bluuebunny/crossref_metadata_2025 huggingface dataset:
Synchronized vibrations measurements at multiple locations using a single continuously scanning laser doppler vibrometer. Applications to non-contact sensing of human body vibrations
Authors: Salman Muhammad , Sabra Karim G.
Published: October 2011

Laser Doppler vibrometry (LDV) is a non-contact method to measure surface velocity. Typical LDV configurations uses one fixed laser (He-Ne) beam at a specific point and orientation on a surface under test. A continuously scanning laser Doppler vibrometry (CSLDV) technique using a single laser beam performing quickly a long scan was developed to measure surface velocity at each laser position during its scan. This fast CSLDV can then replace several fixed LDVs. This technique is especially advantageous for sensing human body natural vibrations (typically below 100 Hz) at multiple locations (e.g., along small muscles) as it does not require traditional skin-mounted sensors (e.g., accelerometers array), which eliminates mass artifacts and the set-up time to attach those sensors. Experimental measurements were conducted using a CSLDV with a 200 Hz linear scan rate, over scan lengths up to 5 cm, to measure low-frequency vibrations (f<100 Hz) on gel samples which mimic human soft tissues. Validations of the CSLDV measurements were done using an array of several fixed LDVs distributed along the same scan line. The effects of speckle noise on CSLDV measurements will be quantified. Applications of this CSLDV technique for active and passive elastography measurements will be presented.
Calculating piezoelectric parameters of stripe-electroded cylinders and bars with continuous no-uniform electric fields
Authors: Sarangapani Sairajan , Brown David A. , Aronov Boris
Published: October 2011

Tangentially poled thin-walled stripe-electroded piezoelectric bars and hollow cylinders are used in several electromechanical and electroacoustic applications. The 33 mode properties of the stripe-electroded bars and hollow cylinders are not fully realized due to the non-uniform polarization and non-uniform operational electric field due to fringing from the surface electrode geometry. A numerical finite difference method (FDM) was used to analyze the nonuniform electric field in the bar but under the assumption that the piezoelectric element is fully polarized. The effective electromechanical coupling coefficient k3'3, the effective piezoelectric modulus d3'3, the effective compliance sE3'3, and the effective relative dielectric constant ε3'3 (where the prime indicates field nonuniformity) are calculated using the energy method by accounting for the effects of nonuniform operational electric field and non uniform strain distributions. Analytical and experimental results are in good agreement and design optimizations are presented.
Modeling piezoelectric parameters of bending mode transducers
Authors: Sarangapani Sairajan , Brown David A. , Aronov Boris
Published: October 2011

The piezoelectric bender bar vibrator is commonly used for generating low frequency flexural plate mode vibrations. This study considers the excitation of “benders” using stripe-electroded piezoelectric elements of various electrode patterns and poling configurations using the k3'3 and k3'1, where the prime indicates field nonuniformity. A numerical analysis is used to calculate the nonuniform electric field lines and the corresponding coupling coefficients as well as other related electromechanical parameters by developing a Lagrangian description of the electromechanical body and using the energy method. The effective electromechanical coupling coefficients are calculated by taking into account the internal energies due to transverse, longitudinal, and shear vibrations in the bar. The contribution of the passive and the active capacitance is also explained and taken into account while calculating the electromechanical parameters.
Design for a modular and scalable sonar source using displacement amplifying lamina
Authors: Lyon Richard H.
Published: October 2011

A sonar sound source is described that is capable of radiating increased sound power at low frequencies in a non-resonant mode of operation. Non-resonant operation is used so that the amplitude and phase of the generated signals are smooth over a range of frequencies. The improvement in output is achieved in part by the use of Galfenol, a fairly new magnetostrictive (MS) material with a high MS strain coefficient. The enhanced output is also due to the use of non-resonant amplifying volume displacing lamina. The system is modeled using a simplified equivalent circuit linear model that allows prediction of several quantities of interest, such as the radiated output, the strain in the MS material, the excitation power, and the sensitivity to ambient pressure fluctuations. [Work supported in part by the US Air Force and the US Navy.]
Why does musical training benefit the neural encoding of speech? A new hypothesis
Authors: Patel Aniruddh D.
Published: October 2011

Mounting evidence suggests that musical training benefits the neural encoding of speech. This paper offers a hypothesis specifying why such benefits occur. The OPERA hypothesis proposes that such benefits are driven by adaptive plasticity in speech-processing networks, and that this plasticity occurs when five conditions are met. These are (1) Overlap: there is anatomical overlap in brain networks that process an acoustic feature used in both music and speech (e.g., waveform periodicity, amplitude envelope), (2) Precision: music places higher demands on these shared networks than does speech, in terms of the precision of processing, (3) Emotion, (4) Repetition, and (5) Attention: the musical activities that engage this network elicit strong positive emotion, are frequently repeated, and are associated with focused attention. According to the “opera” hypothesis, when these conditions are met neural plasticity drives the networks in question to function with higher precision than needed for ordinary speech communication. Yet since speech shares these networks with music, speech processing benefits. The OPERA hypothesis is used to account for the observed superior subcortical encoding of speech in musically trained individuals and to suggest mechanisms by which musical training might improve linguistic reading abilities.
Spatio-temporal characteristics of countryside soundscapes in Hong Kong
Authors: Lam Kin-che
Published: October 2011

