bluuebunny/crossref_metadata_2025 huggingface dataset:
Mode studies in triangular bellplates
Authors: Hansen Uwe J. , Lavan Daniel , Hogg Suzanne
Published: October 2013

Preliminary results from mode studies in triangular aluminum bellplates using electronic holographic interferometry were reported at the 136th ASA meeting [Uwe J. Hansen, J. Acoust. Soc. Am. 104, 1767(A) (1998)]. Since then the TU Sydney co-authors of this paper have performed finite element calculations with results which are remarkably congruent with the holographic data. The first 13 modes will be discussed and shown in holographic as well as FEM representation.
Transcending boundaries with Ira Hirsh
Authors: Singh Punita G.
Published: October 2013

Ira Hirsh has made many contributions to various fields of acoustics from speech, hearing, psychological and physiological acoustics, to musical and architectural acoustics. It was a privilege for me to have been his student in all these areas, and to have had him as a guide through masters and doctoral degree programs that focused on topics that lie at the boundaries connecting these disciplines. Ira was not a prescriptive advisor, imposing particular research topics or procedures on his graduate students. Rather, he encouraged originality, innovation, and personal goal setting. He would subtly suggest starting points and provide landmarks as references, rather than explicit directions leading to them. One had to navigate the path by ones own wits. This approach encouraged lateral, out-of-the box thinking, while also leading to respectful appreciation of historic trajectories in scientific research. During our time together, we worked on several aspects of music, including, rhythm, melody, pitch, and timber perception. Some of this work will be recapitulated, highlighting Ira’s role in its exposition and development. His multidimensional personality, astute insights, colorful remarks, wry humor, care, and concern are qualities to be cherished—beyond the boundaries of campus, city, country, and contemporaneity.
Ad cerebrum per scientia: Ira Hirsh, psychoacoustics, and new approaches to understanding the human brain
Authors: Lauter Judith
Published: October 2013

As Research Director of CID, Ira emphasized the importance of combining information from biology with rigorous studies of behavior, such as psychophysics, to better understand how the brain and body accomplish the goals of everyday life. In line with this philosophy, my doctoral dissertation sought to explain brain functional asymmetries (studied with dichotic listening) in terms of the physical dimensions of a library of test sounds designed to represent a speech–music continuum. Results highlighted individual differences plus similarities in terms of patterns of relative ear advantages, suggesting an organizational basis for brain asymmetries depending on physical dimensions of stimulus and gesture with analogs in auditory, visual, somatosensory, and motor systems. My subsequent work has employed a number of noninvasive methods (OAEs, EPs, qEEG, PET, MRI) to explore the neurobiological bases of individual differences in general and functional asymmetries in particular. This research has led to (1) the AXS test battery for assessing the neurobiology of human sensory-motor function; (2) the handshaking model of brain function, describing dynamic relations along all three body/brain axes; (3) the four-domain EPIC model of functional asymmetries; and (4) the trimodal brain, a new model of individual differences based on psychoimmunoneuroendocrinology.
Visualization of the energy flow for a guided forward wave in and around a fluid loaded elastic cylindrical shell: Color coding of the Poynting vector field
Authors: Dean Cleon E. , Braselton James P.
Published: October 2013

Previous work [Cleon E. Dean and James P. Braselton, ‘‘Visualization of the energy flow for a guided forward wave in and around a fluid loaded elastic cylindrical shell,’’ J. Acoust. Soc. Am. 109, 2379 (2001)] showed the energy flow for a forward propagating fluid loaded elastic cylindrical shell at the resonance frequency. The results were difficult to interpret since although the two counterpropagating guided waves were separated and displayed independently, the conventional grid of vector arrows was hard to interpret in part because they were hard to see individually. The current work uses color encoding to show the Poynting vector field. Hue is used to indicate the direction of the energy flow while intensity of the color is used to denote the magnitude of the Poynting vector at that point.
Preliminary results of horizontal array coherence from the 2001 ASIAEX South China Sea experiment
Authors: Schroeder Theodore H. , Lynch James F. , Newhall Arthur
Published: October 2013

The 2001 ASIAEX (Asian Seas International Acoustics Experiment) South China Sea experiment was performed in April–May, 2001 off the southern coast of the People’s Republic of China. This experiment was a combined acoustics/physical oceanography/marine geology effort that endeavored to measure basic acoustic propagation and scattering processes in a well-supported manner. As part of the experiment, a combination vertical/horizontal autonomous receiving array was deployed in 124 m of water, where it listened to a combination of moored and towed acoustic sources spanning a bandwidth of 50–600 Hz. These acoustic measurements were supported by geological surveys and extensive oceanographic measurements from fixed and towed instruments, providing a 3-D picture of the overall oceanography in the experimental area. The initial interest in this data centers about horizontal array coherence issues, as few experiments have had a horizontal array coupled with extensive environmental support, allowing for a direct correlation of the array coherence with the environment. The frequency dependence, time variability, and along-shelf vs. across-shelf variation of coherence are of particular interest. The latest results in these topics will be shown. [Work supported by ONR.]
Ultrasonic scattering models for cancellous bone
Authors: Laugier Pascal , Padilla Frederic , Jenson Frederic
Published: October 2013

