bluuebunny/crossref_metadata_2025 huggingface dataset:
Pitch accommodation in synchronous speech.
Authors: Kim Miran , Nam Hosung
Published: October 2013

Synchronously read speech, in which a pair of speakers reads a text together, has been shown to reduce variability in speech tempo and unveil underlying properties of speech competence. Our study question is whether a synchronous speech condition also influences a pitch domain as well as a temporal one, which has been the main focus in studies of synchrony. We investigated how tones are modulated in the synchronous speech condition. Eight speakers of Mandarin Chinese were instructed to read a story text alone and together in pairs. Speakers also read the text together with recorded speech. Each trial was repeated five times. We measured F0 at onset, center, and offset of a resonant period for each syllable and compared read-alone to read-together speeches. Results show that (1) speakers in the synchronous speech condition tend to tune their pitch to each other such that F0 difference in pairs decreases overall; (2) they exhibit less variability in F0 across their own repetitions; (3) tonal targets in the read-together condition are achieved more stably in time. The pitch accommodation found in our study implies that speakers attend to F0 manifestation as well as tempo when F0 changes are phonologically contrastive in their language.
Effects of semantic context and regional dialect variation on speech intelligibility in noise.
Authors: Clopper Cynthia G.
Published: October 2013

Speech intelligibility in noise is affected by the semantic content of the utterance; semantically predictable utterances are more intelligible than semantically unpredictable or anomalous utterances. However, dialect variation interacts with semantic predictability in production; talkers produce more dialect-specific variants in semantically predictable contexts and more standard variants in semantically unpredictable contexts. The goal of the current study was to explore the interaction between dialect variation and semantic context in perception. Participants were asked to transcribe the final word of semantically predictable, unpredictable, and anomalous sentences produced by talkers from four regional dialects of American English and mixed with speech-shaped noise. The listeners exhibited an intelligibility benefit in the predictable context relative to the other two semantic contexts, regardless of talker dialect. However, differences in intelligibility between the dialects were reduced in the unpredictable and anomalous contexts relative to the predictable context, suggesting greater online adaptation to dialect variation in the unpredictable and anomalous contexts than the predictable context. These results are consistent with the finding that dialect differences may be attenuated in production in low predictability contexts, and suggest that perceptual dialect adaptation is affected by fine-grained intratalker acoustic variation.
Investigating perceptual measures of speech alignment: Do matching tasks make the grade?
Authors: Miller Rachel M. , Sanchez Kauyumari , Rosenblum Lawrence D.
Published: October 2013

Speech alignment is the tendency to produce speech which sounds similar to that of a person with whom one is speaking. It is often measured perceptually using an AXB-matching task [e.g., S. D. Goldinger, Psychol. Rev. 105, 251 (1998)]. In this procedure, naïve raters determine which of two utterances of a talker, produced prior (baseline) and after interaction with a model (e.g., shadowed), sounds more similar to that model. However, utilizing this type of perceptual measure has come under scrutiny due to its reliance on baseline utterances produced by talkers reading text. It has been suggested that AXB matching results reveal more about inherent differences between read and produced (shadowed) speech, than actual alignment. The present research addressed this concern. Experiment 1 involved a modified AXB task for which raters judged whether a subject sounded more like the model they had shadowed or another model. In Experiment 2, raters judged whether a subject sounded more similar to the model they had shadowed or to another subject who shadowed a different model. In both cases, results revealed that subjects sounded more similar to the model they shadowed. This suggests that alignment is perceivable by raters even when removing the comparison to read text. [Work supported by NIDCD Grant R01DC008957.]
Underwater target detection and classification using high resolution sensors and wide band sonar.
Authors: Petillot Yvan , Pailhas Yan , Capus Chris , Brown Keith
Published: October 2013

In this presentation, our work on integrated target detection and identification using sonar systems is presented. Standard high-resolution imaging sonar such as side scan and synthetic aperture are used for detection. Existing methods focus on statistical techniques using Markov models and machine learning-based techniques. Results on both synthetic and real data acquired in a large variety of terrains are presented. Identification can be based on either the shape of the target or its internal structure. Techniques-based active contours for shape analysis have been developed but these techniques only work well on very high-resolution data such as SAS and can be difficult to use on cluttered terrain. We propose to use the wide-band bio-sonar we developed to perform this task. In that case, the analysis focuses on the resonances induced by the internal structure of the target and the material used. Simulation confirmed by theoretical analysis on simple targets and experimental results demonstrate the effectiveness of this approach. These techniques are integrated on real vehicles in a collaborative vehicle framework to perform detection, classification, and identification of targets. [This work was supported by Thales, The Ministry of Defence, and the European Union under contract MRTN/CT/2006/036186.]
Krylov methods in time-reversal imaging by multiple-signal-classification.
Authors: Barbone Paul E. , Oberai Assad A. , Feijóo Gonzalo R.
Published: October 2013

