in evaluating humans’ ability to perceive the size of an acoustic enclosure. We calculated the impulse response of 3D meshes of different sizes and shapes, and asked the listener to rate such responses according to the perceived size of the enclosure. Results of this experiment will be shown during the presentation.
Piano sound synthesis: Relating physical phenomena to sound quality
Authors: Bensa Julien , Dubois Daniele
Published: October 2013

The piano is a complex instrument with a large number of mechanical elements, the majority of which contribute to the sound production. The physical characteristics of these elements together with their interaction influence the timbre of the piano sound. Thus, in order to give a precise description of the behavior of this instrument and effectuate a satisfactory sound synthesis, the totality of the physical phenomena that are part of the sound production ideally should be taken into account. However, due to the complexity of the sound production system, this is not possible. Still, works on piano sound synthesis have made it possible to model (usually non-real-time) high quality piano sounds. These models represent a great tool when studying the perception of piano timbre. We therefore propose, thanks to sound modeling and subjective studies, to determine the perceptual effect of phenomena involved in a sound production system. This approach hopefully will give a better understanding of the relation between the physical behavior of the instrument and the perception of its sound quality, and hereby give clues to how the piano model can be simplified without loss of quality. This is crucial for the conception of real-time high-quality synthesis models.
Distinction between adhesive and cohesive defects in a structural bond
Authors: Valentina Vlasie , Martine Rousseau , Laurent Champaney , Silvio De Barros
Published: October 2013

The ultrasonic guided modes in an aluminum/epoxy/aluminum tri-layer are used to characterize the adhesion and the cohesion of this structure. Different models are compared. The exact model (I) takes into account the adhesive layer; the two aluminum/adhesive interfaces are assumed to be perfect. The rheological model of the interfaces (II) consists to describe the two contact zones by a distribution of springs; the boundary conditions at the two aluminum/adhesive interfaces are given by Jones. The rheological model of the adhesive (III) consists to replace the whole adhesive layer by a distribution of springs with inertia; the Jones conditions are then written at the aluminum/aluminum interface. The theoretical comparison between the models (I) and (II) [respectively, (III)] gives the stiffnesses of the interface (respectively of the adhesive layer). For the model (II), the theory/experiment comparison allows us to define interface damage, i.e., adhesive defects. For the model (III), we define global damage in the adhesive layer, i.e., cohesive defects. Nondestructive tests are realized on samples with different levels of adhesion and any cohesive defect. The rheological models confirm an interface damage and any global damage. The same conclusions are obtained by destructive tests.
Selective influences of nonphonemic variability on early word recognition
Authors: Singh Leher , White Katherine
Published: October 2013

Experience with words is necessarily episodic: Each encounter with a word is distinct from previous encounters of that word due to contextual or indexical factors. Nevertheless, we must recognize phonetically distinct instances of a word as lexically equivalent. The normalization problem is particularly challenging for prelexical infants who may not know which acoustic dimensions are phonemic, evidenced by findings that young infants only recognize words when words are perceptually similar across encounters (e.g., spoken by talkers of the same gender). By contrast, older infants are able to recognize dissimilar tokens of words, raising the question of why young infants consider nonphonemic acoustic detail in word recognition. In a series of studies investigating conditions that disrupt early word recognition, it was found that young infants treated as deterministic acoustic detail that may be phonemic in any given language (e.g., vowel length, pitch). Conversely, they effortlessly disregarded details that would never prove phonemic in any language (e.g., amplitude, extralinguistic noise). This suggests infants approach the normalization problem conservatively, initially ascribing relevance to all potentially phonemic details when constructing a lexicon. Later in development, infants perceive as relevant only those details that are phonemic in their language, revealing striking parallels to native phonological attunement in infancy.
Adapting automatic speech recognition methods to speech perception: A hidden semi-Markov model of listener’s categorization of a VC(C)V continuum
Authors: Nearey Terrance M.
Published: October 2013

