bluuebunny/crossref_metadata_2025 huggingface dataset:
The perception of auditory-tactile integration
Authors: Wilson E. Courtenay , Reed Charlotte M. , Braida Louis D.
Published: September 2008

This project explores the perceptual interactions between certain auditory and tactile stimuli in an objective manner. Our hypothesis states that if the auditory and tactile systems integrate into a common pathway, the d-prime measure of the two sensory stimuli presented simultaneously will be significantly greater than the d-prime measure of the individual sensory stimuli. If the stimuli are judged independently, the resulting d-prime will be close to the root-squared sum of the individual sensory d-primes. If the stimuli are integrated into a single percept, the d-prime will be close to the sum of the individual d-primes. This experiment presents 250 Hz vibratory stimuli to the fingertip and 250 Hz tones binaurally at the subject’s detection threshold. Experimental measurements of d-prime were obtained for auditory-alone, tactile-alone, and combination of auditory plus tactile. All testing used auditory white noise of 50 dB SPL. Effects of relative tactile-auditory phase and temporal asynchrony of the stimuli are explored. Preliminary data suggest that under certain conditions the two sensory stimuli integrate in a common pathway to form a single percept, that the stimuli must be synchronous for integration to occur, and that relative tactile-auditory phase has no effect on integration. [Hertz Foundation, NIH RO1-DC000126-25, ROI-DC000117.]
Numerical difficulties with boundary element solutions of interior acoustic problems
Authors: Fahnline John
Published: September 2008

Although boundary element methods have been applied to interior problems for many years, the numerical difficulties that can occur have not been thoroughly explored. Various authors have reported artificial damping due to acoustic radiation and low-frequency breakdowns. In this presentation, it is shown through a simple example problem that the numerical difficulties depend on the solution formulation. When the boundary conditions are imposed directly, the solution suffers from artificial damping due to sound radiation to the farfield. This difficulty can be alleviated by first computing an impedance matrix or admittance matrix, and then using its reactive component to derive the solution for the acoustic field. Numerical computations are used to demonstrate that this technique eliminates artificial damping, but does not correct errors in the reactive components of the impedance or admittance matrices, which then cause nonexistence/nonuniqueness difficulties at the interior resonance frequencies for hard-wall or pressure release boundary conditions, respectively. It is shown that the admittance formulation is better suited to boundary element computations for interior problems because the resonance frequencies for pressure release boundary conditions do not begin until the smallest dimension of the boundary surface is at least one half of the acoustic wavelength.
Development of a general statistical energy analysis subsystem formulation using finite element periodic structure theory
Authors: Cotoni Vincent , Shorter Phil , Langley Robin
Published: September 2008

Statistical energy analysis (SEA) represents a field of study in which statistical descriptions of a system are employed in order to simplify the analysis of complicated vibro-acoustic problems. In SEA, a vibro-acoustic system is represented by a collection of subsystems that can receive, store, dissipate, and transmit vibro-acoustic energy. Traditionally, the SEA parameters for a given subsystem are formulated analytically based on consideration of wave propagation through the subsystem. While such analytical algorithms can be readily applied to the majority of systems encountered in practical problems, there are certain types of sections that are difficult to describe using existing analytical formulations. Examples include: Isogrid in launch vehicle fairings, extruded aluminum sections in train floors, and modern corrugated aircraft fuselage constructions. This paper describes the development of a generic SEA subsystem formulation based on the use of finite element (FE) periodic structure theory. A small unit cell of the section is created and computationally efficient algorithms are developed to calculate wave propagation through a large array of such cells. The resulting algorithms are used to calculate the SEA parameters for the section. The approach is described and a number of numerical validation examples are presented.
Modeling of statistics of structural elements vibration, induced by near-wall turbulence
Authors: Yablonik Leonid R. , Agrest Emmanuil M.
Published: September 2008

The statistical characteristics of elastic elements fluctuations, generated by the dynamic effect of near-wall turbulent pressures field, are analyzed. The probabilistic properties of vibration of elements are determined by the characteristic functional of the random pressure field. A superposition of Gaussian and Poissonian field is used to model turbulent pressure in accordance with [E. B. Kudashev and L. R. Yablonik, Acoust. Phys. 48(3), 321–324 (2002)]. The Poisson component of turbulent field, which is associated with the processes of the generation of spontaneous splashes in the near-wall zone of flow, has a basic impact on the statistical features of vibrations. The model relationships, which connect flow conditions with the parameters of the characteristic functional of Poisson component, are proposed. Characteristic functions of the amplitudes of vibrations with the different values of the parameters of the acting turbulent field simulations are represented. The statistics of the inertia-free pistons that are usually used in transducers for pressure turbulent field diagnostics is investigated in detail.
Frequency spectra of elliptic cylindrical shells
Authors: Boisvert Jeffrey E. , Hayek Sabih I.
Published: September 2008

