bluuebunny/crossref_metadata_2025 huggingface dataset:
Attenuation of shear and compressional waves in surficial sediments.
Authors: Richardson Michael
Published: October 2013

Recent in situ measurements of shear and compressional wave attenuation in sediments provide an appropriate data set to develop empirical relationships among seafloor acoustic and physical properties. Compressional wave attenuation increases with increasing mean grain size and bulk density and with decreasing porosity, whereas the relationships among shear wave attenuation and these physical properties display the opposite trends. The ratio of shear to compressional attenuation ranges from 25 to 60, with the highest values occurring in fine-grained, high-porosity sediments. Empirical relationships defined by regressions of compressional and shear wave speeds on sediment physical properties have high confidence levels. However, confidence levels for the prediction of attenuation are poor due to a combination of measurement technique, spatial variability, and presence of strong near-surface gradients.
Hearing impairment and speech communication handicap: Deconstructing the Tower of Babel.
Authors: Soli Sigfrid
Published: October 2013

This presentation brings together a body of international research focused on a common problem, the effects of noise on speech communication in normally hearing and hearing impaired individuals. My research on the problem is infuenced by Jim's emphases on interdisciplinary research, measurement, and importance of a good practical problem. The challenges of objectively measuring speech communication handicap are well known and longstanding. The subject research embodies an approach to this problem based on a set of principles that provides a quantitative methodology for equivalent assessment of speech communication handicap in any language. Our approach is based on the earlier work of Stevens and Plomp, as well as Plomp’s model of speech communication handicap, which expresses handicap quantitatively as the elevation of the speech reception threshold (SRT) in quiet and/or noise over that of a normally hearing individual (normals). The performance of normals provides a normative reference that is functionally equivalent across languages. Elevation of the SRT above the norm for a language defines a quantitative measure of handicap with the same meaning for each language. Our research has led to the creation of SRT-based measures of handicap in 16 languages. Examples of these measures and their use in clinical outcomes research, device development, and occupational health will be given.
Adventures of a J. J. Jenkins student in speech technology research.
Authors: Syrdal Ann
Published: October 2013

Two of the most valuable lessons I learned from Jenkins were (1) to focus on what interests me and explore why it interests me and (2) that an experiment with unexpected results can be more valuable than one that confirms the hypothesis. My graduate student years in Minnesota at the Center for Research in Human Learning, which Jenkins directed, were an exciting and revolutionary time, both on a large societal scale and academically. Experimental psychology at Minnesota had been a bastion of behaviorism and learning theory. Jenkins was our fearless leader in advancing the revolutionary ideas and emerging paradigms of cognitive psychology and psycholinguistics. In this new field, it was now possible to be scientifically rigorous and to study mental as well as behavioral phenomena. Jenkins and co-workers who played a role in my education at Minnesota have influenced both my earlier academic research and my research in speech technology over the past 22 years. After a brief overview of how I as an experimental/cognitive/perceptual/psycholinguist contributed to several speech technology projects, my talk will focus on unit selection text-to-speech synthesis and how studying and modeling the perception of speech is central to the technology.
Speech perception within a biologically realistic information-theoretic framework.
Authors: Kluender Keith R.
Published: October 2013

Fundamental principles that govern all perception, from hair cell to cortex, are shaping our understanding of the perception of speech and other familiar sounds. Following modest presentation of historical and philosophical background, I will explain how ecological and sensorineural considerations encourage an information theoretical approach to speech perception. Information theory and biology of sensorineural systems are emphasized in explanations of classic characteristics of speech perception, including perceptual resilience in the face of degradation, signal variability, segmentation, and categorical perception. Experimental findings will be used to illustrate how a series of like processes operate on the acoustic signal with increasing levels of sophistication on the way from wave forms to words. Common to these processes are ways that perceptual systems absorb predictable characteristics of the soundscape, from temporally local to extended periods (learning), and new information (change) is enhanced. [Work supported by NIDCD.]
Coded signals: A challenge for acoustic wind profiling.
Authors: von H|$$̈unerbein Sabine , Bradley Stuart
Published: October 2013

Use of coded signals for acoustic wind profiling presents special challenges because the scattering mechanism is highly bandwidth-sensitive. We outline the physical principles involved and show that the signal coding methods commonly used for underwater acoustics or for transmission in the atmosphere (such as for tomography) do not apply for scattering of sound by turbulence. The degree of detuning and loss of signal strength is examined for FM chirps, in relation to the corresponding increase in signal-to-noise ratio (SNR) from matched filters. The optimum bandwidth does not give a large improvement in SNR for this physical situation. The alternative, and very conventional, use of stepped frequency chirps is examined in comparison. This too requires special consideration as to the length of each constant-frequency part. Finally, we give some insight into future developments using a combination of these approaches.
939 Cafe at Berklee College of Music: From an old office to a performing space.
Authors: Pieleanu Ioana
Published: October 2013

