bluuebunny/crossref_metadata_2025 huggingface dataset:
Music and science: Workshops for teachers in elementary schools
Authors: Hansen Uwe
Published: July 2012

A number of workshops have been conducted with support from ASA Technical Initiative funds. The emphasis in the workshops is on assisting teachers to use music as a vehicle to introduce science concepts. A monochord is constructed. Teachers are provided a tuning fork, a resonance tube, a spring, a ‘‘singing’’ tube, and material to construct a monochord. Concepts discussed include wave properties such as wavelength, frequency, amplitude, phase, and speed of propagation. In addition the connection to music is made by observing standing waves and relating frequency ratios to musical intervals. The teaching approach and workshop content will be illustrated in the presentation.
Websites, video, and audio recordings for informal education in acoustics
Authors: Rossing Thomas D.
Published: July 2012

It is becoming increasingly easier to study acoustics (or any subject) outside the classroom walls. This is partly due to the ready availability of learning materials on the Internet, and video and audio recordings that lend themselves to home study and informal study. We discuss some of the materials that are now available for informal education in acoustics.
How many meta-analyses fit on the head of a pin?
Authors: Fidell Sanford
Published: July 2012

Meta-analyses of social survey findings on source-specificity of annoyance indicate that the prevalence of annoyance attributable to aircraft noise may be somewhat greater than the prevalence of annoyance attributable to noise produced by surface traffic of similar cumulative level. Likewise, the prevalence of annoyance induced by impulsive noise may differ from that of general transportation noise of similar level. But how annoyed are people who live next to highways that happen to be located near runway ends by the combination of aircraft and surface traffic noise? How annoyed are people who live next to railroad tracks that pass by shooting ranges? One approach to modeling the total annoyance engendered by exposure to multiple noise sources has been to assume that the interactions among source-specific annoyances are negligible, so that total annoyance can be expressed as some form of summation of individual source-specific annoyances. This simplifying assumption may not always be warranted, nor is it often the case that social and physical measurements yield data precise enough to reliably distinguish among alternate summation hypotheses. Policy-related interpretations of the findings of studies of combined annoyance of noises of differing origin should thus be viewed with a healthy skepticism.
The acceptor principle in German regulations for environmental noise
Authors: Gottlob Dieter , Ortscheid Jens
Published: July 2012

According to the acceptor principle, environmental exposure shall be assessed from the point of view of the affected persons, i.e., exposures from various sources shall be evaluated as a whole. While the acceptor principle is well established in environmental fields such as air pollution, it is rarely applied in noise regulations. In general, the noise sources are assessed separately. Sometimes the existence of residual noise leads to reduced requirements for the specific noise source under consideration. Important obstacles against the practical application of the acceptor principle in some countries are inconsistent noise descriptors, measurement and prediction procedures for different sources, and different legal approaches to control noise. Furthermore, there are not enough social field studies available which deal systematically with the assessment of the exposure of several noise sources. Therefore, the proposed procedures for assessing situations with combined noise sources are still lacking scientific support, especially concerning the temporal and spatial distribution of noise sources. In this lecture, the current state of the enforcement of the acceptor principle in German noise regulations will be presented. Some discussions within the framework of the new European noise policy will be reported.
The importance of loudness functions in assessing noise annoyance
Authors: Schomer Paul
Published: July 2012

Outdoors, Schomer et al. have shown that loudness weighting according to ISO 226 can be used to great advantage as a direct substitute for A-weighting. That is, loudness-weighted sound exposure level (LLSEL) can be used as a direct substitute for A-weighted sound exposure level (ASEL). LLSEL, computed with a time constant commensurate with the time constant of the human hearing process, provides significantly better correlation with community response across different noise sources than does ASEL. Indoors, room noise criteria (RNC) curves have been developed using these same human hearing function considerations. The RNC curves and associated computational procedure successfully bridge the gap between the PNC curves of Beranek and the RC curves of Blazier. Taken together, this body of outdoor and indoor research results shows the great importance of the human hearing function in assessing noise annoyance.
How to define synergetic effects of combined noises
Authors: Schulte-Fortkamp Brigitte
Published: July 2012

Evaluation of noise annoyance has to take into account the multidimensionality in a given social situation. Noise annoyance research needs an interdisciplinary procedure methodologically including acoustics, physics, psychology, and sociology. People’s judgments depend on multiple factors like environmental area, noise source, characteristic of noises, number of noise events over a day, subjective experience with noises, the social situation, etc. Judging annoyance includes a wide range of variability, which is highly correlated with the variability of living conditions. Considering those contextual conditions of noise annoyance judgments is one important procedure regarding the measurement on annoyance toward noise of combined sources. Taking into account the knowledge on annoyance judgments relying on different subject-oriented conditions, a measurement is needed which refers to objective and subjective parameters. The combination of noise sources is for the judgment of annoyance as well as important subjective parameters. Moreover, the relationship of both defines the background for assessments. Based on an analysis of interviews concerning noises from different sources and on the literature [e.g., Fields et al. (1998), Hatfield and Job (1998)], a proposal for an approach in noise annoyance measurement will be presented.
A statistical method for the evaluation of discrete noise sources submerged in background
Authors: Heiss Alois , Harrison Robin T.
Published: July 2012

