bluuebunny/crossref_metadata_2025 huggingface dataset:
Absorption coefficient error propagation into room acoustics parameters.
Authors: Vorländer Michael
Published: March 2010

It is well known that random-incidence absorption coefficients suffer from measurement uncertainties. Whether or not these uncertainties affect the quality of results from room acoustic prediction models depends on the specific case. One might argue that the absorption of the most relevant material must be known accurately. This, however, could be the material with highest absorption or the material with the largest surface area. In this presentation, the true random-incidence absorption coefficient and measurement uncertainties related to the current ISO 354 are briefly discussed. Then, in order to get a better view on the consequences of those uncertainties, quantitative uncertainties of some predicted parameters such as reverberation time, strength, and clarity are calculated by using an error propagation. Effects of uncertainties of absorption coefficients distributed in various room configurations are presented and discussed.
Investigation of the just noticeable difference of scattering coefficient in auralized concert halls.
Authors: Vitale Renzo , Vorländer Michael
Published: March 2010

The use of scattering coefficient in room acoustics simulations has proved to be an essential factor for improving the validity of results, as it quantifies the amount of the diffuse sound field in enclosed spaces. Measurement methods have been described in the norm ISO 17497. Available data, whose lack is still one of the weak points, are fairly growing. Moreover, the relationship between the physical quantity and perceptual aspects still remains unclear. Aim of this study is a first investigation toward the comprehension of the influence of scattering coefficient on the sound as perceived from the audience. The target is to quantify the just noticeable differences for variable scattering coefficients associated with lateral wall diffusers of a simulated concert hall. Several musical stimuli convolved with binaural room impulse responses are used as source signals for listening tests. Results focusing on perceptual aspects will be presented and discussed.
Inverse boundary and finite element formulations for the determination of high-frequency specific impedance.
Authors: Bockman Alexander , Xiang Ning
Published: March 2010

Material databases for consulting acousticians require accurate determination of specific impedance. Such data are typically gathered from the composition of data sets obtained from impedance tubes. In such tubes, the restriction of frequencies under test to those that satisfy a plane wave assumption for the tube geometry in question allows for the application of a one-dimensional transfer function analysis. Such tubes rarely achieve accuracy at the upper and lower ends of their operating spectra. Thus, the compositing of detailed data sets may produce significant error. For researchers of wave based methods of acoustic wave propagation, this represents a severe limitation. However, these data sets may be re-purposed for an extension of frequencies under test by the application of an inverse problem formulation of the boundary element method. The method accurately predicts data obtained within a larger impedance tube and further well extrapolates to data observed in a smaller impedance tube. Moreover, the method provides confidence in the consistency of specific impedance determination in composite data sets.
Assessing and regulating the impact of sound and vibration upon fish.
Authors: Hawkins Anthony
Published: March 2010

The generation of very high-sound levels in water has the potential to change the behavior of fish and in extreme cases cause injury. Such sounds may be generated by pile driving, seismic exploration, low-frequency sonar equipment, ships, and underwater dredging and drilling activities. Some land-based activities like drilling, excavation work, and vibroseis may also generate sound and vibration which subsequently enters adjacent water bodies like lakes and rivers. It has become commonplace for regulatory agencies to require the impact of these sound-making activities to be formally assessed for their impact upon aquatic animals, including fish. The procedures for carrying out these assessments vary and, in many instances, are poorly performed or subject to uncertainty. The uncertainties which come into play when impacts upon fish are assessed include lack of knowledge on the sensitivity and response of fish to sounds, the physical conditions surrounding sound generation and propagation, and the metrics to be applied to the stimulus received by the fish. This paper will consider those sound exposure criteria applied to fish for regulatory purposes and how they might be refined.
Including passive acoustic capability in Arctic ocean observing systems.
Authors: Moore Sue E. , Stafford Kathleen M. , Berchok Catherine L. , Melling Humfrey , Wiig Oystein
Published: March 2010

Over the past decade, long-term deployments of passive acoustic recorders have provided a new baseline on the seasonal occurrence of large whale species in remote regions of the world ocean. In the Arctic, passive acoustic sampling has identified both whale calls and sounds from anthropogenic sources (ships and seismic profiling), activities that are expected to increase with diminished sea ice cover. In 2008, NOAA capitalized on an opportunity to join on-going IPY projects by inclusion of recorders at three High Arctic mooring sites: one on the Chukchi Plateau and two on either side of Fram Strait. The recorders (AURAL-M2) provided a year of sub-sampled (9 min on/11 min off) recordings at 0.1 Hz to 4 kHz (8192 sampling rate), which encompasses the bandwidth of whale and ice seal calls. Data from the recorders were complemented by a suite of standard oceanographic measures from other instruments on the mooring line. Provisional results show novel occurrence of both marine mammal and anthropogenic signals in the High Arctic. To realize the vision of a Global Ocean Acoustic Observing Network [Dushaw et al. (2009)], passive acoustic technology must become a standard sampling component, especially in the Arctic during this time of rapid climate change.
Are they really not there? Using passive acoustics to overcome false absences in the study of vocal species that are rare, secretive, or distributed at low densities.
Authors: Rogers Tracey L. , Hogg Carolyn J. , Ciaglia Michaela B. , Cato Douglas H.
Published: March 2010

