bluuebunny/crossref_metadata_2025 huggingface dataset:
Trends in preference, programming and design of concert halls for symphonic music
Authors: Gade Anders C.
Published: May 2008

This paper discusses the evolution in taste regarding concert hall acoustics and how this can be reflected in the new halls being built today. The clients' and listener's preferences are not only based on listening in existing halls; but also on listening to reproduced music recorded with microphones close to the orchestra and with artificial reverberation added. The result may be a desire for higher clarity as well as a more full reverberation than what is found in most existing halls. Without being very specific in the brief regarding geometrical detailing - which is not desirable as it will limit architectural freedom and evolution - we can only specify a desire for acoustic conditions in this direction by setting targets for standardized objective room acoustic parameters. In this paper, measured ISO 3382 data are used to illustrate typical differences between "live" and recorded concert experiences, and it is seen how visionary hall designs over the last four decades tend to move the acoustics of halls in the same direction. Finally, it is suggested how target values for ISO 3382 parameters - in spite of their limitations - can be set up to drive the design in such a direction.
Simplified Room Acoustic Measurements
Authors: Halmrast Tor , Buen Anders
Published: May 2008

Standardised room acoustic measurements are needed for concert halls etc., but they imply heavy equipment. Thus, many interesting rooms are not measured. Most musicians (and even some acousticians) find that clapping and shouting in a room/hall might give an overview of the room acoustics. In the literature we even find that acoustic parameters are derived from scratchy recordings of music. Modern handheld high quality recording technology and possibilities of analysing sound files gives that one should investigate simpler (non standardised) measurements for simpler rooms/halls. This paper gives analysis of Impulse-Responses recorded from balloons, paper bags, clapping, compared with measurements taken with more academic measurement equipment.
Acoustics of concert halls with organs in Russia: trends and problems
Authors: Kravchun Pavel
Published: May 2008

Over the past decades the organ music has become one of the most popular kinds of classical music in Russia. About 30 new organs were built in concert halls, and several old instruments were restored or rebuilt. Acoustical properties of 15 well-known Russian concert halls with organs (Moscow, St. Petersburg, Perm, Kazan, Astrakhan, etc.) are presented and considered in the paper. In many cases acoustics in the concert halls is not so good for the solo organ music. The reasons are discussed. Acoustics of the Russian concert halls with adjustable acoustics is considered (Moscow, Kazan). It was noted that the “optimum” reverberation time recommended by different acousticians for organ music had a tendency to be longer and longer in the 20th century. Values of the average sound absorption coefficient for organ front were estimated. Some problems in organ-building connected with the concert hall acoustics are discussed.
A new symphonic hall, Musikhuset Aarhus, Denmark
Authors: Fog Carsten Lemvigh , Ballinger Richard M.
Published: May 2008

During the past 3 years Musikhuset Aarhus in Denmark has been enlarged by an area of approximately 17.000 m2 to a new total area of approximately 34.000 m2. The new part of the complex contains a symphonic concert hall for Aarhus Symphonic Orchestra with 1200 seats, a hall for rythmic contemporary music with 600 seats and a hall for classical music with 160 seats. The complex also houses the new premises for Aarhus Academy of Music. Important design considerations will be highlighted in the paper and the results of the preliminary and final computer modeling of room acoustics will be presented using examples of auralisation. In conclusion the room acoustic parameters (measured according to ISO 3382 standard) will be discussed, also in respect of the initial reaction from ochestral musicians.
Qualitative Standard for Symphonic Concert Environment
Authors: Jaffe Christopher
Published: May 2008

All acousticians strive to obtain a symphonic concert environment that will be well received by musicians, professional music critics and the general public. Currently, this environment corresponds to the reflective energy measurements found in what might be designated as the rectangular European or American Concert Hall of the late nineteenth century, such as the Grosser Musikvereinssaal in Vienna and Symphony Hall in Boston Massachusetts. It is well known that these measurements can be correlated to subjective musical judgments and that halls incorporating these measurements have been universally designated as having excellent environments for symphonic concerts. But how did these specific reflections become an acoustical standard. This paper presents a theory of how the rectangular European and American style concert hall became an acoustical standard at the beginning of the twentieth century and poses the question as to whether this standard is still applicable in the twenty first century?
On the Reverberation time of Gamelan Bali Concert Hall based on the Physio-Acoustic Responses
Authors: Merthayasa I Gde Nyoman , Muchtadi Farida Idealistina
Published: May 2008

Based on the fourth orthogonal acoustic factors of a concert hall design theory, it is possible to calculate the acoustical quality at any position in a proposed Gamelan Bali concert hall. And, it is well known that the value of preferred sound fields depends upon the characteristics of the sound source signal. Previous research has reported the most preferred value of the four orthogonal factors of Gamelan Bali sound fields based on the subjective response. It would be important to obtain the objective response, based on the physio-acoustics measurement using Electroechepalograph (EEG), when the subjects were excited by a certain variation of sound fields while other parameters were kept constant. In this research, the subjects were excited by a serial variation of the subsequent reverberation time of Gamelan Bali music. The brain activities were measured using EEG in the temporal areas. The result shows that the maximum power spectral of Alpha Waves of the subjects occurred when the reverberation time of Gamelan Bali were between 750 mS to 1750 mS.
Room-acoustic factors in attentional tracking
Authors: Watkins Anthony J. , Makin Simon J. , Raimond Andrew
Published: May 2008

