bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and analysis of a silicon condenser microphone
Authors: Huang Jin H. , Kao Han
Published: October 2013

The design and analysis of a capacitive microphone is presented in this paper. Capacitive microphone with considerably higher sensitivity and low power consumption offers the innovative design for sound pressure microsensors. Polysilicon with smooth surfaces and incredible low residue stress is used for diaphragm of the capacitive microphone. Two methods—equivalent circuit method and finite element method—have been applied in this research to achieve the highest sensitivity of capacitive microphone. Optimal diaphragm edge width, thickness, and air gap have been determined through analyzing and simulating sound pressure microsensors, understanding the variation of geometry dimensions parameters between diaphragm and air gap distance, and dissecting the impact among sensitivity, nature frequency and electric field. Consequently, the valuable design model is able to be provided for the best choice of sound pressure microsensors among different materials. In addition, the results can improve and control the performance and dimensions of this microsensor. Furthermore, the microphone is fabricated using a combination of surface and bulk micromaching techniques which has favorable integrated capability of CMOS (Complementary Metal-Oxide Semiconductor). These device and techniques are promising for the future production.
Radiated fields of thin and flexible high frequency loudspeakers
Authors: Hutchins David A. , Medley Andrew P. , Billson Duncan R.
Published: October 2013

Thin and flexible electrostatic loudspeakers have been constructed, which can be curved into different shapes. This allows some interesting geometries to be explored, at frequencies in the range 10 kHz to 100 kHz. The research has compared the radiated fields measured experimentally with those predicted using established theory. The theoretical approach uses a new geometrical formulation to more efficiently predict radiated field patterns, where the curved surface is considered as a series of elements at specific angles to the beam axis. These elements can be of increased width compared to previous methods, making the approach computationally efficient. It is also a more robust approach than the traditional impulse response methods, in situations where the source size is comparable to the radiated wavelengths in air. Predictions could be made for both continuous and transient excitation. A comparison between theory and experiment has demonstrated that interesting field patterns can be generated. For instance, focussed sound fields can be produced using concave shapes, with predictable focal positions which are not at the center of curvature. These and other geometries will be described.
The future of acoustics distance education at Penn State
Authors: Brooks Karen P. , Sparrow Victor W. , Atchley Anthony A.
Published: October 2013

For nearly 20 years Penn State’s Graduate Program in Acoustics has offered a graduate distance education program, established in response to Department of Defense needs. Using satellite technology, courses provided synchronous classes incorporating one-way video and two-way audio. Advancements in technology allowed more sophisticated delivery systems to be considered and courses to be offered to employees of industry. Current technology utilizes real time video-streaming and archived lectures to enable individuals anywhere to access course materials. The evolution of technology, expansion of the geographic market and changing needs of the student, among other issues, require a new paradigm. This paradigm must consider issues such as faculty acceptance and questions facing all institutions with regard to blurring the distinction between residence and distance education. Who will be the students? What will be the purpose of education? Will it be to provide professional and/or research degrees? How will the Acoustics Program ensure it remains attractive to all students, while working within the boundaries and constraints of a major research university? This is a look at current practice and issues with an emphasis on those relevant to constructing the Acoustics Programs distance education strategy for the future.
Loudspeaker and listener positions for optimal low-frequency spatial reproduction in listening rooms
Authors: Griesinger David
Published: October 2013

This paper will briefly describe the physical and physiological mechanisms that enable low-frequency externalization and spatial reproduction in listening rooms. These mechanisms depend on reproducing a time-varying interaural time difference at the listening position through interference between symmetric and asymmetric room modes. The effect works successfully when the symmetric and asymmetric room modes are driven by independent portions of a multi-channel signal, typically the in-phase and the anti-phase component of a two-channel recording. The paper will describe how this overlap can be optimized by adjusting the loudspeaker and listener positions for a variety of playback rooms. The results show that certain common room shapes yield low spatiality regardless of loudspeaker and listener positions.
A variable passive low-frequency absorber
Authors: Larsen Niels Werner , Thompson Eric R. , Gade Anders Christian
Published: October 2013

Multi-purpose concert halls face a dilemma. They can host classical music concerts, rock concerts and spoken word performances in a matter of a short period. These different performance types require significantly different acoustic conditions in order to provide the best sound quality to both the performers and the audience. A recommended reverberation time for classical music may be in the range of 1.5–2 s for empty halls, where rock music sounds best with a reverberation time around 0.8-1 s. Modern rhythmic music often contains high levels of sound energy in the low frequency bands but still requires a high definition for good sound quality. Ideally, the absorption of the hall should be adjustable in all frequency bands in order to provide good sound quality for all types of performances. The mid and high frequency absorption is easily regulated, but adjusting the low-frequency absorption has typically been too expensive or requires too much space to be practical for multi-purpose halls. Measurements were made on a variable low-frequency absorber to develop a practical solution to the dilemma. The paper will present the results of the measurements as well as a possible design.
From seismology to oceanography: Locating the sources of the Earth’s hum
Authors: Romanowicz Barbara , Rhie Junkee
Published: October 2013