Long due for the world renowned jazz and contemporary music school, and open in October 2007, the 939 Cafe is the first club-type performing space at Berklee College of Music in Boston. Given the urban location of the college and the shortage of available real estate in the area, the Cafe is a retrofit of an old architect's office space. Among the Cafe’s neighbors in the building there is the Bostons Tennis and Racket Club, a building tenant since 1902, and an independent restaurant/bar. All aspects of the acoustical design, including the room acoustics, sound isolation, and mechanical system noise control, presented challenges in this limited volume historical setting. This presentation discusses these challenges, limitations, and the proposed acoustical solutions.
Acoustic challenges of converting a historical hall to multipurpose use.
Authors: Bontomase Anthony , Bleedorn Kristin
Published: October 2013

The Great Hall of the historical Cunard Building in New York City was originally used for the Cunard passenger ship lines ticketing beginning in 1921 and later converted to a US Post Office branch. After years of vacancy, a hospitality company proposed to take advantage of the attractive Renaissance Revival inspired hall for events ranging from speeches to weddings and concerts. The Great Hall features a huge vaulted ceiling and is surrounded by occupied office spaces, with original windows between. The acoustic goals were to reduce sound transmission into offices and to tame the reverberation time to accommodate various programs. Several acoustic tests were performed to establish the reverberation time and the noise isolation class between the hall and offices. Further testing with windows covered overyielded the achievable noise isolation without modification of walls within office spaces. Only nonpermanent interior acoustic treatments were permitted as preserving the visual appeal of the interior is critical. Insulating glass additions on the interior of offices is expected to provide a noise isolation class above 50. The use of carpet and suspended drapery is expected to reduce the reverberation time to be more manageable for a variety of programs.
Predictions of sound energy flows in coupled spaces using a diffusion equation model.
Authors: Jing Yun , Xiang Ning
Published: October 2013

In this work, a diffusion equation model [J. Xiang, J. Acoust. Soc. Am., 123, 145–153 (2008)] is applied to two coupled spaces to study the time-dependent sound energy flows through the coupling area (aperture). The energy feedback is found when the primary room is less reverberant than the secondary room. The Bayesian framework is applied to quantify double-slope characteristics of sound-energy flow decays obtained from the diffusion equation numerical simulations. This work also reveals that the turning point on a double-sloped energy decay is highly correlated to the time instant when the energy flow direction flips over.
Backscatter measurements of three species of salmon using simulated killer whale echolocation signals.
Authors: Au Whitlow W. L. , Horne John K. , Jones Christopher D.
Published: October 2013

The resident ecotype of killer whales (Orcinus orca) in the waters of British Columbia and Washington State has a strong preference for Chinook salmon even in months when Chinook are 5%–10% of the salmon population. The foraging behavior of killer whales suggests that they rely on echolocation to detect and recognize their prey. In order to determine possible cues in echoes from salmon, a series of backscatter measurements was made at the Applied Physics Laboratory, University of Washington Facility on Lake Union, on three different salmon species using simulated killer whale echolocation signals. The fish were tied to a monofilament net and rotated while echoes were collected, digitized, and stored on a laptop computer. Three transducer depths were used; same depth, 22o, and 45o above the horizontal plane of the fish. Echoes were collected from five Chinook, three Coho, and one Sockeye salmon. Radiograph images of all the specimens were also obtained to examine the swim bladder shape and orientation. Results show that the echo structure from similar sized but different species of salmon were different and probably recognizable by foraging killer whales. The results also suggest that a broadband echo-sounder pointing downward could be used to discriminate salmon species.
Perception of echoes with FM1-FM2 delay disparities: Bats have selective direction-of-gaze high-resolution imaging.
Authors: Simmons James A. , Bates Mary E. , Stamper Sarah A. , Benedicto Douglas
Published: October 2013

Echolocating big brown bats (Eptesicus fuscus) emit frequency-modulated (FM) biosonar sounds containing two prominent downsweeping harmonics, FM1 from 55 to 23 kHz and FM2 from 100 to 45 kHz. Acoustics of echoes in air ordinarily keep FM1 and FM2 aligned in time; however, if FM1 and FM2 are segregated artificially with low-pass and hig-hpass filters and delivered to bats at different delays, accuracy of delay perception is disrupted. As a direct confirmation of delay-resolution results from echo jitter experiments, harmonic delay offsets of 1–2 us are sufficient for the bat to reject echoes from accurate delay determination. Echoes ordinarily do arrive with differentially greater attenuation of FM2 relative to FM1 for longer ranges (FM2/FM1 is −3 dB for a range of 2 m) and for off-axis targets (FM2/FM1 added −3 dB for angles of 15 deg at a 2-m range). The resulting greater neuronal amplitude-latency trading for FM2 relative to FM1 activates the harmonic delay-offset effect to prevent accurate determination of delay. Noncoherence of harmonics in auditory neuronal spectrograms shunts information about the off-axis and far away targets to a different display of range and crossrange than for targets located in the direction of gaze. [Work supported by the ONR and the NIMH.]
Underwater sound measurements of the Hawaii super ferry and the potential impact to humpback whales in the main Hawaiian Islands.
Authors: Stimpert Alison K. , Rudd Alexis , Au Whitlow W. L.
Published: October 2013