In a “busy” auditory environment listeners can selectively attend to one of several simultaneous messages by tracking one listener's voice characteristics. Here we ask how well other cues compete for attention with such characteristics, using variations in the spatial position of sound sources in a (virtual) seminar room. Listeners decided which of two simultaneous target words belonged in an attended “context” phrase when it was played with a simultaneous “distracter” context that had a different wording. Talker difference was in competition with a position difference, so that the target-word chosen indicates which cue-type the listener was tracking. The main findings are that room-acoustic factors provide some tracking cues, whose salience increases with distance separation. This increase is more prominent in diotic conditions, indicating that these cues are largely monaural. The room-acoustic factors might therefore be the spectral- and temporal-envelope effects of reverberation on the timbre of speech. By contrast, the salience of cues associated with differences in sounds' bearings tends to decrease with distance, and these cues are more effective in dichotic conditions. In other conditions, where a distance and a bearing difference cooperate, they can completely override a talker difference at various distances.
Effects of reverberation on spatial release from masking
Authors: Freyman Richard L. , Zurek Patrick M.
Published: May 2008

When sounds that we want to listen to (targets) and interfering sounds (maskers) are separated spatially, several advantages are observed relative to the baseline condition in which target and masker come from the same location. This paper will discuss how and to what extent these advantages are disrupted by room reverberation, which reduces better-ear signal-to-noise ratios and interaural intensity differences, and obscures interaural time differences. Statistical analysis of room acoustics combined with a model of binaural release from masking can, with the articulation index, help quantify expected reductions in speech recognition benefits of target/masker spatial separation in reverberation. This paper will also discuss some advantages of target/masker spatial separation that appear to be well preserved in reverberant rooms. Specifically, reverberation does not eliminate the perceptual differences between target and masker that arise from their different physical locations. The advantages of perceived spatial differences are seen when target and masking sounds share similar characteristics and are confusable with one another. In such cases spatial differences appear to resolve the confusion. This paper will describe research indicating that barely discriminable spatial differences between target and masker are sufficient for spatial release from masking in these circumstances. [Work supported by NIH DC-01625]
Binaural room acoustics - cross-correlation
Authors: Hartmann William M. , Aaronson Neil L.
Published: May 2008

The subject of ''Binaural room acoustics" combines the disciplines of room acoustics with facts and models of human binaural physiology and psychology. It considers the linear effects of rooms on the inputs to the two ears of a listener, and it considers the nonlinear effects of binaural hearing processes on perceptually relevant acoustical characterizations of rooms. Linear effects of interest are binaural differences in amplitude and phase spectra, which are combined in the cross-correlation function (CCF). A psychophysically relevant CCF is computed over frequency bands approximately corresponding to auditory filters. Because the bands are narrow, the effects on the CCF of frequency-dependent interaural parameters, most importantly dispersion, can be modeled analytically. The roles of amplitude incoherence and dispersion can also be independently modelled. A systematic experimental approach begins with the dependence of the CCF on head related transfer functions (HRTF) as measured at different azimuths in a free field. Although there are notable individual differences, the effects of HRTFs appear to be almost entirely below detection threshold. An empirical relationship between the CCF for a waveform and for its envelope has been established numerically and in extensive room experiments. [Work supported by the NIDCD, grant DC00181.]
Speech segregation in rooms: Importance of the interferer interaural coherence
Authors: Lavandier Mathieu , Culling John F.
Published: May 2008

When an interferer is present, reverberation degrades speech intelligibility not only by its direct effect on the target, but also by affecting the interferer [Lavandier & Culling, J. Acoust. Soc. Am., 122 (3), 2007]. This latter effect occurs at lower levels of reverberation than the former intrinsic degradation of the target, and can be explained by a binaural mechanism. We show here that the interaural coherence of the interferer is the principal parameter predicting the resulting loss of intelligibility. Speech reception thresholds were measured under headphones, using running speech targets and speech-shaped noise interferers. The stimuli were created by considering a listener and a spatially-separated target and interferer in virtual rooms. The reverberation was varied by modifying the absorption coefficient of every room surfaces simultaneously. Different absorption coefficients were used for target and interferer. With the target anechoic, the interferer was tested in several configurations, in rooms with different sizes and absorptions, at different distances and azimuths from the listener. Several computations of coherence were compared, in order to reveal the one allowing the best prediction of intelligibility.
Effects of pitch and spatial separation on selective attention in anechoic and reverberant environments
Authors: Bressler Scott , Shinn-Cunningham Barbara
Published: May 2008