The observation of continuously excited free oscillations of the Earth, in the absence of earthquakes, was first made by Japanese scientists in 1998. Since then, attention has focused on elucidating the physical mechanism responsible for them. The mechanism must be shallow, as fundamental modes appear to be preferentially excited and it shows seasonal variability. An array-based method has been developed to detect and locate sources of very long period surface wave energy, utilizing the dispersive properties of Rayleigh waves and data from two large aperture arrays of very long period seismometers, in California and in Japan. It is shown that, for each array, there is a well defined preferential direction, which is stable over one season but changes significantly from winter to summer. The fluctuations as a function of time of the maximum stack amplitudes are correlated across the two arrays and point to the northern Pacific Ocean in the northern hemisphere winter and the southern oceans in the summer, correlating with the distribution of maximum wave height. It is inferred that the background oscillations originate primarily in the oceans, and are caused by a non-linear coupling mechanism involving the atmosphere (winds), the oceans (infragravity waves) and the seafloor.
Correlation in ambient seismic noise and the reconstruction of Green function
Authors: Campillo Michel , Stehly Laurent , Shapiro Nikolai , Ritzwoller Mike
Published: October 2013

Cross-correlations between long continuous records of ambient seismic noise at distant stations are investigated. The dominant part of the Green function, namely Rayleigh waves, are reconstructed in a broad period range. This property reminds of the fluctuation-dissipation theorem that relates the random fluctuations of a linear system and the system’s response to an external force. Ambient seismic noise is indeed not a thermal noise but it can be considered as a random and isotropic wave field both because the distribution of the ambient sources responsible for the noise randomizes when averaged over long periods and because of scattering from heterogeneities that occur within the Earth. The dispersion curves of Rayleigh waves for the paths between the stations are measured from the correlations. On paths where direct measurements between earthquake and station are available, we show that they are in good agreement with those deduced from noise correlation. The measurement of correlation along paths crossing different geological structures allows to differentiate them, opening the way for a passive imaging of the Earth structure. The dispersion measurements are applied to seismic tomography at the regional scale. They make it possible to image crustal structures with a resolution higher than conventional techniques.
Seismic interferometry, with applications in passive reflection imaging
Authors: Wapenaar Kees , Draganov Deyan
Published: October 2013

Seismic interferometry is the process of generating new seismic responses by crosscorrelating seismic observations at different receiver locations. A first version of this principle was derived in 1968 by Claerbout, who showed that the reflection response of a horizontally layered medium can be synthesized from the autocorrelation of its transmission response. Later he conjectured a similar principle for crosscorrelations of 3-D wave fields. In a similar fashion, Schuster (2001) introduced the principle of interferometric imaging, i.e., forming an image of the subsurface from crosscorrelated seismic traces. In this paper we first discuss the theory of seismic interferometry for arbitrary 3-D inhomogeneous media (deterministic or random). Starting with the Rayleigh-Betti reciprocity theorem and the principle of time-reversal, we derive a number of relations that form the basis for seismic interferometry (amongst others these relations prove Claerbouts conjecture). Despite the difference in assumptions, these relations show a close resemblance with those of Weaver and Lobkis (2001) for the retrieval of the Greens function from diffuse wave field correlations. Next we discuss a number of applications, like passive seismic reflection imaging, surface wave reconstruction, improving sparse data sets and interferometric imaging for different geometries.
Interferometric imaging and the principle of stationary phase
Authors: Snieder Roel
Published: October 2013

Interferometric imaging where the Green’s function is constructed using the correlation of complex wavefields recorded at two receivers is a rapidly emerging field. The methodology has been justified based on assumptions of equiparitioning of the normal modes of the system, as well as on various versions of the representation theorem applied to time-reversed waves. I will present another point of view that is based on stationary phase arguments. This complementary formulation of interferometric imaging gives insight in the physics of the emergence of the Green’s function, and of the limitations that are encountered when applying this technique to data. Issues that will be covered are the relation between ensemble averaging and time averaging, and interferometric imaging of reflected waves. This example is of particular interest for exploration seismology since it shows that interferometric imaging may introduce spurious multiple reflections. Given the recent effort in ‘‘multiple suppresion’’ in exploration seismology, the introduction of spurious multiple reflections is an undesirable artifact.
Evolution of diffuse fields in heterogeneous slabs
Authors: Turner Joseph A. , Ghoshal Goutam
Published: October 2013