Underwater measurements of the Hawaii Super Ferry were made with a vertical array of four hydrophones. The depths of the hydrophones were 3, 6.5, 10, and 20 m. The Alakai is a 107 m catamaran passenger and automobile ferry that has a waterjet propulsion system with no exposed propellers. The Alakai made three close proximity passes at speeds of 37, 24, and 12 kn on tracks that allowed for acoustic measurements of sounds radiating from the bow, broadside, and stern aspects. The track of the Alakai was recorded on global positioning system. The measurements were conducted while the ferry proceeded on normal scheduled trips, allowing for three measurements a day. All the sound pressure levels were referenced to 91 m (100 yards), the minimum legal approach distance of boats to humpback whales. Sound intensity increased with speed and was the highest at 37 kn in the broadside aspect (160 dB) and was 14 dB lower for both the bow and stern aspects. The sounds had a broadband noise quality with spectra that had a low frequency peak below 100 Hz and decreased continuously with frequency. The effects of the sounds will be discussed from a humpback whale perspective.
Temporal and geographic patterns in the occurrence and distribution of minke whale (Balaenoptera acutorostrata) boings in the central and western North Pacific.
Authors: Oswald Julie , Norris Tom , Au Whitlow , Duennebier Fred
Published: October 2013

Minke whales are elusive and difficult to study using visual methods. The source of the “boing” sound was recently linked to North Pacific minke whales, allowing passive acoustics to be used to study this species. The seasonal occurrence of minke whales was examined using data collected at the Station ALOHA Cabled Observatory, an ocean bottom hydrophone 100 km north of Oahu. Preliminary analysis of data collected between February and June 2007 indicates that boings occur during all of these months, peaking in early April. No diurnal variation was evident. Towed hydrophone-array surveys were conducted in the offshore waters of the islands of Oahu, Kauai and Ni’ihau (February 2005) and off Guam and the Northern Mariana Islands (January–April 2007). Although rarely observed visually, the prevalence of boings detected in these areas indicates that minke whales are common. Distribution patterns from both studies suggest that minke whales prefer deep but not the deepest waters. Boings recorded from Guam and the Northern Mariana Islands appear to be more similar to the “central” boing (which includes the Hawaiian Islands) than the “eastern” boing [which includes those recorded east of 138°W, Rankin and Barlow (2005)]. This has important implications for North Pacific minke whale stock structure.
The presence of low-frequency narrowband phonations in the wild bottlenose dolphins’ acoustic repertoire.
Authors: Lace Natalija , Kuczaj Stan
Published: October 2013

Bottlenose dolphins’ phonations are commonly divided into three major categories: whistles, echolocation clicks, and burst pulses. Other categories are often mentioned and described as yelps, squawks, barks, and low-frequency narrowband sounds. Here, we report the occurrence of low-frequency tonal phonations with fundamental frequency within the 500–2000 Hz range, accompanied by numerous harmonics. Recordings were made using 48 and 192 kHz sampling rates and a 100 Hz high-pass filter in the presence of free-ranging bottlenose dolphins in Mississippi Sound, MS. Auditory sensitivity of the bottlenose dolphins has been studied extensively, and the results indicate that dolphins have their best hearing sensitivity in the higher-frequency range (15–110 kHz). Low-frequency sounds (above 75 Hz) can be detected as well, and it has been suggested that this detection mechanism may be entirely different from that used for higher frequencies and may even include mechanoreception. The occurrence of low-frequency phonations in wild dolphins indicates that low-frequency detection may play an important role in the animals’ everyday activities.
Spatial distribution of right whale “gunshot” sound displays in the Bay of Fundy, Canada.
Authors: Parks Susan E. , Hotchkin Cara F. , Clark Christopher W.
Published: October 2013

North Atlantic right whales (Eubalaena glacialis) produce a distinctive loud broadband signal referred to as the “gunshot” sound. Current hypotheses for the function of this signal include an agonistic threat signal between males, a male reproductive advertisement signal to female right whales, or a combination of both. This sound has been documented both in a social context in mixed sex surface active groups and by lone individual males in a stereotyped display. An array of five archival bottom mounted acoustic recorders was deployed in the Center of the North Atlantic Right Whale Conservation Area in the Bay of Fundy, Canada in August 2005. The five recorders were spaced 3–7 nm apart, allowing for localization of whales producing gunshot sounds within or near the array. These recordings were used to describe the regional distribution, spacing, movement patterns, and timing of gunshot sound displays produced by right whales over a two week period to investigate the potential function of this sound. Further investigations included both the diel trends in the sound production and evidence for interactions between individuals simultaneously producing these displays.
Coupled two-phase model of a gas microbubble containing suspended light absorbing nonoparticles.
Authors: Sassaroli Elisabetta , O' Neill Brian E. , Li King C.P.
Published: October 2013