Estimating abundance and spatial use behavior can be challenging for marine species that are rarely sighted. This situation is exacerbated in the polar regions due to the peculiar logistical difficulties of working in the pack ice, which makes survey effort enormously expensive. Presented is a simple approach for modeling sounds per animal over a unit time as a relative index for species where there is information on the production of vocalizations (acoustic behavior including seasonal calling patterns, diurnal calling patterns, inter-individual stereotypy, inter-sexual stereotypy, audience effect, and predictable calling rate over a unit of time) and the detection range of those vocalizations (survey distance—theoretical estimates calculated with call intensities). We focus on an Antarctic pack ice seal, the leopard seal, and Hydrurga leptonyx, as estimating abundance from survey effort faces challenges. Our case study shows that with the advent of more sophisticated marine engineering coupled with effort focused on the pertinent parameters of acoustic behavioral ecology we can open up the scope to study the behavior of rare, secretive, or low-density species across a range of site occupancy studies, density, and habitat use at a time when we need to develop cost efficient tools to glean an understanding of what is happening in these most vulnerable locations.
Ambient noise in the Chukchi Sea, July 07 Oct 2009.
Authors: Martin Bruce , Delarue Julien , Hannay David
Published: March 2010

Shell Exploration and Production Company and ConocoPhillips Alaska have commissioned a multi-year acoustic study of marine mammal vocalization activity and ambient sound levels in the Alaskan Chukchi Sea. A large acoustic dataset, collected between July 2007 and October 2009, has been analyzed and has provided a wealth of information about the seasonal soundscape of the Chukchi Sea. This paper presents the ambient noise results throughout the acquisition time period. The analysis investigates the contributions made to ambient levels by shipping, marine mammals, seismic activity, and ice. We will show how short term weather conditions can strongly affect the noise levels measured on bottom-moored recorders. Certain mammal vocalizations such as bearded seal trills and bowhead moans can dominate ambient noise levels over large time periods.
Where do the Chukchi Sea fin whales come from? Looking for answers in the structure of songs recorded in the Bering Sea and Western North Pacific.
Authors: Delarue Julien , Mellinger Dave K. , Stafford Kathleen M. , Berchok Catherine L.
Published: March 2010

Fin whales are common throughout the North Pacific and have recently been detected acoustically as far north as the northeastern Chukchi Sea. Non-acoustic evidence suggests that North Pacific fin whales are segregated into two populations wintering along the Asian and North American coast with at least some animals intermingling in the summer in the Bering Sea-Aleutian Islands area. Male fin whales produce regionally distinctive songs which are likely indicative of population structure. In this study we evaluated the relationship of fin whales recorded in the northeastern Chukchi (2007 and 2009) and southeastern Bering (2007–2008) seas by comparing the structure of their song. Additionally, we investigated whether fin whales detected in these areas could be part of an Asian population by comparing their songs to those recorded near the Emperor Seamounts in the western North Pacific (2007). The results will be discussed in light of the current knowledge on North Pacific fin whale population structure.
Analysis of marine mammal detections from the Bering Sea relative to a 10 day retreat of sea ice in March 2009.
Authors: Denes Samuel L. , Miksis-Olds Jennifer L.
Published: March 2010

Patterns of marine mammal detections from an adaptive sub-sampling acoustic recorder deployed in the Bering Sea are related to a temporary retreat of sea ice. Ice coverage data from the NOAA Ice Desk showed a 10 day period in March 2009 during which no ice was detected over an NOAA oceanographic mooring equipped with the acoustic recorder. During periods of ice coverage, bearded seal and bowhead whale vocalizations dominated the soundscape and were the primary sources triggering a high-duty cycle sampling mode. Bearded seal vocalizations decreased immediately following the transition from ice cover to open water. The sub-sampling protocol limits the number of short duration sound clips recorded each day in order to conserve power and storage space during year deployments. Periods with ice coverage preceding and following the ice retreat exceeded the maximum daily limit within the first 2 h of the day. During the first day of open water, there were only two detections. Temporal variation in the number of bearded seal detections is highly coupled to sea ice characteristics, illustrating the importance of this environmental feature to the bearded seal mating system. [Work supported by ONR.]
High-intensity focused ultrasound as a potential treatment modality for heterotopic ossification.
Authors: Poliachik Sandra L. , Khokhlova Tatiana D. , Bailey Michael R.
Published: March 2010

