bluuebunny/crossref_metadata_2025 huggingface dataset:
Application of the coherent-to-incoherent intensity ratio to estimation of ocean surface roughness from high-frequency, shallow-water propagation measurements
Authors: Roux Philippe , Culver R. Lee , Walker Shane
Published: March 2010

For acoustic propagation through a shallow ocean channel or waveguide, the coherence between different transmissions is controlled primarily by the roughness of the ocean surface and to a lesser degree by fluctuations in the volume. In this study, the coherent-to-incoherent intensity ratio (CTIR) is defined as a way to quantify the coherence between multipath transmissions and ocean surface rms wave height and wind speed. A theory that connects the CTIR and the coherent surface reflection coefficient is developed using both Kirchhoff and small-slope approximations as rough surface scattering models. The CTIRs have been evaluated over a period of several days using broad-band experimental results from shallow-water deployment of source and receiver arrays that span most of the water column. Estimates of wind speed and rms wave height obtained using these CTIR calculations are compared with environmental measurements to demonstrate the validity of the theory.
On the significance of phase in the short term Fourier spectrum for speech intelligibility
Authors: Kazama Michiko , Gotoh Satoru , Tohyama Mikio , Houtgast Tammo
Published: March 2010

This paper investigates the significance of the magnitude or the phase in the short term Fourier spectrum for speech intelligibility as a function of the time-window length. For a wide range of window lengths (1/16–2048 ms), two hybrid signals were obtained by a cross-wise combination of the magnitude and phase spectra of speech and white noise. Speech intelligibility data showed the significance of the phase spectrum for longer windows (>256 ms) and for very short windows (<4 ms), and that of the magnitude spectrum for medium-range window lengths. The hybrid signals used in the intelligibility test were analyzed in terms of the preservation of the original narrow-band speech envelopes. Correlations between the narrow-band envelopes of the original speech and the hybrid signals show a similar pattern as a function of window length. This result illustrates the importance of the preservation of narrow-band envelopes for speech intelligibility. The observed significance of the phase spectrum in recovering the narrow-band envelopes for the long term windows and for the very short term windows is discussed.
Classification of a cylindrical target buried in a thin sand-water mixture using acoustic spectra
Authors: Décultot Dominique , Liétard Romain , Maze Gérard
Published: March 2010

A number of papers have shown that it is possible to characterize an air-filled cylindrical shell immersed in water using data obtained from a backscattering spectrum. The scattered impulse time signal is constituted of echoes linked to the reradiation of waves circumnavigating around the cylindrical target. In the first part of this work, the scattered signal is calculated and then measured under conditions where the cylindrical shell is immersed in water. In the second part, the cylindrical shell is buried in a thin sand-water mixture. It is insonified perpendicularly to its axis and perpendicularly to the water mixture interface. The scattered impulse time signal is recorded and processed using a Fourier transform algorithm to obtain a resonance spectrum. Among all the resonances that are established in the explored frequency band, only those related to the circumferential S0 wave are observed on the resonance spectrum of a cylindrical shell buried in the sand-water mixture. Resonances of the circumferential A wave also called A0− wave seem to have vanished. The resonance spectrum obtained by the Method of Isolation and Identification of Resonances (MIIR) reveals that it is possible to detect and classify an object buried in thin sand-water mixture in laboratory conditions.
Using air-coupled sensors to determine the depth of a surface-breaking crack in concrete
Authors: Kee Seong-Hoon , Zhu Jinying
Published: March 2010

Previous studies showed that the surface wave transmission coefficient across a surface-breaking crack in concrete can be used to estimate the crack depth. However, inconsistencies in the surface wave transmission measurements limit the test accuracy and application of this technique. The inconsistencies come from near-field scattering by the crack tip and inconsistent sensor coupling conditions on rough concrete surfaces. This study first investigates the near-field size based on numerical analyses, and then suggests that reliable surface wave transmission should be measured in the far field. Based on the far-field measurement, the relationship between the surface wave transmission ratio and the normalized crack depth (crack depth/wavelength) is obtained. In the experimental study, the air-coupled sensing method is proposed as a solution to the sensor coupling problem. Owing to the non-contact feature, the air-coupled sensing method not only improves testing speed but also enables more consistent signal measurement. The experimental study using air-coupled sensors shows good agreement with the results of numerical simulation and analytic solution.
Self-demodulation of high-frequency ultrasound
Authors: Vos Hendrik J. , Goertz David E. , de Jong Nico
Published: March 2010