The kinetic and strain energy densities were derived for the vibration of an elliptic cylindrical shell of constant thickness. The elastic strain energy density has seven independent kinematic variables: Three displacements, two thickness-shear, and two thickness-stretch. The shell has a constant thickness h, finite length L, and is simply supported at its ends (z=0, L), where z is the axial coordinate. The elliptic cross section is defined by the shape parameter a, and the half-length of the major axis l. Using appropriate comparison functions that satisfy the boundary conditions for a simply supported elliptic cylindrical shell, the system is solved using the Galerkin method. Since the shell has an elliptic cross section, the frequency spectra are categorized into distinct symmetric and antisymmetric displacement fields whose spectra coalesce as the elliptic cross section approaches a circular cross section. Numerical results are presented for two h/l and L/l ratios, and various shape parameters, including the limiting case of a simply supported cylindrical shell (a∼100). [Work supported by the ONR/ASEE Summer Faculty Research Program.]
Psychophysical detection threshold of formant manipulations during speech production
Authors: Purcell D. W. , Munhall K. G.
Published: September 2008

In altered auditory feedback experiments, participants respond rapidly and alter their speech production to compensate for the induced auditory feedback error. This response does not occur with small feedback perturbations, and thus there must be a threshold for compensation by the auditory-vocal feedback system. What is unknown is the psychophysical threshold during speech production (i.e., how large are manipulations that are consciously detectable?). The purpose of this experiment was to compare the threshold for conscious awareness of perturbation, and the minimal change that induces compensation. A real-time auditory feedback manipulation system was employed in a repeated measures design. The compensation threshold was determined using the change point test during a perturbation ramp of 4 Hz/utterance. In the psychophysical measurement, the size of the feedback manipulation followed a two-alternative forced-choice paradigm. With 17 individuals, the mean psychophysical threshold was 105 Hz (SE: 9 Hz). The mean compensation threshold was 64 Hz (SE: 8 Hz). The significant difference between these thresholds is consistent with the hypothesis that the auditory-vocal feedback system can operate without conscious control and suggests that it may have access to a more sensitive representation of speech formants.
Effect of anticipation on voice F0 responses to auditory feedback pitch shifts
Authors: Burnett Theresa A. , Hindmarsh Elise K. , McCurdy Katie E.
Published: September 2008

Reflex-like voice F0 responses to anticipated and unanticipated auditory feedback pitch shifts were compared in healthy adults. Participants pressed a button to self-trigger a 100-cent, 100-ms upward shift in their voice auditory feedback over headphones while sustaining the vowel /u/ at a comfortable pitch and loudness. In separate blocks of 30 trials each, pitch shifts were self-triggered either immediately upon button press (Immediate) or after a random delay of 500 to 2000 ms (Random). In both conditions, participants were instructed to ignore the shifts as much as possible. To study any interaction between volitional voice F0 control and anticipation of the pitch shifts, the Immediate and Random conditions were repeated with pitch shifts that were long enough in duration for participants to volitionally oppose them (500 ms). Voice F0 response latency was significantly shorter when pitch shifts were immediately triggered than when triggered after a random delay, but there was no interaction between stimulus duration and stimulus onset timing for voice F0 response latency, magnitude, or duration. Participants neither suppressed the voice F0 response nor amplified it to completely compensate for anticipated 500-ms pitch shifts. Similarities between the voice F0 response and the long-latency stretch reflex are discussed.
The specificity of sensorimotor learning: Generalization in auditory feedback adaptation
Authors: Munhall K.G. , Pile E.J.S. , MacDonald E.N. , Dajani H.R. , Purcell D. W.
Published: September 2008

An enduring question about sensorimotor learning is how specific the acquired input-output relationship is. In this presentation, we review a series of studies in which the stimuli and conditions during speech motor learning were manipulated to study when and if generalization occurs. In our studies, the first and second formants of vowels were shifted using a real-time signal processing system; when subjects spoke one vowel, they heard themselves saying another vowel. In response to this auditory feedback perturbation, talkers spontaneously compensated by producing formants in the opposite direction in frequency to the perturbation. These compensations persisted after feedback was returned to normal, indicating that a form of sensorimotor learning had taken place. When different vowels were tested following the perturbation of one vowel, they were found not to show evidence of the feedback perturbation nor did the new vowels have any influence on the perturbed vowels’ return to normal baseline levels. Data from studies in which listening versus producing were compared and studies in which the similarity of the feedback voice quality was manipulated will also be presented. In general, the studies suggest that learning is quite local and, thus, that learning does not generalize beyond restricted conditions.
Speech motor learning without hearing
Authors: Nasir Sazzad , Ostry David
Published: September 2008

