bluuebunny/crossref_metadata_2025 huggingface dataset:
Edison phonograph recording and reproduction in a concert hall.
Authors: Case Alex U.
Published: March 2010

A recent recording session at the University of Massachusetts Lowell merged the birth of sound recording with the state of the art. A small ensemble performed an original piece of music—composed in the style of early 1900s American music—on stage in Durgin Concert Hall. It was recorded live to both high-definition digital multitrack and an original Edison wax cylinder phonograph. As the acoustical influence of the phonograph is substantial, several takes were needed to adjust the balance of the live performance to maximize the musical impact of the reproduced sound realized through wax cylinder playback. Multiple sonic viewpoints were simultaneously recorded: stereo, surround sound, close microphones, and Edison phonograph. The resulting recordings are played and discussed.
Soul spaces: How acoustics influence the music production process and the recordings that result.
Authors: Zimmern Matthew B.
Published: March 2010

Spaces in modern recording studios are quite different than those of 40 years ago. While today it is common for recording facilities to have various multi-purpose, acoustically designed spaces, many recordings from the middle of the 20th century were often captured in a single room, one that was not constructed with acoustical principles in mind and often times featured acoustical deficiencies. Soul music production practices of the late 1960s were researched, and an original composition was recorded in two different ways: by using past recording techniques and by using contemporary musical practices. Through listening to audio examples of the same song recorded in two different spaces, the sonic qualities of the different recording environments will be discussed, as well as how the different production techniques affected the recording, musical, and aesthetic attributes of the resulting audio recordings.
A performers guide to venue acoustics.
Authors: Zartman David J
Published: March 2010

Whether in high school or the Vienna Symphony, musicians have little control over their performance venues. An instrument can be upgraded or replaced if there is an undesirable aspect, but replacing a venue is often far too expensive to be a tenable solution. A musician’s perfect venue will also change piece to piece—an incredible venue for lush Wagner operas can cause issues for someone performing an intricate Paganini concerto and vice versa. What then are these effects? Why do they take place? How can a performer anticipate and combat undesirable aspects of venues while drawing out their featured characteristics for an optimized performance?
Vineyard shape variations of the Concertgebouw, Amsterdam.
Authors: Chiang Weihwa , Lin Wei
Published: March 2010

The Concertgebouw, Amsterdam is a unique one of its kind because of the extra width and size for a classical rectangular hall and the significant portion of seats behind the stage. These characteristics make the hall as “semi-surround” as the vineyard halls of the present day. Computer simulation was performed to analyze the possibility of deriving design variations out of the Concertgebouw. Clarity, strength, sectional balance, and stage support of various settings of stage position and overall proportion were compared as the first step. Variations that contain the geometrical features of vineyard shape halls were further developed to optimize the three acoustical qualities and to reduce the differences among seats. The architectural features evaluated included surface treatments, arrangement of individual seating blocks, and the geometry of upper walls and the ceiling.
Simple acoustic source radiation near a large wall.
Authors: Moloney Michael J.
Published: March 2010

An acoustic simple source is predicted to radiate twice as much sound near an infinite rigid wall as it does in free space. As the simple source becomes more distant from the wall, its radiated power is predicted to decrease in an oscillatory way toward the value it has in free space. This behavior can be observed indirectly by fitting a 10-s signal of decaying amplitude from a tuning fork resonator box at various distances from a large unobstructed wall. Each fit determines the damping constant b, which reflects power losses, including radiated acoustic power. In a plot of b versus distance from the wall, the oscillatory part of the damping constant closely matches the theoretical curve of total radiated power from a simple acoustic source near an infinite rigid wall.
Detecting and identifying cetaceans species from their acoustic emissions.
Authors: Au Whitlow , Oswald Julie
Published: March 2010

In the past decade, the use of autonomous remote passive acoustic recorders to detect the presence of cetaceans has grown enormously throughout the world. Since these devices digitize acoustic signals at sampling rates in the tens of kHz, a single device can quickly accumulate many Gbytes of data in a short time. Therefore, automatic detection and recognition algorithms must be developed to handle the large amount of data. There is no general signal method processing method that can be applied to all species of cetacean. The algorithm by the name of ROCCA (real-time odontocete call classification algorithm) developed by Dr. Julie Oswald is probably the most general one that has been applied to the whistles of dolphins. The program, extensible bio acoustics tool (XBAT) developed by Harold Figueroa, is probably the most general tool for use with baleen whales. However, investigators also tend to develop their own algorithms to suit their requirements. The problems and difficulties in developing automatic detection and recognition algorithms will be the focus of this presentation. General principles associated with the geography, biology, and the characteristics of sound emissions in relation to the development of algorithms will be discussed along with examples of different approaches.
Individual identification using hidden Markov models for population monitoring and assessment.
Authors: Johnson Michael T. , Clemins Patrick J.
Published: March 2010