A mathematical model of a micrometer size gas bubble containing nanometer size light absorbing nanoparticles is presented. A description of such a system can be obtained in terms of a coupled two-phase model with the solid particles in suspension in the gas phase. It is assumed that the suspension is diluted so that particle-particle interaction can be ignored. Because the heat exchange between the particles and the gas is of main interest in this calculation, it is assumed in first approximation that the gas and the particles have the same velocity and pressure. The pressure is assumed to be a function of time only. In this case, only the equations of continuity and energy for both the particulate phase and the gas phase are needed. The two-phase model is then solved in a linear approximation, and a system of four differential equations with constant coefficients is obtained. The system is diagonalized and the general solution of the coupled system is obtained. The general solution is a combination of exponential decaying oscillatory functions for the temperature of the two phases, the pressure, and the microbubble radial oscillations. It was found that the oscillatory behavior takes place in the megahertz range.
The effect of scatterer size distribution on the backscatter coefficient.
Authors: King Michael , Madsen Ernest L. , Hall Timothy J. , Haak Alexander , Oelze Michael L. , O'Brien William D.
Published: October 2013

The bias and variance of mean scatterer size estimates made from backscatter coefficients might be reduced by incorporating an estimate of scatterer size distribution into the parameter estimation scheme. Current estimation schemes generally assume a single scatterer size representing the volume-weighted mean diameter of a distribution. When the mean interrogation frequency has a ka value near 0.8 for the mean scatterer size, and the size distribution is relatively narrow, the results are unbiased. However, consideration of the distribution of sizes may improve scatterer size estimation, especially at frequencies for which ka > 1. A phantom of 2% (dry weight) agar spheres (with diameters between 90 and 125 μm) in a 3.4% agar background was scanned over a broad frequency range using several transducers, and the backscatter coefficients were estimated from these data. When accounting for the size distribution, the mean square error between the measured and theoretical backscatter coefficients over the frequency range of 3–14 MHz was reduced by at least 50% in the size range of interest. These results suggest that accounting for the size distribution in backscatter models will significantly improve the ability to parametrize the backscatter coefficient. [Work supported by NIH CA111289]
Modeling of the dynamics of a coated microbubble confined in a blood vessel.
Authors: Martynov Sergey , Stride Eleanor , Saffari Nader
Published: October 2013

Coated microbubbles have been extensively investigated as contrast agents for diagnostic ultrasound imaging and more recently for therapeutic applications such as targeted drug delivery. However, theoretical models for microbubble dynamics have previously been developed either for encapsulated bubbles in an infinite volume of fluid or for uncoated bubbles in a confined volume. In the present study, a numerical model is developed to explore the effects of both encapsulation and confinement in a blood vessel upon the microbubble response in the time domain. Both surfactant-coated microbubbles and polymeric microspheres are examined for a range of vessel:bubble diameter ratios and mechanical properties. The model is validated against other theoretical models of oscillating bubbles, and the theory of buckling of a thin spherical shell. It will be shown that even at low acoustic pressures (20 kPa) the radial oscillations of the bubble and the amplitude and spectrum of the radiated pressure field can be significantly modified as a result of confinement and that these effects are sensitive to the viscoelastic properties of the coating and the vessel. The implications for diagnostic and therapeutic applications of microbubbles will be discussed.
Identifying the inertial cavitation threshold in a vessel phantom using focused ultrasound and microbubbles.
Authors: Tung Yao-Sheng , Choi James , Wang Shougang , Feshitan Jameel , Borden Mark , Konofagou Elisa
Published: October 2013

Unveiling the mechanism behind the blood brain barrier using focused ultrasound (FUS) and microbubbles is essential for brain molecular delivery. Here, B-mode imaging and rf signals were acquired to pinpoint the threshold for inertial cavitation during FUS with microbubbles. A cylindrical hole of 800 μm in diameter was generated inside a polyacrylamide gel to simulate a brain arterial vessel. Definity® (Lantheus Medical Imaging, USA) microbubbles with a 1.1–3.3 μm-diameter and (1,2-distearoyl-sn-glycero-3-phosphocholine) (DSPC) shelled microbubbles with a 1–2-μm-diameter were injected prior to sonication (frequency: 1.525 MHz; pulse length: 100 cycles; PRF: 1 kHz; pulse duration: 40 ms). The cavitation response was passively detected using a 7.5-MHz single-element transducer, confocal with the FUS transducer, and a one-dimensional linear array transducer placed perpendicular to the FUS beam. The broadband spectral response of the acquired rf signals and the B-mode images detected the occurrence and location of inertial cavitation, respectively. Findings indicated that the rarefactional pressure threshold was approximately 0.53 MPa for the definity and 0.69 MPa for the DSPC-shelled microbubbles. Further studies will vary the vessel diameter and microbubble size to determine their role in the pressure threshold. [This work was supported by NIH Grant No. R21EY018505 and NSF CAREER 0644713. The authors thank Jennifer Hui for bubble characterization.]
Single transmitter time reversal focusing characterization using cross-correlation method.
Authors: Sinelnikov Yegor , Vedernikov Andrey
Published: October 2013