Sometimes it is necessary to assess the contribution of a discrete source to the total soundscape even when the overall level of the discrete source is submerged in the background noise. An example of such a situation is the quantification of annoyance from the noise of a factory in the presence of the suburban background of traffic noise, children, birds, etc. The traditional method of making such an assessment, computation and scaling of signal-to-noise ratios in 1/3-octave bands, is not available if spectra of both the discrete source and the background cannot be obtained. Also, this method requires the use of sophisticated instrumentation and time-consuming measurements. This paper describes a methodology which extracts adequate statistical information from stochastic signals to determine the confidence intervals of percentile levels. The Leq of a discrete source in a noisy background can be determined with known high resolution from easily obtained field measurements. The procedure does not depend on frequency analysis. The method is currently being expanded to enable evaluation of level distribution of the source. Basic theory that supports the method is presented and software that facilitates its use is described. An example of its application is given.
Recent development in European legislation concerning construction equipment
Authors: Irmer Volker K. P.
Published: July 2012

European noise legislation since the 1970s consisted of directives on the approximation of the laws of the Member States in order to ensure the smooth functioning of the internal European market. In the late 1990s, the protection of human health and well-being started to play a more important role. A new EU directive on noise emission from equipment for use outdoors replacing former directives concerning construction machines is in force since its publication in the Official Journal of the European Communities on 3 July 2000. It lays down provisions concerning the marking of equipment with its guaranteed sound power level for about 60 types of outdoor equipment (construction machinery, hobby and garden equipment, and some others) and for about 20 of those noise limits in two steps. Noise limits are demanding but the current state of the art of noise reduction allows compliance without excessive additional costs. The current directive states that only equipment complying with these provisions may be placed on the European market that consists of 375 million citizens. The European Directive now must be transposed in national legislation; the provisions have to be applied from 3 January 2002.
Noise control for a vacuum excavator: A mutually beneficial solution
Authors: Thalheimer Erich
Published: July 2012

The Central Artery/Tunnel (CA/T) Project in Boston (the Big Dig) makes use of several vacuum excavator trucks (vac-trucks) in order to reduce accidental utility disruptions. Unfortunately, these vac-trucks generate very loud low-frequency noise due to their vacuum blowers which can cause nearby buildings to vibrate and has led to significant numbers of complaints from distressed abutters. In reaction, the CA/T Project undertook an intensive study to determine what mechanisms were producing the offensive low-frequency noise, and to devise mitigation measures to effectively control the low-frequency noise so as to allow the vac-trucks to continue working without causing noise complaints. Working cooperatively with the manufacturer (Guzzler) as well as with the contractor (Walton Systems), new and improved (Universal) silencers were retro-fitted to a test vac-truck and the improvements in low-frequency insertion loss were measured and documented. The new silencers effectively reduced the 40–125-Hz third-octave band range noise by 10–15 dB, thus approaching the noise control design goals selected to avoid causing nearby buildings to vibrate. This is a prime example of how cooperative efforts between vehicle manufacturers, construction contractors, and project officials can lead to mutually beneficial results.
Survey of worldwide legislation on the control of construction noise
Authors: Ming Li Kai
Published: July 2012

The sustained economic growth in many countries of the world in the past few years has led to significant increases in the construction activities for building new homes, new infrastructures such as highways, and airports for cities. This construction work inevitably causes an increase in noise levels. Indeed, the problem of noise is one of the most important environmental issues in recent years. With increased exposure and the greater sensitivity of much of the population, the number of noise-related complaints has grown at an alarming rate over the past few years. Current legislation imposes a limit of acceptable noise levels, but seems ready to be tightened further in reflection of popular demand. This paper reports a recent survey on the worldwide legislation on the control of construction noise. The survey concentrates on different countries in the Pacific Rim, the USA, and a few countries in the European Union. Relevant guidelines proposed by such international organizations as the World Health Organization and the Organization for Economic Cooperation and Development are also reported.
Demonstration hearing conservation program for construction workers in Washington State
Authors: Suter Alice H.
Published: July 2012