High-frequency (>10 MHz) ultrasound is used in, e.g., small animal imaging or intravascular applications. Currently available ultrasound contrast agents (UCAs) have a suboptimal response for high frequencies. This study therefore investigates the nonlinear propagation effects in a high-frequency ultrasound field (25 MHz) and its use for standard UCA and diagnostic frequencies (1–3 MHz). Nonlinear mixing of two high-frequency carrier waves produces a low-frequency wave, known as the self-demodulation or parametric array effect. Hydrophone experiments showed that the self-demodulated field of a focused 25 MHz transducer (850 kPa source pressure) has an amplitude of 45 kPa at 1.5 MHz in water. Such pressure level is sufficient for UCA excitation. Experimental values are confirmed by numerical simulations using the Khokhlov–Zabolotskaya–Kuznetsov equation on a spatially convergent grid.
The use of interaural time and level difference cues by bilateral cochlear implant users
Authors: Aronoff Justin M. , Yoon Yang-soo , Freed Daniel J. , Vermiglio Andrew J. , Pal Ivan , Soli Sigfrid D.
Published: March 2010

While considerable evidence suggests that bilateral cochlear implant (CI) users’ sound localization abilities rely primarily on interaural level difference (ILD) cues, and only secondarily, if at all, on interaural time difference (ITD) cues, this evidence has largely been indirect. This study used head-related transfer functions (HRTFs) to independently manipulate ITD and ILD cues and directly measure their contribution to bilateral CI users’ localization abilities. The results revealed a strong reliance on ILD cues, but some CI users also made use of ITD cues. The results also suggest a complex interaction between ITD and ILD cues.
Retrieving the exact Green’s function by wavefield crosscorrelation
Authors: Zheng Yingcai
Published: March 2010

Recent development on the Green’s function retrieval by wavefield crosscorrelation has substantially advanced the physical research in a multidisciplinary and unprecedented fashion. However, the underlying assumption of the theory that the sources are in the far-field limits the technology to extracting only the high-frequency part of the Green’s function in an open system. This critical approximation can be eliminated using the exact boundary integral equation method. A scheme involving the crosscorrelation kernel is proposed to recover the exact Green’s function including all-frequency content. Symmetric difference kernels are analytically constructed for sources on a plane or on a circle and can be reduced to the known Dirac delta kernel under the far-field approximation.
Multicenter evaluation of signal enhancement algorithms for hearing aids
Authors: Luts Heleen , Eneman Koen , Wouters Jan , Schulte Michael , Vormann Matthias , Buechler Michael , Dillier Norbert , Houben Rolph , Dreschler Wouter A. , Froehlich Matthias , Puder Henning , Grimm Giso , Hohmann Volker , Leijon Arne , Lombard Anthony , Mauler Dirk , Spriet Ann
Published: March 2010

In the framework of the European HearCom project, promising signal enhancement algorithms were developed and evaluated for future use in hearing instruments. To assess the algorithms’ performance, five of the algorithms were selected and implemented on a common real-time hardware/software platform. Four test centers in Belgium, The Netherlands, Germany, and Switzerland perceptually evaluated the algorithms. Listening tests were performed with large numbers of normal-hearing and hearing-impaired subjects. Three perceptual measures were used: speech reception threshold (SRT), listening effort scaling, and preference rating. Tests were carried out in two types of rooms. Speech was presented in multitalker babble arriving from one or three loudspeakers. In a pseudo-diffuse noise scenario, only one algorithm, the spatially preprocessed speech-distortion-weighted multi-channel Wiener filtering, provided a SRT improvement relative to the unprocessed condition. Despite the general lack of improvement in SRT, some algorithms were preferred over the unprocessed condition at all tested signal-to-noise ratios (SNRs). These effects were found across different subject groups and test sites. The listening effort scores were less consistent over test sites. For the algorithms that did not affect speech intelligibility, a reduction in listening effort was observed at 0 dB SNR.
A review of the new Leadership in Energy and Environmental Design v3 green building rating system.
Authors: Muehleisen Ralph T.
Published: March 2010

Leadership in Energy and Environmental Design (LEED) has become the de facto standard green building rating system in the US. On April 27, 2009 the US Green Building Council launched LEED v3 which is a major change to the previous version, becoming more flexible and prioritizing energy efficiency and greenhouse gas emissions. In particular, the prerequisites and credits amongst the various “flavors” of LEED have been harmonized for increased consistency, credit weights have been adjusted to better reflect impact on human and environmental health concerns, and credit weightings now reflect regional environmental issues. Acoustical consultants and engineers need to be aware of and understand these changes because they need to work with architects and other engineers who are designing buildings to meet the new LEED requirements. In this presentation, LEED v3 and the current implementation, LEED 2009, are reviewed.
Architectural acoustics: Emerging opportunities require new materials and solutions.
Authors: Sykes David M. , Cavanaugh William , Kachur Mandy , Ryherd Erica , Kurtz Alexis
Published: March 2010