Heterotopic ossification (HO) is the growth of bone in abnormal locations such as soft tissue. HO is a frequent secondary complication of common trauma, e.g., amputation or spinal cord injury. HO causes pain, motion restriction, and poor prosthetic fitting. Current HO treatments include non-steroidal anti-inflammatory drugs, radiation, surgery, and shock-waves, but HO often returns. In this work, feasibility of HO treatment using high-intensity focused ultrasound (HIFU) is studied. HIFU may induce destruction of HO nodules by a combination of thermal ablation and mechanical erosion through bubble activity. In preliminary experiments bone sections from rodent proximal tibiae embedded in polyacrylamide gel were used as tissue phantoms; subsequent experiments were performed on HO induced in a mouse calf muscle. A 2-MHz focused transducer was used to generate pulses of shock waves with peak positive pressure of 67 MPa, duration of 10–100 ms, and 1%–10% duty cycle. High-resolution microCT imaging of the samples was performed prior to and following HIFU exposure. Both mechanical damage of the porous bone structure and thermal denaturation of the bone were observed. The data obtained suggest that HIFU may be an option for non-invasive treatment of HO. [Work supported by NSBRI_SMSTO1601 and NIH_DK007742].
Tissue erosion using millisecond boiling in high-intensity focused ultrasound fields.
Authors: Canney Michael S. , Khokhlova Tatiana D. , Wang Yak-Nam , Khokhlova Vera A. , Bailey Michael R. , Crum Lawrence A.
Published: March 2010

High-intensity focused ultrasound (HIFU) transducers can be operated at high-pressure amplitudes of greater than 60 MPa and low-duty cycles of 1% or less to induce controlled bubble activity that fractionates tissue. The goal of this work was to investigate fractionation not from mechanically induced cavitation but from thermally induced boiling created by HIFU shock waves. Experiments were performed using a 2-MHz HIFU source. The focus was placed in ex vivo bovine heart and liver samples. Cavitation and boiling were monitored during exposures using a high-voltage probe in parallel with the HIFU source and with an ultrasound imaging system. Various exposure protocols were performed in which the time-averaged intensity and total energy delivered were maintained constant. The types of lesions induced in tissue ranged from purely thermal to purely mechanical depending on the pulsing protocol used. A pulsing protocol in which the pulse length was on the order of the time to boil (of only several milliseconds) and duty cycle was low (<1%) was found to be a highly repeatable method for inducing mechanical effects with little evidence of thermal damage, as confirmed by histology. [Work supported by NIH EB007643, NSBRI SMST01601, and RFBR 09-02-01530.]
Transcranial microbubble destruction by using re-focusing ultrasound.
Authors: Cheng Po-Wen , Li Pai-Chi
Published: March 2010

Administration of microbubbles (MBs) during transcranial Doppler monitoring further accelerates ultrasound-enhanced thrombolysis. However, low efficiency of transcranial ultrasound transmission resulting from phase aberrations through skull is still an obstacle. To alleviate this, re-focusing by phase aberration correction using echoes from microbubbles can be performed. Two re-focusing methods were designed for transcranial MB destruction. One is adjusting the emission phases derived from the channel-to-channel correlation of received signals. The other is simply adjusting the transmit focal depth. This is possible because the phase aberrations typically result in approximately parabolic delay errors. Focusing quality was compared using finite difference time domain simulations, and the mechanical index (MI) distributions were calculated as indices for likelihood of microbubble destruction. Using the correlation based methods, the beamwidth becomes 45.5% narrower than that by using the time reversal method. The MI can also be increased by 15.9% while keeping it under safety range. Adjusting the transducer position, on the other hand, can also enhance the focusing efficiency and improve efficiency of ultrasound-enhanced thrombolysis. It is also easy to implement using current clinical systems.
Cooperative radiation and losses in bubble clusters.
Authors: Thomas Derek C. , Ilinskii Yurii A. , Hamilton Mark F.
Published: March 2010

In existing models for single bubble dynamics it is necessary to account for radiation damping, a consequence of fluid compressibility. A similar correction is necessary when modeling systems of coupled bubbles. The coupling alters the collective dynamics and therefore the acoustic power radiated. In the linear approximation and for compact clusters in which the bubbles pulsate in phase, the radiation damping per bubble increases in proportion to the number N of bubbles in the cluster, and the acoustic power is N times greater than is radiated by the cluster in the absence of bubble interaction. The latter effect is relevant to passive detection of cavitation noise as an indicator of the onset and degree of cavitation in therapeutic applications such as shock wave lithotripsy and high-intensity focused ultrasound. The effect that collective radiation damping has on the dynamics of several simple systems is considered for both small and large pulsations, and the relative magnitude of the effect is compared with damping due to viscosity and thermal conductivity. [Work supported by the ARL:UT McKinney Fellowship in Acoustics and NIH DK070618.]
Gas content of the medium surrounding a stone has a significant effect on the efficiency of stone breakage in shock wave lithotripsy.
Authors: Pishchalnikov Yuri A. , Zancanaro Anthony J. , Williams James C. , McAteer James A.
Published: March 2010