In recent years, quantitative ultrasound (QUS) measurements have played a growing role in the assessment and management of osteoporosis. This development is attributable to the current wide availability of ultrasonic equipment measuring acoustic parameters in transmission at several skeletal sites. QUS provides equivalent fracture risk assessment compared to conventional x-ray absorptiometric techniques. It is generally accepted that transmission QUS represents a surrogate marker for bone mineral density. Several investigations are currently being conducted to assess innovative QUS techniques to determine and utilize the full potential of this technology for the benefit of detecting pathological conditions that affect bone strength. Among these developments, reflection and scattering techniques may be useful for the quantitative analysis of bone microarchitecture. We will review recent experimental data and theoretical modeling of ultrasound scattering by cancellous bone. Good agreement between experimental data and predictions using a weak scattering model has been reported by different authors for the magnitude and the frequency dependence of the backscatter coefficient. We also found good agreement between the experimental mean trabecular thickness derived from the 3D microarchitecture analysis and theoretical predictions. These results open interesting prospects for bone microarchitecture characterization from in vivo measurements.
Dependence of ultrasonic scattering on frequency and microarchitecture in trabecular bone: Theory and experiment
Authors: Wear Keith A.
Published: October 2013

Measurements of ultrasonic properties of calcaneus (heel bone) have been shown to be effective for the diagnosis of osteoporosis. However, the mechanisms underlying the interaction between ultrasound and bone are currently not well understood. A model that predicts backscatter from trabecular bone has been developed. Scattering is assumed to originate from the surfaces of trabeculae, which are modeled as long, thin, elastic cylinders with radii small compared with the ultrasonic wavelength. Experimental measurements of backscatter using broadband ultrasound centered at 500 kHz from 43 trabecular bone samples (from human calcaneus) in vitro have been performed. Microcomputed tomography has been performed on all 43 samples in order to measure microarchitectural features. The theory correctly predicts the measured dependences of backscatter on ultrasonic frequency and trabecular thickness. [Funding from the FDA Office of Womens Health is gratefully acknowledged.]
Development and validation of a multiecho computer simulation of ultrasound propagation through cancellous bone
Authors: Langton Christian , Church Luke
Published: October 2013

Cancellous bone consists of a porous open-celled framework of trabeculae interspersed with marrow. Although the measurement of broadband ultrasound attenuation (BUA) has been shown to be sensitive to osteoporotic changes, the exact dependence on material and structural parameters has not been elucidated. A 3-D computer simulation of ultrasound propagation through cancellous bone has been developed, based upon simple reflective behavior at the multitude of trabecular/marrow interfaces. A cancellous bone framework is initially described by an array of bone and marrow elements. An ultrasound pulse is launched along each row of the model with partial reflection occurring at each bone/marrow interface. If a reverse direction wave hits an interface, a further forward (echo) wave is created, with phase inversion implemented if appropriate. This process is monitored for each wave within each row. The effective received signal is created by summing the time domain data, thus simulating detection by a phase-sensitive ultrasound transducer, as incorporated in clinical systems. The simulation has been validated on a hexagonal honeycomb design of variable mesh size, first against a commercial computer simulation solution (Wave 2000 Pro), and second, via experimental measurement of physical replicas produced by stereolithography.
A noninvasive method for focused ultrasound surgery through the human skull
Authors: Clement Gregory , Hynynen Kullervo
Published: October 2013

A technique for focusing ultrasound through the skull bone is described and verified. The approach is based on a layered wave-vector-frequency domain model, which simulates ultrasound propagation through the skull bone using input from CT scans of the head. The algorithm calculates the driving phase of each element in a transducer array in order to maximize the signal at the intended focus. This approach is tested on ten ex vivo human skulls using a 500-element hemispherical array operated at 0.74 MHz. A stereotaxic reference frame is affixed to the skulls in order to provide accurate registration between the CT images and the transducer. The focal quality is assessed with a hydrophone placed inside of the skull. In each trial the phase correction algorithm successfully restored the focus inside the skull in a location within 1 mm from the intended focal point. Focusing at high powers (>800-W electrical input) is demonstrated using a brain phantom placed inside a skull. The results demonstrate the feasibility of using the method for completely noninvasive ultrasound brain surgery and therapy.
Current development of high-resolution MCM minehunting sonars for small AUVs
Authors: Commander Kerry W. , Christoff James T. , Lopes Joseph L.
Published: October 2013