Subjects identified a random, spoken sequence of five monotonized digits (F0 = 100 Hz) presented from 0° azimuth. A monotonized masking sentence (F0 = 84, 89, 94, 100, 106, 112, or 119 Hz) was presented simultaneously from either 0° and +90° azimuth (chosen randomly on each trial). The same talker recorded both target and masker speech. KEMAR-derived transfer functions simulated either a reverberant or anechoic environment. In contrast to previous studies, in the anechoic condition, differences in pitch provided little benefit and differences in location gave improvements explainable by improvements in the target-to- masker ratio at the acoustically better ear. In reverberant conditions, differences in target and masker location improved performance more than differences in pitch; however, performance was best when there were differences in both location and pitch. Results suggest that when a target utterance is easy to segregate and select (such as in anechoic space when the target is a digit sequence embedded in a competing sentence), high-level attributes such as pitch and location do not improve the ability to selectively attend in a speech-on-speech task. However, in more challenging, reverberant conditions, location and pitch cues can aid segregation and/or selection.
Effects of reverberation on perceptual segregation of competing voices by difference in fundamental frequency
Authors: Deroche Mickael , Culling John F.
Published: May 2008

Three experiments investigated the effect of reverberation on listeners' ability to use the difference in fundamental frequency (F0) between a target and an interfering voice to perceptually separate them. Speech reception thresholds (SRTs) were measured for a monotonized or frequency-modulated male voice against one or two other monotonized or frequency-modulated male voices or against a speech-shaped, pulse train within a virtual room with controlled reverberation. The sources of targets and interferers were always co-located both straight ahead of the listener. In the two first experiments, the beneficial effect of a F0 difference was reduced in reverberation when the target and interferer's F0 were frequency-modulated at 5 Hz. Experiment 3 investigated this interaction between reverberation, a F0 difference and the target and/or interferer F0's modulation: the results highlighted the relevance of the interferer F0's modulation alone in the presence of reverberation. This finding is consistent with the idea that the effect of F0 difference is mediated by a harmonic-cancellation process. The cancellation of the interferer is disrupted by the reverberation only when the interferer's F0 is frequency-modulated, irrespective of the modulation of the target's F0. A frequency-overlap between the F0 of the target and the maskers does not seem a cause of worse impairment in intelligibility.
Prediction of spatial perceptual attributes of reproduced sound across the listening area
Authors: Jackson Philip J. , Dewhirst Martin , Zielinski Slawomir , Rumsey Francis J. , Conetta Robert , Meares David , Bech So/ren
Published: May 2008

Audio systems and recordings are optimized for listening at the “sweet spot,” but how well do they work elsewhere? An acoustic-perceptual model has been developed that simulates sound reproduction in a variety of formats, including mono, two-channel stereo, five-channel surround and wavefield synthesis. A virtual listener placed anywhere in the listening area is used to extract binaural signals, and hence interaural cues to the spatial attributes of the soundfield. Using subjectively-validated models of spatial sound perception, we can predict the way that human listeners would perceive these attributes, such as the direction (azimuth) and width of a phantom source. Results will be presented across the listening area for different source signals, sound scenes and reproduction systems, illustrating their spatial fidelity in perceptual terms. Future work investigates the effects of typical reproduction degradations.
Measuring perceived spatial quality changes in surround sound reproduction
Authors: Rumsey Francis J. , Zielinski Slawomir , Jackson Philip J. , Dewhirst Martin , Conetta Robert , Bech So/ren , Meares David
Published: May 2008

The spatial quality of audio content delivery systems is becoming increasingly important as service providers attempt to deliver enhanced experiences of spatial immersion and naturalness in audio-visual applications. Examples are virtual reality, telepresence, home cinema, games and communications products. The QESTRAL project is developing an artificial listener that will compare the perceived quality of a spatial audio reproduction to a reference reproduction. The model is calibrated using data from listening tests, and utilises a range of metrics to predict the resulting spatial sound quality ratings. Potential application areas for the model are outlined, together with exemplary results obtained from some of its component parts.
How does spatial auditory perception impact how we enjoy surround sound
Authors: Shinn-Cunningham Barbara , Hoover K Anthony
Published: May 2008

Surround sound has become an essential element of enormously popular home entertainment systems, with consumers becoming increasingly eager to invest in high-quality audio systems. While even a cursory web search can uncover numerous criteria, standards, and blogs describing how to select and set up surround-audio equipment, architectural effects are typically ignored or, at best, treated naively. However, architectural acoustics profoundly affect the perceptual experience of a surround-sound listener. Similarly, sound engineers, producers, and artists agonize over every aspect of soundtrack design and production, including the spatial cues embedded in a surround-sound recording, but they have no control over the acoustic environments in which consumers experience their art. How do the acoustics of surround-listening spaces influence the perceptual experiences of the ordinary listener? Is accurate sound localization a proper, desirable, or achievable goal? Would more loudspeakers or higher fidelity improve the surround experience of a typical consumer? These issues will be discussed, taking into account basic psychophysical issues as well as disheartening truths about how ordinary consumers experience sound from their expensive home entertainment systems.
Acoustics of a large immersive environment, The Allosphere
Authors: Conant David , Chu William , McNally Thomas , Hoover K Anthony , Pope Stephen
Published: May 2008