Multiple signal classification (MUSIC) has been used to form images and identify sound sources since 1986 [R. O. Schmidt, “Multiple emitter location and signal parameter estimation,” IEEE Trans. Antennas Propag., AP-34, 276–280 (1986)]. In active sonar imaging of point targets, the MUSIC method can be used to estimate the range of the time-reversal operator. In this context, the method is related to the decomposition of the time-reversal operator method. Typical implementations of these methods utilize measurements of the entire time-reversal operator, and require computations of its eigenvalues and eigenvectors. By contrast, we show that Krylov iterative methods can be used to perform MUSIC imaging with relatively few acoustic excitations. Furthermore, by using the Lanczos technique, no eigenvalues or eigenvectors need be computed. Rather, an orthonormal basis for the range space of the time-reversal operator can be constructed directly from the received data. Most of the necessary computing is performed by the array itself, performing as a kind of “analog computer.” Finally, we show that useful images can be formed from one iteration to the next, while the data are being collected.
Modeling differential frequency hopping communication in the underwater acoustic channel.
Authors: Cazzanti Luca , Hsieh Julia , Egnor Dianne , Edelson Geoffry S.
Published: October 2013

Differential frequency hopping (DFH) is a fast frequency hopping digital modulation scheme with proven multiple-access and jamming robustness properties in typical wireless channels. Characterizing the capabilities of DFH modulation in the more challenging underwater acoustic channel requires careful analyses that rely on both computer simulations and data collected at sea. The Sonar Simulation Toolkit (SST) is used to model challenging underwater environments and simulate the propagation of DFH waveforms in the corresponding underwater acoustic channels. Our simulations provide baseline performance results that can be used to assess the capabilities of DFH modulation and guide future algorithmic improvements to the receiver. In particular, our simulations show that incorporating equalization techniques into the DFH baseline receiver leads to improved decoding performance in challenging environments characterized by long channel impulse responses, which are known to cause inter-symbol interference in the received acoustic bit stream. To ensure their relevance to practical applications, our computer-based SST models are calibrated to the environmental parameters measured during recent at-sea experiments, including the Rescheduled Acoustic Communications Experiment (RACE08), and the corresponding performance is analyzed.
Achieving maximum space-time-frequency diversity in shallow water acoustic channels: System design and experimental results.
Authors: Pelekanakis Costas , Baggeroer Arthur B.
Published: October 2013

This work sheds light on the individual impact of coded modulation and diversity in achieving reliable underwater acoustic (UWA) communications. Two systems with the same bit-rate and complexity but different diversity order are designed and compared. The “conventional” system combines trellis coded modulation (TCM), symbol interleaving and an 8PSK signal set. The “alternative” or bit-interleaved coded modulation (BICM) system combines a convolutional code, bit interleaving, and a 16QAM signal set. Both systems are coupled with orthogonal frequency division multiplexing (OFDM) to cope with the intersymbol interference (ISI). When two or three projectors are used, the above coding schemes are concatenated with space-time block codes (STBC). Bit-error rates using data recorded during the RACE’08 off the coast of Narragansett, USA are computed demonstrating the superiority of BICM schemes relative to their TCM counterparts over an extensive collection of shallow water channels, thus proving that BICM is a promising technique towards achieving reliable UWA communications. In particular, by using BICM and 4 kHz of bandwidth, we have successfully accomplished a 7150 b/s transmission rate over 1 km range.
Diffraction culling for virtual-acoustic simulations.
Authors: Calamia Paul , Markham Benjamin , Svensson U. Peter
Published: October 2013

Acoustic simulations of complex virtual environments typically are created with geometrical-acoustics techniques. Such simulations can be augmented with edge diffraction modeling for improved accuracy, but not without a significant increase in processing time due to the additional propagation paths which must be considered and the computational complexity of the diffraction calculations. However, for a given modeling scenario, the contribution of a diffracted path to the overall impulse response can vary over a large range, suggesting that certain diffracted paths can be ignored, or culled, to reduce processing time with a limited effect on the accuracy of the simulation. In this talk, we first analyze the effects of diffraction culling through a precomputed, amplitude-based ranking scheme. We then describe a simple procedure for identifying and culling insignificant diffraction components during a virtual-acoustic simulation which approximates the performance of the precomputed ranking. Through numerical and subjective analysis, we show that a significant percentage of diffracted paths can be ignored if the retained paths are those which lead to the highest-amplitude diffraction components, although the audible effects of such diffraction culling are dependent on the input signal.
Singers’ preferences for acoustical characteristics of performing spaces.
Authors: Stetson Kathleen , Braasch Jonas
Published: October 2013