The nervous system receives both auditory and somatosensory information as we talk. Little is known about the role of somatosensory input in speech motor control. It is indeed a longstanding puzzle how post-lingually deaf speakers, in the absence of any substantial auditory input, maintain speech intelligibility. In this study we have assessed the role of somatosensory feedback in subjects with cochlear implants who were tested with their implants turned off. We used a robotic device to alter speech movements, and hence somatosensory feedback, by delivering mechanical loads to the jaw. We found that with training subjects corrected for the loads, such that the motion path approached that normally experienced under no-load conditions. Thus even under no auditory feedback, somatosensory input mediates speech movements in post-lingually deaf adults. In this study all five subjects with cochlear implants showed varying degrees of adaptation compared to only four out of six subjects in an age matched control group. This suggests a prominent role for somatosensory feedback in individuals with hearing loss. Finally, movement kinematic patterns for subjects with hearing loss were no different than those of subjects with normal hearing, which further underscores the reliance on somatosensory feedback in deaf adults.
Model-based array signal processing: A tribute to Dr. Leon H. Sibul
Authors: Candy James V. , Sullivan Edmund J.
Published: September 2008

Dr. Leon Sibul’s contributions to acoustical signal processing are extensive and highly significant. They are marked by a deep intuition and foresight, leading to new and fruitful concepts, especially in underwater acoustic processing. In this paper we discuss how Dr. Sibul’s contributions to adaptive array processing provided the conceptual basis for many of the modern approaches of model-based processing in ocean acoustics. In particular, we show how they were extended to incorporate sophisticated acoustical propagation models. Specifically, we discuss how his incorporation of propagation models in adaptive array processing schemes provided a new paradigm for such problems as source detection and localization. His concepts of an underlying physics-based estimation structure directly influenced efforts to develop environmentally adaptive processors that are capable of providing solutions to detection and localization problems. In this paper, we concentrate specifically on the model-based processing approach to the detection and localization problem, demonstrating how this area has progressed.
Propagation-invariant classification of sonar signals
Authors: Loughlin Patrick J. , Okopal Greg
Published: September 2008

Underwater sound waves can undergo frequency-dependent effects, such as dispersion and damping, that cause the wave to change as it propagates. In active sonar, these changes can be detrimental to automatic classification because the observed backscatter depends on the propagation environment and how far the wave has traveled. We aim to develop signal processing techniques to enable propagation-invariant classification. Toward that end, we have developed a local phase space view of propagation with dispersion and damping that is physically illuminating and suggests new features for classification. In this talk, we will present moment-like features extracted from the backscattered wave that are invariant to dispersion and damping, per mode. Environmental knowledge is not needed, beyond knowing the general form of the damping. Two forms of damping are considered. Classification results on simulations of the backscatter from different steel shells propagating in a Pekeris waveguide with damping and random variations will be presented. A dispersion-invariant matched-filter receiver approach will also be presented. [Supported by ONR Grant No. N00014-06-1-0009.]
Identifying and integrating likelihood functions and signal parameter probability density functions (PDFs) for sonar signal processing
Authors: Culver Richard Lee , Jemmott Colin W. , Ballard Jeffrey A.
Published: September 2008

A likelihood ratio receiver developed using an estimator-correlator structure requires that the noise probability density function (pdf) belong to the exponential class, but need not be Gaussian. The receiver employs a composite hypothesis that takes into account knowledge (or predictions) of the signal parameter statistics. In order to implement the receiver, we must be able to integrate the a priori pdf for the random parameter times the likelihood function over the domain of the random parameter, i.e., ∫p(r−θ)p(θ)dθ. The signal fluctuation models used by Swerling (1960) for radar detection theory belong to the chi-squared family of distributions, which are part of the exponential class. Likewise, the maximum entropy method with moments lnθ and θ could be used to fit p(r−θ) with a chi-squared pdf. If both noise and signal parameters are chi-squared distributed, a closed-form solution may exist. This paper considers approaches to fitting pdfs to noise and signal parameter samples and to solving the integral described above. [Work sponsored by ONR Undersea Signal Processing.]
A coded signal technique for the study of environmental noise propagation
Authors: Angus Jamie A. , Waddington David C. , Duncan Phil J.
Published: September 2008

This paper describes the design of a coded acoustic signal for the study of environmental sound propagation. An increasing awareness of environmental noise problems, and the need to better specify their needs and extent, means that a better knowledge of the effects of weather on sound propagation is necessary. Low signal-to-noise ratio is a common limitation in outdoor propagation investigations. A further problem is time variance. A coded acoustic signal approach consisting of a frequency carrier biphase-modulated by a specially-designed pseudo-random code sequence is proposed to overcome these limitations. This so-called ‘‘inner and outer’’ code sequence is specially designed for environmental sound propagation investigations, combining simultaneous fine time resolution and large range ambiguity. Experiment measurements are used to illustrate how the amplitude of the transfer functions between the receivers together with accurate times of flight may be calculated from the cross-correlation of the measured coded acoustic signal. It is further shown that the mean effect over the total propagation channel of factors such as wind, temperature gradients, turbulence, barrier, and ground reflections can be determined by measurement of the time-varying propagation transfer function using the proposed complex impulse response correlation technique. [Work supported by EPSRC UK.]
Performance classification degradation due to shallow-water propagation
Authors: Gaumond Charles F. , Baer Ralph N.
Published: September 2008