Individually distinct acoustic features are present in a wide range of animal species, just as they are in humans, and the widespread success of speaker identification in humans suggests that robust automatic identification of individual animals from their vocalizations is attainable. Despite this, only a few studies to date have yet attempted to use individual distinctiveness to help assess population structure, abundance, and density patterns. Here we present an approach, based on individual identification and clustering using hidden Markov models (HMMs), which enables a more direct mechanism for using individual vocal variability to monitor and assess populations. Current results indicate that the new method is able to give good estimates of local abundance based on vocalization clustering, which can in turn be used in an acoustic mark-recapture framework to estimate population. Limitations to this approach currently include the need for explicit call-type separation prior to individual clustering, which is possible in many species but can create a problem in species with unknown or variable repertoires. Overall, it is hoped that this new technique may lead to a more accurate understanding of population structure and abundance on a larger scale.
Variation of uncertainty and resolution with problem formulation in continuous geoacoustic inversion.
Authors: Ganse Andrew A. , Odom Robert I.
Published: March 2010

In continuous geoacoustic inversion, the resolution and uncertainty of the estimated ocean bottom are inherently linked by a tradeoff with each other. They also depend on the experiment geometry and the choice of formulation for the data and for the bottom model. For example, the resolution and variance will differ if the data are represented by an intensity envelope timeseries or a tau-p timeseries, or if wave slowness or bottom impedance is estimated. Previous work by the authors investigated variations in resolution and uncertainty with geometry and problem formulation based on linearization of the geoacoustic problem at a given solution. However, the problem is further complicated by the fact that the solution point itself can also depend on the geometry and data and model formulation so that the resolution and uncertainty vary for that reason also. This aspect of the nonlinear geoacoustic inverse problem is explored here. [Work supported by ONR.]
The estimation of geoacoustic parameters via frequencies 25–100 Hz.
Authors: Tolstoy A.
Published: March 2010

This work will discuss recent efforts to extend a previously discussed low-frequency (LF) geoacoustic inversion method to slightly higher frequencies. In particular, the earlier method was “successful” at frequencies 25–50 Hz where an exhaustive search was possible even in the presence of errors in other (assumed known) parameters. However, some of the test data analyzed offered only one appropriate frequency (53 Hz) and did not converge to a unique solution. In fact, thousands of data fits were found. Here, we shall examine efforts to improve convergence by allowing for slightly higher frequencies. Range may also be a consideration at these LFs.
Low-frequency attenuation and sound-speed measurements in marine sediments using an impulsive source.
Authors: Turgut Altan , Schindall Jeff , Means Steven
Published: March 2010

Low-frequency (200–1000-Hz) sediment attenuation and sound-speed measurements were conducted at a site on the New Jersey Shelf where additional data sets from a chirp-sonar bottom profiler (2–12 kHz) and an acoustic-probe system (10–80 kHz) are available. Impulsive sound signals, generated by automated light-bulb implosions, are received by a 16-element vertical line array at short ranges (<500 m). Precursor arrivals and signals reflected from the R-reflector are used to estimate sediment sound-speed and attenuation. Attenuation in dB/m/kHz is estimated using the spectral-ratio technique and sound-speed is estimated from the travel-time analysis. Frequency dependency of sound-speed and attenuation is also investigated within a wide frequency band (200 Hz–80 kHz) using the results from impulsive source, chirp-sonar, and acoustic-probe measurements. Measured attenuation and sound-speed values seem to be well predicted by an extended Biot theory for sediments with distributed pore sizes. [Work supported by ONR.]
An investigation of the combustive sound source.
Authors: McNeese Andrew R. , Sagers Jason D. , Wilson Preston S. , Knobles David P.
Published: March 2010

The combustive sound source (CSS) is a versatile impulsive underwater sound source with an adjustable bandwidth and output amplitude. Unlike typical impulsive acoustic sources, CSS can maintain a wide bandwidth at low amplitude; hence, it is a more environmentally friendly impulsive source for ocean acoustics experiments and surveys. The CSS consists of a submersible combustion chamber, open to the water, which is filled with a combustible fuel/oxidizer mixture. The mixture is ignited and a combustion wave propagates through the mixture. During this process the ensuing bubble expands due to an increase in temperature and can collapse to a smaller volume than before ignition. This bubble activity radiates acoustic pulses. The CSS can be used as a source for low-frequency sediment characterization and TL measurements, and when deployed on the bottom can produce seismic interface waves. In addition to stationary deployments in the water column, CSS can be deployed in a tow body and as an array. Discussion will focus on the latest CSS design including functionality, acoustic output, long-term operational stability, and future development plans.
Detection and classification of sub-surface features based on their seismo-acoustic signatures.
Authors: Lucifredi Irena , Ishii Miaki
Published: March 2010