Classical singers, whose instruments’ close proximity to their ears makes them unique among musicians, require particular attention from acousticians addressing musician support in performance space design. This study expands upon the few previous analyses of acoustics for singers by exploring what is most basic about solo voice self-perception in halls used for concerts and recitals. A questionnaire was given to a number of professional classical singers and their numerical and narrative responses were analyzed. Five concert halls were measured from the singer’s perspective on stage, utilizing a head and torso simulator with a mouth speaker to mimic the proximity of a singer’s voice and ears. The resulting impulse responses were utilized in preference tests featuring real-time binaural auralization of singers’ vocalizations. The correlations between the subjective results, existing objective parameters, and physical hall characteristics were explored. A strong connection was found between increasing preference and increasing reverberation time. Additionally, test subjects indicated a statistically significant dislike of or preference for a hall, regardless of the singing location on stage or the classical genre being sung. Further developments of this study are discussed in the context of ongoing opera house design utilizing computer model simulations.
Thirteen findings in ten minutes.
Authors: Ermann Michael , Crawford Nate , Field Braden , Green Jessica , Kim Sky , Mitchell Julia , Smith Steve , Wagner Matthew Van , Victor John Samuel , Massengill Amanda
Published: October 2013

Nine architecture students in an architectural acoustics course studied the influence of design on the acoustic response of spaces. Thirteen of their projects will be presented, rapidly, with time to delve into some of them more deeply in response to questions from attendees. Areas of focus include: room shaping and balcony composition; ceiling and canopy height; canopy design; perception and preference of double sloped decays; side wall angle and orientation; room length; very tall ceilings; room width; side wall diffusion; mapping background noise levels; and frequency content of noise.
Acoustic sampling for marine mammals in the Beaufort Sea July 2007–March 2008.
Authors: Stafford Kathleen , Moore Sue , Berchok Catherine , Mellinger David K.
Published: October 2013

As climate change is driving rapid, unprecedented warming of the Arctic, there is increasing interest in how such change will impact Arctic marine mammals. Impacts are anticipated from from habitat alteration, including increasing ambient noise levels from shipping, seismic exploration for oil and gas and geophysical research, and (potentially) commercial fishing. In order to monitor natural and anthropogenic sources of noise, four autonomous recorders were deployed along the 100-m isobath between Cape Halkett and Barrow and recorded data from July 2007–March 2008. The instruments sampled at 8192 Hz on a schedule of 10 min on, 20 min off. Marine mammal sounds recorded included pinnipeds (walrus and bearded seals) and cetaceans (bowhead and beluga whales), while anthropogenic sources included shipping and air gun sounds. Seasonal and geographic patterns for these sounds will be presented. These data form part of a broader-scale international, year-round monitoring program in the Arctic that we hope will eventually span the entire Arctic and provide a basin-wide acoustic observatory.
The impact of ocean sound speed variability on the uncertainty of geoacoustic parameter estimates.
Authors: Chapman Ross , Jiang Yongmin
Published: October 2013

This paper investigates the influence of water column variability on the estimates of geoacoustic model parameters obtained from matched field inversions. The acoustic data were collected on the New Jersey continental shelf during the Shallow Water 2006 experiments. The oceanographic variability was evident when the data were recorded. To quantify the uncertainties of the geoacoustic parameter estimates in this environment, Bayesian matched field geoacoustic inversion was applied to multi-tonal continuous wave data. The spatially and temporally varying water column sound speed was parametrized in terms of empirical orthogonal functions and included in the inversion. Its impact on the geometric and geoacoustic parameter estimates was then analyzed by the inter-parameter correlations. Two different approaches were used to obtain information about the variation of the water sound speed. One used only the profiles collected along the experimental track during the experiment, and the other also included observations from a larger area and a greater time period. The geoacoustic estimates from both the large and small sample sets were consistent. However, due to the diversity of the oceanic sound speed, more empirical orthogonal functions were needed in the inversion when more sound speed profile samples are used. [Work supported by ONR.]
Acoustofluidics: Theory and simulation of streaming and radiation forces at ultrasound resonances in microfluidic devices.
Authors: Bruus Henrik
Published: October 2013

During the past few years, there has been an increasing interest in applying ultrasound waves to manipulate biological particles and liquids in microfluidic devices. To obtain optimized designs and functionalities of the acoustofluidic devices, more detailed theoretical studies and numerical simulations are called for. The basic second-order perturbation theory is presented for acoustic fields applied at ultrasound frequencies in silicon/glass systems containing water-filled microfluidic channels and chambers. For various specific device geometries, the resonance frequencies and corresponding modes of the acoustic fields are calculated numerically to first order. At these frequencies, the largest possible acoustic powers are obtained in the microfluidic system. The first order fields are then used as source terms in the equations for the time-averaged second order pressure and velocity fields, which are directly related to the acoustic radiation force on single particles and to the acoustic streaming of the liquid. For the radiation pressure effects, there is good agreement between theory and simulation, while the numeric results for the acoustic streaming effects are more problematic. Possible improvements in the latter case are discussed.
Cylindrical standing wave resonator for liquid food quality control.
Authors: Priev Aba , Sarvazyan Armen
Published: October 2013