The U.S. Navy recently awarded contracts to develop a new generation of autonomous underwater vehicles (AUVs) and high-performance acoustic sensors that are compatible with these vehicles. These new AUV systems will place minehunting crews and marine mammals well out of dangerous waters in the future. The requirement that these vehicles be small, durable, and easily launched and recovered places severe constraints on the sensor system payloads. The sensor systems must be rugged, low-powered, and small, yet effective enough to justify the risk to the vehicle. They must also have very low false alarm rates (high clutter rejection) because reacquisition and neutralization are costly, time consuming, and closely related to the number of targets found. These new acoustic sensor systems will use new broadband techniques along with high-resolution multi-aspect designs to achieve their goals from such small platforms. The acoustic sensor packages will consist of advanced very high-resolution Ahead Looking Sonars (ALS) and very high-resolution Synthetic Aperture sonars (SAS). This paper will review the new sonar system designs being considered by the Navy.
Toward a robust target scattering measurement sonar for low frequencies
Authors: Houston Brian H. , Simpson H. J. , Liskey S. , Yoder T. , Bucaro J. A.
Published: October 2013

In order to develop sonar systems that are non-image-based and that take advantage of target structural acoustics features, broadband capabilities have to be created to operate in shallow water and in the nontraditional frequency band below 30 kHz. Here, source wavelength–aperture ratios are high, resulting in significant source divergence and multipath. At the lowest frequencies, evanescent wave penetration is important in the detection of structures buried below the sediment–fluid interface. Further, the recovery of scattered energy requires nontraditional vertical apertures and synthetic array techniques that have both similarities and differences when compared to high-frequency imaging-based systems. The differences include relatively large resolution cell sizes, robustness to vehicle motion, and the clear potential for higher coverage rates. Towards this end, we discuss the precise measurement of low-frequency scattering cross section in shallow water using an UUV-based synthetic array approach. Broadband environmental acoustic propagation data taken in a bay environment will be presented, together with synthetic aperture data taken with a 20-m horizontal rail. The results of these measurements and the implications for UUV-based broadband sonars will be discussed.
The existence region for melodic pitch and computational models
Authors: Patterson Roy D. , Krumbholz Katrin , Pressnitzer Daniel
Published: October 2013

The pitch of a note is closely related to the repetition rate of the acoustic wave, or the spacing between the harmonics in the Fourier spectrum of the wave. However, algorithms that extract the repetition rate or harmonic spacing from the sound itself, without regard for auditory processing, would assign pitch perceptions to notes that musicians would not attempt to use to convey melody. If a transcription algorithm is to correctly reject notes that humans would not use, it must include knowledge of the complex constraints that govern the existence region for melodic pitch. Similarly, composers designing synthetic tonal instruments need to know whether the listener will hear the melody the instrument is intended to convey. Psychophysical studies have recently been used to delimit the region of melodic pitch within the overall domain of pitch perception, and to distinguish melodic pitch from rattle pitch, rumble pitch, and flutter pitch, none of which conveys melody successfully. This paper describes how time-domain computational models of auditory processing explain the existence region of melodic pitch, and how they might be used to improve melody transcription and instrument design. [Work supported by the UK Medical Research Council, G9901257.]
Fundamental frequency estimation of singing voice
Authors: de Cheveigné Alain , Henrich Nathalie
Published: October 2013

A method of fundamental frequency (F0) estimation recently developped for speech [de Cheveigné and Kawahara, J. Acoust. Soc. Am. (to be published)] was applied to singing voice. An electroglottograph signal recorded together with the microphone provided a reference by which estimates could be validated. Using standard parameter settings as for speech, error rates were low despite the wide range of F0s (about 100 to 1600 Hz). Most ‘‘errors’’ were due to irregular vibration of the vocal folds, a sharp formant resonance that reduced the waveform to a single harmonic, or fast F0 changes such as in high-amplitude vibrato. Our database (18 singers from baritone to soprano) included examples of diphonic singing for which melody is carried by variations of the frequency of a narrow formant rather than F0. Varying a parameter (ratio of inharmonic to total power) the algorithm could be tuned to follow either frequency. Although the method has not been formally tested on a wide range of instruments, it seems appropriate for musical applications because it is accurate, accepts a wide range of F0s, and can be implemented with low latency for interactive applications. [Work supported by the Cognitique programme of the French Ministry of Research and Technology.]
Absence of excess attenuation in Celcor ceramic at low frequencies
Authors: Liu Jin , Garrett Steven L. , Long Gregory S. , Sen Ayusman
Published: October 2013