In shock wave lithotripsy inertial collapse of cavitation bubbles produces daughter microbubbles [Y. A. Pishchalnikov et al., BJU Int. 102, 1681–1686 (2008)]. This will cause proliferation of bubbles only if daughter microbubbles survive until the arrival of the next shock wave (SW). While the time interval between SWs is determined by the firing rate of the lithotripter, the dissolution time of microbubbles depends on concentration of dissolved gas in the water. Thus, the same firing rate may produce different cavitation fields depending on the gas concentration. We assessed how the concentration of dissolved gas in the water tank affected SWs and the efficiency of stone comminution. More numerous bubbles generated in nondegassed water caused a dramatic reduction in the trailing negative-pressure component of the SWs, while the leading positive-pressure phase remained almost unchanged. It required 3.5 times more SWs to break stones in nondegassed water than in water degassed to 30% (P<0.001). This suggests that changes in temporal profiles of the SWs associated with cavitation are responsible for reduced efficiency of stone comminution observed in dense cavitation fields, regardless of whether these denser cavitation clouds were generated by using a faster rate or higher gas content. [Work supported by NIH-DK43881.]
Hydrophone array for instantaneous measurement of lithotripter fields.
Authors: Kracht Jonathan M. , Ketterling Jeffrey A. , Cleveland Robin O.
Published: March 2010

Electrohydraulic lithotripters employ a spark placed within a hemi-ellipsoidal reflector to generate shock waves (SWs). The shot-to-shot jitter in the spark location results in variability in acoustic measurements, e.g., 50% variation in peak positive pressure. Field measurements with a single-element hydrophone therefore only provide average field properties over many SWs. The ability to obtain an instantaneous “snapshot” of the sound field would have broad implications for advancing the understanding of how lithotripters fragment stones and damage kidney tissue. Here linear hydrophone arrays consisting of 20 elements were created by bonding a piezopolymer film to copper-clad polyimide. An array pattern was etched on the copper to provide individual connections to the 20 elements. Failure testing of the hydrophone array was conducted in a piezoelectric lithotripter that generated 60 MPa peak pressure. The sensitivity of the hydrophone remained relatively constant through the first 500 SWs and then gradually decreasing over a 500–1000 SW period. This reduction was attributed to damage from cavitation activity and was confirmed by visual inspection after testing. A new hydrophone was developed and results from measurements of an electrohydraulic lithotripter will be reported. [Work supported by the National Institutes of Health (DK081119 and DK43881).]
Learning by playing: Musical acoustics of found objects.
Authors: McNeil Laurie
Published: March 2010

“Teaching by telling” has been shown to be ineffective in many physics contexts, and acoustics is no exception. In my 10 years of teaching, a freshman seminar “The Interplay of Music and Physics,” about the physics of musical instruments, I have learned that there are some concepts that students learn only by making their own instruments and discovering how the success of the instruments depends on them. My colleague Professor Brent Wissick of our Department of Music and I have team-taught this class to college students of a broad range of backgrounds and majors. The students design and build stringed and wind instruments out of whatever they can find lying around their dorm rooms. At the end of the semester, they give a concert of music of their own composition, played on the instruments they have created. In this presentation, I will discuss what we have learned about how such activities teach the students acoustical principles in ways that more conventional means do not accomplish.
Homemade musical instruments for the classroom.
Authors: Senior Thomas J.
Published: March 2010

Pan pipes produced using drinking straws provide a very inexpensive way for students to study the nature of resonant columns and musical scales. A slide whistle is also easily made using the straws. Most students easily learn to produce tones from the pan pipes/slide whistle. For situations where too many loud sounds would be undesirable, the “Palm Pipe” offers a similar learning experience. The palm pipe is a single length of PVC pipe that can be played by striking the palm on the end of the tube to produce a tuned percussive sound. Methods for the production of slide whistles, pan pipes, and palm pipes will be described and demonstrated in this presentation. A few other “musical” devices will be shown as time permits, including a stadium horn and a thunder drum.
Homemade musical instruments.
Authors: Wiseman Ann Sayre
Published: March 2010

When the creative arts were dropped from the school curriculum for lack of money in 1972, as Program Director at the Boston Children’s Museum Visitor Center (Jamaica Plain), we created low-cost learning by doing workshops for teachers using available materials. Out of this an orchestra of good sounds was born. Good sounds found in the kitchen and junk yard by tapping everything to hear its note. We made excellent conduit-pipe xylophones, drums, horns, strings, and percussion instruments hung from a frame. A low cost musical program any teacher could include in the curriculum, involving math, history, and research, the kind of learning you never forget when making useful things by hand with your own initiative. These recipes became Making Things Handbook of Creative Discoveries, winning awards, and freely photocopied by teachers who wrote this book is my classroom bible. The handmade orchestra became another book: Making Musical Things and in 2002 Storybook Press republished it as Making Music, including John Langstaff’s Inovative Clock Orchestra and the Art of Conducting. As an Expressive Therapist in 2005 with International exchange groups, we took these workshops abroad to show students and medical professionals the healing powers of the creative process.
Petrol-chemical plant noise models: Noise surveys, model development and validation.
Authors: Forschner, Sr. Hans , Steedman Jim
Published: March 2010