Over six hundred 15-min and one hundred 24-h digital sound recordings were undertaken in different parts of the Hong Kong countryside covering different landscape units, different time of day and seasons. Spectrograms were prepared from these recordings and 24-h spectrograms were subdivided into segments with relatively uniform acoustic characteristics. These segments were then analyzed for the sound sources, acoustic and psychoacoustic characteristics. These data were analyzed to determine for their spatial and temporal characteristics. Cluster and discriminant analyses were further undertaken to ascertain how acoustic and sound sources of the countryside vary over space and time. The results indicate that soundscape characteristics are determined primarily by the type of landscape, and then by the diurnal and seasonal characteristics. The implications of these findings on human experience, sampling strategy, and countryside management and planning will be discussed.
Mechanisms of nonlinear saturation in focused acoustic beams of periodic waves and single pulses
Authors: Khokhlova Vera , Karzova Maria , Averiyanov Mikhail , Sapozhnikov Oleg
Published: October 2011

Physical mechanisms leading to saturation of various acoustic field parameters in nonlinear focused beams of periodic waves and single pulses were investigated numerically. A numerical algorithm based on the KZK equation was used in the simulations. Propagation of an initially harmonic wave and a single pulse (one period of a sine wave) emitted by a focused transducer with Gaussian apodization was modeled. It was shown that in periodic fields, saturation of the peak positive pressure is mainly due to the effect of nonlinear absorption at the shock front. In acoustic fields of single pulses the main mechanism of saturation is the nonlinear refraction. Maximum pressure in the periodic field, achieved at the focus, was found to be higher than that of the single pulse. The total energy of the beam of the periodic wave, however, decreases much faster with the distance from the source as compared to the single pulse focusing. These nonlinear propagation effects propose a possibility to use pulsed beams for more effective delivery of the wave energy to the focal region, and periodic waves—to achieve higher pressure values of at the focus. [Work supported by EB007643, NIH DK43881, DK075090, and RFBR 09-02-01530.]
Thoughts on submarine structural acoustics
Authors: Dyer Ira
Published: October 2011

The simplest submarine model is a uniform circularly cylindrical shell with flat end caps. This is too simple to be useful, but the recent phenomenal advances in computational structural acoustics, and the availability of test and laboratory facilities, make it feasible to tackle greater complexity in the submarine structure. But the newer numerical computational analyses, and standard experimental approaches, have as their initial outputs large data sets. So, in effect, structural acousticians have traded simpler and less realistic structural models, for more dense data sets and more useful models, a trade bound to be highly positive. In this context, the author has observed, subjectively, that those who have the ability to aggregate their large data sets with physics-centric descriptions do present their results crisply and with deep understanding. Also, they are better prepared to adjudicate alternate interpretations and to suggest further steps to reach more unique conclusions. Accordingly, the author suggests that specialized data filters be researched and developed for use in data interpretation, these to be formulated from questions such as: Where in the submarine structure, and in what wavenumber band, does wavenumber matching needs to be controlled? What is the modal character of an internal stiffening ring, and where should absorptive sinks of resonance peaks be placed? Additional questions are posed and discussed in the paper.
Being wrong—Insights from the speech-recognition battleground
Authors: Christiansen Thomas U. , Greenberg Steven
Published: October 2011

Speech-recognition studies rarely use more than a single metric to evaluate recognition performance, usually percent correct (or percent wrong). Such a uni-dimensional evaluation may conceal more than it reveals. An alternative, based on information theory, offers greater insight into brain (and computational) processes associated with human and machine speech recognition. In this presentation, we examine errors associated with phonetic-segment recognition in human listeners and compare them with those committed by automatic speech-recognition (ASR) systems. Consonant errors are analyzed into the phonetic features of VOICING, place—(PLACE) and manner—(MANNER) of—articulation. For both humans and machines, PLACE information is far more vulnerable to distortion/interference than MANNER and VOICING, but is more important for consonant and lexical recognition than the other features. Moreover, PLACE is decoded only after VOICING and MANNER and is more challenging for machines to accurately recognize. The origins of these differences can be traced, in part, to the redundancy with which this information is distributed in the acoustic signal, as well as how the phonetic information is combined across the frequency spectrum. For such reasons, ASR performance could benefit by including phonetic-feature-based information in lexical representations. [Work supported by AFOSR and Technical University of Denmark.]
Robust speech recognition with articulatory features using dynamic Bayesian networks
Authors: Mitra Vikramjit , Nam Hosung , Espy-Wilson Carol , Saltzman Elliot , Goldstein Louis
Published: October 2011