The propagation-induced degradation of classification ability for echoes from a finite cylindrical shell and a from a fish school is investigated by use of the class specific method [P.M. Baggenstoss, ‘‘Class-specific feature sets in classification,’’ IEEE Trans. Sig. Proc. 47, 3428–3432 (1999)]. The study is performed with previously displayed numerically simulated data. In prior work, degradation from additive noise was studied at a variety of signal bandwidths. Here, convolution noise caused by two-way propagation in a shallow water environment is shown to increase the duration of non-propagated echoes. The common propagation path between the two classes causes degradation when the classifier is based on non-propagated training data. Ameliorating effects of using training data comprised of either a fixed range or multiple distinct ranges are shown. The performance is quantitatively displayed as either classifier operating characteristic (CLOC) curves or as the integrals of the CLOC curves. The design trade-off space of bandwidth, signal-to-noise ratio (proportional to source level), and complexity of the training set is shown over a limited range of values. [Work supported by ONR.]
Accuracy enhancement of underwater target detection with time-frequency analysis techniques
Authors: Osman Abdalla , El-Sheimy Naser , Nourledin Aboelmagd , Theriaul Jim , Campbell Scott
Published: September 2008

Underwater target detection is mainly based on acoustic emissions generated by the target of interest (TOI) as it propels itself through the ocean, and operates non-propulsion-related onboard systems. The spectral signature of these acoustic emissions is used for identification and localization of TOI. This paper focuses on underwater target detection using passive sonobuoys. Discrete Fourier transform (DFT) is used in most sonobuoy processing systems to provide spectral analysis of the received signals. Due to the relatively high noise level and the several sources of interference that may exist underwater, the DFT may not determine the spectral signature of TOI with adequate accuracy. The low signal-to-noise ratio (SNR) and the presence of strong interference sources with frequencies close to the TOI frequency jeopardize the detection accuracy, the bearing estimation performance, and target tracking capabilities. The aim of this paper is to: (1) examine the performance of both wavelet packet analysis and high resolution spectral estimation techniques, and (2) provide a comparative study between both methods. Based on underwater acoustic simulation developed in this research, results showed that the proposed methods can achieve robust target detection with low levels of SNR and interferences of nearby signatures that cannot be detected by DFT.
Overview of the reverberation modeling workshops
Authors: Perkins John S. , Thorsos Eric I.
Published: September 2008

Two workshops on reverberation modeling are being conducted under joint sponsorship from the Program Executive Office C4I, PMW 180 (as funded by the Office of the Oceanographer of the Navy) and the Office of Naval Research. The overall goal of these workshops is to evaluate recent progress made in reverberation-related research efforts and to make recommendations for further development. The first workshop was held in November 2006 and the second is scheduled for March 2008. The focus of the first workshop was on reverberation from the environment, while the second workshop will emphasize system characteristics. At the first workshop, fifteen different reverberation models were represented and extensive comparisons were carried out before, during, and after the workshop. We present the approach used to conduct the first workshop, discuss issues that have been identified, and outline tentative plans for the second workshop. [Work supported by ONR and PMW 180.]
Finite-element modeling of long range, range-dependent acoustic propagation in shallow water
Authors: Isakson Marcia J. , Yarbrough R. Abe , Wilson Preston S.
Published: September 2008

The current methods of modeling long range, low frequency acoustic propagation in shallow water environments include ray methods, wave number integration, parabolic equations, and normal mode theory. Finite-element (FE) models have also been considered in the past, but computing power and algorithm cost have limited their application. Recent advances in computing power coupled with the advent of low cost, user-friendly, all-purpose finite-element codes have provided new opportunities for the application of FE modeling. We present both time and frequency domain solutions to canonical acoustic problems (scattering from a corrugated surface and propagation in a Pekeris waveguide), and to two-way, range-dependent problems, such as waveguides with surface and bottom roughness. For the latter environment, reverberation time series produced by Fourier synthesis of the FE model output can potentially provide benchmark solutions that no other currently available solution method can provide. [Work supported by ARL IR&D.]
A mostly time-domain reverberation model with application to Reverb Workshop Problem II
Authors: Keiffer Richard
Published: September 2008