Fundamental studies of elastic wave scattering in heterogeneous media are applicable for problems at several length scales from ultrasonic to seismic waves. The intermediate scattering regime that lies between the single scattering and the diffusion limits is perhaps the least understood. In this presentation, both the steady-state and time dependent scattering problems are examined for this regime within the context of radiative transfer theory. The focus here is on slab geometries for which the scattering medium lies between two parallel boundaries separated by a distance investigated over a range from several to tens of mean free paths. The spatial distribution, temporal evolution, and partitioning of the diffuse longitudinal and shear energies are studied as a function of direction and frequency for several types of microstructure including polycrystalline metals, concrete, porous media, and geophysical media. The longitudinal and shear flux reflected from and transmitted through the slab are also discussed due to their importance for experimental materials characterization. Finally, comparisons are made with direct numerical scattering simulations for some of the microstructures considered. The results are anticipated to shed insight on this important intermediate scattering regime. [Work supported by NSF and DOE.]
Frequency-time dispersion products revisited
Authors: Hellman William S. , Colburn H. Steven
Published: October 2013

The interaction of bandwidth and duration is an important aspect of signal choice in psychophysical experiments. The traditional measures yield frequency-time dispersion products which have a lower bound of 0.25. Gabor [J. Inst. Elect. Eng. Part III 93, 429–457 (1946)] argued that the measures for the standard deviation and mean in the frequency domain do not yield formulas in agreement with intuition when applied to the calculation of frequency dispersions for real signals f(t). Gabor’s prescription for correcting the problem was to limit the integrations in frequency statistic calculations to the positive frequency domain and, for consistency, use the analytic signal corresponding to f(t) to calculate time dispersions. A more recent statement of this prescription can be found in L. Cohen [Time-Frequency Analysis, (Prentice Hall, 1995)]. However the elimination of the negative frequencies introduces difficulties which have not been fully addressed in the literature. It is shown here, that unless the Fourier transform of the signal vanishes at zero frequency, a linear divergence will appear in the time dispersion derived from the analytic signal. In such instances, f(t) must be used to calculate the time dispersion. However the restriction to positive frequencies can generate frequency-time dispersion products which fall below the expected lower limit of 0.25.
Diotic and dichotic discrimination of binary sequences
Authors: Sheft Stanley , Yost William A. , Dye Raymond H.
Published: October 2013

Binary-sequence discrimination was compared for diotic and dichotic stimuli. Sequences consisted of 4 to 32 wideband-noise pulses with pulse duration ranging from 8 to 32 ms. Diotic sequences were distinguished by pulse-amplitude pattern, while dichotic patterns differed by their sequence of ear of presentation. Discrimination was measured as a function of the number of pattern elements that differed between the standard and comparison sequences with temporal location of the altered pulses randomly selected on each trial. Additional fringe pulses bracketed the target sequences to avoid onset and offset cuing. Neither diotic nor dichotic performance was monotonic with the ratio of the number of altered to sequence pulses, with greater exception noted in the dichotic results. Except at the shortest pulse duration, diotic performance was significantly better than that obtained in the dichotic condition with similar pulse duration and numbers of altered and sequence pulses. For the range of stimulus parameters used, sequence discrimination often relied on a global percept rather than processing of individual pulse attributes with timbre differences cuing diotic discrimination. Though exhibiting fine resolution, results suggest poorer ability of the binaural than monaural system at extracting a global percept to cue sequence discrimination. [Work supported by NIDCD.]
Within- and across-language spectral and temporal variability of vowels in different phonetic and prosodic contexts: Russian and Japanese
Authors: Gilichinskaya Yana D. , Hisagi Miwako , Law Franzo F. , Berkowitz Shari , Ito Kikuyo
Published: October 2013

Contextual variability of vowels in three languages with large vowel inventories was examined previously. Here, variability of vowels in two languages with small inventories (Russian, Japanese) was explored. Vowels were produced by three female speakers of each language in four contexts: (Vba) disyllables and in 3-syllable nonsense words (gaC1VC2a) embedded within carrier sentences; contexts included bilabial stops (bVp) in normal rate sentences and alveolar stops (dVt) in both normal and rapid rate sentences. Dependent variables were syllable durations and formant frequencies at syllable midpoint. Results showed very little variation across consonant and rate conditions in formants for /i/ in both languages. Japanese short /u, o, a/ showed fronting (F2 increases) in alveolar context relative to labial context (1.3-2.0 Barks), which was more pronounced in rapid sentences. Fronting of Japanese long vowels was less pronounced (0.3 to 0.9 Barks). Japanese long/short vowel ratios varied with speaking style (syllables versus sentences) and speaking rate. All Russian vowels except /i/ were fronted in alveolar vs labial context (1.1-3.1 Barks) but showed little change in either spectrum or duration with speaking rate. Comparisons of these patterns of variability with American English, French and German vowel results will be discussed.
Greek perception and production of an English vowel contrast: A preliminary study
Authors: Podlipský Václav J.
Published: October 2013