Construction workers have traditionally been an ‘‘underserved’’ population in the area of noise control and hearing conservation. Approximately 500,000 of these workers are currently exposed to potentially hazardous levels of noise and little progress has been made to the U.S. to mitigate this exposure. A labor–management–professional team composed of members of the Washington State Building and Construction Trades Council, the Building Trades Labor Management Organization, the Center to Protect Workers’ Rights, and professionals in industrial hygiene, audiology, and medicine, have developed a ‘‘common sense’’ hearing conservation program to serve construction workers and employers. Initiated as a demonstration program in the State of Washington, the program is tailored to the U.S. construction industry. It will include worker and supervisor training using construction-specific materials, training in the fundamentals of construction noise control, fitting and training in the use of hearing protection devices, audiometric surveillance, centralized record keeping, and the evaluation of program effectiveness. Special emphasis is being placed on the use of readily available noise control solutions as well as hearing protection devices that will not degrade communication and the perception of warning signals. Program plans are currently being finalized and training will be initiated in December of 2000.
Rolling noise ANC system: An experimental facility test
Authors: Rossi Federico
Published: July 2012

A new active system for reduction of rolling noise produced at tire-ground contact is proposed. The system is constituted by acoustical emitters installed on the car mudguard close to tire-ground point of contact. Active control is achieved by means of an electronic control unit which generates the control signal according to a digital error minimization technique. The active system has been tested on a stationary condition by means of an original experimental facility built at Acoustic Laboratory of the University of Perugia. The facility reproduces the acoustical emission of rolling noise employing a recorded noise source. Experimental tests show that the proposed active noise control system is particularly suitable for rolling noise low-frequency components attenuation. Application on a traveling car is actually going on.
High-temperature quiet-flow test facility
Authors: Cummins Jim R. , Causey Jim B. , Kapsos David
Published: July 2012

A high-temperature, quiet-flow test facility for the testing and evaluation of exhaust silencers and silencer materials has been developed. This facility is driven by a rotary positive displacement blower delivering up to 110 m3/min (4000 cfm) of airflow. This airflow is put through both a passive and active silencer to achieve minimal uncontrolled noise in the test stream. Controlled sound is injected into the airflow by a set of loudspeakers in a mixing/settling chamber. The airflow is heated up to 540°C [1000°F] by a 144-kW electric heater just prior to entering the test section. The test section is rated for a 10-cm- (4 in.) diam flow path and up to 1.8-m- (6 ft) long sample. The outlet of the test section exhausts outside the test building and a microphone measurement system measures the radiated sound power level. This facility allows tests to be run with flow, sound level and temperature controls to obtain in situ measurements of silencer performance including insertion loss.
Sound transmission characteristics of bulb seals
Authors: Park Junhong , Mongeau Luc G. , Siegmund Thomas
Published: July 2012

Sound transmission through door and window sealing systems is one important contributor to interior noise in vehicles. The noise generation mechanism involves the vibration of the seal due to the unsteady wall pressures associated with turbulent flow over the vehicle. Bulb seals are often used in cars, an application where the seals experience large deflection variations due to build variation between vehicles. The performance of a bulb as a sound barrier was the focus of this study. The vibration response of a bulb seal together with the radiated sound was modeled using a finite element method. Material properties for the elastomeric foams were measured and used in the FEM. Acoustic-structure interactions were considered and the noise generated on the quiescent side of the seal was calculated. Experimental data was obtained for several bulb seal specimens using a reverberant room test method. The radiated sound intensity was measured using an intensity probe. The seal wall vibration was measured using a laser vibrometer. The transmission loss of the bulb seal was calculated from the measured data. It was compared with the value from the numerical simulations. The effects of bulb seal design parameters such as density, elastic modulus, and damping ratio were investigated.
Vehicle door seal modeler for wind noise
Authors: Gur Yuksel
Published: July 2012

Wind-noise performance of a passenger vehicle plays a significant role in the customer’s perception of overall vehicle quality. Wind noise aerodynamically generated on the exterior surface of a vehicle can propagate to the vehicle interior through body panels, window glass, and the seal gap between the door and door opening panel. Experimental studies indicate that automotive door seal systems are generally a major contributor to the vehicle wind-noise performance. Traditionally, automotive door seals are designed using the ‘‘bread board’’ and other ‘‘build and test’’ procedures. Two new finite-element-based acoustic-structure analysis tools have been developed to evaluate the wind-noise performance of door sealing system. These validated CAE techniques allow the engineer to predict door seal system performance in sound transmission and aspiration leakage before the availability of prototype hardware. These methods combine the separate analysis capabilities of finite-element analysis for acoustics, rubber elasticity, steady-state harmonic viscoelasticity, and a unique modeling approach to perform a fully coupled structure/acoustic interaction analysis of door seal systems. These unique CAE methods, experimental validations, and implementation of these techniques on product design will be presented.
An auditory model for the prediction of detection thresholds of impulsive sound events
Authors: Amman Scott , Blommer Mike , Greenberg Jeff
Published: July 2012