A mostly time-domain reverberation model is described and applied in an isospeed shallow water ocean waveguide that has a flat sandy bottom and a rough air/sea boundary (Reverb Workshop Problem II) to predict the received intensity averaged over many realizations of the sea surface. The model described computes the scattering using a time-domain scattering approach called the wedge assemblage method and accounts for volume attenuation and bottom reflection loss under a ‘‘constant Q’’ approximation. Details of the model are discussed and results are presented for both the point and line source excitation of the waveguide. [This work was supported by ONR through NRL.]
Rayleigh reflection loss non-linearity approximation and application to reverberation
Authors: Harrison Chris
Published: September 2008

This paper presents an extremely good approximation to the Rayleigh reflection loss for two half-spaces composed of water over sediment. This has some useful properties. First it demonstrates that the usual linear approximation for the reflection loss (inside the critical angle) can be extended to the nonlinear case. Second it shows that the non-linearity can be expressed as a separate function that multiplies the linear loss coefficient. Third this nonlinearity term depends only on sediment density and does not depend on sediment sound speed or volume absorption. Fourth the nonlinearity term tends to unity, i.e., the reflection loss becomes effectively linear, when the density ratio is about 1.27. There are similar findings for the reflection loss phase which lead to the well-known lateral shift or effective depth. A class of closed-form reverberation (and signal-to-reverberation) expressions has been developed at NURC, [Harrison (2003), JASA, 114, 2744–2756; Harrison (2005), JCA, 13, 317–340; Harrison (2005), JOE, 30, 660–675]. The new approximation enables one to convert these reverberation expressions from simple linear loss to much more general reflecting environments. Correction curves are calculated in terms of sediment density and applied to a test case taken from a recent ONR Reverberation Workshop (Nov 2006).
Propagation modeling via ray bundles
Authors: Brooke Gary H.
Published: September 2008

GD Canada has developed an acoustic propagation model, GDRAY, based on a Gaussian ray bundle propagation engine similar to that used in the CASS/GRAB performance prediction software [H. Weinberg and R.E. Keenan, J. Acoust. Soc. Am. 100, 1421–1431 (1996)]. The GRAB-type model has proved to be useful for a wide-range of underwater acoustic scenarios, including active and passive prediction in shallow and deep water over a wide range of frequencies. Surprisingly, despite its extensive use in USN applications, the theoretical origins of the GRAB model are not well understood. This paper is intended to examine those origins and to outline some of the unique features of the GDRAY model implementation. It will be shown that Gaussian ray bundles, as such, have no particular physical significance in terms of the propagation, but are simply one of a family of possible ray bundle types that can be used to extract eigenray information. Several simple test cases will be employed to demonstrate the underlying concepts and issues. [Work is funded as an internal R&D program at GD Canada.]
Acoustics of modular construction—Industry overview
Authors: Hardiman Thomas E.
Published: September 2008

This session will provide an overview of the issues and efforts impacting the commercial modular construction industry throughout North America, with particular focus on acoustics in relocatable classrooms. The Modular Building Institute is the international nonprofit trade association representing manufacturers and dealers of commercial modular facilites, both temporary and permanent, serving educational, health care, retail, industrial, military, and multi-family markets.
Issues in acoustic field testing of quiet modular classrooms
Authors: Lubman David , Sutherland Louis C.
Published: September 2008

Modular classrooms are important to American education: About 300,000 modular classrooms are currently in use by public school systems here. Good acoustical conditions for learning are no less vital for students in modular classrooms than stick-built classrooms. In an effort to promote good acoustics in modular classrooms, ANSI S12 Working Group 46 is seeking to standardize acoustic field testing. Their efforts are in response to key acoustical issues of modular classrooms: Excessive noise from HVAC (heating ventilating and air conditioning) systems, and poor airborne sound insulation from exterior noise sources. In a recent and notable advance, an HVAC system provider reported good progress in modular HVAC noise reduction: A ducted wall mounted system was used instead of the usual free blowing system with exposed fans. HVAC noise in the unoccupied room was near the maximum 35 dB level required by ANSI S12.60. Interior noise levels were so low that efforts to confirm their values were confounded by noise contamination from exterior sources. The relatively high interior ambient noise levels were due to poor airborne sound insulation. Lessons learned from recent field testing will be discussed. Results of airborne sound insulation tests, now in planning stages, will be reported if available.
Performance and design considerations for modular panel systems used for studios and acoustic test chambers
Authors: Winker Douglas F.
Published: September 2008