This study reanalyzes the categorization of 144 synthetic VC(C)V stimuli by 13 listeners. Medial silent gap duration and frequencies of pre- and postgap F2−F3 transitions were independently varied to cover the response set / aba, abda, ab♯ba, ada, adba, ad♯da/. A simple logistic model was shown to work very well for the complex response patterns [T. Nearey and R. Smits, J. Acoust. Soc. Am. 24, 111, 2434 (2002)]. The former analysis required a static ‘‘spoon-fed’’ description of the variable duration stimuli in terms of synthesis parameters. A new analysis will be presented using a hidden semi-Markov model (HSMM), which is a fully automatic dynamic pattern recognizer. The HSMM includes explicit state durations and is fitted to perceptual data by optimization methods allied to the maximum mutual information (MMI) approach from the automatic speech recognition literature. Given only the waveforms of the stimuli as input, the trained HSMM provides an extremely good fit to the perceptual data. The fully automatic HSMM performs better than the spoon-fed static logistic model, with rms error values of 4.8 versus 5.9 percent, respectively. The flexibility and generality of the HSMM/MMI framework for perception models will be sketched. [Work supported by SSHRC.]
A phonological asymmetry and its perceptual consequence: The case of the velar nasal onset
Authors: Narayan Chandan R.
Published: October 2013

The perception of nasal consonants in onset and coda position by native English and Cantonese speakers was investigated. English exhibits a three-way nasal place contrast in coda position (/m, n, ■/) but only a two-way contrast in onset (/m, n/). Cantonese shows the three-way contrast in both positions. Previous perceptual investigation into the English asymmetry found that the [n]-[■] contrast in onset position was difficult to discriminate for native English speakers. [Larkey et al., Percept. Psychophys. 23(4), 299–312 (1978)]. The present study investigated this asymmetry using real-speech stimuli in a cross-language experiment. In an AXB task (where same pairs were different tokens from the same place category and different pairs were tokens from different categories), both English (n=12) and Cantonese (n=6) listeners accurately discriminated all three nasal place contrasts in coda position. Crucially, Cantonese listeners accurately discriminated the [n]-[■] contrast in onsets (95% correct) while English listeners were less successful (69% correct). The results are interpreted as a perceptual consequence of the asymmetry of nasal place in English, where the lack of a phonological contrast diminishes its discrimination. Future work will extend these findings to an investigation of the development of nasal place discrimination in infancy.
Production and perception of American English vowels in different consonantal contexts by native Japanese speakers
Authors: Nozawa Takeshi , Wayland Ratree , Frieda Elaina M.
Published: October 2013

This is a follow-up study to our previous work on the discriminability and perception of American English vowels by native Japanese speakers. Native Japanese speakers’ production of English vowels was compared to their perception. Participants were recorded saying English words and nonwords with varying CVC contexts with a delayed repetition task in order to assess vowel intelligibility. The accuracy of their productions was assessed by native English listeners to determine whether their utterances were perceived as intended. In general, vowels that were difficult for Japanese speakers to differentiate in perception were also difficult to differentiate in production. In keeping with our previous perceptual results, the effect of consonantal contexts also played a significant role in production. For instance, Japanese speakers discriminated /æ/ better when it was preceded by velar stops and their production of these same CVs received higher identification rates. Further, /≳/-/■/ was a difficult perceptual contrast regardless of the consonantal context and Japanese speakers’ productions of these vowels were also unintelligible. [Work supported by Grant-in-Aid for Scientific Research (C)(1)(1410635).]
Source level measurements of a cavitation noise source in a water tunnel using a time reversal mirror
Authors: Barber Christopher , Lauchle Gerald C.
Published: October 2013

An experiment conducted in 2001 at the Penn State Garfield Thomas Water Tunnel demonstrated the use of a time reversal mirror to acquire acoustic measurements of a cavitation noise source. Preliminary results presented at the 142nd Meeting of the ASA (Fort Lauderdale, FL) indicated an improved capability to measure low signal-to-noise ratio (SNR) sources compared to measurements made using omnidirectional or sum-beam sensors. Final experimental results, including calibrated source level estimates, are presented and compared to results from conventional measurements. Key experimental findings regarding the capabilities and limitations of the technique, as well as applicability to acoustic measurements in other types of flow-facilities, are discussed. [Work supported by ONR Code 334, Naval Surface Warfare Center Carderock Division, and the Penn State Applied Research Laboratory.]
Broadband hf backscattering from a smooth sand surface
Authors: Greenlaw Charles F. , Holliday D. Van
Published: October 2013