The Allosphere is a new audio/visual immersion space for the California Nanosystems Institute at The University of California, Santa Barbara, used for both scientific and performing-arts studies. This three-story sphere with central-axis catwalk permits an unusually large experiential region. The huge perforated-metal visual-projection sphere, with its principle listening locations centered inside the sphere, introduces multiple considerations and compromises, especially since the ideal acoustical environment is anechoic. Video projection requires opaque light reflectivity of the concave projection surface, while audio solicits extreme sound transmissibility of the screen plus full-range sound absorptivity outside the sphere. The design requires high-fidelity spatialization of a large number of simulated sound sources over a large region near the core, and support of vector-based amplitude panning, Ambisonic playback, and wave-field synthesis. This paper discusses considerations that both conform to, and lie outside of, traditional acoustical analysis methodologies, and briefly reviews the electroacoustic systems design.
Case study on assessing audibility by "Perspicuity" for sounds added to factory noise, using different types of speaker in directional performance
Authors: Shimizu Yasushi , Fujiwara Mai , Ito Atsuko
Published: May 2008

Music and other sounds have been played to provide a pleasant sound environment for workers in a factory. In terms of "Sound Perspicuity" this case study was conducted to assess audibility of spatial sounds, which were adjusted in level without increasing total sound pressure level (SPL) at the workstation. Furthermore, the added sounds were not audible at other workstations. Three speaker systems, including line-array speaker (60 cm in length), were used for the case study. The ratio of added sound (Signal) to factory noise (Noise) was analyzed at every measuring point on a grid of 50 cm by 50 cm. Audibility listening tests were performed for the added sounds, such as natural-environment sounds and musical instrument tones, with Signal to Noise ratios analyzed from three types of speaker. As a result, a sound is recognized as "Kiwadachi" by a Japanese adjective word even when the factory noise has higher levels than the added sounds. Audibility test results for each added sound are discussed with different Signal to Noise ratios.
Shape-optimization of several multi-modal resonators accounting for room/resonator acoustical coupling
Authors: Inácio Octávio , Antunes José
Published: May 2008

Helmholtz resonators are often applied for the sound equalisation of control rooms, through adequate leveling of the low frequency acoustic modal room responses. In several recent papers we proposed to improve the efficiency of such devices by, instead of using basic Helmholtz resonators with uniform cross-section, develop shape optimized multi-modal resonators in order to cope with a larger number of intrusive room modes. We thus showed the feasibility of resonator shape-optimization, in order to obtain a target set of acoustic eigenvalues, within imposed physical and/or geometrical constraints. More recently, we developed an efficient substructure theoretical approach to compute the coupled acoustical modes of rooms fitted with several multi-mode resonators, later also including viscous boundary layer absorption effects at the room/resonator interfaces. In the present paper we extend a further step these results by applying the previously developed optimization techniques to the fully coupled room/resonator model. We thus obtain truly representative results for the optimized complex acoustical problem, which highlight the potential of the proposed corrective methodology.
Automated classification of odontocetes in open ocean environments using a novel multiclass suport vector machine
Authors: Jarvis Susan , Dimarzio Nancy A. , Morrissey Ronald P. , Ward Jessica , Moretti David
Published: May 2008

Mid-frequency active sonar has recently been implicated in several marine mammal stranding events in various geographic locations. This has caused increased interest in monitoring and mitigating the effects of anthropogenic noise on marine mammals. Some species can be more susceptible sonar than others. For example, beaked whales (particularly Mesoplodon densirostris) have been the predominant species involved in most of the strandings. Key to effective monitoring and mitigation is the ability to automatically detect and identify the animals present, especially the species of high interest like beaked whales. This paper presents a novel class-specific support vector machine (CS-SVM) methodology for automated, species-level classification of small odontocetes. A CS-SVM has been developed and trained to identify click vocalization from several species of odontocetes including Mesoplodon densirostris. The algorithm processes time series data in a fully automated fashion first detecting and then classifying click vocalizations. The current CS-SVM configuration correctly identifies clicks from M. densirostris over 95% of time. Further results from the application of this automated classifier to data recorded at the AUTEC and SCORE undersea range facilities will be presented.
Effect of vessels and swimmers on the behavior of spinner dolphins (Stenella longirostris) off the Big Island of Hawai'i
Authors: Bazúa Durán Carmen , Luna Valiente Nina V.
Published: May 2008