Previous studies have proposed ways to estimate articulatory information from the acoustic speech signal and have shown that when used with standard cepstral features, they help to improve word recognition performance in noise for a connected digit recognition task. In this paper, I present results from a word recognition and a phone recognition experiments in noise that uses two sets of articulatory representation: continuous (tract variable trajectories) and discrete (articulatory gestures) along with standard mel cepstral features for acoustic modeling. The acoustic model is a dynamic Bayesian network (DBN) that treats the continuous articulatory information as observed and the discrete articulatory presentation as hidden random variables. Our results indicate that the use of articulatory information improved noise robustness for both the word recognition and phone recognition tasks substantially.
Mutual interference signal processing for active sonar
Authors: Unruh Stephen D. , Aughenbaugh Jason M. , Gelb James M.
Published: October 2011

Active sonar for anti-submarine warfare (ASW) can at times be hampered by interference from the transmissions of other vessels—either friend or foe. For practical reasons, there are typically only a limited number of center-frequencies, bandwidths, and useful waveform types available. We explore the cross-correlation of various frequency modulated waveforms with varying characteristics—particularly bandwidths, pulse lengths, and the degree of frequency overlap. The impact on the ambiguity function is also explored, along with the efficacy of several transmitter and receiver filters. Real world data containing interfering transmissions are presented including examples where basic theoretical effects are revealed. This work represents an early stage of research to ultimately explain subtle nuances in real data and to develop novel signal processing techniques to mitigate interference. [Work sponsored by ONR 321US.]
Understanding the feedback effect through the physics of the diffraction-based sensitivity kernel for a target in shallow water: A small-scale experimental demonstration
Authors: Marandet Christian , Roux Philippe , La Rizza Patrick , Nicolas Barbara
Published: October 2011

Using the feedback effect, we experimentally detect a wavelength-sized target in a shallow ultrasonic waveguide between two source-receiver transducers on acoustic feedback. The waveguide represents a 1-km-long, 50-m-deep ocean acoustic channel at the 1/1000 scale. The feedback phenomenon, or Larsen effect, occurs when a source and a receiver are connected both acoustically through the propagation medium and electrically through an amplifier in such a way that the received signal is simultaneously and continuously added to the emitted signal. A resonance is obtained when the emitter and the receiver are in phase. This resonance is very sensitive to any change in the medium which makes it a good observable for target detection. In presence of a target in the waveguide, the numerical gain of the feedback effect has to increase in order to compensate the scattering of the acoustic field from the target. In a separate experiment, the scattered field may also be recorded in a transmission configuration from the same couple of emitter/receiver with an impulse as a source signal. A comparison is made between the two different approaches.
Near-field blind deconvolution in a reverberant environment
Authors: H. Abadi Shima , S. Haapaniemi Eric , J. Femminineo Andrew , M. Williamson Laura , R. Dowling David
Published: October 2011

Artificial time reversal (ATR) is a passive technique for blind deconvolution in an unknown multipath environment that relies on generic features of underwater sound fields. ATR has been found to be effective when the source is far from the receiving array and the receiving array properly resolves propagating modes or ray-path arrival angles throughout the bandwidth of the source signal. This presentation describes the results of an experimental investigation into ATR's performance for a near-field source in a highly reverberant environment. The experiments were conducted with nominally 0.1 ms pulses at frequencies from 20 kHz to 150 kHz in a 1.0-m-deep and 1.07-m-diameter cylindrical water tank having a reverberation time of ∼10 ms using a single sound projector and a linear receiving array of 16 hydrophones. The correlation coefficient between the original and the ATR-reconstructed signals is presented as a function of receiving-array and broadcast-signal characteristics and compared to equivalent signal reconstruction results from spherical-wave delay-and-sum beamforming. The intended application of this research lies in determining the acoustic signature of cavitation bubbles and other hydroacoustic sound sources in hydrodynamic test facilities. [Sponsored by ONR and by NAVSEA through the Naval Engineering Education Center.]
The use of multi-channel microphone and loudspeaker arrays to evaluate room acoustics
Authors: Clapp Samuel W. , Guthrie Anne E. , Braasch Jonas , Xiang Ning
Published: October 2011

