bluuebunny/crossref_metadata_2025 huggingface dataset:
An ultrasound system to identify and characterize kidney stones
Authors: Cunitz Bryan W. , Dunmire Barbrina L. , Sorensen Mathew D. , Hsi Ryan , Lee Franklin , Sapozhnikov Oleg A. , Harper Jonathan D. , Bailey Michael
Published: November 2013

Ultrasound imaging has tissue and blood imaging modes. This report describes development of a kidney stone imaging mode. Two plane pulses generate a B-mode image. Overlaid in color are regions of high decorrelation between the pulses. Our previous data [UMB, 39, 1026–1038 (2013)] indicate the pulses excite bubbles on the stone surface, which causes the decorrelation. As such this mode automatically identifies stones in the image while scanning at a high frame rate. Further in a control box placed on the stone, highly focused beams are scanned across the stone and a harmonic B-mode image is produced to sharpen the lateral resolution. This mode is used to refine the size and shape of the stone. The first mode is used to aid visualization of stones. Our team is also using it to target and track stones that move with respiration during shock wave lithotripsy (SWL) and as an indicator of stone susceptibility to SWL since surface bubbles contribute to comminution. Improved stone sizing by the second mode aids treatment planning, and resolution of surface roughness is another indicator of stone fragility. [Work supported by NIH DK043881, NIH DK092197, and NSBRI through NASA NCC 9-58.]
Optimizing detection of masked vehicles
Authors: Blomberg Leslie D.
Published: November 2013

The 250 million vehicles in the United States make so much noise that it is often difficult for pedestrians to hear a particular approaching vehicle, perhaps one that they do not see or realize is there. This masking effect is a pedestrian safety concern. Solving the general problem of masked vehicles is very difficult, because each vehicle plays conflicting roles–it needs to be heard, while it simultaneously masks other vehicles. This is especially true in urban settings where many vehicles and pedestrians are present. This paper seeks to identify the optimal vehicle noise level to minimize masking.
Sound design concepts meeting minimum sound requirements—Advantages and disadvantages
Authors: Fiebig André , Genuit Klaus
Published: November 2013

A young field of activity for acoustic engineers has emerged in the context of vehicle exterior noise design considering the aspect of pedestrian safety. The fear of blind associations, public authorities, and governmental agencies to have a high collision risk for visually impaired persons with “quiet” vehicles led to the definition of new minimum sound requirements for hybrid and electric vehicles ostensibly leading to ten times fewer pedestrian and cyclist injuries. The requested sound should be detectable under a wide range of background noises when a vehicle is traveling under 18 mi/h. It is still open, whether hybrid and electric vehicles cause verifiably a higher collision risk for vulnerable persons and consequently the German Federal Environmental Agency rejects the idea of introducing additional sounds to enhance the audibility of vehicles operating in electric mode. Nevertheless acoustic engineers have to deal with the new requirements in the context of vehicle exterior noise and must find sustainable solutions considering product sound quality, detectability of vehicles and noise annoyance in equal measure. The paper will discuss the context-related need for additional sounds to improve pedestrian safety and the conceptual scope of sound design taking into account community noise aspects.
An innovative method for the sonification of quiet cars
Authors: Denjean Sebastien , Roussarie Vincent , Ystad Solvi , Kronland Martinet Richard
Published: November 2013

With the development of electric motorizations, the acoustic feedback that the driver perceives in the passenger compartment has deeply changed. The vanishing of engine noise is often associated with better comfort, but it also represents a substantial loss of information for the driver. Internal combustion engine noise indeed plays a major role in the acoustic contribution of the multisensory perception of motion. In a previous experiment, we showed that it was more difficult for drivers to correctly estimate the vehicle speed without engine noise. Thus, more attention is needed from the driver to correctly regulate the speed in electric cars than in internal combustion engine cars. Consequently, we developed an innovative sonification method to compensate for the loss of auditory information in electric cars. The generated sounds are directly controlled by the vehicle’s driving parameters, which give relevant cues on motion. This method has been tested in a driving simulator study to validate its suitability and to show that the control of sound properties can be adjusted to give precise information to the driver.
Application of Mach-Zehnder interferometer to characterize spark-generated spherical N-waves in air
Authors: Yuldashev Petr , Karzova Maria , Blanc-Benon Philippe , Ollivier Sébastien , Khokhlova Vera
Published: November 2013