Many cetaceans live in coastal waters that are accessible to humans. In Kealakekua Bay, Hawai'i human activities occur during morning hours, when spinner dolphins rest and socialize (feeding occurs at night). Five human activities (swimmers, kayaks, motorized-boats, and narrow- or broadband engine noises) within 200 m of the dolphins were monitored to investigate their effect on dolphin behavior. Dolphin behavior was measured as aerial behavior (high, medium, low energy), acoustic behavior (whistles, burst-pulses, echoclick-trains), herd size, herd coordination (high, medium, low), and diving interval (DI<1 min, 1 min<DI<2 min, DI>2 min) in the presence or absence of each human activity. Interactions between human activities and dolphins occurred 71% of the time, having simultaneous presence of several human activities. When only one human activity was present, motorboats and broad-noise increased herd-coordination and number of aerial behaviors; motorboats and both engine-noises reduced number of acoustic behaviors; kayaks and narrow-noise increased herd-coordination, DI and some acoustic behaviors; swimmers reduced herd-coordination and increased number of acoustic behaviors. Therefore, all five human activities studied changed dolphin behavior and changed it differently. Spinner dolphins probably can distinguish efficiently between human activities and may be interrupting their rest cycle to warn each other, which could have effects on this species welfare.
Effects of noise on hearing in odontocetes
Authors: Finneran James J. , Schlundt Carolyn E. , Ridgway Sam H.
Published: May 2008

Increased public concern and regulation of activities involving anthropogenic sound have resulted in a pressing need for specific information regarding safe limits for marine mammals exposed to underwater noise. Since many marine mammals have sensitive hearing and rely upon underwater sound for communicating, foraging, and navigating, the potential effects of noise on their hearing is of particular concern. One of the most familiar consequences of noise exposure is an increase in threshold that persists after the cessation of the noise, called a temporary thresholds shift (TTS) or permanent threshold shift (PTS). Although there are no PTS data for marine mammals, there have been TTS measurements in a number of species, including bottlenose dolphins and belugas. These studies compare hearing thresholds before and after subjects are exposed to intense sounds. The results are analogous to data from terrestrial mammals, where TTS depends on the exposure frequency, sound pressure, duration, and temporal pattern. This talk reviews the major findings related to the growth of and recovery from TTS in bottlenose dolphins and belugas and discusses the application of these data to acoustic exposure guidelines.
Noise-induced permanent threshold shift in a harbor seal
Authors: Kastak David , Mulsow Jason , Ghoul Asila , Reichmuth Colleen
Published: May 2008

Investigation of auditory temporary threshold shift (TTS) in marine mammals has provided a means of predicting the harmful effects of underwater anthropogenic noise. As complete recovery of hearing is requisite in these studies, they have been considered appropriate in light of subject availability and ethical considerations. In our psychophysical studies of TTS in pinnipeds, we have employed methods designed to safely titrate from sound levels of noise inducing no TTS to levels of significant but completely recoverable hearing loss. In the present study, these methods were used with a harbor seal (Phoca vitulina) exposed to an underwater 4.1 kHz pure tone fatiguing stimulus. Sound levels and durations were gradually increased to a maximum received sound pressure of 184 dB re 1 μPa with a duration of 60 s (SEL=202 dB re 1 μPa2s). Upon the second exposure to this fatiguing stimulus, an initial threshold shift in excess of 50 dB was estimated at a test frequency of 5.8 kHz, a half-octave above the fatiguing tone. Recovery from this unexpectedly large shift occurred at a rate of -10 dB per log(min), with an apparently permanent threshold shift of 7 to 10 dB evident after more than two months following exposure.
Characterizing the relative contributions of large vessels to total ocean noise fields: a case study using the Gerry E. Studds Stellwagen Bank National Marine Sanctuary
Authors: Hatch Leila T. , Clark Christopher W. , Van Parijs Sofie , Merrick Richard , Ponirakis Dimitri , Schwehr Kurt , Thompson Michael A. , Wiley David
Published: May 2008

Understanding and mitigating the effects of underwater noise on marine species requires substantial information regarding acoustic contributions from shipping. In 2006, we used the U.S. Coast Guard's Automatic Identification System (AIS) to describe patterns of large commercial ship traffic within a U.S. National Marine Sanctuary. AIS data were combined with low-frequency acoustic data from an array of nine-ten autonomous recording units deployed throughout 2006. Analysis of received sound levels (10-1000 Hz, root-mean squared decibels re 1 μPascal ± standard error) averaged 119.5 ± 0.3 at high traffic locations. High traffic locations experienced double the acoustic power of less trafficked locations for the majority of the time period analyzed. Average source level estimates (71-141 Hz, root-mean squared decibels re 1 μPascal ± standard error) for individual vessels ranged from 158 ± 2 (research vessel) to 186 ± 2 (oil tanker). Tankers were estimated to contribute two times more acoustic power to the region annually than cargo ships, and over one hundred times more than research vessels. Our results indicate that noise produced by large commercial traffic was at levels and within frequencies that warrant concern among managers regarding the ability of endangered whales to maintain acoustic contact within greater sanctuary waters.
Estimates of chronic SNR exposure levels of sperm whales (Physeter macrocephalus) to airguns in the Gulf of Mexico
Authors: Thode Aaron , Winsor Martha , Mate Bruce , Howard Matt , Kim Katherine , Diebold John , Tolstoy Maya
Published: May 2008