Measurements of backscattering from smoothed sand surfaces at frequencies from 200 kHz to 4 MHz and grazing angles from 10° to 80° were made in a laboratory tank. The sand was a well-sorted fine sand with all organics and shell fragments removed. The surface was smoothed prior to making measurements at multiple locations using three different broadband transducers (0.5, 1.0, and 2.25 MHz) driven by an impulse. Waveforms from 32-ping coherent averages were recorded, the spectra averaged and normalized by the transducer beamwidths (as an analog for ensonified area), and joined to produce a relative backscattering spectrum for the sand surface at each grazing angle. The results suggest that scattering is mediated by sandgrain-scale roughness at high frequencies and is reasonably consistent with Lambert’s rule up to near-normal incidence. At lower frequencies, the scattering strength jumps abruptly higher at grazing angles above about 50°, which is consistent with some models for volume scattering. [Work supported by ONR.]
Calibrated seafloor acoustic backscatter imagery with a 160-kHz multibeam sonar
Authors: de Moustier Christian , Schimel Alexandre
Published: October 2013

A fully calibrated multibeam swath sonar operating at 160 kHz was used to collect seafloor acoustic backscatter data in Portsmouth Harbor, NH. Acoustic backscatter levels integrated over each beam’s footprint are compared with levels integrated over the sonar pulse’s footprint commonly used in sidelooking sonar imagery of the seafloor. In both cases, concurrent swath bathymetry is used to convert arrival angles measured at the sonar into angles of incidence relative to the seafloor. These results are contrasted against an extensive sedimentary and acoustic database obtained in 2001 with high frequency seafloor mapping sonars O(100–500 kHz) while assembling a common data set for the 2nd International Conference on High-resolution Surveys in Shallow Water 2001 (http://www.ccom.unh.edu/shallow/shallowsurvey.htm).
High-resolution three-dimensional imaging with synthetic-aperture forward-looking sonar systems
Authors: Lee Hua
Published: October 2013

The concept of synthetic-aperture imaging is to utilize the scanning of data-acquisition transducer(s) to create a larger aperture span for resolution improvement. In the area of underwater sonar imaging, the synthetic-aperture imaging modality has been successfully applied to side-looking sonar systems to improve the cross-range resolution. Forward-looking sonar systems are designed to operate in simple range-profiling mode mainly for obstacle avoidance. Typically, the forward-looking systems are equipped with a physical transducer array, linear or circular. The image formation procedure produces an instantaneous two-dimensional range map converted from the time-delay profile of the echoes. As a result, the three-dimensional landscape is compressed into a two-dimensional range profile. Consequently, the depth information is lost, which seriously compromises the effectiveness of the system’s capability. In this paper, the synthetic-aperture technique is applied to the forward-looking systems. The backward propagation image algorithm is applied for three-dimensional image reconstruction. With motion compensation procedure, similar to that in the side-looking synthetic-aperture imaging, high-resolution three-dimensional dynamic imaging capability can be achieved. In addition to the retention of the depth information, the resolution of the image profiles is greatly improved with dynamic updating. [Research supported by the UC MICRO program and Sonatech.]
The acoustic design of schools in England and Wales
Authors: Shield Bridget M.
Published: October 2013

Legislation governing the acoustic design of schools was introduced in England and Wales in July 2003. The acoustic performance standards which must be achieved are published by the Department for Education and Skills (DfES) in ‘‘Building Bulletin 93: Acoustic Design of Schools.’’ The UK government has recently announced plans for a major school buildings program; over 200 new secondary schools are to be built and many existing schools are to be refurbished. The DfES has published designs for ‘‘exemplar schools’’ by many of Britain’s leading architects. However, current trends in architectural design such as the use of highly reflective materials and the introduction of large open plan spaces make it difficult to comply with the specified acoustic performance standards. There are also conflicts between the acoustic and other requirements, such as the desire for natural ventilation in classrooms. This paper outlines the regulations, presents data to show that many existing schools in England do not comply with previous or current standards, and gives examples to illustrate the effects of various acoustic treatments of classrooms. Issues concerning implementation of the regulations are discussed and examples of ‘‘good’’ and ‘‘bad’’ acoustic designs of schools are given.
Appreciated: Forty years with Paul O. Thompson.
Authors: Cummings William C.
Published: October 2013