Most room acoustic parameters are calculated with data from omni-directional or figure-of-eight microphones. Using a spherical microphone array to record room impulse responses can yield more information about the spatial characteristics of the sound field, including spatial uniformity and the directions of individual reflections. In this research a spherical array was use to measure room impulse responses in a wide variety of concert halls throughout New York State, both on stage and in the audience, with both the microphone array and a dummy head. The results were analyzed using beamforming techniques to determine spatial information about the sound field, and compared to the results of geometrical acoustics and binaural localization models. Of particular interest was how the spatial data can help to differentiate between different spaces or listener positions that exhibit similar values for conventional metrics. Auralizations were created using both headphone playback and second-order ambisonic playback via a loudspeaker array. These systems were evaluated objectively to compare the reproduction systems with the measured data. Subjects were recruited for listening tests using each reproduction method, and asked to evaluate the halls on both objective measures and subjective preference, and the results of binaural and ambisonic playback were compared.
Monitoring a small marine cetacean population using passive acoustic techniques: Vaquita, a critically endangered species
Authors: Jaramillo-Legorreta Armando , Rojas-Bracho Lorenzo
Published: October 2011

In 2008, vaquita population was estimated in only 245 individuals. Between 1997 and 2007, a passive acoustic semi-autonomous system was used for monitoring detection rate of this species. The analysis resulted in decline of approximately 58%. Sighting and acoustic data from a 2008 research cruise, compared to the 1997 estimate of abundance, resulted in a decline of approximately 57%. Hence, passive acoustic detection probed reliable to monitor the population. The Mexican Government implemented a recovery plan, which includes monitoring population trends. At current level, the population can grow at maximum rates lower than 4% annually. The severely reduced population level, and scarcity of acoustic detections, made unreliable to continue the use of the methods applied till 2007. An increase of sampling effort was identified as the key to implement a reliable system, only achievable using completely autonomous detectors. Field test of autonomous detectors identified C-POD as very reliable. Using data collected with this equipment it was determined that an annual effort of 5000 C-POD days is needed to detect population increase. A sampling grid of 62 stations was designed. Work to design and test reliable mooring devices was done. Currently, the first of five years of sampling has started.
Statistical design for acoustic monitoring to detect declines of endangered species and prevent extinction
Authors: Barlow Jay , Jaramillo-Legorreta Armando , Taylor Barbara L. , Rojas-Bracho Lorenzo , Tregenza Nicholas J. C.
Published: October 2011

As populations become smaller and more endangered, the ability to monitor trends in their abundance also decreases. For vocal species, passive acoustic monitoring can provide a powerful, cost-effective method of monitoring relative abundance. However, the monitoring effort should be based on a statistical design that can detect population declines in time to prevent extinction. This is illustrated with an example of the vaquita (Phocoena sinus) an endangered porpoise in the northern Gulf of California, Mexico. A pilot project showed that porpoise detectors (C-PODs) recorded echo-location clicks from approximately one group of porpoises every two days. Based on this, we estimate that 5000 days of C-POD monitoring per year would be needed to obtain a measure of relative vaquita abundance with a coefficient of variation (CV) of 3%. A power analysis shows that five years of monitoring with this CV would give a high probability of detecting a 5% annual increase or decrease in population size. Visual sighting methods could not detect such small changes with any conceivable level of survey effort. This kind of innovative monitoring is a critical tool in the continuing evaluation of conservation measures.
Towed hydrophone surveys for monitoring trends in the abundance and distribution of the critically endangered Gulf of California porpoise, Vaquita
Authors: Swift Rene , Rankin Shannon , Gerrodette Tim , Taylor Barbara , Gillespie Douglas , Gordon Jonathan , Rojas-Bracho Lorenzo , Jaramillo-Legorreta Armando
Published: October 2011

The vaquita (Phocoena sinus) is a critically endangered small cetacean found only in the upper Gulf of California, where fisheries bycatch remains an acute threat. Cost, shallow heavily fished areas, and the vaquitas extreme avoidance of noisy motorized vessels argue against using large vessels typically used for visual line transect surveys. Towed hydrophone surveys, using RainbowClick semi-automatic detection software, were carried out from a 24' sailing trimaran in autumn 2008. Ultrasonic (∼130 kHz) vaquita echolocation clicks were reliably detected and tracked using classification parameters developed for harbor porpoise. Transects were sailed on 49% of days and 31 groups were detected within the vaquitas known range and in areas not easily surveyed using traditional methods. Although very high levels of ambient noise presented challenges for acoustic monitoring, perpendicular distances were calculated to 30 groups giving an estimated strip half-width of 198 m. The detection algorithm has since been implemented in PAMGUARD software and significantly improved using survey data. Shallow, heavily fished areas remain difficult for estimating and monitoring trends in abundance. Towed arrays proved effective for the former and may remain the only alternative for the latter. Precision is likely to remain low for the quick detection of small rates of increase.
Acoustic risk factors and passive acoustic monitoring of endangered southern resident killer whales (Orcinus orca)
Authors: Holt Marla M. , Emmons Candice K. , Hanson M. Bradley , Noren Dawn P.
Published: October 2011