Complex subsurface structure makes seismo-acoustic imaging difficult, raising the need for novel detection, classification, and imaging approaches. For the representation of range-dependent seismo-acoustic propagation, we employ a hybrid, coupled wavenumber integration approach to range-dependent seismo-acoustic modeling based on the OASES environmental modeling framework. In feature identification and classification, time series analysis frequently provides the sought-after recognition clues. Nevertheless, the geometry and the structure of the subsurface features generate a variety of complexities to the wave field caused by different physical mechanisms, geometric constraints, and intrinsic properties. Based on the time series attributes such as the time of arrival, waveform amplitude, and the frequency content, a set of identification features is extracted and a set of corresponding classes is formed. Using the simulated data scenarios, general rules incorporating the identification features of subsurface structures are deduced. This classification methodology is then applied to the data recorded by an array of seismographs and hydrophones on and off the coast of Japan. The results create a basis for classification and description of the structures of interest such as the presence or absence of very low-velocity range-dependent layers below the water-seabed interface.
Inverting for surface displacement fields using directly measured point-to-point sensitivity kernels.
Authors: Sarkar Jit , Walker Shane , Cornuelle Bruce , Kuperman William A. , Roux Philippe , Marandet Christian
Published: March 2010

The effect of surface perturbations on underwater acoustic fields has been directly measured in an ultrasonic tank experiment. High-frequency transducer arrays of 64 elements each are placed 600 mm apart, submerged in ~50 mm of water. A point perturbation is used to displace the surface sequentially in 1-mm steps between the two arrays. At each position a 3.8-MHz signal is transmitted from the source array (round-robin), and the response recorded on the receive-aray, both with and without the presence of the surface probe. The difference between these two measurements yields the point-to-point acoustic sensitivity to that perturbation. These data are explored with respect to inferring the surface structure through both linear full-wave inversions and double-beamforming.
Photoacoustic delivery of molecules into cells.
Authors: Prausnitz Mark R. , Chakravarty Prerona , Qian Wei , El-Sayed Mostafa A.
Published: March 2010

A major barrier to drug and gene delivery is crossing the cell’s plasma membrane. This study presents a physically based mechanism to deliver molecules into cells with high efficiency and viability using photoacoustic effects generated by carbon nanoparticles. The results demonstrated intracellular delivery using this method in multiple cell types for uptake of small molecules, proteins, and DNA. At optimized conditions, calcein uptake was seen in up to 50% of cells with nearly 100% viability and in 90% of cells with ⩾90% viability. Uptake was not observed when cells were irradiated in the absence of carbon nanoparticles. These studies suggest that uptake occurs due to transient membrane permeabilization resulting from explosive photoacoustic forces generated by laser-induced carbon-steam reaction, C(s) + H2O(l) = CO$(g) + H2(g). This synergistic use of nanotechnology with advanced laser technology could provide an alternative to viral and chemical-based drug and gene delivery.
A pre-treatment planning strategy for high-intensity focused ultrasound treatments.
Authors: Andre Billy , White Phillip Jason , McDannold Nathan , Clement Gregory L.
Published: March 2010

High-intensity focused ultrasound (HIFU) therapy is a non-invasive treatment method for uterine fibroids patients. However, there exists focal distortion, due to inhomogeneous tissues, that can divert therapeutic dosage to non-targeted locations. A missing component of current HIFU protocols is a simulated pre-treatment planning, a procedure that can predict the efficiency of ultrasonic energy delivery pathways based on MRI scans using a simulated propagation model. To conduct this study, a 1.502-MHz transducer transmitted HIFU through five ex vivo bovine tissue specimens in an MR-compatible tank setup. A needle hydrophone (aperture = 0.2 mm) scanned the acoustic pressure field orthogonal to the axis of propagation for three different positions of the tissue specimens (0, 4, and 8 deg, about the rotation mounts). To quantify the level of distortion, the distortion index (DI = 1—ratio between local and total acoustic energy fields) were calculated. The data collected confirmed HIFU distortion due to tissue, where 48% of the focal acoustic intensity was redistributed away from the focal field. Focal distortion decreased on average by 7.2% (ranging from 5.6% to 12.3%, SD = 2.8%) upon optimizing the transducer-specimen orientation the default transducer orientation (0 deg). In addition, the propagation simulation model accurately predicted HIFU distortion from a specimen’s MRI data.
The harmonic motion imaging for focused ultrasound system for tumor detection and treatment: Simulation, in vitro and in vivo results.
Authors: Konofagou Elisa , Maleke Caroline , Hou Yi
Published: March 2010

Harmonic motion imaging (HMI) for focused ultrasound (HMIFU) is a novel, all-ultrasound-based system that can simultaneously detect and localize tumors as well as subsequently generate and monitor their ablation based on their distinct stiffness. In this paper, we present the results of a fundamental simulation study that is then validated using in vitro and in vivo findings. The same HMI and HMIFU parameters as in the experimental studies were used, i.e., the high-intensity focused ultrasound (HIFU) frequency was 4.68 MHz and the modulation frequency equal to 25 Hz. An HIFU-simulator was used to predict the lesion and its resulting time-dependent displacement field. Using the same parameters, in vitro bovine liver experiments were performed to validate the size of the simulated lesions. A transgenic mouse model of invasive adenocarcinoma was used for in vivo feasibility using the same parameters. Good agreement between the simulated lesion maps and pathology findings of the in vitro liver experiments was found. The lesion formation was identified by a 30% decrease in displacement amplitude in vivo. Tumor cell death was also confirmed by histology. Based on these results, the HMIFU system may offer a cost-efficient and reliable alternative for real-time monitoring of thermal ablation.
Local tissue-sparing due to blood flow in medium-size vessels.
Authors: Woodford Simon , Rivens Ian , Vilensky Gregory , Saffari Nader , ter Haar Gail
Published: March 2010