Impulsive sound events such as squeaks and rattles experienced in a vehicle can be a major source of customer dissatisfaction. These events almost always occur in the presence of some sort of background noise (e.g., wind, road and powertrain noise). When complete elimination of the impulsive sound event is either not possible, or too costly, the same effect can be had by pushing the level of the sound below the detection threshold. This paper describes the development of an auditory model that has the ability to predict detection thresholds of impulsive sound events in the presence of noise. The model was initially developed using equal-energy exponentially damped sinusoids with center frequencies of 250, 500, 1000, 2000, 4000 and 8000 Hz mixed with pink noise. It was then validated using four different squeak and rattle sounds each mixed with three background noises recorded in a vehicle (wind, smooth and rough road noise). An up–down Levitt procedure was used for threshold determination. Two subjects participated in the first experiment and six in the second. In general, the developed model was able to predict detection thresholds with an error that is on par with the subject-to-subject variability observed in the experiment.
Seismic wave attenuation coefficient for soils
Authors: Khosrovani Hooshang , Ortega Jose
Published: July 2012

Several projects over the past years have provided the opportunity to measure the ground propagation properties of seismic waves. Data from a variety of vibration sources and soil types have been summarized in the form of the coefficient of attenuation versus frequency in the ranges 5–250 Hz. Also included in the summary are data from the published literature. Although the data exhibit a wide scatter their availability will enhance the effort to predict induced ground vibration. This information may in turn be used in predicting noise and vibration levels in structures.
Airflow patterns in hemilarynx models
Authors: Alipour Fariborz , Montequin Douglas
Published: July 2012

Airflow patterns of a hemilarynx were simulated numerically by the method of computational fluid dynamics (CFD) and were investigated experimentally with a flow visualization method. In the numerical model, vocal fold motion was simulated by sinusoidal variations of the inferior and superior glottal widths at different phase conditions. The straight glottal wall alternated between converging and diverging shape, while the input airflow varied sinusoidally between zero and a maximum. The control variables were oscillatory frequency, Reynolds number, and phase difference of the inferior and superior sections used for glottal motion. Flow visualization was performed using a hemilarynx physical model with a rectangular-shaped glottis. Using a Kodak high-speed camera, airflow patterns were recorded for various glottal widths and flow rates. CFD simulation described the complete airflow pattern and velocity distribution which indicated the existence of a high-speed jet near the fixed wall, flow separation, and vortex formations behind the glottis. Flow visualization also revealed similar patterns of flow separation, near-wall jet, and vortices below the jet. [Work supported by NIDCD Grant No. R01 DC03566.]
Acoustic vowel space in 13 large Utah families
Authors: Corbin-Lewis Kim , Liss Julie M. , Coon Hilary , Gray Steven D.
Published: July 2012

Acoustic vowel space was examined in 131 speakers from 13 large Utah families ranging in age from 20-85 years with a median of 40 years. This population provides a unique opportunity to evaluate speech production characteristics in families with known genetic pedigrees and similar environmental influences. The purpose of the study was to determine whether acoustic manifestations of vowel production could be traceable to gender, age, or family membership. Results indicate that gender by itself explains 43.5% of the variance (highly significant, p<0.0001). Controlling for this gender effect, age is not a significant predictor of vowel space area (p=0.29). However, being in the same family is a significant predictor of vowel space area (p=0.002), independent of effects of gender and age. Being in the same family explains an additional 13.5% of the variance in area. [Work supported by NIH-NIDCD and the W. M. Keck Foundation.]
Effects of listener experience on measures of voice quality
Authors: Kreiman Jody , Gerratt Bruce R. , Epstein Melissa
Published: July 2012

Previous studies have shown that clinicians and naive listeners use different perceptual strategies when judging the quality of pathological voices. Naive listeners uniformly rely almost exclusively on F0, while clinicians differ substantially from each other in the features they attend to. Consistent differences between groups in the overall level of rating have also emerged in paired comparison tasks, with naive listeners hearing greater differences between stimuli than clinicians do. We hypothesized that these differences in voice ratings are due to task-related factors, rather than to true differences in the ability of the two listener groups to hear differences in voice quality. Analysis-resynthesis approaches to quality measurement should eliminate such differences in measures of quality, because they require direct auditory matching of stimuli, without reference to internal standards that can be modified by auditory experience. To test this hypothesis, clinicians and naive listeners matched synthetic voice tokens to natural stimuli by adjusting synthesizer parameters of voice quality. No significant differences emerged between groups, suggesting that previously reported group differences are artifacts of traditional quality measurement tasks. Analysis-resynthesis approaches to measuring voice quality perception thus appear to control variability in judgments resulting from differences in internal standards. [Work supported by NIDCD Grant DC01797.]
The role of speaker familiarity in assessment of dysarthric speech intelligibility
Authors: Huang Kuo-You
Published: July 2012