Southern resident killer whales (SRKWs) occur along the coastal and inland waters of the northeast Pacific Ocean. They are currently listed as endangered in both the U.S. and Canada. Risk factors that are potentially affecting population recovery include prey availability and quality and acoustic disturbance. This is because SRKWs specialize on Chinook salmon, of which many stocks are depleted, and there is a well developed whale-watching industry that focuses on viewing SRKWs in their core summer habitat. This review paper will highlight acoustic research conducted to address risk factors, recovery goals, and other conservation considerations of this endangered population. These include investigations on acoustic and behavioral responses to anthropogenic sounds. A previous study demonstrated amplitude compensation as vessel noise increased and an ongoing study is investigating potential acoustic effects on behavior, including foraging, using suction cup attached digital acoustic recorders (DTAGs). This paper will also discuss passive acoustic monitoring efforts involving coastal ship surveys and acoustic recorder deployments which aim to better characterize critical habitat, particularly in areas and during seasons when SRKW occurrence is less well defined. All of these investigations are designed to provide critical data necessary to address and refine recovery goals and management actions for SRKWs.
Acoustic radiation force for rapid detection of particles in biological liquids
Authors: Ostrovsky Lev , Priev Aba , Barenholz Yechezkel
Published: October 2011

As known, ultrasonic standing waves can be used to concentrate particles and biological cells into separated bands. Acoustical separation based on plane standing waves is limited to particles of few microns and larger. This presentation concerns using acoustic radiation force (ARF) produced by cylindrical standing waves for detection of high-density submicron-size particles (bacterial cells) in pressure nodes and low-density particles (fat globules) in antinodes. Theoretical calculations show that in a cylindrical ultrasonic chamber, ARF near the central node can exceed the force at the chamber periphery by about 20 times. In a cylindrical standing wave, ARF may induce movement of bacteria with a speed of the order of a few millimeter per second at a frequency of 2 MHz and pressure amplitude of 100 kPa, whereas the speed of bacteria in plane standing wave does not exceed 0.2 mm/s under the same conditions. The cylindrical standing wave system performance was tested for the E. coli bacteria in water and for a multi-component system containing fat globules and somatic cells in milk. Dilute suspensions of bacteria or fat globules were concentrated by at least 2 orders of magnitude.
Parameterization of the scattering and radiation forces and torques on spheres in terms of complex partial wave s-functions: Applications and interpretation
Authors: Marston Philip L. , Zhang Likun
Published: October 2011

A wide range of physical responses of spheres in acoustic beams, including radiation forces and torques, are closely related to properties of the far field acoustic scattering. See for example the short reviews in [Marston, J. Acoust. Soc. Am. 125, 3539–3547 (2009)] for radiation forces and [Zhang and Marston, J. Acoust. Soc. Am. 129, 1679–1680 (2011)] for torques. When evaluating these properties it can be advantageous to retain the notation of resonant scattering theory from prior work for plane-wave illumination. That notation involves the complex partial wave, s-function such that the nth partial wave, the amplitude, is proportional to (s-1) and s is unimodular in the absence of absorption. Some applications of this parameterization to the interpretation and understanding of the scattering by, and radiation forces and torques on, spheres in acoustic beams will be examined. These include examples of forces and torques associated with helicoidal beams and simple methods for modulating the torque. This formulation of the scattering should be helpful for cross-disciplinary applications. Some potentially confusing points from the literature on acoustic plane-wave scattering from the 1970s and early 1980s will be clarified. [Work supported by ONR and by NASA.]
Modeling of shear waves generated in a soft solid by a piston
Authors: Spratt Kyle S. , Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: October 2011

This work is motivated by the transient elastography experiments described by Catheline etal. [J. Am. Stat. Assoc. 105, 2941–2950 (1999)], the purpose of which was to measure the phase speed of shear waves propagating through tissue phantoms. In that work, a small circular piston was used to generate the shear waves, the motion of which was perpendicular to the bounding surface of the sample. The current work is a theoretical investigation of this type of source condition based on the assumption of a linear elastic medium and using an angular spectrum approach to solve for the entire elastic field, both compressional and shear waves, that results from a given velocity distribution at the source plane. Special attention is paid to the velocity field near the source, in particular how the near incompressibility of the tissue-like medium is conducive to the generation of shear waves from such a compressive piston source. For high-frequency excitation, in which the resulting shear wave disturbances are beam-like, the validity of using a parabolic approximation to describe diffraction of the transverse motion of the field in the paraxial region is investigated. [Work supported by the ARL:UT McKinney Fellowship in Acoustics.]
Ultrasonic sensing using thermal mechanical noise of capacitive micro-machined transducers
Authors: Lani Shane , Satir Sarp , Gurum Gokce , Sabra Karim G. , Degertekin F. Levent
Published: October 2011