High-intensity focused ultrasound (HIFU) is a noninvasive surgical technique that uses ultrasound energy deposition to thermally destroy selected tissue. However, the cooling effect of blood flow can lead to unwanted tissue-sparing during HIFU treatment, particularly in the tissue immediately adjacent to the vessel wall. Regions where large (clinically detectable) vessels are present will require an increase in intensity or treatment time. However, there is a range of vessel sizes that are thermally relevant yet clinically undetectable. The treatment protocol must be chosen such that the spared region around these vessels is minimized or eliminated completely. Using numerical simulations, we have determined preliminary recommendations for suitable treatment protocols.
Dynamics and flow field produced by coupled oscillation of tandem microbubble.
Authors: Yuan Fang , Sankin Georgy , Lautz Jaclyn , Zhong Pei
Published: March 2010

Coupled oscillations of two adjacent laser-induced microbubbles have been shown to produce unique asymmetric bubble deformation and microjet formation. The resultant microstreaming and shear stress can cause localized cell membrane poration with potential application in targeted drug and gene delivery. In this study, we investigate the bubble dynamics and flow field produced by laser-generated tandem microbubble in a microfluidic device. Flow field around the tandem microbubble is analyzed with respect to phase delay, inter-bubble distance, and size ratio between the two microbubbles. In addition, micropatterning technique is used to control the adhesion site and growth pattern of HeLa cells in relation to the tandem microbubble. Flow vorticity is observed to be a key parameter that correlates with the strength of tandem microbubble oscillation and resultant macromolecule uptake efficiency. [Work supported by NIH Grant Nos. R01DK052985, R21CA135221, and S10RR016802].
Two driving constructions of loudspeakers for low-frequency range by piezoelectric ultrasonic motors.
Authors: Ohga Juro , Adachi Takehiko , Saito Hiroki , Suzuki Ryosuke , Takeda Gen , Kubota Hajime , Negishi Hirokazu , Maeda Kazuaki , Oohira Ikuo
Published: March 2010

The loudspeaker driven by piezoelectric ultrasonic motors is characterized by a precise very-low-frequency reproduction due to its high-driving mechanical impedance. It has a lot of merits comparing to the conventional electrodynamic loudspeakers. One of the reason will be that this loudspeaker is a power flow modulator, not a transducer. In this presentation, two sorts of ultrasonic motors are compared as driver elements of the loudspeakers. One is an ordinary revolution-type motor and the other is a reciprocal linear motion type actuator. The authors constructed and improved practical low-frequency-range loudspeakers by using continuous revolution of ultrasonic motors. Its final model uses combination of two motors with same axis, which drive two cone radiators moving oppositely. This model shows a satisfactorily large output sound pressure and stable reproduction. However, its complicated elements for connection of the motors and the cone radiators cause a mechanical weakness. The authors, therefore, propose another new, completely different construction to avoid this defect. It applies linear motion of two ultrasonic actuators. A moving piece driven by piezoelectric ultrasonic vibrators is connected directly to a cone radiator. Comparison at various viewpoints and practical performance of these two constructions are presented at the meeting.
Modeling thermal mitigation and nonlinear behavior in high-power single crystal 1-3 composite transducers.
Authors: Tubbs Tara L. , Meyer Richard J.
Published: March 2010

The desire for high-precision sonar systems has forced 1-3 composite transducers to the forefront of sonar design. Single crystal, which has improved mechanical and dielectric properties over PZT, provides a variety of advantages, and their implementation into a 1-3 composite design makes them a great candidate for sonar transducers. Driving these transducers at high levels, we can get a broad bandwidth and high-power in a smaller device. However, high power introduces overheating and nonlinear behavior in the material properties. Using finite element software GID/ATILA from ISEN along with COMSOL MULTIPHYSICS, it is possible to incorporate these phenomena and solve thermal mitigation problems. This allows for improved high-power single crystal 1-3 composite transducers.
Use of compressively stressed zinc oxide to increase microspeaker response.
Authors: Baumgartel Lukas , Kim Eun Sok
Published: March 2010