The landscape is changing. New 2010 code-level acoustical guidelines for healthcare facilities and new 2009 LEED environmental quality criteria for acoustics in green buildings (LEED) create demand for acoustical solutions that stretch the boundaries of current practice. In many cases, these needs cannot be met by traditional methods, materials, technologies, or best practices in design & construction. Unfortunately, technical development has been constrained for 3 decades by absence of government support for R&D and by litigation against many manufacturers of acoustical materials. As a result, serious re-thinking is needed by materials manufacturers, technology developers, solutions providers, research scientists, and consultants. This paper gives an overview of these emerging needs and outlines new ways of thinking about architectural acoustics. Topics include (1) new requirements (renewable sources, VOCs, recyclability, lightweight construction, infection control/cleanability, and daylight transmission); (2) materials (re-purposed, adapted, and new); (3) construction method & procedures (pre-fabricated solutions, & new sources thereof, and the changing role of value engineering); (4) measurement & monitoring method & equipment (MEMS, wireless sensors, smart-phone applications, and cloud computing); and (5) code & rating systems (including post-construction performance inspection & certification procedures and the need for periodic monitoring & re-certification).
Understanding and specifying green noise control materials.
Authors: Tinianov Brandon D.
Published: March 2010

Specification of green acoustical materials is difficult to implement from the acoustical expert’s perspective. A contributing factor is the accepted definition of “green” that is poorly understood by the acoustical community. The widely accepted interpretation of the term does not refer exclusively to building materials that have a high recycled material content or are made without the use of toxic chemicals but extends to the entire project. Overall building design implications extend beyond material content to water consumption, energy use, and to the health and wellness of the occupants. These larger considerations are reflected in the most prevalent green rating system, the LEED rating system as established by the United States Green Building Council (USGBC). Within the framework of a larger, holistic building system, acoustical material can be considered green on three levels: (a) its contribution to the health and comfort of the building occupants, (b) environmentally preferable nature of its components or manufacturing process, and (c) its secondary performance features that have a positive impact on other building systems. Acoustical experts must therefore review the “green-ness” of sound control materials in this same framework. A review of such an approach and a review of existing green acoustical products will be presented.
Acoustics and the leadership in energy and environmental design rating systems.
Authors: Markham Benjamin
Published: March 2010

The leadership in energy and environmental design (LEED) rating systems address acoustics explicitly in but a few of their many credits. More profound are the implications of LEED-driven design on a building acoustics, typically in pursuit of LEED credits where no explicit reference to acoustics, noise, or acoustical design exists. Using project case studies as a guide, this presentation will outline some of the conflicts as well as synergies between “best practice” acoustical design and design decisions made on the basis of achieving certain LEED credits. A range of example credits will be presented along with the ramifications of such credits on building acoustics, including the effects of sustainable site credits on environmental noise isolation, energy and atmosphere credits on background noise levels, materials and resources credits on acoustical material specification, and indoor environmental quality credits on sound isolation and other acoustical design elements.
Electro-acoustic architecture: Is it Green?
Authors: Schwenke Roger W. , Duty Jason R.
Published: March 2010

Electro-acoustic architecture systems offer a means of changing the acoustic properties of a room electronically. They are an alternative to physically variable acoustics, where acoustic properties are changed by retractable curtains and doors opening to reverberant chambers, etc. This paper will address the question of whether electro-acoustic systems are a Green alternative to physically variable acoustics. In order to have a reverberation time appropriate for symphonic music, a room must have a large cubic volume and hard heavy surfaces. In contrast, in a room with an electro-acoustic system, the physical reverberation time is desired to be low even at low frequencies. Therefore, the cubic volume can be low and surfaces can be made of a lightweight material over an airspace. This affects the amount of energy needed to deliver materials, construct the building, and operate HVAC and lighting systems. A lower volume building means less pollution and waste during construction, and allows for more open space around the building, and/or higher development density. Electro-acoustic systems can easily be designed as a renovation, thus recycling existing buildings. Case studies will be reviewed demonstrating these issues.
Communication behavior of pupils and teachers in highly absorbent classrooms: A pleading for room acoustic comfort in schools.
Authors: Oberdoerster Markus , Tiesler Gerhart
Published: March 2010

This lecture refers to an interdisciplinary research project conducted 2001–2005 by acousticians, pedagogues, and occupational scientists at the Bremen University. It investigates the kind of work and communication behavior in elementary school classrooms and the influence that is given by the acoustic environment. Using a database of 175 examined lessons an analysis is made of how different kinds of work (frontal lessons vs differentiated lessons) have an effect on the sound level in the classroom. Parameters are discussed, which can describe classroom acoustics appropriately. Also discussed are how altered room characteristics (e.g., increased absorption, shortened reverberation time, and improved speech intelligibility) affect the sound level in the context of each kind of work. A methodical examination of the database allows an assessment of mean values but also of the detailed teaching phases, as characterized by certain pedagogical factors. The results provide the basis for discussion of stress and work demands of teachers.
An acoustic modeling graphical-user-interface tool for the marine conservationist.
Authors: Henderson Laurel , Porter Michael , de Moustier Christian
Published: March 2010