Acoustic focusing with reverberating acoustic cavities based on the time reversal acoustic principle has been demonstrated in a range of medical applications from three-dimensional imaging to the generation of high pressure therapeutic pulses for the destruction of kidney and gallbladder stones in the human body. We investigate acoustic focusing in a system comprised of a single transmitter and a layered membrane reverberator. The system is capable of achieving focal peak acoustic pressures up to 0.4 MPa with less than 1 mm focal spot and steering range up to 20 mm. Focusing in the frequency range between 0.5 and 4 MHz is investigated. The parametric investigation of various membrane configurations is performed by a conventional time reversal technique with a hydrophone. In addition, we propose the cross-correlation of hydrophone signals as a method of evaluating the system focusing properties without conducting the actual time reversal focusing experiment. The cross-correlation method predicts the focal spot dimensions for the layered reverberator single transmitter system that compares well with experiment and theory. An important implication is the possibility to use inverse filtering to construct signals of the desired waveform with a low spatial peak pressure amplitude that can enhance the cell’s permeability toward macroparticle uptake.
Galfenol material properties and impact on transducer design.
Authors: Scott Ryan S. , Meyer Richard J. , Thompson Stephen C.
Published: October 2013

A simple measurement technique to accurately characterize magnetostrictive materials such as Terfenol-D and Galfenol is required as they become more widely used. A technique was developed that measures the magnetostrictive d33, μ33T, s22H, and Qm constants using a pair of Helmholtz coils, a laser vibrometer, and a sense coil. Unlike previous methods, this technique does not require that the magnetostrictive sample be built into a transducerlike apparatus. A matrix of magnetostrictive material properties as a function of magnetic bias and ac drive amplitude can be created using the developed method. To demonstrate the usefulness of this technique, stress annealed laminated Fe–18.4%Ga rods were tested. Property trends observed for these samples will be reported as well as their impact on transducer performance. [This work was sponsored by the Office of Naval Research (Contract No. N00014-06-1-0530) and by Etrema Products, Inc.]
Estimating the mechanical properties of acrylic plates via acoustic transmission experiments and modeling.
Authors: Chang Natasha A. , Dowling David R.
Published: October 2013

Clear acrylic [polymethylmethacrylate (PMMA)] is commonly used to separate instruments from the test-section flow in water tunnel experiments. Thus, for some hydroacoustic studies, knowledge of the sound transmission properties of acrylic plates may be essential. Unfortunately, the actual mechanical properties of PMMA plates cover a relatively large range (e.g., the elastic modulus can vary from 2 to 5.5 GPa) and these mechanical properties may be frequency dependent. In this presentation, numerical and experimental results for acoustic pulse transmission through submerged flat PMMA plates are compared to identify plate properties and to calibrate an approximate plate transmission model. The experiments were conducted in a fish tank at sound incidence angles of 0–35 deg with a spherical wave source and two receivers. The transmitted sounds were short pulses with a nominal frequency range of 40–200 kHz. Several plate thicknesses, d, were tested for kd values (k is the acoustic wave number in the water) from 0.25 to 16. A sound propagation code was used to calculate the transmission characteristics of the plate. By minimizing the difference between the calculated and measured waveforms, the mechanical properties of the PMMA plates were estimated. [Work sponsored by ONR.]
Two ultrasonic transducer through-wall communication system analysis.
Authors: Scarton Henry A.
Published: October 2013

The use of ultrasound to convey data from one side of a metallic wall to the other side is presented. A communication channel is established by attaching two ultrasonic crystals to either side of the wall. The outside transducer injects a continuous ultrasonic wave into the wall. The inside transducer operates as an energy harvester and signal modulator. The outside transducer also receives the modulated signal reflected back from the wall containing the inside transducer. A sensor on the inside provides analog data (e.g., temperature) that is then digitized. The digitized bits are used to vary the electrical load applied to the electrical terminals of the inside transducer by changing its acoustic impedance in accordance with the data bits. The impedance changes, in turn, modulate the amplitude of the reflected ultrasonic signal. This modulated signal is detected at the outside receiving (as well as transmitting) transducer, where it is then demodulated to recover the data. Additionally, some of the acoustic power received at the inside transducer is harvested to produce the electrical power needed to operate the communication and sensor system on the inside. Digital data communication rates exceeding 50 000 bits/s are achieved.
Measurement uncertainties caused by tapping machines in floor sound insulation tests.
Authors: Buzduga Valentin
Published: October 2013