Spark-generated spherical N-waves in air are measured by means of the Mach-Zehnder interferometer. A thin laser beam with sub-millimeter cross-section is used to obtain the highest time resolution. The light interference pattern is registered by a photodiode connected to a 10 MHz wideband amplifier. The inverse Abel transform is applied to the phase signal of the interferometer to reconstruct the pressure waveform. The peak positive pressure of 3000 Pa is obtained at the distance 10 cm from the source. It is shown that for the realized experimental setup a time resolution of 0.4 μs is reached. This resolution is 6 times better than the time resolution of condenser microphones (2.5 μs for the Brüel & Kjær 1/8 in.). The experimental waveforms measured at distances up to 100 cm are compared with the results of numerical modeling based on the generalized Burgers equation. The experimental waveform measured at 10 cm is set as a starter waveform for the numerical model. The theoretical waveforms are found to be in a good agreement with the measurements for all propagation distances with less than 5% difference for the peak positive pressure. [Work supported by PICS RFBR 10-02-91062/CNRS 5603, RFBR grant 12-02-31830-mola, the President of Russia MK-5895.2013.2 grants and by LabEx CeLyA ANR-10-LABX-60 and SIMMIC ANR-2010-BLAN-0905-03.]
Auralization of virtual rooms in real rooms using multichannel loudspeaker reproduction
Authors: Pelzer Soenke , Vorlaender Michael
Published: November 2013

When playing auralizations including virtual room reverberation through loudspeaker-based reproduction systems, there is usually an interaction between the auralized virtual rooms with the real room acoustics of the listening environment. In case of a listening room which is not perfectly dry, it is investigated which criteria the listening room should fulfill to avoid considerable interference with the auralizations. In a further step, a computer room acoustics simulation is extended to account for the listening space by modifying the resulting room impulse responses, so that the final room-in-room situation matches best to the targeted virtual room acoustics. The presented technique is then applied in a multimodal immersive virtual display (CAVE-like environment) where room acoustics are not matter of choice due to restrictions of projection screen materials and placement.
Multiple-slope sound energy decay investigations in single space enclosures with specific geometrical and material attributes
Authors: Sü Gül Zühre , Xiang Ning , Caliskan Mehmet
Published: November 2013

Acoustical coupling until now has basically been studied to define the peculiar sound field within acoustically coupled enclosures in which multiple-slope energy decays can often be observed. The key concern of this study is to reveal the potential of multiple-slope energy decay formation in over-size single space structures with particular geometry and distribution of materials in different acoustical performance characteristics. Specifically, multiple dome superstructures, composed of one central dome supported by semi-domes and transitional elements, are selected for the case studies. The interpretation of the acquired data is carried in order to broaden the definition of “the coupled volume system” with an emphasis on invisible sources and apertures of acoustical coupling in a “single volume system.” The methodology of the research involves joint use of in-situ acoustical measurements, acoustical modeling/simulation methods, and computational analyses. Bayesian analysis approach is applied in quantifying multiple-slope decay parameters. Initial results for selected cases indicate double and triple slopes for field tests and even more slope natures for simulations at various frequency bands. Future work aims to elaborate the mechanism of multiple-slope decay occurrence by energy feedback and distribution analysis.
Sound propagation to and around the balcony edge in a performance hall
Authors: Cheung Liu Yee , Tang Shiu Keung
Published: November 2013

To investigate the propagation of sound from the source to and around the balcony, over 150 points were measured in a 1420-seat auditorium. Radial points around the balcony edge with distances of 1.5 and 2 m, as well as intermediate points on the direct paths between the omni-directional sound source on the stage and the centers of the radial positions around the balcony edge, were also measured. A 1:20 scaled-model of this hall was done as a complement to the full-scaled measurement done to study the propagation in finer details. Various acoustic parameters were obtained. With the wave file of the impulse response recorded, the propagation pattern could be traced.
The effects of site and instrument variability on recognizing odontocete species by their echolocation clicks
Authors: Stinner-Sloan Johanna , Roch Marie A. , Baumann-Pickering Simone
Published: November 2013