In this paper, an innovative technology based on the use of ultrasonic cylindrical standing waves for continuous monitoring of quality of various liquid food products, such as milk, juices, beer, wine, and drinking water is described. A proprietary unique feature of the developed ultrasonic analyzer is that it employs a combined mode of operation using both high-intensity and low-frequency (10 W/cm2, 1 MHz) waves for separation and concentration of the high-molecular-weight particles (fat globules or cells) and low-intensity and high-frequency (0.5 W/cm2, 10 MHz) waves for compositional analysis. High accuracy for ultrasound velocity measurements (up to 0.001%) and ultrasound attenuation (of about 1%) and rapid testing time (2–20 s) have been achieved. Comparative analyses of the ultrasonic method with standard reference techniques have produced linear calibration curves for major components with correlation coefficients higher than 0.95. It is thus possible to monitor total protein and fat content, and somatic cell count in raw milk in cowsheds, or salinity, turbidity, specific gravity, and particles (bacteria) in drinking water directly. Advantages of the proposed technology include the reagent-free nature, no need for sample pretreatment, ease-of-use, and low cost.
Movement of liquids and solid particles on multiwall acoustic plates.
Authors: Hawkes Jeremy J. , Mijarez-Castro Rito , Fielden Peter R.
Published: October 2013

Well-defined vibration modes are used to form acoustic wells on flat plates. Within these dynamic traps, acoustic streaming continually stirs the contents. Traps can be used to hold liquids in separate heaps on a surface or to hold particles in levitated arrays. A protocol for creating trap patterns will be described, where FE modelling is used to select modes and then maneuver the modes to the desired frequency.
Time reversal of monochromatic signals in elastic media.
Authors: Anderson Brian E. , Guyer Robert A. , Ulrich Timothy J. , Johnson Paul A.
Published: October 2013

A set of experiments has been conducted to show that time reversal of steady state monochromatic signals can produce spatial focusing in a reverberant elastic cavity when multiple channels are used. The transient portion of the received signals is not used. A single channel does not produce spatial focusing as it only drives the system according to its modal distribution. The amplitude of the energy at the focal location increases as the square of the number of channels used, while the amplitude elsewhere in the medium increases proportionally with the number of channels used. This work has importance in the field of medical ultrasound where the use of a long duration monochromatic excitation may be used for lithotripsy or other ultrasonic therapy. [This work is supported by Institutional Support (LDRD) at Los Alamos National Laboratory.]
A micromachined piezoelectric flexural mode hydrophone for audible frequency application.
Authors: Lee Haksue , Choi Sungjoon , Moon Wonkyu
Published: October 2013

A micromachined hydrophone is designed for audible frequency application (20 Hz–20 kHz). The basic structure is a flexural unimorph consisting of a clamped silicon diaphragm and a piezoelectric film. Two design approaches can enhance its sensitivity. One is a unimorph with unequal radii between the piezoelectric film and the diaphragm, which increases electromechanical coupling. The other is an air-backed chamber, which reduces mechanical impedance in the flexural vibration and, consequently, enhances sensitivity. To predict the effects of these approaches on sensitivity, an equivalent transduction model is composed and used for calculations. In the case of oil backing, compared to air backing, a reduction in sensitivity of about 40 dB is expected. The dimensions of the micromachined diaphragm (piezoelectric film) are 630 μm (400 μm) radius and 15 μm (3 μm) thick. A fabricated microsensor is constructed as a hydrophone by using a rubber housing filled with castor oil. The measured sensitivity is −228.3 dB at 1V/μPa without a preamplifier. A flat frequency response within ±1 dB deviations were measured in the 100 Hz–5 kHz band. Based on the simulation, it can resist the hydrostatic pressure of 100 m depth, without pressure balancing, while decreasing in sensitivity. The results of a larger model having a higher sensitivity of −207.6 dB will also be presented. [Research supported by MRCND and R0A-2007-000-20042-0.]
Advantages of piezoelectric microelectromechanical systems (MEMS) microphones.
Authors: Littrell Robert , Grosh Karl
Published: October 2013

Microphones fabricated using microelectromechanical systems (MEMS) technology are one of the fastest growing applications of MEMS. Capacitive sensing has been the dominant form of transduction in both traditional and recently commercialized MEMS microphones. Models and experiments, however, indicate that the thin layers and fine spatial resolution made possible by MEMS technology lend themselves more appropriately to piezoelectric microphones. Although piezoelectric MEMS microphones have typically been shown to have a relatively high noise floor, this limitation can be overcome with appropriate design and high quality piezoelectric material. Models indicate that piezoelectric MEMS microphones can achieve a comparable noise floor to capacitive MEMS microphones of similar size and bandwidth while achieving 1000 times greater dynamic range. A piezoelectric MEMS microphone utilizing aluminum nitride (AlN) will be presented. Previously experienced film quality issues have been addressed. This microphone is designed to have a noise floor below 40 dB (A), a dynamic range greater than 160 dB SPL, a 10 kHz bandwidth, and a sensing area of less than 1 mm2.
Evaluation of two control parameters of trumpet players as function of sound features.
Authors: Causse Rene , Freour Vincent
Published: October 2013