A micromachined piezoelectric speaker was fabricated on a 5 × 5-mm2, 1-μm-thick silicon nitride diaphragm. A 4 × 4-mm2 zinc oxide (ZnO) piezoelectric transducer sits in the middle of the diaphragm, providing actuation. Two variations were fabricated: one with the compressively stressed ZnO covering the region between the transducer and diaphragm perimeter—causing wrinkling—and another with the ZnO removed in this region. In both variations, the stress gradient causes curvature in the active area, raising the resonant frequency to above 4 kHz. The displacement response is therefore approximately flat from 40 Hz to 4 kHz. The speakers are driven with a sinusoidal voltage, and the response is measured with a laser interferometer. The wrinkled device exhibits 11 times larger response and can be actuated by much smaller voltage, achieving lower THD while still having a larger deflection. The wrinkled device is driven at 2 V0.t.p. from 40 Hz to 4 kHz, demonstrating a response of 55 nm/V0.t.p. and an average THD of 5.1%. The unwrinkled device is driven at 15 V0.t.p. over the same range, yielding a response of 5 nm/V0.t.p. and an average THD of 8.6%. Measured sound output and displacement spectra match each other well.
Analysis and design of a MEMS (microelectromechanical system) directional microphone diaphragm with active Q control.
Authors: Miles Ronald N. , Su Quang T. , Cui Weili , Homentcovschi Dorel , Wu N. Eva
Published: March 2010

The analysis and design of a MEMS directional microphone are described that incorporates electronic feedback to achieve active Q control. The microphone diaphragm consists of a 1 × 2-mm stiffened plate fabricated out of polycrystalline silicon that is supported on a central hinge. The sound pressure gradient incident on the diaphragm produces a rocking motion about the central hinge. Interdigitated comb fingers at each end of the diaphragm enable both capacitive sensing and electrostatic actuation. The diaphragm has been designed to have its dominant resonant mode have a frequency of approximately 1 kHz. By minimizing sources of passive damping, the thermal noise of the microphone has been shown to be lower than the noise floor of existing two-microphone systems used in directional hearing aids [Miles et al., J. Acoust. Soc. Am. 125 (2009)]. However, this low-passive damping also results in an undesirable resonance within the audible frequency range. To minimize the adverse effects of this resonance, a simple analog electronic feedback system is designed that can result in acceptable performance in both the frequency and time domains. [Work funded by NIH Grant R01 DC009429.]
Response of a MEMS (microelectromechanical systems) directional microphone diaphragm with active Q control.
Authors: Su Quang T. , Miles Ronald N. , Cui Weili , Shetye Mihir , Wu N. Eva
Published: March 2010

Measured results are presented that demonstrate the use of proportional and derivative electronic feedback to improve the performance of a directional microphone. The microphone diaphragm consists of a 1 × 2 mm stiffened plate fabricated out of polycrystalline silicon that is supported on a central hinge. The sound pressure gradient incident on the diaphragm produces a rocking motion about the central hinge. Interdigitated comb fingers at each end of the diaphragm enable both capacitive sensing and electrostatic actuation. The sound pressure gradient near the diaphragm has been measured by numerically differentiating the pressure measured by a probe microphone at locations around the diaphragm. The sound-induced motion of the diaphragm was measured using a laser vibrometer. From these measurements, estimates of the mechanical parameters of the diaphragm were obtained. By applying a known quasi-static voltage across the interdigitated fingers and measuring the resulting diaphragm deflection, an estimate for the derivative of the capacitance with respect to the displacement is obtained for the comb fingers of the diaphragm. Using these experimentally determined parameters and a linearized dynamic model of the system, the measured response of the microphone system with feedback is accurately predicted. [Work funded by NIH Grant R01 DC009429.]
Reinventing diversity.
Authors: Ross Howard J.
Published: March 2010

Despite all of the efforts to find strategies to improve the way organizations are addressing diversity, inclusion, and cultural competency issues, some are still finding their goals unrealized. In response to this, we conducted extensive research within the field and focused on how to reinvent diversity for the 21st century. Our research points to the need for three major paradigm shifts: (1) A movement from the classic United States-based approach, which focuses too heavily on race and gender and an assimilation model of diversity, to one that incorporates a deep understanding of globalism and the impact of major changes in population demographics around the world, global business, and interactive communication and networking; (2) a shift from the “good person/bad person paradigm” of diversity, which has developed and permeated a corrective mindset about diversity; (3) a ‘find them and fix them’ approach, which escalates the “us vs. them” way that people approach the issue and makes it more rather than less difficult to address. We have to move away from the event-based way for we have approached diversity, a pattern that has given us many specific activities, but not enough emphasis on systems thinking and culture-based change, to one that is strategic, systemic, and culture based.
Dynamic stabilization of the ultradamped inverted pendulum.
Authors: Carbo Randy , Poese Matthew E. , Smith Robert W.M.
Published: March 2010