A synthesis effort by the Sperm Whale Seismic Study (SWSS) has estimated chronic levels of low-level, long-term acoustic exposures of sperm whales in the Gulf of Mexico due to seismic airgun activity. Between 2002 and 2005, satellite-tags were attached to 53 whales of both sexes in the northern Gulf, with an average tag viability of 187 days. Data provided by the International Association of Geophysical Contractors (IAGC) permitted the range estimation of active seismic vessels to each whale location. The ray-tracing model BELLHOP was used to estimate received levels from each seismic vessel for every space-time data point at frequencies between 10 to 1000 Hz, using simulated source signatures from a 3590 in 3 seismic array. Winds speeds from numeric models at each space-time location were converted into ambient noise levels, and shipping noise levels were crudely estimated. The preliminary synthesis using a simple spherical spreading transmission loss model suggests that over 95% of the whale positions reported during times of airgun activity occurred in circumstances where the received airgun pulses had 0 dB signal-to-noise ratio (SNR) or greater compared to ambient levels, and between 25-60% of all locations have received SNRs of 20 dB or greater, depending on the SNR definition used. [Sponsored by US Minerals Management Service].
Monitoring the temporal and spatial characteristics of the noise radiated from marine piling
Authors: Lepper Paul A. , Robinson Stephen P.
Published: May 2008

Noise is often an unintended by-product of offshore activities, and a significant source of impulsive underwater noise is marine piling, where a pile is driven into the sea-bed using a hydraulic hammer. This paper describes work undertaken to monitor the underwater radiated noise during offshore marine piling. The measurements made include full characterisation of the temporal variation of the resulting sound field, including frequency content of the pulses and the increasing amplitude typically observed during the soft start period. Results are also shown for the spatial variation of the field, including the effect on propagation of significant bathymetry changes (for example, due to the presence of a sand bank). The energy within each acoustic pulse is an appropriate measure of the sound field, having the advantage that it is relatively straightforward to add the contributions from each pulse in order to derive an overall sound exposure level (SEL) in a manner analogous to methods familiar from air acoustics. An example is then given of how the measured data and predictive modeling may be used to calculate an overall exposure for an animal in the vicinity, using various assumptions about the location and mobility of the animal.
Monitoring, measuring and describing ocean noise over ecologically viable scales with applications to impacts on large whales
Authors: Clark Christopher W. , Tremblay Chris , Fowler Melissa , Diamond Christi , Ponirakis Dimitri , McCarthy Clara , Morano Janelle , Muirhead Charles , Murray Anita , Rowland Liz , Vannicola Catherine , Warde Ann
Published: May 2008

Large whales communicate primarily in the low (<1000 Hz) frequency bands; the same frequency range within which anthropogenic ocean noise has been increasing over the last half century at approximately 3-5 dB/decade. The working assumption and hypothesis hold that rising ambient noise levels negatively impact whales by interfering with communication, navigation and predator detection, and that over the long-term such effects could reduce breeding success and population size. There is a lack of empirical data on the spatial-temporal dynamics of ambient noise by which to assess potential impacts. One year of continuous acoustic data from an ongoing distributed array of 19 continuous seafloor recorders covering a 1000 km2 area in Massachusetts Bay, USA were analyzed for ambient noise statistics and the occurrences, locations and vocal behaviors of fin, humpback and right whales. Noise levels were greater than 120 dB rms re 1 μPa in the 10-1000 Hz band throughout the 1000 km2 area for ⩾50% of the season when whales were present. If animals are relying on acoustic cues to coordinate feeding and social interactions, these high noise levels impose a significant loss of acoustic habitat during the whales' residency in the area.
Propagation, scattering and reverberation in an ice-covered Arctic ocean
Authors: Schmidt Henrik , Lepage Kevin D.
Published: May 2008

The Arctic Ocean is a unique acoustic environment due to the ice cover and the strongly upward refracting sound speed profile. A large amount of theoretical and experimental research has focused on the significance of the scattering of sound by the rough ice cover. In spite of this, a strong anomali persisted until the early 1990s in the propagation of low-frequency sound in particular, with prevailing rough-surface scattering theories incapable of explaining the frequency dependence of transmission loss observed experimentally. More recent modeling was cabable of reproducing the observed transmission losses by combining the effects of ice elasticity, rough interface scattering, and waveguide propagation [JASA, 96:1783-1795,1994]. Thus, it was demonstrated that incoherent scattering into Lamb waves in the ice provided a significant loss mechanism. This mechanism itself did not explain the frequency dependence, but when incorporating the bilinear sound speed profile of the arctic ocean, it was found that the lower-order modes become disproportionately attenuated, explaining the high attenuation observed at low frequencies. The finding was later confirmed by succesfully modeling the modal losses observed in 1994 Trans-Arctic Propagation experiments, and the ability of the same model to accurately predict observed, long-range reverberation measurements [JASA, 111:747-760,2001]. [Work supported by ONR.]
Localization of Antarctic ice breaking events by frequency dispersion of the signals received at a single hydroacoustic station in the Indian Ocean
Authors: Li Binghui , Gavrilov Alexander
Published: May 2008