This study focused on language-independent principles functioning in acquisition of second language (L2) contrasts. Specifically, it tested Bohn’s Desensitization Hypothesis [in Speech perception and linguistic experience: Issues in Cross Language Research, edited by W. Strange (York Press, Baltimore, 1995)] which predicted that Greek speakers of English as an L2 would base their perceptual identification of English /i/ and /I/ on durational differences. Synthetic vowels differing orthogonally in duration and spectrum between the /i/ and /I/ endpoints served as stimuli for a forced-choice identification test. To assess L2 proficiency and to evaluate the possibility of cross-language category assimilation, productions of English /i/, /I/, and /ε/ and of Greek /i/ and /e/ were elicited and analyzed acoustically. The L2 utterances were also rated for the degree of foreign accent. Two native speakers of Modern Greek with low and 2 with intermediate experience in English participated. Six native English (NE) listeners and 6 NE speakers tested in an earlier study constituted the control groups. Heterogeneous perceptual behavior was observed for the L2 subjects. It is concluded that until acquisition in completely naturalistic settings is tested, possible interference of formally induced meta-linguistic differentiation between a ‘‘short’’ and a ‘‘long’’ vowel cannot be eliminated.
Narrow band pulses as stimuli in an auditory brain stem recording study with a harbor porpoise
Authors: Beedholm Kristian , Miller Lee A.
Published: October 2013

We have studied several aspects of hearing by a harbor porpoise using the ABR method with pulsed stimuli. Experiments were conducted on a male porpoise in collaboration with Fjord and Baelt, Kerteminde, Denmark. The animal had suction cups containing silver electrodes placed near the blowhole and near the dorsal fin. When fitted with the electrodes he moved to an underwater listening post where his outgoing sonar signal could be used to trigger a phantom echo. EEG signals were amplified differentially and averaged over a variable number of presentations depending on trial duration and experiment. For studying the frequency/intensity response, narrow band pulsed stimuli were generated and presented in several ways. One way was to use the impulse response of a B&K 1/3 octave filter bank (set to 80, 100, 125, or 160 kHz) as a stimulus. This stimulus was presented in both a passive hearing task, when a signal generator triggered the echo, and in an active experiment, where the echo was time locked to the animals emitted signal. Our results show the best response at 125 kHz and indicate a slight, but significantly higher response in the active mode. The latter has a methodological explanation. [Work supported by ONR.]
Initial results from the Pacific Ocean Shelf Tracking System: A permanent continental-scale acoustic tracking array for fisheries research
Authors: Welch David W.
Published: October 2013

The Census of Marine Life is developing POST, a seabed acoustic array for tracking marine animals. The long-range plan involves the deployment of 30 or more cross-shelf monitoring lines forming a permanent continental-scale array, each consisting of autonomous seabed nodes spaced at roughly 1 km intervals. Nodes would be modular and use an acoustic modem to periodically communicate with an overhead ship, which would upload data and download new programming. 2004 was a large-scale test of the tracking array component using 135 km of listening lines and 1050 acoustically tagged juvenile salmon (12–15 cm long). Detection rates for individual fish crossing 20 km long acoustic lines were approximately 91%, and precise measurements of migration timing, speed of movement and survival were obtained for both the freshwater and early marine phases. In subsequent years we plan to include additional oceanographic sensors to provide detailed data on changes in bottom temperature, salinity, and currents over time and implement acoustic modems to allow remote data upload from a visiting boat. These data could then be meshed with the fish movement data to describe how animals move relative to changes in the three dimensional structure of the ocean that they are migrating through.
Acoustic navigation for ultra-precise seafloor mapping
Authors: Hussong Donald M. , Blackinton J. Grant
Published: October 2013

Numerous autonomous underwater vehicles (AUVs) are operating with very precise swath bathymetric mapping systems in ocean depths to 3000 m and greater. Although these systems acquire data from positions known to a few centimeters accuracy with respect to the vehicle position, the positioning of the AUVs is generally no better than tens of meters at great depths. Although not yet assembled into an operational system, the technology now exists to acoustically navigate an AUV to within a 10 cm in x, y, and z. This begins by establishing active reference positions on the seafloor, known to within a few centimeters absolutely, using acoustic mirror transponders that transmit and receive streams of pulse coded signals from an accurately navigated surface vessel. These bottom reference positions can then be the core of a long baseline acoustic navigation system which, when coupled with constant monitoring of oceanographic conditions to calculate pressure corrections for depth measurements, will provide 10-cm navigation accuracy for the mapping AUV. Implementation of this technology will enable observational mapping of highly seismic areas where frequent earthquakes can cause many meters of deformation of the seafloor, and can generate massive tsunamis.
Ambient sound budgets
Authors: Nystuen Jeffrey A. , Howe Bruce M.
Published: October 2013

The underwater ambient sound field contains a lot of information about geophysical, biological and anthropogenic activities in the ocean. Identification and quantification of these signals will complement more traditional measurements collected on future ocean observatories, including systems cabled to shore and remote mooring arrays. Long-term ambient sound measurements using a low duty cycle recorder are reported from remote deep ocean moorings, coastal shelf moorings, inland waterways and even a deep, quiet fresh water lake. Identifiable geophysical signals include accurate measurements of wind speed and rainfall over a wide range of wind speeds and rainfall rates. The character and temporal patterns of biological activity, shipping and recreational boating are monitored. The overall ambient sound budgets will be reported for these different environments. Acoustic monitoring is available from sub-surface moorings, remote locations and under severe weather conditions where and when other ocean instrumentation is likely to fail. [Work supported by ONR Ocean Acoustics.]
Opening the blood-brain barrier with ultrasound
Authors: Mourad Pierre
Published: October 2013