Monolithic integration of CMUTs and CMOS electronics minimizes interconnect parasitics which allows recording the actual thermal–mechanical component of the ultrasonic noise field. Consequently, an estimate of the pulse-echo response (or Greens function) between two CMUT sensors can be obtained from the cross-correlation of thermal–mechanical noise recorded by these two sensors, as shown by Weaver and Lobkiss [JASA, 113(5), 2611-21]. This provides a foundation for passive ultrasound imaging using only the thermal–mechanical noise field, without active transmitter elements. We designed and fabricated monolithic a 32 element CMUT-on-CMOS ring array (d = 725 μm) for intravascular imaging with low noise transimpedance amplifiers (TIAs) implemented in 0.35 μm CMOS technology. The bias voltage was set near the collapse value of the CMUT membrane to maximize receiver sensitivity. Demonstration experiments were conducted by immersing the CMUT array in a water bath to sense/image the water–air interface and compact targets from noise signals in the frequency band 14–25 MHz. These experimental results were consistent with the sensor and target locations and were validated using conventional pulse-echo measurements. This totally passive ultrasonic technique could improve ultrasound imaging of near-field targets in the deadzone created by active transmitters biasing the receivers and may lead to imaging using evanescent waves.
Magnetostrictive micro-loudspeaker
Authors: Albach Thorsten S. , Lerch Reinhard
Published: October 2011

A magnetostrictive MEMS-actuator which performs as a loudspeaker is presented. The design of the device, its theoretical modeling, as well as measurements showing its acoustical performance are outlined. Instead of a closed membrane, two combs of monomorph bending cantilevers are fabricated face to face on a silicon substrate. The small air gaps between the cantilevers lead to an advantageous reduction of the mechanical stiffness. Each cantilever consists of one active (magnetostrictive) layer and further passive layers. The cantilevers deflect simultaneously when a magnetic field is applied. An additional magnetic dc field linearizes the working point. An electro-acoustic lumped element model is developed to calculate the sound pressure level (SPL) generated in a 2 cm3 ear volume coupler. This model incorporates finite element simulations analyzing the mechanical behavior of the cantilevers. Measurement results validate the model. The effect of the variation of different design parameters on the frequency characteristics is demonstrated. The desired characteristics of a closed membrane for example can be achieved, if the air gaps between the cantilevers are smaller than 3 μm. The prototype micro-loudspeakers have active areas of up to 3.0mm×2.5 mm with air gaps of 10 μm and generate a SPL up to 101 dB at 400 Hz.
Foreign accent production and perception: An acoustic analysis of non-native Japanese
Authors: Gubbins Lucy , Idemaru Kaori
Published: October 2011

What are the characteristics of non-native speech and what contributes to the perception of foreign accent by native speakers? In this study, two experiments are conducted to characterize the acoustic features of non-native Japanese production and to examine how these non-native features influence native Japanese perception of foreign accent. In the production experiment, stop consonants and vowel formants were compared between native Japanese speakers and English speakers with 2 and 4 yr of Japanese instruction. The second experiment examines native listener judgments of foreign accent using a visual analog scale. Preliminary analysis reveals that in both stop consonant and vowel production, learners vary considerably from native speakers, specifically in the production of /k/ and /t/ voice onset time, F1 of /e/, and F2 of /u/ and /i/. These features are correlated with judgment ratings by native Japanese listeners. The findings reveal that even after significant experience in the L2 classroom, speakers still struggle to achieve native-like production of various segments, offering insight into specific problem areas which native English speakers might encounter when learning Japanese pronunciation.
Acoustic correlates of stress in Spanish infant-directed speech
Authors: Jacobson Stephanie , Ward Nancy , Sundara Megha
Published: October 2011

In infant speech research, children's input in often examined to determine at what age their production is affected by their language experience. In this study, we examined production of stress in Spanish infant-directed speech. Although the correlates of stress in English infant-directed speech have been examined, the same has not been done for Spanish. We analyzed infant-directed speech from eight native Spanish-speaking adults from Central and South America. The infant-directed speech was acquired by recording half-hour sessions of adults interacting in Spanish with 12-month-old infants. The acoustic measures examined to determine stress were: pitch, duration, and intensity. These measures were selected because they have been shown to be the most consistent correlates of stress in Spanish and English adult-directed speech. These measures were taken over a group of six target words: mama, globo, leche, zapato, mira, and agua. These target words allowed us to examine each of the vowels (/a/, /e/, and /o/) in both stressed and unstressed position, as well as in varying word positions. With these data we hope to discover how stress is instantiated in Spanish infant-directed speech in order to provide a baseline for future investigations of babbling by Spanish-learning infants.
Vibrational assessment of ice hockey goalie sticks
Authors: Hunt Linda J. , Russell Daniel A.
Published: October 2011