Several studies of the excesses attenuation due to the porosity of CelcorTM material have been published [J. M. Sabatier et al., J. Acoust. Soc. Am. 99, 2430–2432 (1996)]. Since we were planning to use CelcorTM in a refrigeration application, we were concerned with this reported excess loss mechanism. To provide an independent measurement of the loss at our frequencies of interest, we placed a 38 mm long sample of CelcorTM at the center of a 700 mm long electrodynamically-driven plane wave resonator. Using the even modes, as per the technique described by Moldover et al. [Modern Acoustical Techniques for the Measurement of Mechanical Properties (Academic, New York, 2001), pp. 395–399], the quality factors were measured between 230 Hz and 1.6 kHz in air at atmospheric pressure on a pristine sample. Pores (but not channels) of that sample were then blocked by a sealing process that involved an initiator, azobisisobutronitrile (AIBN), mixed with the monomer hydroxyethyl methacylate. There was no observed decrease in attenuation of even modes for the coated sample below 1.0 kHz. The volume exclusion due to pore sealing was inferred by the increase in even mode resonance frequencies. Thermoviscous losses were computed with DeltaE and compared to measured losses. [Work supported in part by ONR and the United Technologies Corporation Professorship Endowment.]
Analytical solution of the regenerator temperature distribution in a thermoacoustic device with mean flow
Authors: Weiland Nathan T. , Zinn Ben T.
Published: October 2013

Previous work by the authors has identified a potential for improvement in the efficiency of a traveling wave thermoacoustic engine by replacing the hot heat exchanger with a steady flow of hot gas. An essential step in determining the feasibility of such an engine lies in determining how the mean flow affects the temperature distribution in the regenerator, which in turn affects its acoustic driving capability. In the current work, the second order time-averaged thermoacoustic energy equation with mean flow is solved analytically for the mean temperature distribution in the regenerator. The resulting expression accounts for the dependence of the working fluid’s thermal conductivity and viscosity on temperature, and results in a nearly exponential temperature profile. The specific effects of mean flow, axial conduction, acoustic velocity amplitude, and gas property variation on the temperature distribution in the regenerator will be explored. In turn, the effect of the temperature profile on regenerator performance will also be reviewed. In addition to their usefulness in the feasibility study, these results can also be applied to assess losses in existing thermoacoustic engines and refrigerators where acoustic streaming results in unwanted net mass flux through the regenerator.
Minor losses and streaming in thermoacoustic devices
Authors: Boluriaan Said , Morris Philip J.
Published: October 2013

The efficiency of thermoacoustic devices is limited by streaming and viscous losses. Viscous losses are due to energy dissipation in the vicinity of solid boundaries and minor losses. Minor losses are an additional loss of energy associated with transitions between channels and changes in flow direction. The physics behind minor losses in the high-amplitude oscillatory flows encountered in thermoacoustic devices is not well understood and estimates of its value are often based on results for steady flow. Furthermore, the presence of streaming adds to the complexity in the assessment of minor losses. In the current research, a sudden change in cross-sectional area of a resonator is used as a model to study streaming and minor losses. A time-accurate numerical simulation based on the Navier–Stokes equations is performed to calculate the flow variables in an oscillatory flow inside a resonator with a sudden expansion/contraction. A correlation between the pressure loss due to minor losses and different flow parameters involved in the problem is presented. Comparisons are also made with estimates of minor losses based on a quasisteady flow assumption. [Research supported by ONR.]
Flow noise predictions of a submerged cylinder under turbulent boundary layer excitations
Authors: Wu Kuangcheng , Vlahopoulos Nickolas
Published: October 2013

The unsteady fluctuated pressure underneath turbulent boundary layers (TBL) is one of major noise sources in moving vehicles. Recently, discretized TBL forcing functions have been applied to planar structures in air [Y. F. Hwang and S. A. Hambric, Noise-Con, 2000; M. Allen and N. Vlahopoulos, Computers and Structures, 2000; M. Allen and N. Vlahopoulos, Finite Elements in Analysis and Design, 2001; M. Allen, R. Sbragio, and N. Vlahopoulos, AIAA J. 2001]. This paper discusses prediction of the flow-induced radiated noise and surface responses of a submerged hemisphere-capped cylindrical shell (L/D=11). The FEM/IFEM (infinite finite element method) approach is used to calculate structural acoustic transfer functions and to accurately account for the fluid loading effects. The effect on TBL due to the curvature of a cylinder is captured by utilizing the potential flow—boundary layer theory to determine key boundary layer parameters. Predictions of the surface intensity and far field responses are developed through stochastic analysis due to the natural of the TBL excitations. A MATLAB script is generated to determine the power spectral density of the responses. [Work supported by ONR Code 334.]
Hydrofoil near-wake sound sources at high Reynolds number
Authors: Bourgoyne Dwayne A. , Hamel Joshua M. , Judge Carolyn Q. , Ceccio Steve L. , Dowling David R.
Published: October 2013