This work conducts a systematic study of the impact of variable site and instrument conditions on the performance of a species recognition task. Echolocation clicks were collected from six different sites in the Southern California Bight from multiple deployments of instruments with nine different preamplifiers. The classification performance of a Gaussian mixture model using cepstral features is examined on Risso’s and Pacific White-Sided dolphins. One hundred three-fold Monte Carlo experiments are conducted. When grouped so that each acoustic encounter is either in the training or test set, a mean error rate of 1.9%±4.4σ is obtained. In spite of correction for preamplifier response curves, grouping by preamplifier and site increases error dramatically to 20.9%±18.1σ and 25.9%±28.1σ, respectively. We introduce noise compensation techniques that reduce error rates as follows: by encounter, 0.5%±0.3σ, by preamplifier, 1.7%±2.3σ, and by site, 9.4%±16.7σ.
Comparisons of beaked whale signals recorded in eastern Atlantic to known beaked whales signals
Authors: Gerard Odile
Published: November 2013

Beaked whales are a group of more than 20 genetically confirmed species; they are very elusive and were among the least known species until a few years ago. Because of their sensitivity to sonar, an increased research effort dedicated to these species and in particular to their signals started 10 years ago. Despite this effort, the signals of many beaked whale species remain unknown. Signals of Blainville’s (Mesoplodon densirostris), Cuvier’s (Ziphius cavirostris), Gervais’ (Mesoplodon europaeus), and Northern Bottlenose Whales (Hyperoodon ampullatus) have been studied and described in different articles. The signals of three unknown species (different from the above mentioned species signals) have been reported. All seven species produce upsweep frequency modulated signals which seem species specific. In 2010, NATO Undersea Research Centre (NURC) conducted a sea-trial in Eastern Atlantic Ocean, Southwest of Portugal. Three different types of beaked whale signals were recorded. The characteristics of these signals will be presented and compared to the known signals of beaked whales. The conclusions of this analysis will be presented.
Vocal repertoire of Southeast Alaskan humpback whales (Megaptera novaeangliae)
Authors: Fournet Michelle , Szabo Andy
Published: November 2013

Humpback whales (Megaptera novaeangliae) are vocal baleen whales that exhibit complex social interactions across broad spatial and temporal scales. On low latitude breeding grounds, humpback whales produce complex and highly stereotyped “songs” as well as a range of “social sounds” associated with breeding behaviors. While on their Southeast Alaskan foraging grounds, humpback whales produce vocalizations during cooperative foraging events as well as a range of unclassified vocalizations for which the social context remains unknown. This study investigates the vocal repertoire of Southeast Alaskan humpback whales from a sample of 366 vocalizations collected over a three-month period on foraging grounds in Frederick Sound, Southeast Alaska. We used a two-part classification system, which included aural-spectrogram and statistical cluster analyses, to describe and classify vocalizations. Vocalizations were classified into 19 individual call types nested within four call classes. The vocal repertoire of Southeast Alaskan humpbacks shows moderate overlap with vocalizations recorded in Atlantic foraging grounds and along the Australian migratory corridor.
Sound absorption by fish schools: Forward scattering theory and data analysis
Authors: Feuillade Christopher , Raveau María P.
Published: November 2013

A model used previously to study collective back scattering from fish schools [J. Acoust. Soc. Am., 99(1), 196–208 (1996)] is used to analyze the forward scattering properties of these objects. There is an essential physical difference between back and forward scattering from fish schools. Strong frequency dependent interference effects, which affect the back scattered field amplitude, are absent in the forward scattering case. This is critically important when analyzing data from fish schools to study their size, the species and abundance of fish, and fish behavior. Transmission data can be processed to determine the extinction of the field by a school. The extinction of sound depends on the forward scattering characteristics of the school, and inversion of absorption data to provide information about the fish should be based upon a forward scattering paradigm. Results are presented of an analysis of transmission data obtained during the Modal Lion experiment in September 1995, and reported by Diachok [J. Acoust. Soc. Am., 105(4), 2107–2128 (1999)]. The analysis shows that using forward scattering typically leads to significantly larger estimates of fish abundance than previous analysis based on back scattering approaches. [Research supported by ONR.]
In vitro acoustic characterization of echogenic liposomes with a polymerized lipid bilayer (Pol-ELIPs)
Authors: Paul Shirshendu , Nahira Rahul , Mallik Sanku , Sarkar Kausik
Published: November 2013