Modular panel construction is used to produce a variety of rooms including studios, medical rooms, hemi- and full-anechoic chambers, and reverberation chambers. Prefabricated panels provide many advantages over conventional construction, including the ability to relocate chambers, minimize on-site construction time, and maintain panel-to-panel performance through tight quality control, while maintaining the ability to customize an enclosure for a particular need. The design and performance of the panel systems will be discussed as they relate to their intended applications. The performance of each panel system was evaluated for both normal incidence and random incidence sound absorption in accordance with ASTM E1050 and C423, respectively. The panel’s sound transmission loss was tested in a reverberation chamber suite in accordance with ASTM E90. Fully functioning systems were tested by ASTM E596 noise reduction of an isolating enclosure in one reverberation chamber. The performance of the modular panel systems will also be compared to conventional construction methods.
Cavitation-enhanced ultrasound heating in vivo: Mechanisms and implications in MR-guided high-intensity focused ultrasound therapy
Authors: Sokka Shunmugavelu , Hynynen Kullervo
Published: September 2008

Focused ultrasound is currently being developed as a noninvasive thermal ablation technique for benign and cancerous tumors in several organ systems. Although these therapies are designed to ablate tissue purely by thermal means, cavitation can occur. These bubbles can be unpredictable in their timing and location, and often interfere with thermal therapies. Therefore, focused ultrasound techniques have tried to avoid bubbles and their effects. However, gas bubbles in vivo have some potential useful features for therapy. In this research, we design and test in vivo ultrasound exposures that induce cavitation at appropriate times and take advantage of their absorption-enhancing properties while yielding reliable lesion sizes and shapes. In addition, MRI and acoustic methods to monitor and potentially control cavitation induction and the associated therapy are investigated. Finally, histology of the resulting cavitation-enhanced heating lesions is performed to assess the type of tissue damage. We demonstrate that cavitation-enhanced heating can be reliable and useful with the appropriate therapy protocol and application. If induced and monitored properly, cavitation in focused ultrasound therapy could potentially be very beneficial. Early MR-guided HIFU clinical systems that can utilize and monitor cavitation approaches will be presented.
Therapeutic potential of stable cavitation: From enhanced drug delivery to faster hemorrhage control
Authors: Zderic Vesna , Vaezy Shahram , Luo Wenbo
Published: September 2008

Current studies indicate that mechanical effects of therapeutic ultrasound resulting in a cavitation activity may be advantageous in variety of clinical applications including tumor treatment, treatment of stroke and vascular diseases, targeted gene and drug delivery, and hemorrhage control. Our drug delivery studies using 880 kHz ultrasound have shown that enhancement of drug delivery through the cornea correlated well (R2̂=0.92) with stable cavitation activity. The delivery enhancement ranged from two to ten times and the power of subharmonic ranged form 5 dBm to 20 dBm in the intensity range of 0.2 0.6 W/cm2. Broadband noise, as an indication of inertial cavitation, was also detected at the highest applied intensity. Changes in the front surface layer of the corneal epithelium indicated the presence of both stable and inertial cavitation activity. Our hemostasis studies have shown that introduction of external microbubbles during application of 5.5 MHz high−intensity focused ultrasound (HIFU) led to faster hemorrhage control of solid organ injuries, appearing to result from both stable and inertial cavitation activity at the location of HIFU focus in a bleeding incision. Microbubbles also allowed easier targeting of an incision site under ultrasound guidance, thus facilitating faster localization and sealing of bleeding incisions.
Image-guided cavitational ultrasound therapy histotripsy
Authors: Xu Zhen , Hall Timothy L. , Cain Charles A. , Fowlkes J. Brian , Roberts Williman W.
Published: September 2008

Our recent investigations have demonstrated that mechanical tissue fractionation can be achieved using successive short (3–50 μs), high intensity ultrasound pulses delivered at low duty cycles (0.1–5%). This technique can be considered as soft tissue lithotripsy, which we call histotripsy. The acoustic pressures effective for histotripsy are similar to those used in lithotripter shockwave pulses. In bulk tissue, histotripsy produces extensive fractionation of cellular structures, resulting in a liquid cavity within the treated volume. At a tissue-fluid interface, histotripsy physically removes tissue. Histotripsy lesions have sharp boundaries, with several microns between intact and fractionated cells. The primary mechanism of histotripsy is thought to be cavitation. The production of tissue fractionation depends on initiation and maintenance of cavitation detected by acoustic and optical monitoring. Cavitation bubbles generated by histotripsy are easily detected on ultrasound imaging, which is used for targeting and real-time monitoring of the treatment progress. Histotripsy induced lesions are also clearly identifiable using ultrasound and magnetic resonant imaging. Our investigations suggest that histotripsy has potential to be developed into a new noninvasive ablation tool for many clinical applications where tissue ablation, remodeling, or removal is needed. [This research is supported by grants from NIH R01-HL077629 and Wallace Coulter Foundation.]
Unit-generator architectures in computer music
Authors: Smith Julius O.
Published: September 2008