An important hydroacoustic noise source from a fully submerged noncavitating hydrofoil is often the unsteady separated turbulent flow near its trailing edge. Here, hydroacoustic noise may be produced by boundary layer turbulence swept past and scattered from the foils trailing edge, and by coherent vortices formed in the foils near-wake. Such vortices may generate an energetic tonal component that rises above the broadband trailing-edge hydroacoustic noise. This presentation describes results of an experimental effort to identify and measure vortical flow features in the near-wake of a two-dimensional hydrofoil at chord-based Reynolds numbers ranging from 0.5 to 60 million. The experiments were conducted at the U.S. Navy’s William B. Morgan Large Cavitation Channel with a test-section-spanning hydrofoil (2.1 m chord, 3.0 m span) at flow speeds from 0.25 to 18.3 m/s. Two trailing-edge shapes were investigated, and foil-internal accelerometers were used to monitor structural vibration. Velocity fluctuation spectra were measured in the foils near-wake with a two-component LDV system, and dynamic surface pressures were measured near the foils trailing edge with flush-mounted transducer arrays. Both indicate Reynolds number and trailing-edge shape-dependent vortex shedding. [Significant assistance provided by personnel from NSWC-CD. Work sponsored by Code 333 of ONR.]
Understanding speech in single-talker interference: Normal-hearing listeners and cochlear implant users
Authors: Nelson Peggy B. , Jin Su-Hyun
Published: October 2013

Our previous data [Nelson et al., ASA (2001)] indicated that users of cochlear implants experience little release from masking when listening to speech in modulated maskers. Although normal-hearing listeners take advantage of temporal dips in modulated maskers, cochlear implant users do not. The current study investigated listeners with normal hearing and cochlear implants for their understanding of speech in the presence of a single-talker masker. Participants listened to IEEE sentence material spoken clearly at a slow rate (3.5 syllables per second) by either a male (average F0=110 Hz) or a female (average F0=210 Hz) talker. Maskers included continuous speech from other male and female talkers spoken at both slow and fast rates. Results from normal-hearing listeners indicated that when the signal and masker had a similar F0 and rate, identification was poorer than when signal and masker differed in F0 and/or rate. The primary factor affecting performance was the F0 of the masker. It is hypothesized that cochlear implant users will not show the effect of talker/masker F0, but will show decreased performance when talker and masker have the same rate. Results from cochlear implant listeners will be reported. [Work supported by NIDCD P01DCD00110.]
Consonant identification in noise: Effects of temporal asynchrony, noise fluctuations, and temporal envelope expansion
Authors: Apoux Frederic , Garnier Stephane , Lorenzi Christian
Published: October 2013

The effects of two temporal envelope expansion schemes on consonant identification performance were investigated with normal-hearing listeners. These effects were examined in the presence or absence of short-term energy fluctuations in the masker. The effects of adding a 500-ms forward fringe to the background noise was also investigated. Speech stimuli were 16 consonant–/a/ syllables. The expanded stimuli were obtained by raising their original envelope to the power k. In the first scheme, k was fixed at 2. In the second scheme, k varied from 4 to 0.3 as a function of the envelope power; the low-level parts of the envelope were therefore expanded whereas the high-level parts were compressed. As reported in many studies, identification was substantially improved by the presence of energy fluctuations in the masker. Adding the forward fringe generally degraded identification in fluctuating noise, but could improve identification in the stationary noise. Overall, expansion led to (i) poorer consonant identification when k was a constant and (ii) better consonant identification when k was varied. These effects were larger in stationary noise. This study suggests that consonant identification can be improved by a dual expansion/compression scheme. Some results obtained with hearing-impaired listeners will be presented.
Recognition of word and nonsense syllables in noise
Authors: Benkí José R.
Published: October 2013

In the recognition of human speech, listeners use sensory information from the speech signal as well as signal-independent information, such that acoustic-phonetic salience, lexical status, frequency of usage, and neighborhood density interact in speech recognition. This paper presents detailed results from a replication of a study of context effects reported by Boothroyd and Nittrouer [J. Acoust. Soc. Am. 84, 101–108 (1988)]. 240 phonetically matched word and nonsense CVC syllables at different SNRs were presented to 32 listeners for identification. The results are consistent with the original study, with greater accuracy for words than nonsense items as quantified by a j-factor analysis according to lexical status. Online response collection enabled detailed analyses not reported in the original study. Values for the j-factor according to usage frequency and phonetic confusability are presented. Confusion matrices of the phonemes are presented, and are largely consistent with previous studies for the initial consonants and vowels. Accuracy in the final consonants of nonsense syllables is substantially lower than the corresponding phonemes of words or than the initial consonants of nonsense syllables. Final nasals were particularly difficult to identify.
Virtual glides and duplex perception
Authors: Fox Robert Allen , Feth Lawrence L. , Jacewicz Ewa , Iyer Nandini
Published: October 2013

Duplex perception occurs when a tone glide is presented to one ear and an ambiguous synthetic CV is presented to the other ear. Listeners simultaneously perceive a syllable (e.g., /dɑ/ or /gɑ/) and a tone chirp. The present study examines whether duplex percepts can be generated when the tone glide presented is actually a virtual glide in which the frequency transition is evoked by modifying the amplitudes of two tones whose frequencies do not change [see Jacewicz et al., J. Acoust. Soc. Am. 110, 2657 (2002)]. A base synthetic CV token 250 ms in duration (with initial F1 and F2 transitions appropriate to both /d/ and /g/) was combined with a set of F3 transitions (representing either a synthetic formant transition, a true tone glissando, or a virtual glide transition) which produced a set of /dɑ/–/gɑ/ continua. These F3 transitions were either combined with the base and presented to both ears (diotic presentation) or presented simultaneously to different ears (dichotic presentation). Listeners heard the stimulus sets and were required to identify each token as /dɑ/ or /gɑ/. Preliminary results indicate that similar identification functions for all versions of F3 are generated in the monaural condition, but that these functions are shallower in the dichotic condition.
Relative roles of consonants and vowels in perceiving phonetic versus talker cues in speech
Authors: Cardillo Gina , Owren Michael J.
Published: October 2013