Liposomes are typically lipid bilayer vesicles with an aqueous interior. A modified preparation protocol can make them echogenic, i.e., capable of scattering incident acoustic pulses, by incorporating gas pockets in their structure. Here we study echogenic liposomes with a polymerized lipid bilayer that can potentially improve their stability and nonlinear behavior. The Pol-ELIPs prepared were found to have a very polydisperse size distribution with an average size of 3μm. The frequency dependent attenuation experiment did not show any distinct peak due to the high polydispersity. They showed echogenicity in our in vitro scattering experiments, even without the presence of bovine serum albumin in the reconstituting media. Scattered response measured from Pol-ELIP suspension showed non-linear behaviors with distinct second-harmonic and subharmonic peaks, in contrast to non-polymerize ELIPs that did not show any subharmonic response. Scattered fundamental, second-harmonic and subharmonic responses at a lipid concentration of 1µg/ml showed up to 35, 30, and 35 dB enhancement, respectively. The subharmonic response showed all its characteristic features—its appearance only above a threshold excitation level (150 kPa) and then a sharp rise with a subsequent saturation. The study proves the echogenicity of the novel Pol-ELIPs with interesting nonlinear properties. [Work partially supported by NSF.]
A method for obtaining high-resolution directivities from the live performance of musical instruments
Authors: Eyring Nicholas J. , Leishman Timothy W. , Strong William J.
Published: November 2013

Directivity measurements for live performance of musical instruments present several experimental challenges, including the need for musicians to play consistently and reproducibly. Some researchers have chosen to implement fixed, limited-element microphone arrays surrounding instruments for rough directivity assessments. Unfortunately, with practical numbers of microphones and data acquisition channels, this approach limits spatial resolution and field decomposition bandwidth. Higher-resolution data may be obtained with a given microphone and channel count by rotating a musician in sequential azimuthal angle increments under a fixed semicircular microphone array. The musician plays a selected note sequence with each increment, but corrections must be made for playing variability. This paper explores the development of this method, which also uses rotating reference frame microphones and frequency response function measurements. The initial developments involve a loudspeaker, with known directivity, to simulate a live musician. It radiates both idealized signals and anechoic recordings of musical instruments with random variations in amplitude. The presentation will discuss how one can reconstruct correct source directivities from such signals and the importance of reference microphone placement when using frequency response functions. It will also introduce the concept of coherence maps as tools to establish directivity confidence.
Difference thresholds for melodic pitch intervals
Authors: McClaskey Carolyn M.
Published: November 2013

Pitch-interval processing is an important aspect of both speech and music perception. The current study investigated the extent to which relative pitch processing differs between intervals of the western musical system and whether these differences can be accounted for by the simplicity of an interval's integer-ratio. Pitch-interval discrimination thresholds were measured using adaptive psychophysics for sequentially presented pure-tone intervals with standard distances of 1 semitone (minor second, 16:15), 6 semitones (the tritone, 45:32), and 7 semitones (perfect fifth, 3:2) at both high (1500–5000 Hz) and low (100–500 Hz) frequency regions. Results show similar thresholds across all three interval distances with no significant difference between low and high frequency regions. Consistent with previous studies, thresholds obtained from musicians were considerably lower than those from non-musicians. Data support enhanced pitch-interval perception by musicians but argue against an effect of frequency-ratio simplicity in the case of pure-tone melodic intervals.
Individuals with congenital amusia respond to fractal music differently from normal listeners
Authors: Liu Fang , Livengood Sherri L. , Jiang Cunmei , Chan Alice H. , Wong Patrick C.
Published: November 2013