The dynamic behavior of the damped inverted pendulum is analogous to the modes of fluid systems with nonzero viscosity where a denser fluid is situated above a lighter fluid (e.g., the Rayleigh–Taylor instability). Thermoacoustic devices have such configurations whenever a hot heat exchanger is situated below a cold heat exchanger. It has been shown that such systems can be stabilized by effectively modulating gravity and can be described by a damped Hill equation. A numerical solver was developed that uses a stroboscopic technique to determine whether solutions are stable (bounded) or unstable (unbounded). While it is sometimes assumed that the stability boundaries of undamped systems bound the damped cases, for large values of damping (Q < 0.05, where Q is the quality factor), the numerical solution predicts that damping can destabilize the system for certain regions of the parameter space. Results of an experiment performed by the authors using a physical pendulum and eddy current damping to verify this rather counterintuitive result are described. [Research supported by the Office of Naval Research and ARL Exploratory and Foundational Research Program.]
Generation of sound by flow instabilities in a low-speed helium jet.
Authors: Alberts W. C. Kirkpatrick , Ligon David A.
Published: March 2010

Schlieren images of low-speed helium flow from a nozzle of circular cross section reveal instability in the jet occurring approximately 1 cm from the nozzle orifice. Accompanying this instability is a pronounced whistle. In this presentation, both qualitative and quantitative analyses of the observed phenomenon will be discussed.
Parametrically excited oscillations: Where does the energy come from?
Authors: Strasberg Murray
Published: March 2010

Recent discussions of parametrically excited oscillations seem to have overlooked an obvious question. How is energy transferred to a parametrically excited system to replace the energy lost to dissipative elements? The conventional analysis converts the linear differential equation representing the parametrically excited system into a Mathieu equation which is a lnear differential equation with a periodically varying coefficient, such as a periodically varying stiffness or length. This does not explain the physical mechanism involved in the energy transfer. To indicate how the energy is transferred, several systems are examined here, viz., (1) the simple pendulum where work is done when the length of the pendulum is varied periodically at half the period of the pendulum to increase the amplitude of its oscillation, (2) the taught string where work is done while sinusoidally varying the tension so as to excite transverse vibration at half the frequency of the varying tension, and (3) shape oscillations of gas bubbles in water excited by spherical volume pulsation at twice the frequency of the shape oscillation. These and other examples lead to the suggestion that more is required to excite parametric oscillation than being a solution of a Mathieu equation.
Individual differences reveal the basis of consonance.
Authors: McDermott Josh H. , Oxenham Andrew J.
Published: March 2010

Some combinations of musical notes are consonant (pleasant), while others are dissonant (unpleasant), a distinction central to music. Explanations of consonance in terms of acoustics, auditory neuroscience, and enculturation have been debated for centuries. These debates have remained largely unresolved, in part, because the various theories are difficult to distinguish with conventional methods. This talk will describe our recent studies applying the method of individual differences to this problem. We measured preferences for musical chords as well as nonmusical sounds that isolated particular acoustic factors, including the beating and harmonic relationships between frequency components. Listeners preferred stimuli without beats and with harmonic spectra, but across over 250 subjects, only the preference for harmonic spectra was consistently correlated with preferences for consonant over dissonant chords. Harmonicity preferences were also correlated with the number of years subjects had spent playing a musical instrument, suggesting that exposure to music amplifies preferences for harmonic frequencies because of their musical importance. Preferences for stimuli lacking beats, in contrast, were not correlated with musical experience. Harmonic frequency relations figure prominently in many aspects of hearing, and our results indicate that they also underlie the perception of consonance. [Work supported by NIH Grant R01DC05216.]
Auditory and tactile integration in music meter perception.
Authors: Huang Juan , Gamble Darik , Wang Xiaoqin , Hsiao Steven
Published: March 2010

Meter is a fundamental temporal structure of music. The perception of meter is typically inferred from the occurrence of accents in the music surface. Under normal listening conditions, listening to or playing music is usually accompanied by vibro-tactile input which we hypothesize contributes to meter perception. Previous studies have shown that beat perception can occur via purely tactile stimulation. Whether vibro-tactile stimulation can give rise to meter perception and how it interacts with auditory meter perception is unknown. Here we used accent occurrence and strength as cues to study meter perception in subjects performing auditory only, tactile only, and combined auditory-tactile psychophysical discrimination tasks. We find that subjects can perceive meter through purely auditory only and tactile only stimulation. Furthermore, when stimuli were ambiguous, tactile stimulation was found to enhance meter perception when subjects were given weak auditory amplitude-accented cues. Similarly, auditory stimulation enhanced meter perception when subjects were given weak tactile amplitude-accented cues. These results indicate that meter perception is processed cross-modally, and that auditory-tactile integration plays an important role in the neural representation of temporal structures in music.
Musical experience impacts hearing speech in noise.
Authors: Kraus Nina
Published: March 2010