As longtime professional associate, ASA Fellow, and close personal friend, I have pleasured in knowing Paul O. Thompson for 40 years. In 1965 he was first to join my newly established Applied Bioacoustics Branch at NEL. He authored or co-authored 30 papers and reports on the sounds and related behavior of marine mammals in the North and South Pacific and South Atlantic oceans. Educated at St. Olaf College, MN, and USC, Paul’s earliest research resulted in 36 papers and reports on psychoacoustics often in collaboration with John Webster or Bob Gales. (Along with Past President Bob Young, we all were co-workers in the Listening Division headed by Past President Gales.) Ever unassuming, Paul is noted for stubborn devotion to detail that often uncovered new findings in seemingly rote data. Unmatched were his aural memory and skills at analog sound recording and processing. Paul could ferret and dissect whale signals among the ambient like very few contemporaries. Even after ‘‘retirement,’’ his research in the Sea of Cortez markedly added to earlier findings of 20-Hz and other low frequency utterances from blue and fin whales. This presentation focuses both on Paul and his contributions that are sure to permanently mark the literature on marine mammal bioacoustics.
Recording blue whales in the North Pacific: Building on the legacy of Paul Thompson
Authors: Stafford Kathleen M.
Published: October 2013

All of the well-documented blue whale call types for the Pacific were first recorded and described by Paul Thompson. Early work by Thompson and colleagues W. C. Cummings and W. A. Friedl, in particular, laid the foundation for what we know today about blue whale sounds. Among these contributions is the first published confirmation of blue whale sounds recorded off Chile [W. C. Cummings and P. O. Thompson, J. Acoust. Soc. Am. 50, 1193–1198 (1971)]. These sounds have since been recorded seasonally in the eastern tropical Pacific, suggesting a possible migration route. Thompson’s early work with Naval data not only provided the first description of northeast and northwest Pacific calls, but also documented diel calling patterns [P. O. Thompson, US Naval Elec. Lab. Rep. (1965); P. O. Thompson and W. A. Friedl, Cetology 45, 1–19 (1982); W. C. Cummings and P. O. Thompson, J. Acoust. Soc. Am. 95, 2853 (1994); P. O. Thompson et al., Marine Mammal Sci. 12, 288–292 (1987)]. Based on these descriptions, long-term seasonal and geographic studies of blue whale calls have been used to examine the Pacific basin-wide occurrence of calling blue whales. Lastly, Thompson and colleagues first remarked that blue whale sounds show distinct geographic variation, an observation that has promoted acoustics as a tool for distinguishing among populations of blue whales worldwide.
Acoustic surveys of killer whales during winter along the Pacific Northwest Coast
Authors: Norris Thomas , Hanson Brad , Noren Dawn , Jones Linda
Published: October 2013

An acoustic and visual survey was conducted along the outer coast of the Pacific Northwest (Washington to Central California) between 26 February and 14 March 2004 to determine the winter-time distribution and behavior of the southern resident ecotype population of killer whales (SRKWs). SRKWs are vocally active with a vocal repertoire that is well documented. A towed hydrophone array was deployed on 17 of the 20-day cruise resulting in an average of approximately 19 h of acoustic effort per day. Eleven of the 49 unique detections of marine mammal made were attributed to killer whales (22.5% of the total). Three of these killer whale detections occurred at night. Two of the three known SRKW pods (J, K, and L) were detected acoustically and positively identified as the J and L pods. Interestingly, the remaining nine unique acoustic encounters with killer whales were of either the offshore form or the transient form, considered to be vocally less active relative to the resident form. The hydrophone array substantially increased the number of detections of killer whales that would have been made using visual methods alone. Determining estimates of group size using acoustics remains problematic. Planned improvements to the acoustic system will be discussed. [Work funded by NOAA/NWFSC-Seattle, WA.]
New ultrasonic ranging transducer using 200-KHz corrugated polyvinylidine fluoride film
Authors: Toda Minoru , Dahl Jerry
Published: October 2013