Developments in computer modeling & presentation software has changed how acoustical engineers approach noise planning, mitigation, trending projects. The ability to quickly and accurately develop a three dimensional (3-D) noise model of a project area and/or to create noise contours from measured data allow for a more rigorous analysis in a shorter period of time while maintaining a level of consistency with current acoustical engineering standards and practices. This paper describes the procedures and methods for generating 3-D computer noise models, validating noise models, and graphically comparing measured and predicted noise levels.
Noise prediction for industrial facilities.
Authors: Probst Wolfgang
Published: March 2010

The methodologies used to predict the noise caused by industrial facilities are presented and ranked. There are a lot more scientifically based methods that use certain approximations to solve or apply the wave equation in a layered atmosphere. These methods are usable to predict even meteorological influences with long distance propagation but can hardly be used with complex source and surface geometries for receivers nearby. This latter case is the preferred application of engineering models using simple geometric ray approximations. The techniques to use it with complex and extended sources are presented. This includes the use of parametrized source description for technical sources such as motors, gears, pipes, and cooling towers and numerical aspects such as projection or angle scanning. It is shown how an intelligent software technique like the “object tree” supports the generation of variants of a plant including different steps of noise reduction measures.
Suggested modifications to the American Society for Testing and Materials E-477.
Authors: Lilly Jerry
Published: March 2010

ASTM E-477 is the current standard test method used in North America for evaluating the acoustic and aerodynamic performance of duct silencers. The test method uses, at a minimum, a source chamber, a test duct (that includes a test specimen), and a reverberation chamber. If testing under flow is desired, the system also requires a fan chamber that can provided quiet airflow through the test duct. The results of the test method yield silencer insertion loss, self-generated noise, both as a function of acoustic frequency and flow velocity, and pressure drop. There are several problems with the current test method, some that are being addressed by the ASTM working group that is responsible for the development and maintenance of this standard. This paper will highlight the most significant problems associated with the current standard and propose modifications to the standard that should, if adopted, improve the intra-laboratory reproducibility of the test results.
Evaluation of hydraulic silencers.
Authors: Earnhart Nick , Marek Ken , Cunefare Ken
Published: March 2010

Hydraulic silencers are devices used to mitigate fluid-borne noise in fluid power systems. Fluid-borne noise may be produced by positive-displacement pumps and interacts with system components to generate vibration and air-borne noise. It is of interest to quantify the performance of silencers with regard to the input reflection coefficient and transmission loss. A test rig has been constructed that uses a six-sensor method to determine these quantities. Construction and methodology will be presented along with results for apparent transmission loss comparing a commercially available silencer to a novel prototype.
Optimal silencer baffle positioning within an air handling unit.
Authors: Storm Mark
Published: March 2010

A stationary bank of rectangular modular sound traps or free-standing sound attenuating parallel baffle “columns” installed within a central station air handling unit (AHU) is a common technique for controlling fan noise in a ducted heating, ventilating, or air-conditioning system. Recent design developments by a leading custom AHU manufacturer offer the ability to move these columns within the AHU, so that they can be positioned close to a noise source (e.g., a plenum fan) during operation and pushed away in order to allow AHU component inspection and maintenance. While the columns have a fixed shape and set of features (perforated facing, sound absorbing fill, etc.), this study examines their sound attenuating performance relative to position variance from the source (i.e., fan noise) and the AHU inlet or outlet port at which desired sound levels are often specified. The objective, should such column position variance has meaningful influence on net transmission loss or noise reduction for the AHU, is to estimate optimal geometry(ies) than can be tested and subsequently established as guidance for superior AHU noise control design.
Noise reduction under the hood of a portable air-purifying respirator system by means of a muffler insert.
Authors: Marsh Robert
Published: March 2010

Speech intelligibility is probably never more important than in emergency situations. Recently a manufacturer of a portable air-purifying respirator system requested assistance in lowering the noise level that users were encountering under the hood. In operation, the noise level and sound quality in the hood were reported to be objectionable and concern about the ability of personnel to communicate effectively was expressed. Typically, choosing quieter components would be the first step in evaluating various acoustical treatment packages. However, since the components of the blower exposed to the air path were already NIOSH approved, choosing an alternate blower was not a viable option. Polymer Technologies embarked on a study that evaluated the blower and the paths to the receiver, successfully providing attenuation options that could be easily implemented. Prototype testing proved that substantial acoustical attenuation could be achieved by utilizing an in-line muffler lined with acoustical absorption material. The maximum benefit achieved was in excess of a 14 dBA reduction in the overall sound pressure level under the hood at ear level and resulted in what was considered to be a more “acceptable” sound.
Comparison of sea modeling approaches for vibration transmission through beam structures.
Authors: Vaz Ignatius , Gardner Bryce , Cotoni Vincent , Wang Shuo
Published: March 2010