We develop an interactive tool to estimate the total level of anthropogenic and natural noise received by marine animals. This tool will help the marine conservationist assess potential noise-exposure risks. It uses physics-based underwater-acoustic models from the Acoustics Toolbox (http://oalib.hlsresearch.com/). Input choices include ocean area, seasonal sound speed profiles, and wind speed from NOAA and OAML databases. Sound sources can be chosen individually from a panel or by the dozens from a table with built-in representative values of various noise sources, including ships of various sizes, marine construction, navy sonars, and explosives. The user can either study the effects of the built-in noise sources or alter the table with actual noise-sources at known locations. Databases of marine mammal densities can be overlain, or the received acoustic level at chosen points on the map can be saved. We will review the background of the acoustic models used in the GUI and give a short demonstration of the capabilities of this tool.
Modeling marine mammal sound exposure levels due to ship traffic noise.
Authors: de Moustier Christian , Porter Michael B. , Henderson Laurel
Published: March 2010

Noise due to ship traffic is a pervasive component of the global and local ocean noise from 10 to 500 Hz, but little is known of its effects on marine mammals because such effects depend on the sound exposure levels at a given location. The approach presented here consists of modeling the sound field due to various spatial distributions of noise sources located 5–10 m below the sea surface. We approximate a three-dimensional sound field by computing the sound propagation from each source along a prescribed number of two-dimensional vertical radial slices of a range-dependent environment, which includes bathymetry, seafloor geoacoustic properties, water column sound speed profiles, and sea surface roughness. Propagation results from all sources are incoherently summed to form the overall sound exposure map. By varying the density of ships in a given area we can simulate the effects of shipping lanes and assess how the characteristics of the underlying seafloor alter the results.
Odontocete hearing: Effects of noise and measurement during echolocation.
Authors: Nachtigall Paul E. , Supin Alexander Ya.
Published: March 2010

Noise that interferes with active echolocation can come from either outside sources or be self-generated. Our work on temporary threshold shifts has shown that either lower levels of anthropogenic noise presented for long time periods or intense sonar pings for short time periods can produce temporary reduction in sensitivity and temporary threshold shifts. Intense anthropogenic sounds intended to disrupt echolocation can also reduce echolocation performance. Our measurements of hearing during echolocation have shown that self-generated intense outgoing signals are managed by the whale’s auditory system by (1) the use of forward masking as an automatic gain control system, (2) anatomical (or neurological) damping of outgoing signals, and (3) active manipulation of sensitivity levels of over all hearing. These processes of hearing allow the whale to adjust its hearing during echolocation to maximize the hearing of echoes. Measurements of hearing while a false killer whale actively echolocated, by measuring auditory evoked potentials, showed that the whale heard returns from a small cylinder better than it heard its own outgoing 180-dB clicks that produced the echo returns from the cylinder. Interactions between outside anthropogenic noise and the hearing of self-generated intense sounds during echolocation remain largely unexplored.
Observing the behavioral response of herring exposed to mid-frequency sonar signals.
Authors: Handegard Nils Olav , Doksaeter Lise , Godoe Olav Rune , Kvadsheim Petter H.
Published: March 2010

There is general concern on how mid-frequency military sonars might affect aquatic animals. Approaches used to investigate possible effects on Norwegian spring spawning herring (Clupea harengus) are presented. Experiments were performed in a sheltered fjord area, in the open ocean, and in a net pen. In the fjord area, the behavior of the exposed herring was monitored using an upward-looking bottom-moored echo sounder. For the open ocean experiment, schools of exposed herring were tracked using omnidirectional sonar. In the controlled net-pen experiments, the herring were towed into a fjord basin. The net-pen was equipped with a horizontal pointing and an upward-looking split-beam echo sounder to monitor the behavior, a hydrophone to measure the exposure levels, and a video camera to verify the observed behavior. In all experiments the herring was exposed to relevant naval sonar signals using operational sources mounted on a research vessel or operated from a frigate. For the net-pen experiments, the herring were also exposed to other audible sound sources to investigate the robustness of the methodology to detect reaction patterns. The pros and cons of the different observational approaches are discussed. [Work supported by the Research Council of Norway Grant No. 184705.]
Loggerhead turtles dive in response to airgun sound exposure.
Authors: DeRuiter Stacy L. , Larbi Doukara Kamel
Published: March 2010

Visual observations of the behavior of over 150 loggerhead turtles (Caretta caretta) were collected over a period of 2 weeks during a seismic survey in the Mediterranean Sea off Algeria in September and October 2009. All turtles were observed during active operation of an airgun array that had a peak source level of 252 dB re 1 μPa. Recordings from three hull-mounted hydrophones allowed concurrent estimation of near-surface airgun array source signatures and sound exposure levels. Of the 53% of turtles that were successfully visually tracked until they had passed more than 100 m behind the seismic vessel, 51% dived at or before their closest point of approach to the airgun array. Among animals that dived, approximately 20% did so immediately following an airgun shot, often showing a startle response that was clearly distinguishable from the predominant basking behavior. Turtle dive probability as a function of distance from the airgun array and sound exposure level will be considered in detail. The observed diving behavior may be interpreted as an avoidance response and may have negative consequences for turtles if it interferes with thermoregulation (basking) or results in inhabitual energy expenditures.
Soundscapes under sea ice: Can we listen for open water?
Authors: Nystuen Jeffrey , Miksis-Olds Jennifer
Published: March 2010