This paper illustrates how the parameters of the tapping machine may influence the measurement accuracy when testing the impact sound insulation of floors. The analysis connects the specifications for tapping machines given in ISO 140-6 and ASTM E 492-4 standards with the requirements for repeatability and reproducibility of the sound insulation measurements given in ISO 140-2. The paper also discusses calibration and testability aspects for tapping machines and presents the method developed at Scantek for measuring the impact velocity of the hammers. The paper gives modeling equations, preliminary calculations for measurement uncertainties, and experimental results obtained at Scantek on calibrating the Norsonic tapping machine N-211.
Effect of sound amplitude on the acoustic attenuation characteristics of Helmholtz resonators.
Authors: Iqbal Asim , Selamet Ahmet
Published: October 2013

Influence of sound amplitude on the acoustic attenuation performance of a Helmholtz resonator is investigated computationally. Time-dependent and compressible flow field is determined by solving two-dimensional unsteady, turbulent, and compressible Navier–Stokes equations through an implicit and noniterative pressure-implicit-splitting-of-operators algorithm. The solution of full Navier–Stokes equations remedies the constraints in small-amplitude-wave treatments, thereby allowing a proper modeling of nonlinearities due to large amplitudes. Transmission loss of the Helmholtz resonator is then calculated for discrete inlet amplitudes using the pressure obtained from the flow field. Higher amplitudes are shown in this study to reduce the peak transmission loss significantly.
Experimental characterization of a biomimetic differential microphone diaphragm.
Authors: Miles Ronald , Cui Weili , Shetye Mihir
Published: October 2013

The identification of mechanical properties for a microphone diaphragm based on the coupled ears of the fly Ormia ochracea and fabricated out of polycrystalline silicon is described. An acoustic test setup using a laser vibrometer has been developed that facilitates the characterization of the diaphragm on a bare die level. A major problem with using a laser vibrometer for acoustic measurement of microstructures is the close working distance between the sensor head and test device, resulting in measurements corrupted by reflections. Time select windowing procedures are often used to obtain anechoic response estimates from measurements taken in reverberant environments, but are not effective for characterization at lower frequencies or testing of lightly damped structures where the time window length needs to be more than the reverberation time. It is shown that the reflections from the measured response of the biologically inspired diaphragm can be reduced through comparison methods for the calibration of the sound field using a closely placed probe microphone and a commercially available pressure differential microphone. Equivalent mechanical parameters for the diaphragm are estimated with a least squares identification procedure. Characterization results for a diaphragm with two different back volume configurations are compared. [Work supported by NIH.]
Testing microphones in small acoustical enclosures.
Authors: Buzduga Mariana , Buzduga Valentin
Published: October 2013

For both instrument calibration and testing, there is a need for faster and more economical test methods, while keeping the test accuracy within acceptable limits. We analyze the use of a small acoustical enclosure that is not strictly “anechoic” but provides a test environment that can be used to make measurements with a predictably high degree of repeatability for testing the frequency characteristics of the microphones or the influence of their accessories (windscreen and grids). First, the characteristics of the acoustical field in the enclosure are discussed. Then the sensitivity of two test methods to specific influencing parameters is analyzed. The first method is the successive comparison using a reference microphone. The second method is a simultaneous comparison based on the constant divergence of the sound pressure in the field [V. Buzduga and M. Buzduga, “Acoustical test methods based on the constant divergence of the sound pressure level,” Noise Control Eng. J., 51(6), 343–347 (2003)]. The accuracy of the tests and the frequency domain of possible use for each method are discussed.
Synchronization and acoustics in network performance.
Authors: Caceres Juan-Pablo
Published: October 2013

The limitations that transmission delays impose on telecommunications are explored and used to the advantage of music making in network performances. This presentation discusses several strategies and practical applications that the SoundWIRE group at Stanford University has implemented in recent years. Performances with Belfast, New York, and Beijing are showcased. Strategies to synchronize remote musicians show how one performance can generate separate instances of a piece in different locations. The Internet’s acoustic path (i.e., the delay in the sound transmissions) is used as part of musical effects and physical models that are embedded in the network. These processes make the distance “audible” for performers and support (and sometimes extend) musical ideas that otherwise would be impractical. Finally, a project with an application to attest the quality of service (QoS) in an audio connection is presented. Remote clients can “sound-ping” to a server running the JACKTRIP application and get an idea of its quality. Different physical model instruments can be used. The longer the distance, the lower the pitch. With higher variability in the connection, vibrato is heard. This technique enables musicians to tune a link using the most appropriate and simplest tool, their ears.
Creating systems for collaborative network-based digital music performance.
Authors: Van Nort Doug
Published: October 2013

The internet has proven to be an important catalyst in bringing together musicians for remote collaboration and performance. Existing technologies for network audio streaming possess varying degrees of technological transparency with regard to allowable bandwidth, latency, and software interface constraints, among other factors. In another realm of digital audio, the performance of “laptop music” presents a set of challenges with regard to human-computer and interperformer interaction—particularly in the context of improvisation. This paper discusses the limitations as well as newfound freedoms that can arise in the construction of musical performance systems that merge the paradigms of laptop music and network music. Several such systems are presented from personal work created over the past several years that consider the meaning of digital music collaboration, the experience of sound-making in remote physical spaces, and the challenge of improvising across time and space with limited visual feedback. These examples include shared audio processing over high-speed networks, shared control of locally generated sound synthesis, working with artifacts in low-bandwidth audio chat clients, and the use of evolutionary algorithms to guide group improvisations.
Constructing an integrated system for the practice of playing the guitar.
Authors: Ichise Mamoru , Emura Norio , Miura Masanobu , Yanagida Masuzo
Published: October 2013