Transient acoustic signals from Antarctic ice cracking and breaking events, featuring significant frequency dispersion, were observed at the hydroacoustic stations deployed in the Indian Ocean as part of the International Monitoring System (IMS) of the Comprehensive Nuclear-Test-Ban Treaty. Based on a comparison with numerical predictions, the measured dispersion characteristics were used to estimate the range between ice events and the receiver. Combined with the bearing capability of the IMS stations, these estimates allow us to locate ice events from a single hydroacoustic station. An analysis of range estimation errors due to uncertainty of the measured time-frequency structure of signal arrivals and due to variations of the sound speed profiles was also conducted. The analysis showed that the location accuracy from a single hydroacoustic station for the typical ice events was of the same order, as that determined from an intersection of bearings from two remote stations, if the signal frequency bandwidth is as wide as at least 5 Hz and lies within 5 Hz to 35 Hz frequency range. This localization method was examined by analysing several ice events detected at both the Cape Leeuwin IMS station and a sea noise logger deployed off the Antarctic shelf.
Year-round acoustic monitoring of large whales in polar environments: a comparison of Davis and Bransfield Straits
Authors: Stafford Kathleen , Simon Malene J. , Dziak Robert , Mellinger David K.
Published: May 2008

Both Davis Strait, in the Arctic between Canada and Greenland, and Bransfield Strait, in the Antarctic between the Antarctic Peninsula and the South Shetland Islands, are areas that experience extreme inter-seasonal differences in temperature, ice cover and productivity. The seasonally productive nature of both of these ice-influenced areas provides habitat for foraging large whales such as blue (Balaenoptera musculus) and fin (B. physalus) whales. In order to monitor and compare the seasonal occurrence of these species at high latitude regions at opposite ends of the globe, autonomous underwater hydrophone packages were deployed for one year in each Strait. Three instruments were deployed and recovered in Davis Strait from October 2006-07 and five in Bransfield Strait from November 2006-07. Blue and fin whales were recorded seasonally in both regions and exhibited the geographic acoustic distinctions between northern and southern hemisphere populations. Comparisons of the seasonal occurrence and the influence of ice cover on this occurrence will be compared and contrasted between north and south.
The Fram Strait acoustic tomography system
Authors: Sagen Hanne , Sandven Stein , Worcester Peter , Dzieciuch Matthew , Skarsoulis Emmanuel
Published: May 2008

The deep and wide Fram Strait between Greenland and Spitzbergen is the main influx and efflux gate to the Arctic Basin. Although major resources are invested in measurements of current and temperature here (http://asof.npoar.no), the flux estimates still have significant deficiencies and errors. Our objective is to build, test, validate and use an innovated integrated observing and modeling system, including acoustic tomography, for improved monitoring of volume, heat and freshwater transports in the Fram Strait. As part of the DAMOCLES-IP, (=Developing Arctic Modeling and Observing Capabilities for Long-term Environmental Studies - Integrated Project) a first step acoustic tomography system is to be installed in the Fram Strait between East Greenland and West Spitzbergen in August 2008. The first step tomography system consists of one acoustic source near the Svalbard shelf and one receiver array in the middle of the Fram Strait. An extended acoustic system serving both tomography and glider navigation is planned implemented in 2009 within the recently funded project "Acoustic technology for observing the interior of the Arctic Ocean" (ACOBAR). We will present the specification of the tomography systems; our experimental plans, and plans for data analysis, including data assimilation.
Saguenay fjord entrance whale feeding ground: Acoustic study of sill dynamics and tidal aggregation of forage fish
Authors: Simard Yvan , Roy Nathalie , Saucier François , Gagné Jacques , Giard Samuel
Published: May 2008

The Saguenay fjord entrance in the St. Lawrence Estuary at Tadoussac is a world famous site where beluga and minke whales can be regularly observed from the coast. Strong tidal upwelling over the shallow sill of the fjord controls the exchanges with the St. Lawrence. In May 2005, an intensive oceanographic and acoustic survey was conducted to understand how the complex 3D hydrodynamics may contribute to concentrating whale preys. High time-space resolution acoustics (38 and 120 kHz split-beam), ADCP (acoustic Doppler current profilers), CTD profiles, plankton and micronekton sampling were used to track the 3D movements of water masses, zooplankton and forage fish. During flood, the dense cold waters that jump over the sill block the Saguenay outflow and subduct into the fjord with their fish and zooplankton content. This complex 3D circulation generates fronts and convergence zones where biomass is concentrating until current reversal occurs during ebb. These concentrations are then advected and dispersed downstream over the sill with the Saguenay surface plume. This whale prey tidal concentrating process depends on the existence of sufficient forage fish densities in the mesoscale neighbourhood. It is likely at the basis of the persistent high frequentation of this area by whales.
Acoustic characteristics of vertically migrating and non-migrating organisms observed in the North Pacific Ocean
Authors: Sawada Kouichi , Yasuma Hiroki , Ichii Taro , Takahashi Hideyuki , Abe Koki
Published: May 2008