Different geophysical conditions at the ocean surface generate distinctive sound spectra underwater, thereby allowing the physical environment to be monitored using passive acoustics. In the central Bering Sea, a passive aquatic listener (PAL) was deployed on the NOAA M5 mooring through the 2008 and 2009 winter seasons, allowing the ambient sound under sea ice to be recorded. Distinctive features of sea ice soundscapes include loud sound levels during periods of ice formation and very quiet high-frequency levels during periods of solid ice coverage. These soundscapes do have distinctive spectra features that distinguish them from other geophysical conditions, including wind-generated spectra, drizzle, and rainfall onto open water. This indicates that it is possible to listen for ice-free surface conditions. In turn, this will allow sub-surface ocean instrumentation on drifters, profilers, or moorings to detect open water and surface during relatively safe ice-free surface conditions (by listening), thus minimizing damage risk and allowing data transfer by satellite data links, an important advance for engineering oceanographic studies in ice covered seas. [Work sponsored by ONR Marine Mammals.]
Acoustic monitoring of a melting Arctic Ocean.
Authors: Mikhalevsky Peter N.
Published: March 2010

The waters of the Arctic Ocean have been warming since the early 1990s. Average maximum temperatures have risen by more than 1 °C. In the last 20 years submarine measurements of sea ice draft have shown a 40% reduction in average sea ice thickness while satellite remote sensing has shown a 14% reduction in sea-ice extent over the same period decreasing at a rate of 3%–5% per decade with thicker multi-year ice at 7%–10% per decade. Forecasts indicate that if these trends continue the Arctic Ocean could be ice-free in the summer before the end of this century. Significant effort is needed to expand our observational capabilities in the Arctic Ocean to support better modeling, forecasting, and improve our understanding of this critical ocean and the linkages to global climate. One technique acoustic thermometry has been shown to be a very effective for monitoring average heat content and average temperature in the Arctic Ocean and, in particular, in the Arctic Intermediate Water layer. Two experiments conducted in 1994 and 1999 measured the warming and demonstrated the feasibility of long term observations. Plans are in process to incorporate acoustic thermometry and tomography in in-situ Arctic Ocean observatories.
Improved assessment of Arctic and Antarctic zooplankton: From acoustic scattering models to a better understanding of polar ecosystems.
Authors: Warren Joseph D. , Smith Joy N. , Ressler Patrick H. , Demer David A.
Published: March 2010

Polar regions contain some of the most productive (and in some cases unspoiled) ecosystems on the planet. Zooplankton, particularly krill, are the preferred prey for numerous fish, bird, and mammal species including animals that are endangered, commercially fished, or ecologically important. Acoustic echosounders provide an excellent method for assessing the abundance and distribution of zooplankton over large areas (> 100 s km2) through ship-based surveys and with high-temporal and spatial resolution. However, in order to accurately convert acoustic backscatter into a biologically meaningful measure (e.g., animal abundance, biomass, and calories), validated scattering models with well-understood input parameters are needed. This talk will present data from both Antarctic and Arctic (Bering Sea) zooplankton with regard to improvement of scattering models and the range and variability of model inputs for krill and other zooplankton, implications of these changes on acoustic estimates of zooplankton biomass or other metrics, and how these data may be used in ecosystem studies, particularly the relationships between zooplankton and their higher-trophic level predators.
Quantifying fish behavior with high-frequency scientific echo sounder and parametric sonar.
Authors: Godo/ Olav Rune , Korneliussen Rolf J. , Foote Kenneth G.
Published: March 2010

Schools of Norwegian spring-spawning herring (Clupea harengus) were observed in their wintering area off the northwest coast of Norway in November 2009 with the Simrad EK60 scientific echo sounder operating at 18, 38, 70, 120, and 200 kHz and Kongsberg TOPAS parametric sub-bottom profiling sonar, with nominal difference-frequency bandwidth 0.5–6 kHz. The beamwidths are 7 deg except at 18 kHz, where it is 11 deg. The TOPAS difference-frequency beamwidth decreases with both range and frequency, but lies within the range 3–5 deg at the depths of the detected schools, typically 50–300 m. The registered depths of the upper surfaces of the detected schools have been compared, indicating that the apparent depth often, but not always, is inversely related to beamwidth. The phenomenon seems to be related to the pattern of backscattering with respect to frequency within the same school, which appears to have two distinct modes. The results are analyzed and discussed relative to the phenomenon of gas release and avoidance reaction. [Work partly supported by Norwegian Research Council Grant No. 184705 and ONR Award No. N000140910482.]
Visualization of atherosclerotic plaque mechanical properties using model based intravascular ultrasound elastography.
Authors: Richards Michael S. , Jing Shayin , Doyley Marvin M.
Published: March 2010