It is well known that dysarthric speech is often more intelligible to familiar listeners. The underlying mechanisms for this speaker familiarity effect, however, are not fully understood. The present study was conducted to investigate effects of speaker familiarity and laboratory training on perception of dysarthric speech. In the first experiment, a Chinese-speaking woman with cerebral palsy produced lists of bisyllabic words, pseudowords, and isolated monosyllables. Familiar and naive listeners transcribed these items. Results showed that familiar listeners yielded substantially higher intelligibility scores, and that the effect was more pronounced for meaningful words than pseudowords and monosyllables. It was shown that familiarity effect resulted from the interaction between speech decoding and word knowledge. In the second experiment, different intensive training programs were carried out to discover the dynamics of the familiarity effect: (1) feedbacks about the target words were or were not given to listeners; and (2) a forced-choice paradigm was applied in the training task and confusability among syllable pairs was manipulated, so that top-down and bottom-up influences could be differently observed during the training course. Results indicated that laboratory training was effective and it can, in fact, mimic the development of the familiarity effect in the naturalistic environment.
Intonation and emotion
Authors: Pell Marc D.
Published: July 2012

Preliminary data were gathered on how simulated emotional characteristics of the voice influence the acoustic form of English utterances containing specific combinations of intonational and stress features [extending Eady and Cooper, J. Acoust. Soc. Am. 80, 402–415 (1986)]. Utterances varying in intrasentential focus position (initial, final, none) were elicited as both statements and questions in each of four emotional ‘‘modes’’ (neutral, sad, happy, angry) employing a structured elicitation procedure. Parameters of duration and fundamental frequency (f0) were then determined for the productions elicited from eight elderly speakers to specify important acoustic dimensions associated with specific combinations of stress, ‘‘modality,’’ and emotional features of the stimuli. Results of the acoustic analyses largely reaffirmed past accounts of how contrastive focus is encoded in (affectively neutral) statements and questions for English, and cohered well with the acoustic literature on how basic emotions are expressed vocally for three key acoustic parameters (mean f0, f0 range, speech rate). The impact of emotion on linguistic attributes of prosodic structure was most evident in the speakers’ modulation of f0, which was notably constrained in prosodic conditions where speakers were required to signal ‘‘marked’’ emotional and nonemotional intentions conjointly within the intonation contour. [Work funded by FCAR.]
The scattering of low-grazing angle pulse beams at interfaces between fluid and porous media
Authors: Stephen Ralph A.
Published: July 2012

Many environments in bottom interacting ocean acoustics consist of mud and sands which can be modeled as fluid saturated, porous solids with low shear moduli. To study the physical mechanisms responsible for forward- and backscattering in these media it is useful to have a forward modeling technique which applies to rough and heterogeneous porous bottoms. A numerical scattering chamber using the time-domain finite-difference method applied to the range-dependent Biot equations can be used to study the scattering of low-grazing angle pulse beams from fluid-saturated porous media. For example, for a flat seafloor over a homogeneous porous half-space, converted shear waves and converted compressional ‘‘slow’’ waves are shown to be excited in the subbottom even when the grazing angle is below the critical angle for compressional ‘‘fast’’ waves. Any scattering element near the seafloor will act as a secondary point source by Huygen’s principle and when excited by an acoustic wave will have the potential to generate a family of interface waves and body waves of ‘‘fast’’ compressional, ‘‘slow’’ compressional and shear type.
High-resolution measurements of volume heterogeneity in sandy sediments
Authors: Wheatcroft Robert A. , Fritz Cara E. , Hunt Louise
Published: July 2012

As part of SAX 99, a multi-investigator study focused on the penetration and scattering of high-frequency (10–300 kHz) sound in marine sediments, two independent measurements of sediment volume heterogeneity (SVH) were made. The first tool used to measure SVH was an in situ resistivity profiler (IRP) that logs sediment resistivity at 0.25-mm vertical intervals to depths of 15 cm. Robust empirical calibrations are used to calculate sediment porosity. The second method used to measure SVH was a digital x-ray system that comprises a constant-potential x-ray source and an amorphous silicon x-ray detector. The IRP data indicate little between-site variability and bottom-type (i.e., ripple crest, ripple trough, mound) specificity. Profiles are characterized by a zone from 0- to 3-mm subbottom of exponentially decreasing porosity, underlain by a zone of roughly constant porosity characterized by 5%–10% fluctuations. The digital x radiographs indicate three sources of SVH: (1) biogenic structures, (2) mud inclusions, and (3) shell fragments. Of these, the shell fragments are likely to be the most important sound scatterers. Estimates of shell fragment concentrations, distributions, and orientations will be discussed. [Work supported by ONR.]
APL-UW environmental measurements during SAX99: Sediment conductivity and tomography
Authors: Tang Dajun , Williams Kevin L. , Jackson Darrell R. , Thorsos Eric I.
Published: July 2012