Experiments were performed by five trumpet players with the same trumpet and mouthpiece. For each subject, two control parameters are measured: mouth-pressure and force applied by the lips on the mouthpiece. The sound is also recorded. The players are asked to play sustained notes at different pitch and sound levels. We calculate fundamental frequency, sound pressure level, and some spectral features: noisiness, spectral roll-off, etc. Although little mouth-pressure variability as function of pitch and dynamic appears between subjects, clear differences were obtained in terms of the force applied on the mouthpiece. Therefore, we suggest to focus on the link between sound features and the ratio of these two control parameters measured, sort of “gesture estimator.” The representation of the ratio as function of the sound features shows a good classification of musicians. Moreover, in some specific cases such as noisiness, the relation seems independent from the players. These observations suggest that these two control parameters could be efficient to characterize players’ embouchure and to access some sound characteristics without knowledge of the mechanical characteristics of the lips. These results will be described and discussed, and direction for future works suggested. [Consonnes project, supported by the French Research Agency.]
Optimization of valve tube lengths for brass instruments.
Authors: Young Frederick
Published: October 2013

The intonation deviations from the well-tempered scale are presented for valve brass wind instruments. Compensating and full double instruments are considered. Systems including descending valves and less popular ascending valves are studied. The lengths of the valve tubes are optimized by minimizing the overall root mean squared (rms) intonation error using the method established in 1967 [R. Young, J. Acoust. Soc. Am. 42, 224–235 (1967)]. Open note detuning is considered in each case and improves the overall intonation. The worst three valve instrument without open note detuning has an rms deviation 24 cents The best of the three and four valve instruments is a three valve compensating euphonium tuned 3 cents sharp on the open notes and flat on valves 2, 1, and 3 by 3, 3, 10 cents, respectively. It exhibits only 2 cents rms deviation on single valves and less than 3 cents on combinations of valves. The comparisons also include several new three, four, and five valve systems. Included is a double horn with only two double valves and a switch valve.
The input impedance of an alphorn including an Alexander mouthpiece.
Authors: Young Frederick J.
Published: October 2013

The alphorns built and sold by the late Joseph Littleton of Hammondsport, NY are used in this study. His dimensions of bore as a function of position are used in solution of the Webster equation for impedance solved numerically earlier [F. J. Young, Acustica, 10, 91–97 (1960)]. The musical notation for the frequencies of the impedance peaks are given below. Here the subscripts refer to the harmonic number. The fundamental, rarely used, is 13 cents flat from A at 55 Hz. The intonations errors for. C1, C2, G3, C4, E5, G6, B7b, C8, D9, E10, F11, G12, A13, B14b, B15, C16, C17#, and D18 are 287, 58, 195, 28, 1.5, 0.83, -28, -0.85, -2.63, 1.5, 40, 14, -49, 1, -3, 16, 24 and 28 cents.
Numerical modeling of weak shock propagation: Past, present, and future.
Authors: Piacsek Andrew
Published: October 2013

This presentation provides an overview of the subject of numerical modeling of weak shock propagation, with the aim of providing context for subsequent talks in this session. First is a brief history of analytical approaches to the problem of weak shocks in both one and two dimensions, emphasizing the characteristic physical behavior of the solutions. This leads to a discussion of the physical processes that must be modeled, including the Rankine-Hugoniot conditions at the shock interface, nonlinear steepening, and self-refraction, refraction and diffraction due to an inhomogeneous medium, dissipation, relaxation, and heating of the medium. Next is a summary of paraxial numerical methods, specifically the NPE and KZK equations, and their recent applications, followed by a description of efforts to develop “wide-angle” versions of these codes. Computational challenges, and possible approaches, to extending these methods to three dimensions are also presented. Last, a brief introduction to new approaches to 3-D modeling will be given, along with a discussion of the applicability of computational improvements such as adaptive meshing and parallel processing.
Numerical simulation of the propagation of three-dimensional helical shock waves in a weakly heterogeneous medium.
Authors: Marchiano Regis , Coulouvrat Francois , Thomas Jean-Louis
Published: October 2013