Acoustic characteristics of vertically migrating and non-migrating organisms in a day were investigated for species identification. In July 27-30, 2004, both organisms were observed using ship echosounders (38 kHz and 120 kHz) and a tethered acoustic-optical composite system (J-QUEST) from several hours before sunset to several hours after the sunrise, drifting a research vessel, Shunyo-maru, in the North Pacific Ocean. The J-QUEST is an instrumental package composed of an split-beam echosounder (70 kHz) and a stereo TV camera system. The J-QUEST depth was changed from 220 m to 25 m to observe vertical migration. Boreopacific gonate squids were observed by the stereo TV camera and they are considered to conduct diurnal vertical migration to feed migrating organisms. Average TS of the ascending layer and Boreopacific squid were measured in situ using the J-QUEST. Average area scattering strength (SA) values of the ascending layer, non-migrating layer, descending layer, aggregation of Boreo pacific squids, and that of Japanee anchovy were measured at 38 kHz and 120 kHz, There was a constant and different SA difference between the two frequencies at each layer except migrating layer. The ascending and the descending layer have almost the same SA differences. It indicates that the both layers composed of the same organisms.
Using multifrequency acoustic scattering techniques to study mixed zooplankton populations
Authors: Lavery Andone , Wiebe Peter , Stanton Timothy K. , Lawson Gareth , Benfield Mark , Copley Nancy
Published: May 2008

Zooplankton populations can be highly heterogeneous and variable on spatial scales of centimeters to kilometers and temporal scales of minutes to years. High-frequency acoustic scattering techniques allow a synoptic view of zooplankton distribution and abundance on these scales. However, there are well-known complications in the interpretation of acoustic scattering returns, often limiting the inference of quantitative parameters (such as size or abundance) to restricted locations and conditions. Multifrequency and broadband acoustic scattering techniques, combined with sophisticated instrument platforms that combine multiple sensors allowing acoustical, optical, and other environmental measurements, reduce the ambiguities typically associated to the interpretation of acoustic scattering at single frequencies and expand the conditions under which inference of quantitative biological parameters is possible. The focus of this talk is a decade-long study aimed at understanding the distribution and abundance of mixed zooplankton populations in the Gulf of Maine. Simultaneous multifrequency acoustic, optical, environmental, and net measurements were performed. Insights gained from this study are presented together with recent measurements involving broadband acoustic scattering from zooplankton in the presence of nonlinear internal solitary waves. These studies highlight the importance of an integrated approach to understanding heterogeneous zooplankton populations on relevant spatial and temporal scales.
Adaptive focusing for bone and motion artifacts corrections in High Intensity Focused Ultrasound Therapy
Authors: Tanter Mickael , Pernot Mathieu , Aubry Jean-François , Fink Mathias
Published: May 2008

Despite extensive and fast progress of HIFU clinical applications, many issues still need to be addressed. Distortions caused by defocusing obstacles, such as the skull or ribs, on the ultrasonic therapeutic beam are still being investigated. Multi-element transducer technology must be used in order to achieve such transcranial or transcostal adaptive focusing. Second, the problem of motion artifacts, a key component in the treatment of abdominal lesions, has been shown to significantly influence the efficacy and treatment time. Though many methods have been proposed for the detection of organ motion, little work has been done to develop a comprehensive solution including motion tracking and feedback correction in real time. This paper is a review of the work achieved by authors in transcranial HIFU, transcostal HIFU, and motion compensated HIFU. For these three issues, the optimal solution can be reached using the same technology of multi-element transducers devices able to work both in Transmit and Receive modes.
Noninvasive temperature estimation using diagnostic ultrasound: In vivo results
Authors: Liu Dalong , Shrestha Ajay , Visaria Rachana , Bischof John , Ebbini Emad S.
Published: May 2008

In this paper, we present temperature imaging data obtained before and after HIFU-induced lesions in implanted tumors in the hind limb of nude mice in vivo. The RF data was acquired using a 9 MHz 192-element linear probe on a diagnostic scanner at 90 frames per second. Approximately 2 s of frame data was collected before, during and after sub-therapeutic exposures of 0.2 s duration. The frame rates were sufficiently high to capture the effects of local tissue deformation due to breathing and pulsation near blood vessel. Using a physics-based spatial-temporal filtering of tissue displacement, we were able to produce accurate spatial-temporal maps of the temperature change with fine spatial and temporal resolution. These results are in good agreement with directly measured temperatures using fine temperature sensors near the HIFU focal spot. The results show that robust temperature estimation in the presence of tissue motion/deformation is feasible. Applications of this method in measuring the local thermal properties of tissue will be addressed. In particular, tissue absorption can be estimated and it appears to increase by a factor of 2 - 4 after lesion formation.