Transmission through beams can become a significant path in many structure-borne problems, especially in aircraft or launch vehicles. Statistical energy analysis (SEA) is widely used for the vibro-acoustic modeling of high-frequency problems. However, in a system-level SEA model, even at higher frequencies, some beams can exhibit low-modal behavior and might not be a good SEA representation. Vibration transmission through beams involves both resonant and non-resonant transmission paths. Typically the non-resonant path is dominant at low frequencies and the resonant path at high frequencies. This paper describes various modeling approaches for describing the transmission through beams over a broad frequency range. SEA modeling techniques will be compared to the hybrid FE-SEA method, energy flow method, and the finite element method for various beam configurations. Modeling beams under pre-stressed conditions is also investigated.
A user friendly, cost-effective and portable tool for locating multiple arbitrary sound sources in three-dimensional space in real time.
Authors: Zhu Na , Wu Sean F.
Published: March 2010

In many engineering applications, it is highly desirable to quickly and easily locate sound sources even if the accuracy and spatial resolution are not very high. Most systems and tools available in the market are based on beamforming technology, which are portable, easy to use, and easy to understand. However, beamforming requires a prior knowledge of the general location of a target source and a large number of microphones, which increases the overall costs. Also, its frequency range is limited by the size of the microphone array. In this paper, a user friendly, cost-effective and portable system for locating multiple arbitrary sound sources in three-dimensional space in real time is presented. In particular, this system requires four microphones only, covers the entire audible frequency range, and does not require any prior knowledge of whereabouts of the target sources. The underlying principle of this methodology is a hybrid approach consisting of modeling of sound radiation from point sources in a free field, triangulation, and signal processing techniques. Both numerical and experimental validations are demonstrated and an error analysis in locating arbitrary sources is performed. The main cause of errors is found to be due to the fact that the basic formulations are for a free field, whereas in practice the measurement environment is a non-free field.
The daily rhythm of the soundscape “Nauener Platz” in Berlin.
Authors: Schulte-Fortkamp Brigitte
Published: March 2010

Rhythm in soundscape characterizes the time structure of the soundscape with its distinctive sound events embedded in comprehensive acoustical scenery. The “Nauener Platz” evaluation was balancing between acoustic measurements, architectural planning, and the expertise from people living in the area to contribute to the reconstruction of the place. Information of a new understanding and concept of a public place was underlying the development of the new Soundscape based on noise reduction and audio islands playing the sound people like to live with in that area. This Soundscape will be provided here in musical performance also explaining the cultural and social issues behind. The Soundscape Project is a module of the Project “Nauener Platz-Remodelling for Young and Old” in the framework of the research program “Experimental Housing and Urban Development (ExWoSt)” of the “Federal Ministry of Transport, Building, and Urban Affairs (BMVBS)” by the “Federal Office for Building and Regional Planning (BBR).” It is related to the fields of research (ExWoSt) concerned with “Innovation of Urban Neighbourhoods for Families and the Elderly.”
Numerical and experimental studies for reducing the transmission of low frequency sound through windows.
Authors: Jessop Andrew M. , Li Kai Ming , Bolton J. Stuart
Published: March 2010

Windows are a common path for low-frequency sound transmission from outside to inside due to their light weight and low damping. The use of non-periodic stiffening elements to increase window transmission loss without reducing visibility is considered here. The effect of elastic mounting of the window to the surrounding structure as a possible contributor to low-frequency noise transmission was also examined. A finite element model allowing for panel stiffening, either by clamping or by adding variable-stiffness beams within the panel, was constructed; the model allowed for variable positioning of such elements. Several double-panel configurations, representing double-pane windows typically used in energy-efficient constructions, were also modeled with various clamped-stiffening elements. Scale-model measurements of transmission loss of aluminum panels were performed to verify the character of the predictions with variable edge stiffness as used in the numerical models. The computational results show that low-frequency sound below 150 Hz can be reduced by several dB through careful use of stiffening elements and that resilient mounting can reduce the transmission loss of low-frequency sound through windows.
Noise attenuation by two-dimensional sonic crystals made of rubber crumb.
Authors: Sanchez-Dehesa Jose , Garcia-Chocano Victor M. , Torrent Daniel , Cervera Francisco , Cabrera Suitberto , Simon Francisco
Published: March 2010

It is shown that sonic crystals consisting of cylindrical rods made of rubber crumb can be used as efficient structures to attenuate noise in a wide range of frequencies. A structure made of three rows of cylinders (3-m height) has been fabricated and its isolation properties have been characterized in a transmission chamber. Two different numerical algorithms have used to simulate the experimental characterization. A good agreement between theory and experiment is obtained and gives support to design barriers based on this technology. [Work supported by MICIIN of Spain.]
Matched field processing applied to diffraction of sound around 90 deg corners: Modeling and experiment.
Authors: Singh Victor , Knisely Katherine E. , Grosh Karl , Dowling David R. , Yonak Serdar H.
Published: March 2010