Max Mathews is well known as the ‘‘Father of Computer Music,’’ having written the first program for generating digital sound samples from high-level ‘‘note’’ and ‘‘instrument’’ specifications. Instruments were specified as interconnections of elemental building blocks called unit generators. This presentation reviews some of the history and impact of the unit-generator concept in computer music over the past half-century. Widespread dissemination of the unit-generator architecture for sound synthesis began with the Music V Program (the first Fortran version), written by Max Mathews in 1968. Derivatives soon appeared at research universities, such as csound (Vercoe, MIT), Mus10 (Chowning’s group, Stanford), and cmusic (Moore, UCSD). Hardware acceleration for unit generators appeared in the 1980s. Later, Music-V descendants included Lisp-based music compilers such as Common Lisp Music (CLM), the Synthesis Tool Kit in C++ (Cook et al., Princeton), and graphical programming languages for real-time music processing/synthesis, such as Max/MSP and Pure Data (PD) started by Miller Puckette. More recent descendants include SuperCollider (McCartney, UCSB) and ChucK (Wang et al., Princeton). Thus, the unit-generator architecture, introduced by Max Mathews half a century ago, has firmly taken root as a preferred modular approach to the problem of constructing virtual musical instruments and digital audio effects.
The Mathews legacy on the $100 Laptop
Authors: Vercoe Barry
Published: September 2008

The Mathews Music 4 program was the inspiration for a series of audio-processing languages by this author: Music 360 (1968), Music 11 (1973), Csound (1985), XTCsound (1997), and CsoundXO (2007). Instruments modeled in any one of these systems will run almost unmodified in any other, a testament to the long reach of Max’s original concepts. But Max’s longest reach is yet to come, for CsoundXO has been developed for the $100 Laptop—a machine designed by One Laptop Per Child (OLPC) which aims to put a laptop in the hands of every child on the planet (www.laptop.org). These machines are mesh-networked so that a child in one village can connect to a child in a neighboring village, and so on, until an international access point is reached. But CsoundXO on each machine is also designed for collaborative performance, so that a child in one country can ‘‘share’’ his/her original composition with a child in a similar or different culture. And if the work is interactive, each child can perform collaboratively with others who may be near or far. This paper will describe how all this works, along with a live demonstration.
Tapping into the internet as an acoustical/musical medium
Authors: Chafe Chris
Published: September 2008

Recent work in network audio transport transforms advanced networks into a new kind of acoustical medium in which sound waves propagate, as if traveling through air, water, or solids. Waves sent through the medium are reflected or altered as they bounce between hosts. Propagation delays are used to create echo chambers and build the resonances for ‘‘distributed musical instruments.’’ As a side-effect, tones created by network resonances can be used to monitor the quality of the underlying network. The presentation presents three areas of research: (1) Auditory methods for monitoring QoS, especially for networks supporting real-time, interactive, bidirectional flows; (2) remote musical collaboration using professional-quality, low-latency audio; (3) empirical study of human factors affected by some unique acoustical properties of the medium network latency; jitter and delay asymmetry affect the speed of sound and are never uniform. By creating distributed virtual sound objects like instruments and rooms, and by studying distributed ensembles, we can begin to understand this new sound world. Some effects have been measured empirically and the results contain some surprises.
Max Mathews’ magical music machines
Authors: Chowning John , Chowning Maureen
Published: September 2008

For nearly 40 years, Max Mathews has worked on real-time control of computers that he first programmed to make music in 1957. Beginning with a simple telegraph key to control tempo, followed by more sophisticated controllers that he developed while at Bell Telephone Laboratories and at Stanford’s Center for Computer Research for Music and Acoustics (CCRMA), his latest and most sophisticated controller is his radio baton. We will demonstrate the extraordinary impact of Mathews’ work on the world of music performance as the newest of musical instruments—computer and radio baton—joins with the oldest of musical instruments—the singing voice—in the performance of compositions where the soprano controls her computer generated accompaniment and computer processes. The presentation will include Sea Songs by Dexter Morrill, and Richard Boulanger’s Solemn Songs for Evening, which uses the Bohlen-Pierce scale.
Quantifying lost opportunities to hear natural sounds
Authors: Fristrup Kurt
Published: September 2008

Hearing provides an omnidirectional alerting sense for wildlife that seems to be universal: No deaf vertebrate species are known and invertebrates display a remarkable diversity of hearing mechanisms. Anthropogenic noise elevates ambient sound levels, which masks natural sounds that would otherwise be heard. The costs of this masking can be assessed by calculating the loss of listening area or alerting distance that results. Listening area metrics are appropriate when a search function might be affected (e.g., foraging), while alerting distance metrics are appropriate when the distance to the sound source mediates the function (e.g., avoiding predation). Analytical approaches for calculating loss of listening area and alerting distance should incorporate available hearing data to account for the effects of hearing thresholds and critical bandwidths. A range of models for masking can be used. Very simple models may sacrifice accuracy to suggest metrics that are readily calculated using existing noise models. More complex models can capture the idiosyncrasies of each species hearing capabilities to render more detailed results. Examples of applying these metrics to National Park Service contexts are discussed, to illustrate the use of these concepts to render environmental acoustic data for resource managers and NPS leadership.
Monitoring, prediction, and management of sonic booms in a valued ecosystem
Authors: Plotkin Kenneth J. , LaPierre Louis , Boulton J. Wayne
Published: September 2008