Two new instruments were developed and deployed during SAX99 to measure surficial sediment variability at centimeter scales. Such data serve as input to acoustic models predicting sound scattering in the frequency range of 10–50 kHz. One instrument, IMP (In situ Measurement of Porosity) measures sediment conductivity at 1-cm resolution in the horizontal dimensions and at 3-mm resolution in the depth dimension. From this instrument the following information is derived: (1) 3-D porosity or density variation in the top 12 cm of sediments, and (2) 2-D bottom roughness and associated spectra. The second instrument, the Acoustic Imager (AI), is a 3-D sediment tomographic tool with 1-cm resolution operating at 170 kHz. Information derived from the AI includes (1) 3-D sediment sound speed variability, (2) 3-D variability of sediment attenuation coefficients, (3) the presence and distribution of discrete scatterers such as shell pieces, and (4) the temporal variability of the above parameters over 3 days. These results and their implications to the acoustic measurements taken during the SAX99 experiment will be discussed. [Work supported by ONR.]
Imaging the permeability structure within near-surface sediments by acoustic crosswell tomography
Authors: Yamamoto Tokuo
Published: July 2012

Permeability structure within near-surface sediments is imaged by analytically inverting the measured fields of acoustic wave velocity and attenuation. The acoustic velocity and attenuation fields at 1000 Hz were previously measured by a pseudorandom binary sequence (PRBS) based crosswell acoustic tomography device [T. Yamamoto, J. Acoust. Soc. Am. 98, 2235–2248 (1995)]. A quadratic equation of permeability derived from the Biot theory is used for the permeability imaging. The porosity and shear modulus images are also extracted from the velocity and attenuation fields using the newly derived quadratic dispersion equation and an empirical shear modulus porosity depth of burial relation. The acoustically measured images of permeability, porosity, and shear modulus are favorably compared with the engineering tests performed on the cores and boreholes.
Application of the Gelfand–Levitan method to geoacoustic inversion in shallow water
Authors: Becker Kyle M. , Frisk George V.
Published: July 2012

The Gelfand–Levitan inverse technique is an exact inversion method originating in quantum scattering theory [I. M. Gelfand and B. M. Levitan, Am. Math. Soc. Transl. 1, 253–304 (1955)]. At a single frequency, the required input data are the Fourier transform of the plane wave reflection coefficient as a function of incident vertical wave number. The method was originally employed in underwater acoustics for a deep-water environment where a simple relationship exists between the reflection coefficient and the depth-dependent Green’s function, which is obtained by Hankel transforming measurements of the point source pressure field [A. A. Merab, Sc.D. thesis, MIT/WHOI Joint Program, Woods Hole, MA (January 1987)]. In shallow water, the Green’s function is characterized by poles corresponding to the eigenvalues of the perfectly trapped modes in the waveguide. These poles complicate the relationship between the Green’s function and the reflection coefficient, and therefore the application of the Gelfand–Levitan technique. However, through application of the Darboux transform to the governing wave equation and the reflection coefficient, the Gelfand–Levitan method can be employed for shallow-water geoacoustic inversion [J. R. McLaughlin and S. Wang, in Mathematical and Numerical Aspects of Wave Propagation, edited by J. A. DeSanto (SIAM, Philadelphia, 1998), pp. 232–236]. In this talk, the Darboux transform will be illustrated and examples of geoacoustic inversion for synthetic shallow-water acoustic data will be presented. [Work supported by ONR.]
New control technologies for virtual orchestra playback
Authors: Smith David B. , Umezaki Kojiro , Bianchi Frederick W. , Campbell Richard H.
Published: July 2012

A new software application running on the Linux operating system has been developed exclusively to support live performance by a virtual orchestra (VO). The core engine, which allows unlimited expansion, has a rich feature set including temporal flexibility, arbitrary performance navigation, printed score compliance, multiple input/output devices, and editing capability. The base configuration supports 64 MIDI channels and utilizes metaevent extensions to the MIDI 1.0 specification. MIDI files from multiple platforms can be imported. Considerable attention has been given to human factors in VO real-time music production with meaningful display screens and specialized keyboard designs resulting in a rapid and intuitive user learning curve. [Work supported by Realtime Music Solutions, L.L.C., New York.]
Synthesized space in pop music production
Authors: Case Alexander U.
Published: July 2012

The sonic vocabulary of the pop music recording engineer is not constrained by the architectural acoustics of any space. Equipped with racks and RAM full of signal processing tools, the engineer tries to create musical timbres, textures, ambience, and emotions to support whatever feeling the music inspires. Perhaps nowhere is this departure from the physical to the contrived more apparent than in reverb. Acoustic analogies like the chamber, mechanical simulations like the plate, and the wholly invented spaces of the digital reverb device are part of a family of effects which—inspired by the great halls and opera houses of the world—have an identity and freedom all their own. Reverb time, early decay time, bass ratio, initial time delay gap, and so on become independent variables freely manipulated by the engineer to create sonic ‘‘spaces’’ that may not be physically possible outside of the studio. This paper surveys contemporary pop music production trends in reverb and analyzes them through the lens of the architectural acoustician.
Alternative voices for electronic sound
Authors: Trueman Dan , Bahn Curtis , Cook Perry
Published: July 2012