A numerical method for the simulation of 3-D acoustical shock wave propagation through a homogeneous or weakly heterogeneous medium is presented. It is based on a generalization of the KZ equation taking into account weak heterogeneities. The algorithm is based on a spectral treatment of the linear diffraction (angular spectrum), coupled with quasianalytical solutions for the heterogeneous part and for the nonlinear one. This last one solves Burgers’ equation with the so-called Burgers-Hayes method using the potential instead of the pressure field. The combination of these several algorithms lead to the development of an efficient software, allowing to solve full 3-D problems for standard personal computers. This software is used to study the dynamics of helical shock waves also called acoustical vortices (AVs) which are the acoustical equivalent of optical vortices. The 3-D helical spatiotemporal wave field is characterized by azimuthal shocks. The dynamics of the so-called topological charge, an intrinsic property of AVs, is studied in the nonlinear regime through different focusing lenses.
A nonlinear computational method for the propagation of shock waves in ducts: Application to buzz-saw noise.
Authors: Fernando Rasika , Druon Yann , Marchiano Regis , Coulouvrat Francois
Published: October 2013

A numerical method to compute shock wave propagation in uniform waveguides in 2-D and 3-D is presented. The solution is searched under the form of a modal solution of the Kuznetsov equation for which the modal amplitudes of the analytical linear modes are supposed to vary along the duct axis due to nonlinear interactions between the different modes and frequencies. This finally yields to a differential system on the mode amplitudes, which is solved numerically using a standard Runge-Kutta algorithm for ordinary differential equations after numerical truncation of the modal series. Examples are presented of the nonlinear evolution of the pressure field for a 2-D waveguide. One important 3-D application is the so-called “buzz-saw” noise occurring for high-bypass-ratio turbofan engines, when fan blade tip relative flows exceed the sound velocity. First results on 3-D simulations for nonlinear propagation of a saw-tooth waveform spiraling inside a hard-walled cylindrical will be presented. Extensions of the model to ducts with uniform flows or with liners (walls with impedance) will finally be discussed.
Evaluation of a wave vector frequency domain method for nonlinear wave propagation.
Authors: Jing Yun , Clement Greg
Published: October 2013

In this paper, a wave vector frequency domain method is presented to describe both forward and backward nonlinear wave propagations in acoustic media. A frequency domain nonlinear wave equation is first derived based on the Westervelt equation by taking the Fourier transform in the temporal and spatial domains. Since the model works directly in the frequency domain, arbitrary dispersion relations can be elegantly considered. The nonlinearity is further evaluated by multidimensional autoconvolution of the Fourier transform of the sound pressure. An implicit solution of the equation is proposed by employing the Green’s function, and is solved numerically. Comparisons between the numerical simulations and the Burger’s solution show good agreements within the shock formation distance. Error study is also carried out to test the efficiency of the model. It is found that the error grows as the initial pressure increases and the spatial resolution decreases. Finally, the present model is compared with a time-domain approach for a practical case, where the diameter of the transducer is 100 mm, the fundamental frequency is 1 MHz, and the focus range is 150 mm.
Spatial maps of modal damping from frequency response measurements.
Authors: McDaniel J. Gregory , Boucher Craig , Öztürk Hande
Published: October 2013

A method is proposed for constructing spatial maps of modal damping for viscously damped structures. These maps are intended to be useful in assessing the effectiveness of spatially distributed damping, particularly in complex structures that are damped by a variety of mechanisms. The method uses frequency response measurements and modal analysis to determine the natural frequencies and mode shapes of the damped structure. The damping matrix is estimated directly from the frequency response measurements and is expressed as a sum over connectivity matrices weighted by dashpot constants. This sum is substituted into the well-known approximation for the modal loss factor that results by neglecting off-diagonal elements of the modally transformed damping matrix. The resulting expression quantifies the contribution of local dashpot properties to the modal loss factor, and may be visually presented as a spatial map of damping. A significant advantage of this approach is its independence from a detailed model of the structure or its damping, allowing it to be used for complex structures. The resolution of the map is directly correlating to the number of measurement locations, as will be illustrated by examples. [Work supported by ONR under Grant No. N000140810531.]
Innovative structural acoustic strategies to reduce sound transmission through lightweight flexible structures.
Authors: Bliss Donald , He Qinxian , Franzoni Linda , Palas Cassidy
Published: October 2013

This paper describes research utilizing structural acoustics in novel ways to cancel the transmission of sound and vibration through multielement flexible barriers. Configurations analyzed include panels with different thickness and elastic modulus in different regions and layered structures connected by an elastic suspension. The purpose of the research is to demonstrate that flexibility and controlled resonant behavior can be used to block sound transmission even when structural damping is very low. Strategies are considered to alter vibrating surface wavenumber spectra to reduce coupling between the structure and the acoustic field. Another approach that can be employed is the utilization of structural wave cutoff with multielement multipath (MEMP) structures. Finally, multiple differentially tuned subsidiary elements acting as resonators can be used to greatly reduce the structural response. Examples of acoustic transmission loss through panel barriers using different strategies are presented, and the potential advantages and possible shortcomings of various approaches are evaluated. Possible configurations for layered sound reduction materials are proposed. The work has particular application to the reduction of vehicle interior noise and addresses the need for good acoustic performance of the lighter weight flexible structures that will be used in the future.
The role(s) of capacity limitations in speech perception.
Authors: Francis Alexander L.
Published: October 2013