Acoustic diffraction allows sound to travel around opaque objects and therefore may allow beyond-line-of-sight sensing of remote sound sources. This presentation reports simulated and experimental results for detecting and localizing sound sources at blind city-street intersections based on shadowed microphone array measurements. The generic geometry includes a point source, a solid 90 deg wedge, and a receiving array that lies entirely in the shadow defined by the source location and the wedge. Sound source detection and localization performance are assessed via matched-field (MF) ambiguity surfaces as a function of source frequency, receiving-array configuration, and received signal-to-noise ratio for the Bartlett and minimum variance distortionless MF processors. Here, the sound propagation model is developed from a Green’s function integral treatment and the geometric theory of diffraction. The simulations suggest that sound sources may be localized by fully shadowed arrays for signal-to-noise ratios as low as 20 dB when ambiguity surfaces from several different source frequencies are incoherently combined. The experiments were conducted using an approximate 50-to-1-scaled tabletop model of a blind city-street intersection and chirp signals from 500 Hz to 30 kHz and suggest that the propagation model must be improved before the simulations’ performance can be reached.
The statistical interpretation of a simple ambient noise model.
Authors: Evans Richard
Published: March 2010

Theoretical analyses of the statistics of ambient noise levels can yield distributions that are either narrow and symmetric, or broad and non-symmetric [I. Dyer, J. Acoust. Soc. Am. 53, 564–570 (1973)]. Their standard deviations vary between nearly 0 and 5.6 dB. The assumptions regarding the nature of the noise source are the key in determining what distribution to expect. A simple computational model that exhibits both extremes, of the potential statistical distributions, can help in understanding what assumptions determine the statistics. The paper presents a simple ambient noise model that allows such a statistical interpretation.
Model-data comparisons of deep water ambient noise.
Authors: Murray James J. , Worcester Peter , Dzieciuch Matthew , Heaney Kevin D.
Published: March 2010

During the North Pacific Laboratory (NPAL) Philippine Sea 2009 experiment, a distributed vertical line array (DVLA) was deployed for several weeks in the northern Philippine Sea. The array, described in detail in a previous talk, consisted of two 1000-m sections, one spanning the sound channel axis and the other covering the deep ocean, extending from above the surface conjugate depth down to within roughly 100 m of the bottom. In this paper, a hybrid propagation model for handling low-frequency ocean noise will be presented. The model uses analytic solutions (rays) for ranges to 5 km, the parabolic equation for ranges from 5 to 100 km, and normal modes for ranges beyond that. The model predicts ambient noise levels vs depth. The fall off of the ambient noise with depth below the surface conjugate has been reported. The level of the fall off and its frequency dependence are sensitive to the local geo-acoustics. A geo-acoustic inversion will be performed using a range-independent version of the acoustic model with Monte-Carlo realizations of surface ship distributions.
Characteristics and variability of ambient noise in the South China Sea basin.
Authors: Chiu Ching-Sang , Joseph John E. , Miller Christopher W.
Published: March 2010

A hydrophone was moored at mid depth in the South China Sea basin from November 2005 to October 2006. Operated with a 1-min-on and 14-min-off duty cycle and sampled at 1.6 kHz, the measured time series captures the spectral characteristics and variability of the ambient noise in the 0–800-Hz band over an annual cycle. In this paper, we provide a description on the daily, monthly, and seasonal variabilities and variances in the measured noise spectrum and band levels. In order to gain insights into the predictability of the ambient noise field in this marginal sea, the interpretation of the data is facilitated with historical shipping density data and nowcast wind fields from the Navy Operational Global Atmospheric Prediction System (NOGAPS). Attention is made to the evolution of the ambient noise spectra during major storm events. Intermittent noises are also examined. The potential sources for these intermittent noises are discussed. [Research sponsored by the Office of Naval Research.]
Three dimensional parabolic equation modeling of an internal wave event during Shallow Water 2006.
Authors: Dossot Georges A. , Miller James H. , Potty Gopu R. , Lynch James F. , Lin Ying-Tsong , Badiey Mohsen , Smith Kevin, B.
Published: March 2010

During the Shallow Water 2006 (SW06) experiment, a J-15 acoustic source deployed from the Research Vessel Sharp transmitted broadband (100–500 Hz) chirp signals 15 km away from a vertical line array. The array was intentionally positioned near the shelf-break front and in an area where internal waves are known to occur. During the same time an internal wave, “Event 44,” passed through the sound field such that the internal wave front was near parallel to the acoustic transmission path. Measured data show substantial intensity fluctuations that vary over time and space due to complex multimode and multipath (both two and three dimensional) interference patterns. Of specific interest are fluctuations of measured intensity preceding the internal wave’s arrival. Additionally, depth variability of the measured acoustic intensities can be attributed to a warm water intrusion coinciding with the internal wave event. This presentation shows recent modeling results using the experimental geometry, acoustic signal parameters, and a simulated oceanographic environment based on environmental moorings and ship-born sensors. A new version of the three-dimensional Monterey–Miami parabolic equation code, which incorporates a user-defined sound speed field, is used. [Work sponsored by the Office of Naval Research.]
Calculating the waveguide invariant for non-ideal waveguides.
Authors: Cockrell Kevin L. , Schmidt Henrik
Published: March 2010