While the vast majority of offensive and defensive ice hockey players prefer composite sticks over wood, a majority of goalies prefer wood sticks over composite. To investigate this goalie preference, experimental modal analysis was performed for one wood and two composite goalie sticks in order to extract mode shapes, frequencies, and damping coefficients. Wood and composite sticks were both shown to exhibit modes with antinodes close to the hand location, and frequencies within the range of maximum sensitivity. The sequence of mode shapes was consistent for wood and composite sticks. The wood stick had lower mode frequencies and higher damping coefficients than the composite sticks. Additional testing was performed on a composite goalie stick with and without the addition of tape at the knob end (required by the NHL). This mass loading lowered the frequencies and increased the damping coefficients and moved the nodes of vibration. These differences in mode shapes, frequencies, and damping along with the effects of tape will be discussed in terms of the influence on the perception of feel for goalies preferring wood sticks.
Acoustical effect of progressive undercutting of percussive aluminum bars
Authors: Laukkanen Eric M. , Worland Randy
Published: October 2011

Standard vibraphone bars consist of aluminum beams which are traditionally tuned with an arched undercut, for the purpose of aligning the musical overtones harmonically. The acoustical effect of various progressions of undercuts on aluminum bars was studied using both an aluminum bar and a finite element computer model. The spectral signature of the aluminum bar was examined with a spectrum analyzer, and the corresponding eigenmodes were imaged with an electronic speckle pattern interferometer. These methods were used to analyze the changes in natural frequencies of the bar as matter was removed from various locations. Additionally, the aural character of each cut was captured with an audio recording, and the fundamental tone was normalized over all recordings to make possible a subjective comparison of the timbral differences of differently cut bars.
Experimental investigation of shock structure in turbulent Coanda jets
Authors: Shafer Richard J. , Lubert Caroline P.
Published: October 2011

Although Coanda surfaces are extremely useful for applications in industrial exhaust, the generation of noise in supersonic flows around such surfaces is not well understood. In order to effectively engineer a solution to this noise problem, the noise generation must be able to be accurately modeled. The two dominating generators of sound are turbulent mixing noise and shock associated noise (SAN). The first step necessary to model SAN is a precise predictor of the shock structure within the jet. A MATLAB algorithm is developed to translate Schlieren photos of the flow into qualitative shock location data. This data will be used in conjunction with the method of characteristics to create a model which predicts shock location around a Coanda surface for several slot widths and exit pressures.
Effects of auditory feedback on instrumentalists timber production
Authors: Huberth Madeline R. , McKay Timothy A.
Published: October 2011

Previous work has shown that the presence or absence of auditory feedback in musicians has little effect on the performance factors such as note accuracy, timing, and dynamics. This study explored the extent to which an instrumentalist's timber is affected by various feedback conditions. Nine cellists were recorded playing excerpts from the orchestral literature with their hearing completely unimpeded, masked by pink noise, and masked by orchestral recordings of the excerpts requested for the experiment, simulating orchestral playing. Changes in relative harmonic strengths across the three conditions were focused on in analysis. Overall, the results show that the auditory feedback condition has minimal effect on timber production.
The influence of talker and accent variability on spoken word identification and discrimination
Authors: Villines Kierra , Bent Tessa , Holt Rachael F.
Published: October 2011

In spoken word identification and memory tasks, stimulus variability from numerous sources impairs performance. The phonetic-relevance hypothesis (Sommers etal., 2006) proposes that only acoustic properties that influence phonetic perception (e.g., speaking rate) cause decrements in perception. In the current study, the influence of foreign-accent variability on identification and discrimination of spoken words was evaluated. In experiment 1, word identification in noise was tested in single-talker and two multiple-talker conditions: multiple talkers with the same accent or multiple talkers with different accents. In experiment 2, participants discriminated minimal pairs from a single talker, different talkers with the same accent, and talkers with different accents. Identification and discrimination performance was the highest in the single-talker conditions, but there was no difference between the single-accent and multiple-accent conditions. However, reaction time in the discrimination task was the highest in the multiple accent condition with no difference between the single-talker and single-accent conditions. Thus, the presence of multiple accents does not decrease accuracy beyond the multiple-talker effect, but processing time increases with the addition of multiple accents. These results provide partial support for the phonetic-relevance hypothesis. [Work supported by NIDCD R21DC010027 and Indiana University.]
Synthesis of bowing controls applied to violin sound generation
Authors: Maestre Esteban
Published: October 2011