The blood-brain barrier (BBB) constitutes a unique anatomical structure within the brain that prevents many therapeutic chemicals within the blood from entering the brain. Research at the University of Washington has shown that it is possible to transiently disrupt the BBB without damage in an intra-operative setting, as verified by the flux of vital dyes from the blood-stream into the brain. This talk will review the research we have done to date on this subject, and discuss potential applications of this approach to BBB disruption.
Ultrasound-accelerated thrombolysis using microbubbles
Authors: Culp William
Published: October 2013

Current thrombolytic therapy for ischemic stroke reaches less than 3% of cases and is only moderately successful. Numerous studies have demonstrated increased thrombolytic activity when ultrasound is delivered to clot in the presence of tissue plasminogen activator. Initial human reports using trans-cranial Doppler technology (2 MHz) to deliver continuous ultrasound to intracranial clot are very promising with improved clot lysis and no increase in symptomatic bleeding. However, another human study using low-frequency therapeutic ultrasound resulted in excessive bleeding and was discontinued. Microbubble augmented ultrasound clot lysis has proven successful in several studies ranging from lysis of very small peripheral clots in rabbits to very large clots in dialysis grafts in dogs. Early human studies of thrombosed dialysis grafts show success and no adverse events. Intracranial clot lysis in pigs has been successful with both intra-arterial and intravenous microbubble techniques. Better definition of possible combination therapies and of efficacy and safety is still required in animal models, but human studies should be designed to avoid some of the complications of current therapy. This presentation will review the subject, present recent advances, and define some requirements for successful clot destruction in peripheral vessels and intracranial vessels.
Acousto-mechanical and thermal properties of clotted blood
Authors: Nahirnyak Volodymyr M. , Yoon S. Wang , Holland Christy K.
Published: October 2013

The efficacy of ultrasound-assisted thrombolysis as an adjunct treatment of ischemic stroke is being widely investigated. In order to determine the role of ultrasound hyperthermia in the process of blood clot disruption, the thermal and acousto-mechanical properties of clotted blood were measured in vitro. Whole blood clots were prepared from either fresh porcine or human blood by aliquoting 1.5 or 2.0 ml into 10 ml glass tubes (BD VacutainerTM, Franklin Lakes, NJ), immersing the tubes in a 37°C water bath for three hours and storing the clots at 5°C for at least three days prior to assessment of the properties, which ensured complete clot retraction. Direct calorimetric measurements using calibrated E-type thermocouples (Omega Engineering, Inc., Stanford, CT) were performed to determine the heat capacity and thermal conductivity of the human and porcine thrombi against a standard fluid, saline [0.9%]. The amplitude coefficient of attenuation of the clots was determined from 120 kHz to 3.5 MHz with a calibrated hydrophone (TC4038, RESON, Inc., Goleta, CA) in a 20±2°C water bath using the substitution method. The experimentally measured values of heat capacity, density, and thermal conductivity of porcine clotted blood are 3.23±0.46 J/g⋅K, 1.058±0.014 g/cm3, and 0.52±0.14 W/m⋅K. The attenuation coefficient ranged from 0.10 to 0.30 Nepers/cm over 120 kHz to 3.5 MHz. Measurements of the acousto-mechanical and thermal properties of clotted blood can be helpful in theoretical modeling of ultrasound hyperthermia in ultrasound-assisted thrombolysis.
Lytic efficacy of apoli protein E2 (ApoE2) and recombinant tissue plasminogen activator (rt-PA) treatment with 120 kHz ultrasound in an in-vitro human clot model
Authors: Meunier Jason M. , Cheng Jason Y. , Clark Joseph F. , Shaw George J.
Published: October 2013

Currently, the only FDA approved therapy for acute ischemic stroke is recombinant tissue plasminogen activator (rt-PA). However rt-PA has substantial side effects such as hemorrhage. This has led to interest in other potential therapies. For example, ultrasound (US) increases the lytic efficacy of rt-PA. Also, apolipoprotein E2 (ApoE2) increases rt-PA activity. This suggests combining US, ApoE2 and rt-PA to improve thrombolysis, but the efficacy is not known. Here, the lytic efficacy of apoE2, rt-PA and 120 kHz US is measured in a human clot model. Whole blood was obtained from volunteers, after local institutional approval. Clots were formed in 1.7 mm micropipettes, and placed in a water tank that allowed microscopic video imaging during US and thrombolytic exposure. Clots were treated with rt-PA ([rt−PA]=3.15 μg/ml), rt-PA and apoE2 ([apoE2]=9.8 μg/ml), or rt-PA, apoE2 and 120 kHz US (0.35 MPa, PRF=1667 Hz, 80% duty cycle) for 15 min at 37°C in human plasma. Clot lysis was visually recorded and the lysis depth (LD) determined from these data using an image analysis algorithm. LD was linear with time for all treatments (R2≥0.81), allowing the determination of a lytic rate (LR). LR was found to be 0.35±0.03, 1.55±0.11, and 0.75±0.04 μm/min for the rt-PA, rt-PA and apoE2, and US treated groups respectively. The thrombolytic efficacy of rt-PA is enhanced by ApoE2. The interaction of 120 kHz with apoE2 and rt-PA showed a reduced lytic efficacy compared with rt-PA and apoE2 treatment alone. It is possible that US interferes with the ApoE2-mediated activation of rt-PA.
A unified digital waveguide (infra)structure for synthesizing wind instrument sounds
Authors: Scavone Gary
Published: October 2013