Musical experience profoundly impacts how sound is transcribed by the nervous system. This influence is likely mediated by cognitive processes such as attention and memory through the corticofugal system [Tzounopoulos and Kraus, Neuron 62, 463–469 (2009)]. Hearing in noise is difficult for everyone but especially for children with developmental dyslexia and older adults. We have identified objective neural signatures—from the human auditory brainstem—that reflect hearing in noise [Chandrasekaran et al., Neuron 64, 311–319 (2009) and Hornickel et al., Proc. Natl. Acad. Sci. U.S.A. 31, 13027 (2009)]. Musicians develop the ability to hear relevant signals embedded in a network of melodies and harmonies. This ability transfers to hearing a target speaker’s voice in background noise. We are beginning to understand the biological basis for this perceptual advantage [Parbery-Clark et al., J. Neurosci 29, 14100–14107 (2009)]. Sensory processing of speech and music is tightly coupled with the cognitive abilities that underlie language and musical expertise; this knowledge can be used to advantage in the consideration of educational and remediation strategies. [Work supported by NSF SGER 0842376.]
A biomimetic multi-resolution spectrotemporal model for musical timbre recognition.
Authors: Patil Kailash , Elhilali Mounya
Published: March 2010

Timbre is usually defined as that property of sound that is neither pitch nor loudness that helps in identifying sounds. Such a definition of what it is not is in itself problematic and unsatisfactory. The complexity of characterizing a timbre space stems from the intricate interactions between spectrotemporal dynamics of sound, which overcasts the simple description of individual acoustic dimensions as usually captured by techniques such as multidimensional scaling. By contrast, sound encoding in the mammalian auditory system, and particularly its sensitivity to spectrotemporal modulations, offers a rich feature space to explore perceptual representations of timbre. In the present work, the problem of musical timbre modeling was casted as a generative model based on a reduced set of multi-resolution spectrotemporal features inspired from encoding of complex sound in the auditory cortex. A probabilistic system based on Gaussian mixtures was built to perform a timbre recognition task on a data set consisting of 12 instruments. The system was able to achieve an accuracy of 98%, hence corroborating the claim that physiologically inspired features are effective in properly outlining a timbre space. These results could have significant implications in terms of better understanding the neural correlates of timbre perception.
Comparison of techniques of acoustically interrogating a fluid-filled pipe.
Authors: Osterhoudt Curtis F. , Dudley Christopher , Sinha Dipen N.
Published: March 2010

Through-transmission of sound in a fluid-filled pipe was experimentally investigated, with comparison to a one dimensional computational model. Pipe curvature is shown to be a contributor to deviations from the model, as is dynamical interaction between the finitely yielding pipe walls and the fluid contents. Various techniques of acoustically interrogating the system are considered. These include the different information which may be extracted via continuous-wave acoustical excitation, swept-frequency interferometry, and tone- and chirp-burst excitations. Each of these techniques has their advantages and disadvantages, especially in situations where short-time measurements must be made, and a version of the gain-bandwidth product must be taken into account. Some algorithms for automatically extracting fluid sound-speed are discussed, and it is shown that no one dominates under all circumstances. [This work was supported by Chevron USA.]
On the cancellation of acoustic waves scattered from an elastic sphere.
Authors: Guild Matthew D. , Alù Andrea , Haberman Michael R.
Published: March 2010

Recent research has suggested the possibility of creating non-absorptive elastic covers that eliminate the acoustic field scattered from an elastic object, also known as acoustic cloaks [Norris, Proc. R. Soc. London, Ser. A 464, 2411 (2008)]. The work presented here employs the scattering cancellation technique [Alù and Engheta, Phys. Rev. E 72, 016623 (2005)] to investigate the effectiveness of a single isotropic elastic layer to cloak an elastic sphere. The presentation discusses the benchmarked analytical and finite element scattering models which were employed to explore the design space of the cloaking layer. Parametric studies showing the influence of cloak stiffness and geometry on the frequency dependent scattering cross section are then presented. These case studies clearly illustrate the fundamental physical behavior leading to the observed reduction in scattering cross section at design frequencies. Finally, material selection and the creation of composite materials required to produce a functional scattering cancellation layer are presented and discussed.
Coherent backscattering enhancement in cavities. Simple shape cavity revisited.
Authors: Catheline Stefan , Gallot Thomas , Roux Philippe , Ribay Guillemette , de Rosny Julien
Published: March 2010

Coherent backscattering effect (CBE) is classically introduced in disordered, random, or chaotic media. In this work, the attention is focused on simple parallepipedic cavities since, contrarily to a widespread idea, CBE can also be observed for a pure-tone source in a one-dimensional (1-D) cavity. This approach is of two-fold interest. First, analytical computations predict a dimensional dependence of the coherent backscattering enhancement according to a (3/2)d law, d being the dimensionality of the cavity, that have not yet been compared to experiments. Second, it opens a new ballistic interpretations for which each multiply reverberated path is associated with more (rectangle and parallelepipedic cavities) or less (1D cavity) than one single reciprocal counterpart. This paper is the first of two, the second paper dealing with some impacts of symmetry on CBE.
How does the scattering from an empty cylinder change with the level of filling?
Authors: Williams Duncan P. , Craster Richard V. , Adams Samuel D. M.
Published: March 2010