Through the design and construction of unique sound diffusion structures, the nature of electronic sound can be reinvented. When allied with new sensor technologies, these structures offer alternative modes of interaction with techniques of sonic computation. This paper describes several recent applications of Geosonic Speakers (multichannel, outward-radiating geodesic speaker arrays) and Sensor-Speaker-Arrays (SenSAs: combinations of various sensor devices with outward-radiating multichannel speaker arrays). Geosonic Speakers, building on previous studies of the directivity of acoustic instruments (the NBody Project), attempt to reproduce some of the diffusion characteristics of conventional acoustic instruments; they engage the reverberant qualities of performance spaces, and allow electronic and acoustic instruments to blend more readily. In collaboration with the U.S. Enclosure Company, over a dozen Geosonic Speakers were produced, varying in size from 8 to 14 in. Their use in the performance and recording of two major new works by composer Steven Mackey is detailed. The electronic improvisation ensemble ‘‘Interface’’ has integrated a family of these Geosonic Speakers into their standard setup, completely replacing their previous P.A. diffusion model; this has encouraged them to substantially reinvent their approach to the performance of live interactive computer music.
Spectro-temporal control parameters for synthetic orchestra applications
Authors: Beauchamp James W.
Published: July 2012

Several spectral properties can be exploited for control of individual voices in a synthetic orchestra. Sounds can be synthesized from their spectral representations using time-varying additive synthesis, inverse Fourier transform, or, more efficiently, using multiple wavetable synthesis. Primary parameters to be controlled are amplitude and spectral centroid versus time envelopes, spectral envelope, spectral irregularity, vibrato, noise content, and inharmonicity. These parameters can be further resolved into subparameters. For example, amplitude versus time curves can be partitioned into attack, steady-state, and decay segments which can be manipulated separately. For sustained sounds, it is also important to consider how these parameters vary with fundamental frequency and intensity. In the case of percussion sounds, the density of partials as well as their spectral evolution are important. In all cases, detailed management of parameters is necessary to maintain timbral clarity, uniqueness, and naturalness. Examples of synthetic orchestral instruments will be played.
Acoustic and visual monitoring for marine mammals at Cortez and Tanner Banks
Authors: Oleson Erin M. , Hildebrand John A. , McDonald Mark A. , Calambokidis John
Published: July 2012

We have implemented continuous acoustic monitoring for baleen whales in the region surrounding Cortez and Tanner Banks, offshore of Southern California, complemented by bimonthly ship-based visual and acoustic observations. Our objective is to develop methods for acoustic monitoring of baleen whales using seafloor acoustic recording packages, the results of which will be used to produce abundance estimates. The joint acoustic and visual effort will answer questions regarding the probability for acoustic detections of individual animals, the quantitative association of calls with a particular species, and how well the number of animals in an area can be assessed acoustically. These findings can then be used to generate a detectability curve for each baleen whale species, from which the seafloor recorder data can be translated into absolute abundance estimates. The use of continuous acoustic monitoring with seafloor recording packages offers the potential for efficient and economical monitoring of marine mammals. The continuous acoustic census approach will be discussed, and compared to opportunistic visual and acoustic survey methods.
Comparison of acoustic and visual surveying of humpback whales off East Australia
Authors: Noad Michael J. , Cato Douglas H.
Published: July 2012

Many species of whales produce intense sounds that are audible to substantial distances and thus may be useful in censusing, especially in conditions where visual methods have limited effectiveness. Acoustic methods of surveying, however, have their own limitations and are relatively untried compared with visual surveying. This paper describes the results of an experiment to test the effectiveness of acoustic surveying, by applying it to the East Australian humpback whale population, which has been well-surveyed visually. At the experimental site in southeast Queensland, most of this stock passes within visual range of the coast during migrations. Whales were tracked visually using a theodolite on a hill near shore and acoustically using three buoy systems which received the sounds and transmitted the signals to shore. Almost all whales within 10 km could be tracked visually, thus providing a benchmark for the acoustic surveying. Although only a proportion of the stock is vocalizing at any time, the result tests how representative this is of the total stock. The results show that acoustic surveying can be useful for censusing.
Lack of species-specific vocal recognition in Amazonian manatees: Trichechus inunguis
Authors: Sousa Lima Renata S. , da Silva Vera M. F.
Published: July 2012

Playback experiments were conducted in order to test for the existence of species-specific vocal recognition in Amazonian manatees. The animals were isolated in pools while acoustic stimuli were played from a tape recorder and transmitted underwater through a loudspeaker. Nine animals were monitored for response to playback vocalizations from eighteen different individuals, nine from each species (Trichechus inunguis and T. manatus manatus). No significant differences were detected in the response of manatees exposed to the different stimuli. Only the time spent close to the speaker was greater when the animals were exposed to conspecific vocalizations (ρ=0.375). This result suggests that Amazonian manatees cannot recognize differences between their own and another manatee species’ vocalization. The methodology was also tested and no difference in the response of animals exposed to silence or to tape hiss (blank tape used as control) was found. Testing the response to the presence or absence of vocalizations, significant differences were found in time elapsed between the playback and the response (ρ<0.001) and in the time spent next to the speaker (ρ=0.032), confirming their great ability to perceive sounds underwater. [Work supported by FBPN, MacArthur Foundation, CI, FINEP, MCT/PPG7 and CNPq.]
The F factor: Ocean climatology and internal-wave acoustic effects
Authors: Flatté Stanley M. , Noble Kimberly J.
Published: July 2012