Corrugated PVDF transducers were originally developed for use in parametric arrays to demodulate audio sound in air from modulated high intensity ultrasound. These arrays were designed to operate at ∼40 KHz. PVDF has recently been used in low-cost short-range-distance ranging transducers and provides accurate distance measurements in consumer, industrial, and medical applications. For this purpose, we designed, fabricated, and tested a corrugated PVDF transducer that operates at 200 KHz. This results in a small, directional, and low-cost transducer. The transducer has an area of ∼1 cm2 and produces a beam width of 16°. Combined with a sensor circuit that converts the measured time of flight into distance, we have demonstrated a detection range of 17–500 mm with a resolution of 25 mm. The resonance frequency of curved PVDF film was increased to 200 KHz by reducing the curvature radius to 1/5(∼1 mm) of that for previous devices operating at 40 KHz. The concave and convex regions of the corrugation vibrate with opposite phase and the radiated ultrasonic waves from both regions have a half-wavelength path difference that cancels the opposite vibration phase due to the half-wavelength effect.
Investigation of vibration of polyvinlidine fluoride cylindrical film by use of acoustic probe
Authors: Toda Minoru
Published: October 2013

Ultrasonic pen and white board digitizing systems are a rapidly growing market for PVDF transducers, utilizing an ultrasonic transmitter in the pen tip and two stationary ultrasonic receivers. The transmitter is constructed of piezoelectric PVDF welded into a cylindrical shape. Radius vibration (breathing mode) creates an 80-kHz airborne acoustic wave. The initial cycle is used to determine the time of flight, used to calculate the pen position by triangulation. An ideal cylindrical transmitter would have a uniform 360 horizontal radiation pattern. However, practical devices have a 65% to 85% minimum/maximum ratio for the initial pressure peak. A novel acoustic probe was devised to investigate this nonuniformity. The probe tip is a needle with 0.5-mm through hole, and the acoustic wave propagates through the needle to a conventional reference microphone. The probe was positioned using a precision XYZ stage. Investigations with this probe revealed the details of the nonuniformity in horizontal radiated pressure. It was found that (1) vibration at the welded seam of the PVDF cylinder is a maximum, opposite the expected behavior, and (2) the pressure distribution profiled along the height of the cylinder has a central plateau and decreases linearly at the cylinder ends.
Active noise reduction hearing protectors; 50 years of development
Authors: Cunefare Kenneth A.
Published: October 2013

This paper will review the technology development of active noise reduction (ANR) hearing protectors. Such devices have been in development for close to 50 years. Early studies by Meeker on feedback implementation of ANR identified many of the issues and performance criteria that are still relevant today. These issues include compensation, minimum phase filter design, and out-of-band control stability. Numerous patents and publications since the early developments focused on means to address the issues discussed by Meeker, and, to introduce alternative implementations of ANR hearing protectors or headsets. Such alternatives include feed-forward designs, as well as open-back and closed-back designs (open-back designs rely solely upon active control for noise protection; closed-back designs include passive attenuation from an ear muff). Development has also proceeded on designs which include communication elements; here, the active control system must attenuate the noise, but not the communication. Fifty years on, ANR hearing protectors represent the most successful commercial application of active noise control technology.
Hearing protector labeling for active noise reduction devices
Authors: Murphy William J. , Franks John R. , Behar Alberto
Published: October 2013

The US EPA regulation 40 CFR part 211b does not specify how to label hearing protectors that use active noise reduction (ANR). Real-ear attenuation at threshold (REAT) measurements are appropriate for testing the passive noise reduction performance of the earmuff. The contribution of ANR to the overall attenuation must be measured either with an acoustic test fixture (ATF) or using the microphone in real ear (MIRE) technique. ATFs must adequately mimic the coupling of the protector with either the skin of the ear canal or the side of the head, as well as provide sufficient attenuation to eliminate effects of bone conduction. The MIRE technique uses a miniature microphone positioned in the ear canal either at the entrance or at the tympanic membrane, and can be used to measure the insertion loss between the occluded and unoccluded conditions for both the passive and active modes of the protector. ATF and MIRE measurements made for several protectors demonstrate effective performance below 1000 Hz. This paper will examine methods for combining ATF and MIRE measurements with REAT to develop effective and informative rating for the ANR class of hearing protectors. [Portions of work supported by the U.S. EPA IA 75090527.]