The acoustic scattering from elastic objects features in many tasks stretching from the use of sonar to search for underwater objects such as submarines and mines to the inspection of shipping containers and cargo screening. The properties of canonical objects, such as cylindrical and spherical shells, which are completely filled with fluid, or immersed in fluid, have been widely studied, but typically stop short of studying shells containing different levels of filling. Not knowing the extent of the effect of filling on the scattering from different objects can limit how well one can discriminate between similar objects or inspect the interior of objects and, for example, find contraband or other suspicious materials. This paper looks at the two-dimensional response of a partially filled elastic cylinder. A computational method to model non-uniform domains is introduced and the use of perfectly matched layers is discussed. Results are shown for combinations of cylinders and different levels of filling. In particular, we show how the response of the cylinder depends on the level of the filling. The results are used to comment on the usefulness, or otherwise, of the response to estimate the nature and level of filling based on short- or long-range observations.
Modeling of a two-transducer through-wall ultrasonic communication system.
Authors: Roa Prada Sebastian , Wilt Kyle R. , Scarton Henry A. , Saulnier Gary J. , Ashdown Jonathan D. , Das Pankaj K. , Gavens Andrew J.
Published: March 2010

Ultrasound at 1 MHz is used as a carrier of information across solid walls without penetration. A communication channel is created by bonding two transducers on either side of a solid wall. The outside transducer transmits a continuous wave generating an acoustic field. The inside electronics are powered by harvesting the electrical output of the inside transducer. Digitized bits, representing the value of an analog signals measured on the inside (such as temperature), are used to alternate the electrical load of the inside transducer between two finite values. Changes in the electrical load of the inside transducer modify its acoustical impedance as seen by the incident waves coming from the wall, which in turn modulates the amplitude of the reflected signal. This modulated wave is detected at the electrical terminals of the outside transducer, where it is then demodulated to recover the data. The mechanical components of the system are modeled in connection to the electronic circuits by means of electro-mechanical analogies. Simulation of the communication system is performed using the electric circuit simulation package PSPICE. Simulation, finite element solutions, and experimental results are presented and discussed. Digital data communication rates exceeding 50 000 bits/s are achieved.
Relationships between structural energy density, power flow, and their influence on acoustic intensity.
Authors: Fisher Jeff M. , Manwill Dan A. , Blotter Jon D. , Sommerfeldt Scott D. , Gee Kent L.
Published: March 2010

Power flow in structures has been a topic of research for the past few decades. Many different methods for determining structural power flow magnitude and direction have been developed and proven. Structural energy density methods have likewise been developed. In this paper, a study of both structural energy density and power flow in a plate and their influence on the acoustic field is presented. Structural energy density and power flow were determined using equations typically used with accelerometer arrays but adapted for use with a scanning laser doppler vibrometer. Experiments were performed from 25 to 100 Hz by exciting the plate at single frequencies but using different excitation points and methods at each frequency. In some cases two sources of excitation were used to alter the power flow response, giving a broader basis for concluding relationships. Both speaker and shakers were used as sources. The acoustic intensity in the room was calculated at approximately 3 in. from the vibrating plate. Relationships between structural energy density, power flow, and the acoustic field variables are presented.
Real-time active control of structural energy density and structural power flow.
Authors: Manwill Daniel A. , Fisher Jeff M. , Sommerfeldt Scott D. , Gee Kent L. , Blotter Jonathan D.
Published: March 2010

Structural energy density and structural power flow have long been used as metrics in the active control of vibrating structures. The greater portion of this previous work has focused on frequency-domain methods which incorporate assumptions about the relative contributions of near-field and far-field energy components. This paper describes the implementation of filtered-x-based time-domain control schemes which utilize 9- and 13-accelerometer arrays to estimate and control structural energy density and structural power flow, respectively. Experiments were performed on a clamped steel plate excited and controlled by various combinations of loudspeakers and electrodynamic shakers in a frequency range from 25 to 100 Hz. Analog circuitry was used to estimate spatial derivatives and reduce channel count. The development of control laws incorporating the effects of the analog circuitry is presented. Control attentuation results are given, sensor placement is discussed, and implementation challenges are addressed. [This work is supported by NSF Grant 0826554.]
Perceptual and production training of allophones and phonemes in Spanish.
Authors: Herd Wendy
Published: March 2010

American English learners of Spanish often do not acquire native-like pronunciation of intervocalic /d/, tap, and trill in words like CODO “elbow,” CORO “choir,” and CORRO “I run.” The trill proves difficult because it does not exist in English. Although the tap exists as an allophone of /t/ and /d/ in English, students of Spanish must learn to process it as a phoneme rather than an allophone. Similarly, learners have difficulty acquiring the spirantization of voiced stops, where intervocalic /d/ is produced as a voiced dental fricative or approximant. This study investigates whether American English learners of Spanish can be trained to perceive and produce the intervocalic /d/, tap, and trill contrasts in Spanish. Both perceptual and production training methods were used. Past research has reported that perceptual training alone improves both perception and production, and that production training alone improves both as well; however, the production training studies have not been limited to production as trainees have been able to listen to the training stimuli. This study systematically controls both training modalities and introduces a third training methodology that includes both perception and production to discover whether perceptual, production, or combination training is most effective. [Research supported by NSF.]