Perceptual experiments tested whether consonants and vowels differentially contribute to phonetic versus indexical cueing in speech. In 2 experiments, 62 total participants each heard 128 American–English word pairs recorded by 8 male and 8 female talkers. Half the pairs were synonyms, while half were nonsynonyms. Further, half the pairs were words from the same talker, and half from different, same-sex talkers. The first word heard was unaltered, while the second was edited by setting either all vowels (‘‘Consonants-Only’’) or all consonants (‘‘Vowels-Only’’) to silence. Each participant responded to half Consonants-Only and half Vowels-Only trials, always hearing the unaltered word once and the edited word twice. In experiment 1, participants judged whether the two words had the same or different meanings. Participants in experiment 2 indicated whether the word pairs were from the same or different talkers. Performance was measured as latencies and d values, and indicated significantly greater sensitivity to phonetic content when consonants rather than vowels were heard, but the converse when talker identity was judged. These outcomes suggest important functional differences in the roles played by consonants and vowels in normative speech.
Cerebral responses to across- and within-category change of vowel durations measured by near-infrared spectroscopy
Authors: Minagawa-Kawai Yasuyo , Mori Koichi , Furuya Izumi , Hayashi Ryoko , Sato Yutaka
Published: October 2013

The present study examined cerebral responses to phoneme categories, using near-infrared spectroscopy (NIRS) by measuring the concentration and oxygenation of hemoglobin accompanying local brain activities. Targeted phonemes used here are Japanese long and short vowel categories realized only by durational differences. Results of NIRS and behavioral test revealed NIRS could capture phoneme-specific information. The left side of the auditory area showed large hemodynamic changes only for contrasting stimuli between which phonemic boundary was estimated (across-category condition), but not for stimuli differing by an equal duration but belonging to the same phoneme category (within-category condition). Left dominance in phoneme processing was also confirmed for the across-category stimuli. These findings indicate that the Japanese vowel contrast based only on duration is dealt with in the same language-dominant hemisphere as the other phonemic categories as studied with MEG and PET, and that the cortical activities related to its processing can be detected with NIRS. [Work supported by Japan Society for Promotion of Science (No. 8484) and a grant from Ministry of Health and Welfare of Japan.]
Analytic prediction of sidelobe statistics for matched-field processing
Authors: Tracey Brian , Lee Nigel , Zurk Lisa
Published: October 2013

Underwater source localization using matched-field processing (MFP) is complicated by the relatively high sidelobe levels characteristic of MFP ambiguity surfaces. An understanding of sidelobe statistics is expected to aid in designing robust detection and localization algorithms. MFP sidelobe levels are influenced by the underwater channel, array design, and mismatch between assumed and actual environmental parameters. In earlier work [J. Acoust. Soc. Am. 108, 2645 (2000)], a statistical approach was used to derive analytic expressions for the probability distribution function of the Bartlett ambiguity surface. The distribution was shown to depend on the orthogonality of the mode shapes as sampled by the array. Extensions to a wider class of array geometries and to broadband processing will be shown. Numerical results demonstrating the accuracy of the analytic results and exploring their range of validity will be presented. Finally, analytic predictions will be compared to data from the Santa Barbara Channel experiment. [Work sponsored by DARPA under Air Force Contract F19628-00-C0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the Department of Defense.]
Complex spatial envelopes, invariants and matched field processing
Authors: Heaney Kevin D. , Cox Henry
Published: October 2013

The waveguide invariant was introduced in the Russian Literature (S. D. Chuprov, Ocean Acoustics, 1982) to explain range-frequency interference patterns of intensity. The concept of the spatial envelope is introduced here to show how the waveguide invariant can be derived and interpreted in terms of pressure rather than intensity. It is shown how this leads to range-frequency scaling that can be used to generate finely spaced (in frequency) matched field replicas from course spaced propagation calculations. For a downward refracting sound speed profile the acoustic propagating modes can be separated into groups (refracted bottom interacting, surface-bottom interacting). These mode groups have very similar waveguide invariants. The frequency scaling can be applied to these mode groups separately. An example is presented where 150 Hz shallow water replicas are computed every 20 Hz and interpolated, yielding a factor of 30 in reduction of replica computation for MFP.
Blood velocity estimation by Doppler ultrasound: Problems and issues
Authors: Cobbold Richard S. C. , Steinman Aaron H.
Published: October 2013