Cardiovascular disease related deaths occur primarily from fatty plaques inside an artery that rupture and cause clots that disrupt blood flow. The study of arterial plaque mechanics is essential to the monitoring of atherosclerosis and the detection of vulnerable plaques or the likelihood of their rupture. The aim of this work is to measure and image the mechanical behavior of plaques using a clinically available intravascular ultrasound system (IVUS). To test the methods, radial displacements were measured from simulated images and phantom data within two dimensional IVUS rf images using standard elastography techniques. Simulations and phantom experiments were designed to mimic arterial geometries and deformations, which include plaque regions of varying stiffnesses. In addition, an optimization inversion algorithm was used to infer the elastic modulus of the underlying material. This algorithm utilizes a finite element based model and assumes that the deformation is quasi-static, plane strain and that the material is incompressible and linear elastic. The full spatially reconstructed modulus images, with no geometric constraints, are presented and compared to radial strain images. The phantom results are compared to the known modulus contrasts, and the simulated images are compared to contrasts and distributions.
In-vivo time reversal blastography: A passive correlation tomography of complex shear wave field within in soft tissues.
Authors: Catheline Stefan , Gallot Thomas , Roux Philippe , Brum Javier , Negreira Carlos
Published: March 2010

Heartbeats, breathing, and muscle activity: the human body presents natural sources of vibration creating a complex shear wave field. Such a noise is demonstrated in this work to be useful for quantitative elasticity imaging. Indeed, the shear wave noise inside soft tissues is measured by ultrasonic techniques developed in elastography. The particle motions estimated along lines or planes inside the medium can be used as artificial stars for time reversal experiments. In another language, Green’s functions can be recovered from noise correlations which results in a totally passive imaging technique. The use of shear wavelength or phase speed to reconstruct an elasticity mapping will be discussed.
Time reversal elastography: A correlation tomography of complex shear wave field in soft solids.
Authors: Gallot Thomas , Catheline Stefan , Roux Philippe , Brum Javier , Negreira Carlos
Published: March 2010

Shear waves in a soft solid can be focalized using time-reversal (TR) methods. The shear velocity, directly related to the elasticity of the medium, can be evaluated from the TR field. This study proposes to perform quantitative imaging of the mechanical properties inside a soft solid. Shear waves are created by finger impacts all over the surface of the solid. One component of the vectorial field inside the solid is measured by ultrasonic techniques developed in elastography. Inspired from Green’s function retrieval methods, the TR field is computed from cross-correlation of this random-like displacement signal. One point is chosen as a virtual source where the spatio-temporal refocusing is observed. Thus the method allows focalization of shear wave everywhere inside the solid without any source embedded in the solid. The local shear velocity is then deduced from the TR field. Finally, a two dimensional velocity map of a bi-layer medium is performed.
Clutter and sources of image degradation in fundamental and harmonic ultrasound imaging.
Authors: Pinton Gianmarco , Dahl Jeremy
Published: March 2010

Although harmonic imaging is used extensively, the mechanisms for image quality improvement are still poorly understood. Complex simulations or experiments that incorporate the effects of tissue heterogeneities and multiple scattering are required to describe image quality metrics such as clutter noise and less sensitivity to phase aberration. A finite difference simulation of ultrasonic propagation in a medium with heterogeneities in nonlinearity, attenuation, density, and speed of sound is presented. We investigate scattering from sub-wavelength targets and from macroscopic tissue structure. The simulated acoustic response from a single sub-wavelength scatterer is compared to analytical results for different scatterer sizes. This numerical implementation is then used to model tissue in the human body based on the visible human project and insonication from a from a 2.1-MHz diagnostic transducer. There is a close agreement between the analytical Rayleigh distribution, where the scattered intensity is proportional to f4, and simulation. The primary source of image degradation in the fundamental PSF comes from reverberation in the near-field abdominal structures. Phase aberration is the largest source of clutter in the harmonic PSF. Clutter in the PSFs occurs primarily from low-level contributions distributed over a large area.
Estimating ultrasound attenuation along the propagation path using a reference phantom.
Authors: Labyed Yassin , Bigelow Timothy
Published: March 2010

The objective of this study is to develop an algorithm that uses backscattered data to estimate the total attenuation of ultrasound along the propagation path. The sample and a reference phantom are scanned using the same transducer and same power settings. The power spectrum of the gated window in the ROI of the sample is divided by the power spectrum of the reference phantom. The resulting ratio is then multiplied by four Gaussian filters at four different center frequencies to obtain four new spectra. The center frequency of each new spectrum is equal to the center frequency of the Gaussian filter shifted by a term that is proportional to the total attenuation. The total attenuation is calculated by monitoring the shift in the center frequencies of the new spectra with respect to the center frequencies of the Gaussian filters. The algorithm is tested using rf data generated by computer simulations. The sample and the reference had attenuation coefficients 0.7 and 0.5 dB/cm MHz, respectively. The error in the attenuation estimate is less than 5% for an ROI that is five pulse lengths long and contains 50 independent beam lines. [Work supported by NIH Grant CA111289.]
Array measurement and imaging of sound transmission through the lungs.
Authors: Dai Zoujun , Peng Ying , Royston Thomas J.
Published: March 2010