Constructed here is an integrated system for the practice of playing the guitar for novice guitar players. Novice guitarists for popular music often give up playing it because they cannot keep practicing for the difficulty of realizing finger positions. An algorithm YG for giving optimal chord-form sequence for given chords was proposed [Emura et al., AST, 104–107 (2006)]. Authors construct an integrated system for guitar practicing by implementing YG. The new system deals with thousands of MIDI files combined with names of chords for them. The proposed system shows chord sequences as the TAB score, with corresponding fingerings generated by YG as the chord diagram. By using the system, users are able to play excerpts using not the difficult but simple pattern of chord-form. The system interacts with the user playing the MIDI guitar by showing the performed notes with an accompanying playback for current excerpt. The user is expected to be supported on playing it under a performance evaluation, where errors of fingerings are simultaneously shown with accompanying playback stopping or slowing down. The performance of the system is confirmed as better than the usual style of practicing in terms of occurrence frequency of errors. [Work supported by HRC, Ryukoku University.]
New musical interface for playing the guitar solo.
Authors: Cho Sangjin , Kang Myeongsu , Chong Uipil
Published: October 2013

This paper describes the development of a new musical interface to play guitar solo with the nonstringed guitar. The previous work of authors is the implementation of the nonstringed guitar comprised of laser strings and a chord glove [J. Acoust. Soc. Am. 122, 3055 (2007)]. It is hard to express guitar solo, so voltage dividers are set up on the neck to represent frets. In the case of the chord glove, the same voltage source of the TMS320F2812 is supplied instead of attaching force sensing registers to the fingertip. Consequently, there are three essential components for the proposed interface: voltage dividers, laser strings, and the chord glove. Voltage dividers replace the six strings on the neck and send fret information to DSP, laser strings represent strokes, and the chord glove expresses playing chords and solo. This proposed interface represents many kinds of playing styles. In the case of hammering on, pulling off, and sliding, it needs fret information from voltage divider to express these things. On the other hand, bending that varies the pitch in a fret needs to detect how much flex sensors are bent to play. [Work supported by the Korea Research Foundation Grant funded by the Korean Government(MOEHRD)(KRF-2006-521-H00002)]
Intensity and temperature variance in sonoluminescence.
Authors: Gillett Lyric
Published: October 2013

Sonoluminescence is the process in which light is produced through ultrasonic pressure waves causing the expansion and subsequent collapse of a gas/vapor bubble, held in an ultrasonic standing wave pattern, in water. This study measured sonoluminescent bubble light intensity output utilizing a photomultiplier tube and a lock-in amplifier to determine the relationship of the sonoluminescent intensity to variance in water temperature. The results could be indicative of the optimal temperatures at which to conduct sonoluminescence research, and assist in facilitating and advancing sonoluminescence research ventures relating to further study of energy production and nuclear reactions. Though not part of the experimental design, the initial experimentation suggested a positive correlation between the drive level of the transducer and the light intensity from the sonoluminescent bubble. Further experimentation was conducted in which the transducer drive signal and frequency were continuously optimized as the water temperature rose. After data were graphed and analyzed, it was determined that there was a decrease in sonoluminescent intensity as the water temperature increased. It is believed that this experimentation resulted in a greater plasma density inside the sonoluminescent bubble. To that end, future experimentation, as well as potential military and medical applications, interests this researcher.
Prediction and measurement of particle velocities in ultrasonic standing waves.
Authors: Lipkens Bart , Dionne Jason , Trask Alex , Szczur Brian , Rietman Ed
Published: October 2013

A numerical model has been developed to predict particle trajectories in ultrasonic standing waves. The model includes an electroacoustic model that calculates the characteristics of the one-dimensional standing wave as a function of the input voltage to the piezoelectric transducer driving the cavity. Next, the acoustic radiation force is calculated for particles residing within the water filled cavity. Finally, the particle trajectories are calculated through integration of the equations of motion of the particles. Particle translation is achieved through a periodic sweeping of the excitation frequency. Translational velocities of 6-μm-diameter polystyrene spheres are calculated for a 2-MHz standing wave driven by a PZT-4 transducer. In the experiment a cavity is filled with water and polystyrene particles. A PZT-4 transducer operates near its resonance frequency of 2 MHz. Through a periodic sweeping of the frequency the particles are translated away from the transducer face and ultimately clump together near the rigid reflector at the opposite end. The particle translational velocity is a function of the sweep parameters, i.e., frequency range and sweep period. The calculated particle velocities are then compared to the measured velocities. Needle hydrophone measurements are used to characterize the acoustic standing wave.
Spectral weights and the transition between two auditory processes.
Authors: Berg Bruce
Published: October 2013