Virtual acoustic models provide researchers a means for testing and verifying their scientific understanding of physical systems. As well, they allow explorations in a world free from physical constraints. A digital waveguide structure is presented which implements a generalized air column, or resonator, model for wind instrument sound synthesis. This system has a physical inspiration and interpretation, a ‘‘blowed string,’’ but is an otherwise impossible reality. The structure produces harmonic resonant modes at integer multiples of a fundamental, with controls to vary harmonic content. It is useful for simulating both cylindrical and conical air columns of such instruments as clarinets, saxophones, flutes, oboes, and trumpets. Further, this structure robustly interconnects with several different non-linear ‘‘reed’’ models to produce a rich variety of wind instrument sounds. The result is a highly efficient computational algorithm that can be used to perform real-time sound synthesis on consumer-grade computers. [Work supported by the Canadian Foundation for Innovation.]
Experimental study of sound propagation in a street
Authors: Picaut Judicaël
Published: October 2013

This paper presents an experimental study of the sound propagation in a street, performed during July 2002, in order to measure impulse responses at numerous locations in a street canyon, and, for several positions of the sound source. A specific attention has been paid on the processing of the experimental data, in order to obtain accurate values of the reverberation time and the steady-state sound pressure level, including also the compensation of the atmospheric attenuation. In total, 11592 useful data have been collected during this experiment, and are available by contacting the author. Reverberation times and sound levels, in the narrow street, are then analyzed and compared, for the 4 source positions in the street. This experimental study gives interesting results on the behavior of the sound field in the street.
Modeling the characteristics of wheel/rail rolling noise
Authors: Lui Wai Keung , Li Kai Ming , Frommer Glenn H.
Published: October 2013

To study the sound radiation characteristics of a passing train, four sets of noise measurements for different train operational conditions have been conducted at three different sites, including ballast tracks at grade and railway on a concrete viaduct. The time histories computed by the horizontal radiation models were compared with the measured noise profiles. The measured sound exposure levels are used to deduce the vertical directivity pattern for different railway systems. It is found that the vertical directivity of different railway systems shows a rather similar pattern. The vertical directivity of train noise is shown to increase up to about 30× before reducing to a minimum at 90×. A multipole expansion model is proposed to account for the vertical radiation directivity of the train noise. An empirical formula, which has been derived, compares well with the experimental data. The empirical model is found to be applicable to different train/rail systems at train speeds ranging up to 120 km/h in this study. [Work supported by MTR Corporation Ltd., Innovation Technology Commission of the HKSAR Government and The Hong Kong Polytechnic University.]
Infrasound remote sensing of the upper atmosphere
Authors: Drob Douglas , Picone Micheal , Meier Robert
Published: October 2013

We investigate the prospects for utilizing infrasound signals from geophysical sources to improve our knowledge of upper atmospheric winds and temperatures. We present results from numerical experiments designed to quantify the statistical performance of an idealized infrasonic upper atmospheric remote sensing network over a range of propagation modeling assumptions, source types, and geophysical variables. For a series of hypothetical events, infrasonic observables are calculated with a spherical 3-D ray tracer and series of atmospheric profiles spanning the range of geophysical parameters. These synthetic measurements are then inverted to estimate the original atmospheric background fields. A nonlinear least-squares estimation procedure that accounts for uncertainties in both the dependent and independent variables is used. The retrieved atmospheric profiles are represented by a set of truncated empirical orthogonal functions to incorporate a priori knowledge of atmospheric structure and reduce the number of parameters. Our numerical experiments indicate that it is indeed possible to make meaningful estimates of upper atmospheric environmental profiles with today’s infrasound networks. [Work supported by the Office Naval Research.]
Recognition of function words in 8-month-old French-learning infants
Authors: Shi Rushen , Gauthier Bruno
Published: October 2013