Within instrumental sound synthesis, one of the most challenging aspects of automatic performance resides on the ability to faithfully reproduce the expressive nuances naturally conveyed by a musician when controlling a musical instrument. To that regard, much research effort has been devoted in the seek for obtaining natural-sounding synthetic performances from an annotated input score. Despite continuous improvements on sound synthesis techniques, appropriately mapping score annotations to synthesize controls still remains an interesting research problem, especially for excitation-continuous musical instruments. Along these lines, it is presented here our recent work on modeling bowing control in violin performance and its application to sound synthesis. Nearly, non-intrusive sensing techniques allow for accurate acquisition of relevant timber-related bowing control parameter signals. The temporal contours of bow velocity, bow pressing force, and bow-bridge distance are modeled as sequences of short Bzier cubic curve segments. A database of parametric representations of real performance data is used to construct a generative model able to synthesize bowing controls from an annotated score. Synthetic bowing controls are used to generate realistic performances using a digital waveguide physical model, and a spectral-domain sample-based synthesizer. Obtained results demonstrate the potential of explicitly modeling instrumental control for expressive sound synthesis.
Detection of turbulence aloft by infrasonic wind noise measurements on the ground
Authors: Cain Jericho , Raspet Richard
Published: October 2011

Wind turbines can be damaged by the inflow of high amplitude wind turbulence. The goal of this project is to determine if potentially damaging turbulent structures at hub height can be detected by infrasonic wind noise measurements at the ground. A large eddy simulation is used to model the atmospheric turbulence structures of interest and the resulting pressure fluctuations on the ground. Preliminary studies of the relationship between the time development of the pressure structures on the ground and the velocity fluctuations in the atmosphere will be described. If elevated turbulent structures can be detected on the ground, the predictions will be used to design an optimized pressure sensing array for experimental tests.
When do which sounds tell you who says what? A phonetic investigation of the familiar talker advantage in word recognition
Authors: Winters Stephen J.
Published: October 2011

This study investigated whether voice quality, which is a highly salient cue to talker identity, facilitates the process of word recognition for familiar talkers. Two groups of listeners were trained to identify the same set of talkers. One group of listeners heard these talkers speaking in a variety of voice qualities (modal, creaky, and breathy), while another group of listeners heard each talker speaking in only one voice quality. Both groups of listeners were then tested on their ability to identify words spoken by these familiar talkers—in a variety of voice qualities—and also words spoken by a group of unfamiliar talkers. Results showed that voice quality had a significant effect on word recognition scores. Both groups also exhibited better word recognition scores for familiar talkers. However, the familiar talker advantage in word recognition did not depend on voice quality; the familiar voice qualities of familiar talkers did not produce better word recognition scores than the unfamiliar voice qualities of familiar talkers. These combined results suggest that any integration of linguistic and indexical information in word recognition emerges from a subset of the phonetic features of the speech signal and is not, therefore, a strictly general property of speech perception.
Perception of speaker sex in children's voices
Authors: Assmann Peter F. , Nearey Terrance M.
Published: October 2011

To determine how accurately adult listeners can identify speaker sex in children's voices, we presented vowels in /hVd/ syllables produced in isolation and in a brief carrier sentence by five boys and five girls from each of four age groups (5–8, 9–12, 13–16, and 17–18 yr). Speaker sex identification improved with increasing age of the speaker, but even in the youngest group performance was significantly above chance. Strong biases were noted, with older boys more accurately classified than older girls, while the reverse pattern was found at younger ages. Listeners sometimes reported difficulty distinguishing the older girls from younger pre-adolescent boys. Recognition of speaker sex from isolated syllables was more accurate and listeners were more confident of their responses when informed of the age of the speaker. Performance was also higher when syllables were embedded in a carrier phrase, and in this condition the advantage provided by knowledge of the speaker's age was reduced. The results indicate that the perception of speaker sex can be informed by knowledge of the speaker's age, and that sentence context provides additional cues to speaker sex in children's speech.
The role of linguistic and indexical information in improved recognition of dysarthric speech
Authors: Borrie S. A. , McAuliffe M. J. , Liss J. M. , O.Beirne G. A. , Anderson T.
Published: October 2011

This investigation examined perceptual learning of dysarthric speech. Forty listeners were randomly assigned to one of two identification training tasks, aimed at highlighting either the linguistic (word identification task) or indexical (speaker identification task) properties of the neurologically degraded signal. Immediately following familiarization, all listeners completed an identical phrase transcription task. Analysis of post-training listener transcripts revealed remarkably similar intelligibility improvements for listeners trained to attend either the linguistic or the indexical properties of the signal. Perceptual learning effects were also evaluated with regard to underlying error patterns indicative of segmental and suprasegmental processing. Comparisons revealed no significant difference at either level of perceptual processing for the two training groups. The findings of this study suggest that elements within both the linguistic and indexical properties of the dysarthric signal are learnable and interact to promote improved processing of this type and severity of speech degradation. Furthermore, error pattern analysis indicates that similar cognitive–perceptual mechanisms may underlie the processing of indexical and linguistic information. Thus, the current study extends support for the development of a model of perceptual processing in which the learning of indexical properties is encoded and retained alongside linguistic properties of the signal.