Modern methods of estimating blood flow have advanced considerably since Dr. Satamura and his colleagues at Osaka University reported the first measurements in 1959 using CW ultrasound. Most current methods involve the use of linear or phased arrays, which make possible 2-D color flow mapping, measurements from a single sample volume, and simultaneous B-mode imaging. However, along with this technology, troubling reports have been published (including our own) concerning the accuracy with which the velocity can be estimated and this has serious potential consequences in the quantitative assessment of vascular disease. The cause has not yet been completely identified, but appears to be partially associated with the wide range of Doppler angles within the sample volume, the complexity of the ultrasound propagation process, and the stochastic nature of the red blood cells flowing in the blood vessels. These causes will provide a focus for our review of the current status of Doppler ultrasound for vascular disease assessment and suggestions for future research. Specifically, a complete model of the entire measurement system is needed, and this includes the beamforming architecture, signal processing, possible nonlinear effects, scattering process, and nature of the 3-D vector flow field being measured.
Measurement of volumetric flow rates with ultrasonic contrast agents using a depletion method
Authors: Ketterling Jeffrey A. , Deng Cheri X. , Lizzi Frederic L. , Silverman Ronald H. , Coleman D. Jackson
Published: October 2013

A high-intensity focused transducer was used to deplete a small, well-defined volume of contrast agent flow in a small diameter tube. The depleted volume was probed both confocally and downstream with a 7.5-MHz focused diagnostic transducer. The depletion volume was found from theoretical calculations of the acoustic beam profile. Volume flow rates were then calculated by measuring the time required for the depleted volume to pass the diagnostic transducer. Additionally, a beam with known sidelobe spacing can give information about the flow velocity if the high-intensity transducer exposure is short and the sidelobes form spatially separated subdepletion regions. A 4.7-MHz ‘‘strip electrode’’ high-intensity transducer with 0.5-mm sidelobe spacing was used to study the flow velocity in dialysis tubing with a 3.1-mm outer diameter. Flow of known volume velocity was generated with a syringe pump. Both Optison and Albunex contrast agents were used. Experimental flow velocities were in excellent agreement with the known flow measurement.
A synthesized tri-modal directional transducer
Authors: Butler Alexander L. , Butler John L. , Curtis Alan R. D. , Rice Joe
Published: October 2013

A new cylindrical transducer, which achieves directional beams through the synthesis of the omni, dipole, and quadrupole extensional modes of vibration is presented. The three cylindrical radial modes are related in resonant frequency by the formula fn=f0(1+n)1/2, where n=0, 1, and 2, respectively, and may be excited individually or together by the selection of the circumferential voltage distribution. It will be shown that, in the frequency band between the dipole and quadrupole modes, a simple four-step real voltage distribution can be used to synthesize a smooth transmitting response with constant beamwidth patterns. From this comparatively simple, small diameter transducer, steered beam widths of 90 deg and 10 dB front to back ratios can be obtained. Theoretical and measured transmitting response and beam pattern results on a 4.5-in.-diam. cylindrical transducer design will be presented and compared in the operating frequency range from 15 to 20 kHz. [SBIR work supported by ONR and SPAWAR.]
Noise reduction of a table saw
Authors: Carlson John
Published: October 2013

The National Institute for Occupational Safety and Health (NIOSH) is sponsoring a design project to address the noise levels that commonly exist at construction worksites. Through engineering control, the problem of noise emission from a table saw will be addressed. The noise emitting sources will be pinpointed using a sound pressure level meter. With this knowledge, the next step will be to reduce the sound pressure levels at the noise sources. This will be done by using noise reduction techniques such as insulation, and vibration dampening. The goal is to reduce the noise emission to a level between 85 and 90 dB(A).
Aeroacoustics of microphones
Authors: Finfer Daniel
Published: October 2013

Several commercial options exist for prevention of the pseudo-sound often introduced by a microphone in the presence of a flow field. One such device is a so-called ‘‘slit-tube.’’ A slit-tube is a tube approximately the diameter of the microphone with which it is used. The length of such a tube can vary anywhere from 25 cm to 50 cm, and it is most generally fit with a stream-lined noise cone. In theory, a perforated slit along the length of the tube encourages net cancellation of turbulent pressure variations, while not interfering with the acoustic field. This poster compares the effectiveness of two similar slit-tube designs. Each tube was placed inside of a wind-tunnel and exposed to white noise. The effects of increasing flow velocities on the transfer-function between the source and receiver signals are analyzed.
On the effect of viscosity in scattering from partially coated infinite cylinders
Authors: Ginsberg Jerry H.
Published: October 2013