Evidence of broad auditory filters for processing temporal information was obtained with a molecular psychophysical technique. The standard in the 2IFC discrimination task consisted of n equal intensity sinusoids, with frequency separations ranging from 10 to 40 Hz. The signal was an intensity increment of the central sinusoid, which on average was 1000 Hz. Pitch cues were degraded by randomly selecting the center frequency over a 100 Hz range on each stimulus presentation. Single channel intensity cues were degraded with a roving-level procedure. As tones were added symmetrically to the ends of the complex, thresholds increased until a certain bandwidth was reached, beyond which thresholds decreased. Previous results showed that transition bandwidths ranged from 100 Hz to more than 1000 Hz across individuals [B. G. Berg, J. Acoust. Soc. Am. 121, 3639–3645 (2007)]. This discontinuity presumably represents a change in the underlying auditory processes, with envelope cues at bandwidths narrower than the breakpoint and across channel level comparisons for wider bandwidths. Findings show that the pattern of spectral weight estimates before the breakpoint is consistent with an envelope processing model, whereas the weights for bandwidths greater than the transition point were consistent with an across-channel comparison. [Work supported by ONR].
Rapid efficient encoding of correlated complex acoustic properties.
Authors: Stilp Christian E. , Rogers Timothy T. , Jacobs Stephanie L. , Kluender Keith
Published: October 2013

Early sensory processing is long thought to extract and exploit redundancy and regularity in the input, but perceptual evidence supporting this hypothesis has been limited. Experiments are reported demonstrating efficient encoding of multiple acoustic attributes resulting in the reduction of perceptual dimensionality. Stimuli varied across two complex independent dimensions: attack/decay (AD) and spectral shape (SS). A subset of 24 stimuli captured a near-perfect correlation between these dimensions (r2= 0.95). Participants passively listened to 25 presentations of these correlated stimuli over 7.5 min before discriminating sound pairs in AXB trials without feedback. For trials where both SS and AD varied, listeners successfully discriminated sounds consistent with the correlation of SS and AD during exposure, but they were at chance discriminating pairs varying orthogonal to the correlation presented in exposure. After exposure, participants were also significantly poorer at detecting differences among stimuli varying in only SS or AD. Thus, passive listening to stimuli with correlated attributes resulted in the collapse of two physically and perceptually distinct stimulus dimensions onto a single dimension that efficiently encoded exposure covariance. Data are consistent with Hebbian models of cortical adaptation but contradict models derived from anti-Hebbian and competitive-learning principles. [Work supported by NIDCD.]
Binaural loudness summation by cochlear implant users.
Authors: Kordus Monika , Tyler Richard S.
Published: October 2013

The loudness summation in people with bilateral and unilateral cochlear implants (CIs) was investigated. The stimuli were 1/3-octave bands of noise centered at frequencies of 0.25, 1, and 4 kHz presented frontally from a loudspeaker in an ascending or random sequence of level. Subjects rated different intensity levels between the threshold of hearing and level of discomfort on scales from 0 to 100. Eight intensity levels were used for normally hearing subjects who served as a control group. For the CI users, results showed difference in loudness between monaural and binaural conditions with substantial amount of binaural loudness summation. The shape of the intensity-loudness function varied between monaural and binaural conditions, depending on the listener. The power function of control group exhibited an exponent of near 0.5. In binaural condition, stimuli of the same sound pressure level were about 1.8 louder than in monaural condition. For 0.25- and 4-kHz bands of noise, no consistent differences between monaural and binaural thresholds were observed. For a 1-kHz band, the binaural loudness ratings were about 3% and 9% lower for mid- or high-intensity levels as compared to the monaural condition. The results suggest future application for fitting bilateral devices. [Work supported by NIH 5 P50 DC00242.]
Temporal structure and syntactic disambiguation across lexical biases.
Authors: Jeon Yoon-Shil , Schafer Amy J. , Anderson Victoria B.
Published: October 2013

The present study investigates prosodic cues across three lexical biases in the production of syntactically ambiguous sentences such as “Walkers and runners with dogs use the outer portion of the park,” in which “with dogs” can modify either the second conjunct alone (low association) or both conjuncts (high association). A phrase-combination task induced speakers to produce high- and low-association tokens for each of 48 test sentences, split across three pretested lexical biases (high bias, equibias, and low-association bias) that were controlled for the number of syllables in the critical region. Results showed a significant lengthening difference between association conditions in the second noun, while the lengthening effect was minor in the first noun. In the high-association condition, the second noun region was significantly longer than the same region in the low-association condition. This is consistent with a stronger prosodic boundary at the end of the second conjunct for high-association productions than for low-association ones. The interaction of lexical bias and association was not statistically significant, suggesting that speakers’ tendency to disambiguate through durational differences was not significantly affected by lexical bias.