Non-contacting scanning laser Doppler vibrometry (SLDV) was used to measure torso surface motion at an array of points caused by sound introduced into the lungs in human subjects. The SLDV serves as a gold standard as it does not have the complexity of surface contact dynamics. Additionally, a sensor array integrated into a compliant mesh fabric chair was constructed and tested as a less expensive and faster means of acquiring similar acoustic array data. Silicone gel-coupled, piezoelectric contact sensors for the detection of subsurface acoustic sources at the skin surface were used in the array. Array measurements were processed to determine the response at each measurement point as a function of frequency up to 1.6 kHz. Acoustic images were generated indicating the amplitude level at each point relative to the amplitude measured at the suprasternal notch, which served as the reference input. The acoustic measurements illustrated the complexity of sound transmission in the human lung and chest. Expected attenuation over the scapulae and below the diaphragm was observed. There were other significant variations as a function of location and frequency; measurement results are discussed. [Work supported by NIH Grant # EB008373.]
Traditional string instruments of the world.
Authors: Wheeler Paul A.
Published: March 2010

The string instruments best known to musicians, educated in western music, are the orchestral strings (violin, viola, cello, and double bass) with the addition of the guitar and harp. This represents a very small sample of string instruments used throughout the world. This paper is intended to introduce the variety of string instruments used in traditional music of world cultures. The instruments include the following: (1) musical bows—the berimbau of Brazil; (2) African and European lyres—the krar of Ethiopia and crwth of Wales; (3) harps—the ennanga of Uganda, saung gauk of Burma, and the Paraguyan harp; (4) plucked lutes—the charango of the Andes of Arabia, the balalaika of Russia, sitar of India, and the pipa of China; (5) fiddles (bowed lutes)—the hurdy-gurdy and nyckelharpa of Europe, the imzad of North Africa, the sarangi of India, and the morin khuur of Mongolia; (6) plucked zithers - the valiha of Madagascar, kantele of Finland, dan bau of Vietnam, and the zheng of China; and (7) dulcimers (hammered zithers)—the cimbalom of Hungary, santoor of Iran, and the yangqin of China.
Acoustic changes produced by hydration and burnishing of violin plates.
Authors: Denaro F. J. , Serbyn M. R.
Published: March 2010

To achieve the proper balance of tone and loudness throughout the frequency range of a fine violin, various methods of plate tuning have been proposed. Unfortunately, their effectiveness can be judged only a posteriori, for even if a violin plate response is well characterized, where to work the wood is poorly known. What is needed is a process that does not remove wood until the desired acoustical characteristics are produced regardless of the method used. The technique proposed by us consists of systematic hydrations and/or compressional burnishing of focal areas of the violin plates or corpus. Hydration is acoustically equivalent to a decrease in stiffness, while burnishing increases stiffness. Both are reversible without marked changes to the wood. In order to establish how these treatments affect the material constants of the plates, strips of maple and pine were tested in both treated and untreated states and the changes noted. Results suggest temporary changes to plate stiffness. The magnitude of these changes is sufficient to affect acoustic signatures and holographic patterns and hence can be detected. The accumulative effects of such changes to violin tone are noted in our companion paper.
Systematic optimization of violin tone by an acoustically reversible approach: The burnish/hydration technique.
Authors: Denaro F. J. , Serbyn M. R.
Published: March 2010

The companion paper supports the hypothesis that focal alterations to the stiffness of the wood can be produced by compressional burnishing or hydration of discreet areas of the plates or corpus. The effects of both burnishing and hydration are reversible. Therefore, one has real-time-feedback for modeling optimal violin tone. As a result only those acoustic changes which are desired are made permanent by removal of wood. To develop proof of concept we applied this approach to both top and back plates and to violins in the white. The experiments consisted of evaluation of tap tone frequencies and evaluating violins played in the white. Standard recording- and signal-analysis equipment was used. The conclusions drawn from measurements correlated well with those from listening, that is, incremental changes in the tone produced by this technique can guide the carving of the plates. An important strength of the technique is that it can be applied with other methods of plate tuning, namely, tap-tone methods, holographic techniques, computer analysis, etc. The approach should provide a valuable adjunct in making instruments of the violin family.
Estimation of loop filter coefficient for the silk stringed instruments.
Authors: Cho Sangjin , Chong Uipil
Published: March 2010

It is very important to represent an exact attenuation of a sound in a physical modeling of the plucked string instruments. Vlimki et al. proposed a simple one-pole low-pass filter called loop filter to depict the attenuation of the sound in the extended KS algorithm. In order to estimate the filter coefficient, attenuations and gains of each harmonic are measured and calculated, respectively. The coefficient can be obtained by using the mean squared error between magnitude response of the filter and the gains of each harmonic. In this case, unlike steel stringed instruments, the accuracy of filter coefficient estimation for the silk stringed instruments depends entirely upon choosing the specific region of the recorded sound. In this paper, 84 different notes of the silk stringed instrument called Gayageum, Korean traditional plucked-string instrument, were recorded, and estimation of filter coefficient was performed for the following regions: entire, decay, sustain, and RT1 (reverberation time) region. The estimation results were good in order of decay, RT1, sustain, and entire region. Especially, the performance for the decay region was very good. [This work was supported by the Korea Science and Engineering Foundation (KOSEF) grant funded by the Korea government (MEST) (No. R01-2008-000-20493-0).]
Effect of intrinsic parameters on sound absorption and transmission loss: A parametric study.
Authors: Shravage Paresh , Jain Sachin , Karanth Nagesh
Published: March 2010