The waveguide invariant describes striations in a range versus frequency plot of a waveguide’s Green’s function. Analytic expressions for the waveguide invariant only exist for a few select waveguides, but experiments and simulations have shown that the waveguide invariant is approximately equal to unity for almost all realistic shallow-water waveguides. A quasi-analytic method will be presented for estimating the value of the waveguide invariant in waveguides with arbitrary sound speed profiles, including the effects of a bottom fluid halfspace. The method is approximate but allows for an intuitive understanding of why the value of the waveguide invariant does not strongly depend on the details of the sound speed profile.
The three-dimensional acoustic field of primary arrivals from a seismic airgun array.
Authors: Tashmukhambetov Arslan M. , Ioup George E. , Ioup Juliette W. , Sidorovskaia Natalia A. , Niculescu Anca , Newcomb Joal J. , Stephens James M. , Rayborn Grayson H. , Summerfield Phil
Published: March 2010

The Source Characterization Study 2007 (SCS07) measured the three-dimensional (3-D) acoustic field of a seismic airgun array. The Littoral Acoustic Demonstration Center (LADC) performed the experiment, collecting acoustic and related data on three moored hydrophone arrays and one ship-deployed hydrophone array which together spanned the full water column. Sensitive and desensitized phones were deployed at each position to extend the dynamic range. An ultra short baseline localization system was deployed with the EARS moorings to provide array shape. With postanalysis this results in time-dependent positions for each of the acoustic sensors. Every channel is calibrated. A seismic source vessel shot a series of lines designed to give detailed angle and range information concerning the field of the primary arrival. Peak pressures, sound exposure levels, total shot energy spectra, and one-third octave band analyses give important insights into details of the acoustic field. Images of these quantities are generated to show dependence on emission and azimuthal angles and range. 3-D visualizations and two-dimensional cuts through the data are shown. [Research supported by the Joint Industry Programme through the International Association of Oil and Gas Producers.]
Defense Advanced Research Projects Agency (DARPA) Blast Program–Preventing violent neurologic trauma.
Authors: Ling Geoffry
Published: March 2010

DARPA is directing a comprehensive program to determine the causes of explosive neurological trauma. The current status of the program will be discussed.
Blast associated traumatic brain injury.
Authors: Moore David F. , Jaffee Michael S.
Published: March 2010

Blast tissue injury is familiar problem in military medicine for gas filled organ such as the lung and gut. Solid tissue organs such as the brain have more recently come into prominence in relation to blast through the current conflicts in Iraq and Afghanistan with blast injury regarded as the “signature injury” of these wars. Enhancements in personal protective equipment allowing survivability of abdominal and thoracic injury may have exposed a previously obscured brain vulnerability. Free field explosive detonation results in rapid conversion of chemical energy into the shock wave and pressure field, the kinetic energy associated with fragments and shrapnel, thermal energy, chemical products of detonation, and electromagnetic radiation. The variation and coupling of these physical fields result in a uniquely complex problem in understanding blast biological effects especially in such a functionally intricate organ as the brain. The clinical effects of concussion following blast exposure are still undergoing evaluation most notably in the military context. Significant effort is, however, underway to determine the relative contributions of shock wave stress, the effects of cavitation, and the effects of the electromagnetic field induced by the piezo-electric effect of the skull experiencing blast associated stress in brain injury and recovery.
The Strad 3D Project: Scientists, musicians, and violinmakers study three classic violins.
Authors: Zygmuntowicz Samuel
Published: March 2010

In 2006 the first ever three dimensional (3-D) modal laser scanning of violins was performed on three Guarneri and Stradivari violins, along with acoustic scanning and subjective evaluations. CT scanning was used to determine shape and density properties and to provide a 3-D model for future finite element analyses. These studies and images have been combined with empirical observation, photography, music recordings, and traditional documentation in an interdisciplinary survey of unprecedented scope presented in a two DVD set. From my violinmaker perspective acoustic studies of the violin have had remarkably little impact on the practice of violinmaking. Similarly, traditional empirical traditions continue to be effective in guiding violinmakers, without transferring clinically useful insights to the scientific researchers. This split is reflective of divergent vocabulary, goals, and the requirements of quantitative evidence. The Oberlin Violin Acoustics Workshops has attempted to bridge this gap by bringing together researchers, engineers, musicians, and violinmakers for interactive study, with equal weight given to these separate disciplines. The Strad3D project grows out of that ongoing collaboration and is intended to generate and collect images, documentation, and data that can be viewed and utilized from multiple perspectives and to further a mutually comprehensible dialog.