This paper reviews some current research exploring the role that capacity limitations play in recognizing speech, particularly in the presence of competing speech. Load theory [Lavie, Trends Cogn Sci 92 (2005)] suggests that perceptual capacity limits the number of objects (or features) that can be processed simultaneously, while cognitive capacity limits rejection of irrelevant information. Functional imaging studies show increased cognitive (working memory) load corresponding to failure of inhibition of (increased activity in) brain regions associated with processing distractor stimuli [de Fockert et al., Science 291 (2001)], whereas increased perceptual load results in decreased activity in distractor-related areas [Rees et al., Science 278 (1997)]. However, all of these studies were carried out in the visual modality, and it is unclear whether the same predictions were obtained in audition or speech perception. A series of experiments in which perceptual and working memory load were varied as listeners identified words produced by one talker while ignoring another provides qualified support for the predictions of load theory and lays the groundwork for subsequent studies of the effects of hearing impairment, cognitive deficits, and perceptual and cognitive training on the perception of speech in competing speech. [Work supported by NIDCD R03DC006811.]
The learning of lexical tones.
Authors: Ji Sunjing
Published: October 2013

Our understanding of speech perception suggests that categorization is an essential task of our cognitive system. Based on previous research on segment perception, this study explores the questions of what mechanism is involved in the acquisition of lexical tones and whether contour tones are decompositional in the process of cognitive learning. An experiment adopting the statistical training method from Maye et al. (2002) and Hayes-Harb (2007) was conducted on the learning of lexical tones by adult naive tone learners. The results show that statistical distribution of stimuli along a pitch continuum in training affects naive tone learners’ formation of level lexical tone categories. In addition, the perception of level tones behaves more like the perception of vowels rather than consonants. Moreover, exposure to statistical training on a level tone continuum alone affects participants’ performance in contour tone discrimination. This indicates that participants were able to apply level tone categories to generate new mental categories of contour tones, providing psychological evidence for the auto-segmental argument that contour tones are composed of a sequence of multiple level tones.
The perceptual organization of sine-wave speech under competitive conditions.
Authors: Roberts Brian , Summers Robert J. , Bailey Peter J.
Published: October 2013

Speech comprises dynamic and heterogeneous acoustic elements yet is heard as a single perceptual stream, even when accompanied by other sounds. The relative contributions of grouping primitives and of speech-specific factors, for example modulation patterns, to the perceptual coherence of speech are unclear, and the critical acoustical correlates of the latter remain unknown. The parametric manipulations possible with simplified speech, such as sine-wave analogs, make them attractive experimental stimuli to explore this issue. Given that the factors governing perceptual organization are generally revealed only where competition operates, the second-formant competitor (F2C) paradigm was used, in which the listener must resist competition to optimize recognition [Remez et al., Psychol. Rev. 101, 129–156 (1994)]. Three-formant (F1+F2+F3) sine-wave analogs were derived from natural utterances and presented in a dichotic configuration (one ear = F1+F2C+F3; opposite ear = F2). Different versions of F2C derived from F2 by manipulating its amplitude and frequency contours were effective at reducing intelligibility except when the frequency contour was constant. Manipulation of relative F2C level indicated that competitor efficacy was not due primarily to energetic masking. The findings suggest that modulation of the frequency, but not the amplitude, contour is critical for cross-formant grouping. [Work supported by EPSRC.]
The development of infants’ sensitivity to modified spectral tilt: Fricatives, approximants, and vowels.
Authors: Beach Elizabeth , Kitamura Christine
Published: October 2013

In early infancy, speech perception is based on innate psychoacoustic thresholds allowing young infants to discriminate a wide range of speech contrasts. However, as infants accumulate knowledge of their native language, they begin attuning to native speech sounds: first vowels around 6 months; then consonants around 9–12 months. Now that hearing-impaired infants are being diagnosed and fitted with hearing aids early in life, there is a need to investigate how speech is amplified in infant hearing aids. This study examined whether infants would benefit from positive, negative, or unmodified spectral tilt. Spectral tilts of +6dB/octave and −6dB/octave (as found in hearing aids) were applied to three speech contrasts (fricatives, approximants, vowels) and in a third condition the contrasts remained unmodified. Normal-hearing 6- and 9-month-olds were tested using an habituation procedure to determine whether positive, negative, or unmodified tilt aids discrimination of the speech contrasts. The results showed 6-month-olds benefit when relevant frequency information is amplified, i.e., high-frequency for fricatives and approximants, low-frequency for vowels. Nine-month-olds, on the other hand, discriminated all contrasts best when unmodified. The developmental change between 6 and 9 months might be explained by infants shifting from an acoustic to a linguistic mode of speech perception.
Change detection deconfliction process for sonar clutter items.
Authors: Dubberley John , Gendron Marlin
Published: October 2013