Sound absorbing materials are indispensable nowadays for noise control treatments in transport industry. The acoustical behavior of these acoustic materials is governed by five physical (e.g., porosity, flow resistivity, tortuosity, viscous characteristic length, and thermal characteristic length) as well as three mechanical parameters (e.g., Young’s modulus, Poisson ratio, and loss factor). The characterization of these porous materials is very crucial as it plays an important role in design and development stage itself for predicting acoustic behavior of multilayer porous materials for higher sound absorption and transmission loss. This prediction depends on measurement accuracy of macroscopic physical parameters which are very difficult to measure except porosity and flow resistivity, which is the only standardized test until today; also availability of such rigs is also a problem for manufactures as they are available only at specialized test laboratories. This paper presents effect of all of these parameters on sound absorption coefficient and transmission loss of the porous materials using Johnson—Champoux—Allard and Biot model for poroelastic materials. It also discusses results of simulation with effect of each parameter on acoustic behavior of the sound absorbing materials.
Hand troweled and spray applied sound absorbing acoustical plasters.
Authors: Podolsky Howard , Sarcinella Andrew
Published: March 2010

This paper will discuss the types of hand applied and spray applied sound absorbing acoustical plasters manufactured by Pyrok Inc. Pyrok Acoustement products are spray applied acoustical plasters which are formulated with gypsum plaster or Portland cement. The Portland cement Acoustement 40 can be used for exterior as well as interior applications. Acoustment Plaster 20 and Acoustment Plaster 40 are gypsum based and are for interior applications only. The Pyrok StarSilent System has a smooth hand trowel applied finish that looks like monolithic drywall as well as a superfine sprayed finish. This paper will also discuss ASTM C423 testing and how it relates to spray and hand applied acoustical plasters. Although all spray applied and hand applied sound absorbing products are tested to ASTM C423, there are differences and inconsistancies when evaluating and comparing their sound absorption data.
Numerical study of noise transmission through functionally graded panels.
Authors: Huang Changzheng , Nutt Steve
Published: March 2010

Functionally graded panels are panels made of either functionally graded materials (FGMs) or functionally graded structures. FGM panels are traditionally used as thermal insulation barriers and they find applications in space and launch vehicles. Functionally graded structures include foams with continuous variations in pore size from one side to the other side. Such foams are incorporated as the core layer in sandwich panels. The latter is often used as partition walls in the building and transportation industries. In this study, we are concerned with the noise transmission characteristics of functionally graded panels. We developed an analytical model to derive the transfer matrix for the functionally graded medium. Using this model, we were able to make numerical predictions for sound transmission through functionally graded panels. The gradation parameter provides an additional degree of freedom in controlling the noise transmission characteristics. This is helpful in maximizing the noise reduction in panel design. Furthermore, our transfer matrix model applies to conventional discretely layered panels as well. In fact, the latter is just a special case in our modeling formulation. Numerical examples and results are presented and discussed.
Achieving minimum impact insulation class 50 rating using resilient clip technology in lightweight construction.
Authors: Byrick Wilson
Published: March 2010

Resilient clip technology is an alternative to resilient channel for supporting gypsum wallboard in fire rated wall and floor-ceiling assemblies. Lightweight wood frame construction presents challenges in meeting building code requirements for impact insulation class (IIC) and sound transmission class (STC) ratings in floor-ceiling assemblies. Through laboratory testing we were able to compare different floor-ceiling assemblies commonly used in multi-family construction. Two different structures were tested, an 18 in. open web truss, 24 in. o.c., and a 12 in. engineered joist (TJI) 24 in. o.c. Various finish floor coverings were used including ceramic tile, vinyl, and engineered wood. Structures achieved minimum IIC and STC 50 with and without 3/4 in. Gypsum concrete. Resilient rubber underlayment of varying thickness can further improve the IIC and STC ratings of the assembly as can adding a second layer of gypsum wallboard.
Quieting small centrifugal fans: A material manufacturer's view.
Authors: Brown Steven M. , LaForgia Dan
Published: March 2010

Noise control treatments have been developed for small centrifugal fans in fan trays. The fan trays are employed in cooling mobile electronics equipment. Similar treatments can be employed in stationary equipment racks used in the information technology and telecom industries. The noise control treatments incorporate especially sculpted sound absorbing material. This paper discusses the considerations used in developing the treatments, the resulting sculpted design of the treatments, and the acoustical material used in producing the treatments. The achieved noise reductions are presented. Comments are made on the resultant improvements in airflow and accompanying cooling capacity.