Previous work has shown that German-learning 7-9-month-old infants recognize function words (Hoehle and Weissenborn, 2003). English-learning infants recognize function words around 10.5-11 months (Schafer et al. 1998; Shady, 1996; Shi et al., 2003, 2004), and the highly frequent determiner ‘‘the’’ at 8 months (Shi et al., 2004). The present study investigates French-learning infants’ recognition of function words. As French is a syllable-timing language, the fuller syllabic status may allow infants to recognize function words earlier than English-learning infants. Syntactically and morphologically, functional elements occur more systematically in French than in English, providing reliable statistical cues to functor segmentation. Using a preferential looking procedure, we familiarized 8-month-olds with a target function word (‘‘des,’’ ‘‘la,’’ ‘‘mes’’ or ‘‘ta’’), and tested them with phrases containing the target versus a non-target. Results showed that infants’ looking time to the phrases containing the targets versus those containing the non-targets differed significantly. Thus, infants recognized the target functors in continuous speech. As the targets included both high-frequency (‘‘des,’’ ‘‘la’’) and low-frequency (‘‘mes,’’ ‘‘ta’’) function words, we suggest that infants may begin segmenting high-frequency functors at an even younger age. The implications of early processing of function words to language acquisition will be discussed.
Relation between perception and production ability during a speech training course
Authors: Tsushima Teruaki , Hamada Mayumi
Published: October 2013

Previous research has indicated that perception and production ability are significantly related among L2 learners in natural learning settings. The present study focused on the relation between these two abilities during speech training, specifically examining whether perception or production training alone led to improvements of production or perception ability, and whether the order of perception and production training influenced the improvement of the abilities. Forty-five Japanese university students received thirteen-week perception and production training on six American English contrasts (e.g., b/v, l/r). One group received perception training first, followed by production training, while the order of training was reversed for the other group. It was found that the initial perception training in the former group resulted in a significant but relatively weak transfer to improvements of production ability, while the initial production training in the latter group showed a significant and strong transfer to those of perception ability. It was also shown that the improvements of perception and production ability during the speech training were significantly related in both groups. The order of training, however, did not significantly influence the overall degree of improvements in either of the abilities. Implications for speech learning models will be discussed.
The effect of L1 prosodic backgrounds of Cantonese and Japanese speakers on the perception of Mandarin tones after training
Authors: So Connie K.
Published: October 2013

The present study investigated to what extent ones’ L1 prosodic backgrounds affect their learning of a new tonal system. The question as to whether native speakers of a tone language perform differently from those of a pitch accent language will be addressed. Twenty native speakers of Hong Kong Cantonese (a tone language) and Japanese (a pitch accent language) were assigned to two groups. All of them had had no prior knowledge of Mandarin, and had never received any form of musical training before they participated in the study. Their performance of the identification of Mandarin tones before and after a short-term training was compared. Analysis of listeners’ tonal confusions in the pretest, posttest, and generalization tests revealed that both Cantonese and Japanese listeners had more confusion for two contrastive tone pairs: Tone 1–Tone 4, and Tone 2–Tone 3. Moreover, Cantonese speakers consistently had greater difficulty than Japanese speakers in distinguishing the tones in each pair. These imply that listeners L1 prosodic backgrounds are at work during the process of learning a new tonal system. The findings will be further discussed in terms of the Perceptual Assimilation Model (Best, 1995). [Work supported by SSHRC.]
How auditory discontinuities and linguistic experience affect the perception of speech and non-speech in English- and Spanish-speaking listeners
Authors: Hay Jessica F. , Holt Lori L. , Lotto Andrew J. , Diehl Randy L.
Published: October 2013

The present study was designed to investigate the effects of long-term linguistic experience on the perception of non-speech sounds in English and Spanish speakers. Research using tone-onset-time (TOT) stimuli, a type of non-speech analogue of voice-onset-time (VOT) stimuli, has suggested that there is an underlying auditory basis for the perception of stop consonants based on a threshold for detecting onset asynchronies in the vicinity of +20 ms. For English listeners, stop consonant labeling boundaries are congruent with the positive auditory discontinuity, while Spanish speakers place their VOT labeling boundaries and discrimination peaks in the vicinity of 0 ms VOT. The present study addresses the question of whether long-term linguistic experience with different VOT categories affects the perception of non-speech stimuli that are analogous in their acoustic timing characteristics. A series of synthetic VOT stimuli and TOT stimuli were created for this study. Using language appropriate labeling and ABX discrimination tasks, labeling boundaries (VOT) and discrimination peaks (VOT and TOT) are assessed for 24 monolingual English speakers and 24 monolingual Spanish speakers. The interplay between language experience and auditory biases are discussed. [Work supported by NIDCD.]
Validation of an automatic measurement of Spanish speaking proficiency
Authors: Rosenfeld Elizabeth , Bernstein Jared , Balogh Jennifer
Published: October 2013