When resurveying a seafloor area of interest during change detection operations, an automated method to match found bottom objects with objects detected in a previous survey allows the surveyor to quickly sort new objects from old objects. Here we will demonstrate a software system that accomplishes change detection. The change detection system contains modules for automatic object detection by geospatial bitmap technique, object collocation, feature matching using shadow outlining, scene matching by control point matching, and visualization and filtering capabilities. Emphasis will be placed on the new elements of the system, namely, shadow outlining and optional spatial filtering.
Bistatic synthetic aperture sonar images of penetrable cylinders.
Authors: Dudley Christopher , Marston Philip L.
Published: October 2013

Bistatic synthetic aperture sonar (SAS) and acoustic holographic images and monostatic backscattering by penetrable tilted cylinders in water were investigated. Refracted rays internally reflected from the cylinder’s backside often dominated the scattering. Ray theoretic models predict scattering enhancements for cylinders made of some isotropic and anisotropic materials. Experiments involved solid cylinders and liquid-filled cylindrical shells of polymers and fiberglass. The experiments used transient insonification and ka in the range of 9<ka<40, where ka is a product of the acoustic wave number and the cylinder radius. Bistatic measurements used a hydrophone scanned along a line. Transversely isotropic fiberglass rods produced rich features in the images and in the backscattering plotted as a function of tilt and time. The timing of some features could be explained from a ray model based on properties of quasi-shear and quasi-longitudinal waves computed from the stiffness matrix measured for the fiberglass. Bright features for solid cylinders and liquid-filled shells were typically associated with refracted waves having phase velocities less than the speed of sound in water. For some tilt angles, radiated wavefronts were relatively flat producing enhanced farfield scattering. [Work supported by ONR.]
The Italian connection: Ralph Goodman’s close ties to NATO over 45 years.
Authors: Jensen Finn B.
Published: October 2013

Ralph’s enduring and very intense professional relationship with SACLANTCEN (now NURC) in La Spezia, Italy, started in September 1961 when he joined the Centre as a young scientist. He worked in Italy for two years publishing on “convergent zone propagation” and “reverberation from smooth ocean floors.” This was also the time of his first sea trial, which on Ralph’s watch nearly led to the ship running aground. His love for life in Italy and the NATO Centre as such led to many visits in the coming years. He returned in 1981 to become the first American director of SACLANCEN. His primary task was to plan and undertake the construction of a new NATO research vessel named Alliance, a task which involved many crucial decisions about ship specifications and performance, plus guidance to the in-house ship building team, and excruciating negotiations with NATO agencies to secure the funding. Ralph’s broad scientific background and superb people management skills ensured the success, and his “yacht” is still one of the best research vessels around, here 20 years later. Ralph’s tenure as director lasted an unprecedented 6 years and he left in 1987 having secured SACLANTCEN a top-rated seagoing capability for years to come.
Bubble research with Ralph Goodman at Penn State.
Authors: Gilbert Kenneth E.
Published: October 2013

During the years 1992–1998 at Penn State, I collaborated closely with Ralph Goodman on scattering from the near-surface oceanic bubble layer. Ralph’s enthusiasm, physical insight, and encyclopedic knowledge of at-sea experiments proved to be invaluable. I will outline the research and discuss Ralph’s contributions to graduate theses and scientific papers that were published. I will also give some personal observations on what it was like collaborating with Ralph.
Observations and theory of dispersion in rip currents at the Scripps Pier Bubble Experiment of 1997.
Authors: Caruthers Jerald W. , Stanic Steve , Novarini Jorge C. , Henyey Frank
Published: October 2013

Two of the authors (Caruthers and Stanic), with help and advice from Ralph Goodman, were instrumental in planning and conducting the 1997 Scripps Pier Bubble Experiment. Ralph’s participation was invaluable in making this effort a success. A number of institutions were involved in the overall experiments, but the main experiments, conducted by the Naval Research Laboratory, centered on what was termed the “delta frame” [Caruthers et al., J. Acoust. Soc. Am., 106, 617–625 (1999)]. The delta frame was a triangle 10 m on a side with sources at two apexes and eight hydrophones distributed along the arms. Eight frequencies (39 to 244 kHz) were propagated from the two sources. The NRL personnel and other participants in the experiment published a number of detailed measurements and analyses. In the delta frame experiments, a significant amount of the data was relevant to sound-speed-dispersion analyses. Ralph was always keenly interested in dispersion, but we never fully analyzed, nor published those observations. With that oversight and regret in mind that the relevant analyses were not conducted during Ralph’s lifetime, we have revisited that data in his honor. [Work supported by ONR and NRL.]