Partial coating of a submerged object introduces discontinuities in the surface properties that complicate an acoustic scattering analysis. Some analyses, such as the work by Feit and Cuschieri [J. Acoust. Soc. Am. 92, 1721–1728 (2000)], have used weighted residual techniques based on global series representations, thereby generating a solution that satisfies discontinuous boundary conditions in an average sense. Others, such as Ferri, Ginsberg, and Rogers [J. Acoust. Soc. Am. 92, 1721–1728 (1992)] have used collocation-type formulations. Another issue arises from the fact that the normal velocity changes discontinuously at an impedance discontinuity. The associated large velocity gradients give rise to concern that viscous shear might play a role. The present work considers the two-dimensional problem of scattering of a plane wave incident on an infinite cylinder that is coated with strips of pressure-release material extending over quadrants on the illuminated and shadowed sides, with the remainder of the surface considered to be rigid. The analysis represents the scattered field in terms of acoustic and vortical contributions, both of which are represented in series form. Solutions obtained by the method of weighted residuals are shown to be less accurate than those obtained from a collocation procedure. The results for surface pressure and farfield directivity indicate that viscous effects are important only if the Reynolds number is extremely small.
Fan noise control using Herschel–Quincke resonators on a production turbofan engine
Authors: Burdisso Ricardo A. , Gerhold Carl H.
Published: October 2013

The Herschel–Quincke (HQ) resonator concept is an innovative technique that consists of installing circumferential arrays of HQ waveguides around the inlet of a turbofan engine. An HQ waveguide is essentially a hollow side tube that travels along (but not necessarily parallel to) the engine axis and attaches to the inlet at each of the two ends of the tube. To investigate the potential of the concept, the approach was tested on a full-scale production Honeywell TFE731-60 engine. An HQ–inlet system containing two arrays was designed to attenuate the blade passage frequency (BPF) tone at approach condition, i.e., 60% engine power. However, the system was tested over the full range of engine power settings. The effects of each array both individually and together were evaluated as compared to the hard-wall case. Both far-field and induct data were recorded during the tests. The results show good attenuation of both the BPF tone and broadband components. Furthermore, reduction of ‘‘buzz-saw’’ tones, i.e., additional tones radiated from the inlet when the fan-tip speed goes supersonic, was observed with the HQ system. Some fan distortion effects and increase in noise was observed at higher engine speeds. [Work supported by NASA Langley Research Center.]
Multi-channel active control of axial cooling fan noise
Authors: Gee Kent L. , Sommerfeldt Scott D.
Published: October 2013

A multi-channel active control system has been applied to the reduction of free-field tonal noise from a small axial cooling fan. The experimental apparatus consists of an aluminum enclosure which houses the fan, an infrared detector-emitter pair which serves as a reference sensor, loudspeakers, microphones, and appropriate filters and amplifiers. The research fan and loudspeakers have been modeled theoretically as point sources to derive a mathematical expression for radiated power. The minimization of this power has served to guide the number and location of control sources, as well as to discover potential error microphone locations in the extreme near-field. Experiments with these microphone positions have shown that there are predictable near-field locations which consistently lead to significant reductions in the global mean-squared pressure for the first four harmonics of the blade passage frequency. For example, a four channel configuration with the error microphones placed appropriately results in global mean-squared pressure reductions on the order of 10 dB or more for the targeted frequencies.
From speech perception to word learning and beyond
Authors: Werker Janet F.
Published: October 2013

From his undergraduate days at Brown, Peter Jusczyk revolutionized our understanding of the link between infant speech perception and language use. This talk reviews how Jusczyk’s work influenced my research in three important domains. The talk begins with a discussion of Jusczyk’s early work on infant speech perception, and illustrates how that led to my initial work on infant cross-language perception. This is followed by a discussion of Jusczyk’s work on sensitivity to probabilistic information and how this influenced the more recent work [Maye, Werker, and Gerken] on the mechanisms underlying changes in phonetic perception. The third research section briefly describes how Jusczyk’s work on word segmentation influenced ongoing research in the laboratory on early word learning. In the final few minutes of the talk, an attempt will be made to give a sense of the enormous influence Peter Jusczyk’s work had, and continues to have, on our field.
Imaging sonar development for mine countermeasure applications
Authors: Johnson Bruce
Published: October 2013

Over the past decade the Office of Naval Research (ONR) has sponsored research to improve the mine countermeasures (MCM) community’s ability to detect, classify, reacquire, and identify mines. In the first stage of wide area detection and classification, the single biggest problem is the ability to distinguish mines from clutter with side-scan sonar assets. In the reacquire-identify stage, divers employ a single-beam aural sonar for guidance to close proximity for visual identification of targets. Current sonar research efforts in wide-area search focus on clutter rejection through high-resolution imaging by synthetic aperture processing and cuing from broadband response characteristics. For reacquisition and identification, research has focused on compact, multibeam imagers. ONR’s focus on transition from towbodies and divers to numbers of small, unmanned underwater vehicles (UUVs) to improve MCM clearance rates has had a major impact on sensor development as well. The presentation will provide an introduction to the session by providing a brief history of the development of navy imaging sonars, how they are employed, and an overview of the current thrusts that will lead to the next generation of Navy MCM sonars.