A 15-min computer-based test of spoken Spanish was designed to measure candidate proficiency in Spanish. The test presents seven tasks: reading, elicited imitation, word opposites, short-answer questions, sentence constructions, opinion questions, and story retellings. The tests were presented to 579 adult non-native Spanish learners and to 552 native Spanish speakers. Expert human judgments of the non-native responses showed that the spoken response material carried sufficient information for highly reliable judgments of proficiency. In the development and validation process, 57000 responses were transcribed and 21000 human judgments were analyzed. The paper describes the validation of the automatic scoring system with reference to concurrent oral proficiency interviews conducted by professional raters certified by the US Government or by ACTFL. The outcomes of the comparisons of the machine scored tests with interactive human interviews and with human ratings from recorded speech indicate that the test produces scores that have virtually the same information that is found in oral proficiency interviews. Almost all assessments correlate highly with the other assessments with coefficients in the range 0.86–0.96. The test correlation with the combined interview scores (r=0.92) is higher than the inter-rater reliability of the professional interviewers themselves.
Voice onset time (VOT) in Canadian French and English: Monolingual and bilingual adults
Authors: MacLeod Andrea A. N. , Stoel-Gammon Carol
Published: October 2013

This study focused on the contrasts produced by early bilingual speakers (n=6) across their two languages in comparison with monolingual speakers (Canadian English (CE), n=5; Canadian French (CF), n=6). VOT production was measured in monosyllabic CE and CF words that began with one of four stop consonants, /p, b, t, d/ followed by one of three vowels. A total of 14–18 words for each of the four stop consonants for each language was elicited with a total number 1700 acoustically analyzed productions. The participants were tested individually in quiet rooms using a single target language throughout the session. As expected, the monolingual speakers produced a two-way contrast (statistically significant: p<0.05): for CE speakers, short-lag VOT versus long-lag VOT; for CF speakers, lead VOT versus short-lag VOT. Rather than producing a two-way contrast (e.g., lead VOT versus lag VOT) or a three-way contrast (e.g., lead VOT versus short-lag VOT versus long-lag VOT), the bilingual speakers produced a four-way contrast (statistically significant: p<0.05): long lead VOT (CF /b, d/), short lead VOT (CE /b, d/), short-lag VOT (CF /p, t/) and long-lag VOT (CE /p,t/). These results suggest that bilinguals are maintaining phonetic contrasts both within and across their two languages.
Global seismic tomography: Present status and future perspectives
Authors: Romanowicz Barbara
Published: October 2013

Global seismic tomography of the Earth’s mantle has traditionally focused on the inversion of travel times from a small number of seismic phases, well isolated in time domain seismograms. The resulting uneven sampling of the Earth, dictated by the available distribution of earthquake sources and receivers, greatly limits the resolution of 3-D structure that can be attained. With recent progress in the simulation of wave propagation in realistic 3-D Earth models combined with significant increases in computational power, seismologists are well positioned to start fully exploiting the wealth of information contained in the rapidly expanding database of high quality broadband seismic waveforms, accumulated globally and regionally over the last twenty five years. New opportunities presented by 3-D forward and inverse modeling of long period waveforms will be presented with illustrations from recent work on deep and shallow elastic and anelastic mantle structure, addressing, among others, such questions as: what is the fate of subducted slabs or the nature of the lower mantle ‘‘superplumes’’?
Close-range acoustic scattering from mud volcanoes
Authors: Holland Charles W. , Weber Thomas C. , Etiope Giuseppe
Published: October 2013

Submarine mud volcanoes occur in many parts of the world’s oceans and form an aperture for gas (mostly methane) and fluidized mud emission from the earth’s interior. Their characteristics are of considerable interest to the geology, geophysics, geochemistry, and underwater acoustics communities. For the later community, mud volcanoes are important because they pose a potential source of clutter for active sonar. Close-range (single boundary interaction) scattering measurements from a mud volcano in the Straits of Sicily were conducted with a vertical source and receive array. The data show target strengths from 800–3600 Hz of 6–12 dB for a monostatic geometry with grazing angles of 3–5 degrees. The target strengths are very similar for vertically bi-static paths with incident grazing angles of 3–5 degrees and scattered angles of 33–45 degrees. The evidence suggests that the scattering mechanism is the mud volcano (carbonate) structure. [Work supported by the Office of Naval Research and NATO Undersea Research Centre.]
Benefits of teaching voice amplification as related to subjective laryngeal symptoms in teachers, and to the listening conditions for pupils
Authors: Jonsdottir Valdis
Published: October 2013

Teachers unfavorable working conditions—large classrooms with poor acoustics, background noise and the great distance between teacher and pupils often are the main reasons for teachers voice problems. For pupils, the same circumstances simultaneously create unfavorable listening conditions. One way to diminish the vocal load of teaching is by making use of technical equipment. This Icelandic study explores whether voice amplification usage: (1) diminishes the teachers subjective symptoms of vocal fatigue; (2) makes it easier for pupils to listen and follow lessons; and (3) reveals other benefits and/or disadvantages of the usage of amplification in classrooms. Thirty-three teachers with their students (total 791), from grade school to university level, volunteered as subjects. The teachers used amplification in class for at least a week. At the end of the research period, the participants answered questionnaires, except the pupils between 6–9 years of age who were asked two questions. The results showed: (1) the majority of teachers found it easier to talk and experienced less fatigue using vocal amplification; (2) the students found it easier to hear the teacher through class chatter and to follow the lessons; (3) the disadvantages mentioned were mainly technical problems.