The strength of acoustic fluctuations due to internal waves is affected by the temperature-salinity relation of an oceanic region. We define an acoustic fluctuation strength parameter F as the ratio of the fractional potential-sound-speed change to the fractional potential-density change. F is calculated at three depth levels (275, 550, and 850 m), on a one-degree grid of latitude and longitude, using NODC/OCL’s World Ocean Atlas 1994. Representative values of F in upper waters range between 5 and 35. Results for intermediate depths range from 5 to 60. In general, F exhibits higher values in the Atlantic Basin than in the Indian or Pacific, and has a maximum at 550 m. The main use of F will be the prediction of travel-time fluctuations in acoustic propagation experiments, which will be proportional to the value of F, given a universal strength of internal waves.
Imaging acoustic fluctuations in shallow water using dislocation theory
Authors: Williams D. P. , D’Spain G. L. , Hodgkiss W. S. , Kuperman W. A.
Published: July 2012

The distribution of the amplitude of a moderate-frequency sound field in a shallow ocean is considered in relation to the existence of dislocations in the phase front [Nye and Berry (1974)] where the amplitude is close to zero. Phase front dislocations strictly occur when the amplitude is zero; in actual ocean acoustic measurements, only low-field amplitudes at a minima can be distinguished due to the interference of background noise. The dislocations are sensitive to temporal variability in the ocean environment [Kuz’kin, Ogurtsov, and Petnikov (1998)] and their space-frequency fluctuations lend qualitative insight into environmental characteristics. A model is developed to predict the patterns of the sound-field minima resulting, in particular, from internal wave-induced fluctuations in the environment. The model is then applied to the interpretation of the results of 2–7-kHz broadband transmissions collected during a noisy shallow-water acoustics experiment off the coast of San Diego. [Work supported by ONR.]
Fourier component fluctuations of wideband ocean tomography signals: Empirical temporal statistics from AST96
Authors: Andrew Rex K. , Howe Bruce M. , Mercer James A.
Published: July 2012

Current theories for wave propagation in random media can predict fluctuations for narrow-band (single-frequency) signals, but do not explicitly address wideband signals. Recent ocean acoustic tomography experiments, however, have employed wideband ‘‘m-sequence’’ signals. Processing here assumes a periodic signal, and hence, involves a unique set of Fourier series components. A technique is presented for decomposing such wideband signals into their Fourier components and then analyzing the space–time fluctuations of these ‘‘narrow-band’’ components. The technique is applied to AST96 data transmitted over 150-km and 1-Mm paths for single-point and two-point (temporal separation) statistics. [Work support by ONR.]
Characterization of the internal waves and its effect on signal propagation in the Adventure Bank area
Authors: Yang T. C. , Yoo Kwang , Siderius Martin
Published: July 2012

During the Advent-99 experiment, which took place in the Sicily Strait in May, 1999, multitone (in the band 200–1500 Hz) narrow-band signals were transmitted from a bottom-mounted tower and received on a 64 phone line array (VLA) covering the water column; the water depth was 80 m. Data at a source–receiver range of 10 km will be presented and modeled using an internal wave model. A CTD chain containing 48 CTDs on a vertical string was towed continuously during the acoustic experiments between the source and VLA, yielding a time-evolving sound speed profile between the source and receiver. From that the average buoyancy frequency and sound speed profile were determined as a function of range. Internal-wave-mode depth functions were calculated using the measured buoyancy profiles. Internal-waves-mode amplitudes were determined from the eigenvalues of the sound speed covariance matrix for the lowest 5 modes. Internal-wave-frequency spectrum has the typical 2-power dependence as in the Garrett–Munk model. The modeled results of mean transmission loss and amplitude fluctuations with and without internal waves will be presented and compared with data. [Work supported by the Office of Naval Research and SACLANTCEN.]
Acoustic detection and classification of hurricanes
Authors: Wilson Joshua D. , Makris Nicholas C.
Published: July 2012

Hurricanes are some of the most destructive natural disasters known to man. Currently, it is difficult to detect, track, and classify hurricanes in areas of the world that lack satellite coverage and specialized aircraft. The purpose of this research is to investigate the feasibility of using underwater hydrophone arrays to detect and classify a tropical cyclone. A wave theoretic model is developed for the spatial covariance of the ambient noise field generated by a hurricane. Simulations are performed to determine whether ambient noise due to a hurricane is detectable over the more typical wind-wave noise accumulated from the rest of the ocean. Scenarios where a hydrophone array is placed directly beneath the storm and at a remote distance from the storm are investigated.