Goose Bay, Labrador, is a sensitive ecosystem under airspace that has been host to military flying operations since World War II. Since 1995, the Institute for Environmental Monitoring and Research has documented and helped mitigate the effects of low altitude flight operations, serving to protect the welfare of aboriginal people and the survival of wildlife species in the area. There are current plans to conduct supersonic operations in part of the airspace. Based on experience with this type of operation in other places, there is an expectation that resultant sonic booms can be safely accommodated, but it is necessary to monitor effects. The Institute has sponsored the development of a sonic boom forecast model that combines real-time three-dimensional weather forecasts with sonic boom ray trace modeling. A set of new digital noise monitors has been developed to record noise and sonic booms in the airspace. Field biologists will observe behavioral response of key species. These elements will be key components of an adaptive management system that will ensure preservation of this highly valued ecosystem.
Environmental noise studies in Puget Sound
Authors: Dall’Osto David , Dahl Peter H.
Published: September 2008

The ambient noise environment at a site in North Puget Sound, Washington, depth ∼100 m, located within the nearby Smith Island marine sanctuary, is studied. The measurement system consists of a buoy for which the surface expression houses a microphone at nominal height 2 m above the sea surface, with multiple underwater acoustic sensors suspended in the water column. The recording bandwidth for the air system corresponds to audio band, whereas the underwater system records ambient noise at frequencies up to 50 kHz. The two systems are recorded coherently. One goal of this pilot study is to examine different components of the noise budget, including injection of noise from airplane flyovers, and correlation between pressures above and below water. Another goal relates to properties of the noise field that could possibly impact echolocation by southern resident killer whales; these properties likely being restricted to noise levels at frequencies above 25 kHz. Besides representing an important marine mammal habitat, a key advantage of this site is the availability of meteorological and sea surface wave data, obtained from Smith Island and a nearby NOAA buoy, and vessel and air traffic data. Results from the summer 2007 field work will be presented.
A procedure for the assessment of residential low-frequency noise complaints
Authors: Waddington David C. , Moorhouse Andrew T. , Adams Mags D.
Published: September 2008

Although the number of people that complain about low-frequency noise (LFN) is comparatively small, those that do tend to suffer severe distress. LFN is a recognized problem in many developed countries, and this paper describes a procedure for the assessment of LFN complaints that has recently been developed in the UK. Human reaction to sound is dependent not just on the sound itself, but on a complex array of other factors including personal associations with the sound. Consequently, the procedure does not provide a prescriptive indicator of nuisance, but rather gives guidance notes and a pro-forma report with step-by-step instructions to help environmental health practitioners to form their own opinion. In particular, an interview-based questionnaire is used to complement physical recordings of low-frequency sounds in the complainant’s home, together with an event log completed by the sufferer. Examples of field measurements and application of the procedure are presented. [Work funded by the Department for Environment, Food and Rural Affairs (Defra) UK.]
Analysis of reverberation characteristics for sniper localization in an urban environment
Authors: Libbey Brad , Perea James
Published: September 2008

Acoustic sniper localization algorithms have proven useful to soldiers, but are difficult to implement in urban environments, due to reverberation and diffraction. Research is being performed to assist traditional localization methods by interpreting reverberant responses present in urban environments. Measured sniper responses are processed to establish if the first acoustic path is direct or indirect, based on characteristics of the received signal. If the first arrivals on several receivers are direct, an accurate relative time delay can be determined for each, which leads to accurate source localization. Indirect microphone arrivals can adversely affect the localization algorithm. Various metrics were used to characterize received signals: Arrival energy, reverberation decay time, initial arrival crest factor, and relationships between first and subsequent arrivals. Combining these factors aids in the identification of obstructed receivers, providing information about the effectiveness of a channel in a localization algorithm.
Assessment of ground vibration impact from automotive and transit sources on future biotechnology research center using finite element analysis (FEA)
Authors: Phillips James E.
Published: September 2008

A new science and biotechnology research center was to be built in a metropolitan industrial area. There was concern that ground vibration from a nearby freeway, street traffic, and trains on an adjacent railroad would impact vibration sensitive research equipment inside the building. Ground vibration was measured at the project site prior to construction. Finite Element Analysis (FEA) was used to develop a computer simulation of the building structure using the measured ground vibration as input to the FEA model. The study determined the building floor vibration due to exterior sources would achieve the project’s criteria for the building structure as designed.