Congenital amusia is a neurogenetic disorder predominately defined by impaired perception of musical tonal relationships. This study examined amusics’ responses to a gradient of pitch interval complexity in fractal music. Eighteen Mandarin-speaking amusics and 18 controls rated random tone sequences for perceptual (complexity, melodicity) and affective (interest, ease, mood) attributes, and performed a recognition memory task. Sequences were created using fractal model (1/fß) with ß-values ranging from 0.0 (most complex) to 2.6 (least complex). As predicted, both groups rated complexity based on the ß-values, demonstrating that amusics perceived the gradient of pitch interval complexity. However, amusics’ ratings deviated from controls in measures of melodicity, affect, and memory performance. For controls, moderately complex sequences (fractal ß-values =1.4–1.6) were rated the most melodious, drove the highest emotional responses, and were the easiest to remember, whereas amusics’ ratings did not respond to this range, but rather followed a more linear trend. These findings suggest that amusics not only have problems with perception of pitch interval relationships (not complexity), but also lack heightened sensitivity to the moderate range in fractal music. This deficit is reflected in broader musical processing including the perception of melody, affective response, and memory for musical sequences. [This work was supported by National Science Foundation Grant BCS-0719666 to P.C.M.W. and Shanghai Normal University funding to C.J.]
Vibrato lab: A signal processing toolbox for woodwind sound analysis
Authors: Wen Zhe , Yang Xuchen , Shu Cheng , Ke Fangyu , Ren Gang , Bocko Mark
Published: November 2013

Vibrato is an important performance technique for woodwind instrument that produces amplitude and frequency modulation inside a musical note. We present a MATLAB-based toolbox for detailed analysis of recorded vibrato notes. The harmonic structure of a music note is identified from its spectrographic analysis. Then we separate the harmonic structure into sonic partials using band-passed filters. The sound analysis algorithms, which provide the signal features of the vibrato note, are then performed over these separated sonic partials. In our implementation, each individual sonic partial is modeled as a quasi-monochromatic component, which is a sinusoidal signal with narrow-band amplitude modulation and frequency modulation. Based on this signal modeling technique, the modulating components are extracted from a separated sonic partial using modulation detection algorithms including short-time analysis and Hilbert transform. This toolbox provides comprehensive visualization tools to allow the users to interact and experiment with these signal features. We also implemented an auralization module that allows the users to experiment with the signal parameters and synthesize artificial vibrato sound. The analysis and visualization functionalities are all integrated in a compact graphical user interface that allows the users to intuitively implement complex sound analysis functionalities with simple analysis procedures.
Nonlinear and transient acoustic holography for characterization of medical ultrasound sources and their fields
Authors: Sapozhnikov Oleg A. , Kreider Wayne , Tsysar Sergey A.
Published: November 2013

Holography is based on the possibility of reproducing a 3D wave field from a 2D distribution of the wave amplitude and phase measured along some surface transverse to the wave propagation. Such a measured distribution thus can be considered as a hologram. It provides a boundary condition for the wave equation, and as such is an important characteristic of any ultrasound source. In our previous work we have implemented various holographic approaches for medical ultrasound sources, including transient and nonlinear versions. Here we illustrate the approach with several experimental examples. Transient holography was performed to characterize the surface vibration of a circular, single-element, flat diagnostic probe with a 2.5 cm diameter and a 1 MHz resonance frequency after excitation by a submicrosecond pulse. Nonlinear holography was applied to a single-element focused source with a diameter and focal length of 100 mm. Forward- and backward-propagation algorithms were based on the Westervelt wave equation. A single-element focused source was excited at a sufficiently high power level so that harmonics were developed during nonlinear propagation in water; the nonlinear hologram was recorded as a set of 2D distributions of magnitude and phase for several harmonics. [Work supported by RFBR and NIH EB007643.]
Dynamic acoustical imaging systems with reconfigurable transceiver arrays and probing waveforms
Authors: Lee Michael , Lee Hua
Published: November 2013

The data-acquisition format of traditional acoustical imaging systems has been operating with structured transceiver arrays and predetermined illumination waveforms. The fixed physical array configurations have been largely linear or planar, for computation simplicity. The conventional systems started with the coherent mode with narrow-band illumination. The coherent illumination waveforms were then replaced by wideband signals to operate in the pulse-echo format for the improvement of range resolution. This paper presents the functionalities of reconfigurable acoustical imaging systems with FMCW probing waveforms, and the equivalence to the conventional modalities. The reconfigurable configuration is applied to both the transceiver aperture arrays and the probing signals for the enhancement of the resolving capability. The reconfigurable array allows us to actively optimize the aperture coverage for superior resolution. To achieve reconfigurable illumination waveforms, programmable stepped-frequency FMCW signaling modality is employed. The presentation of this paper includes the algorithm structure, range estimation, and frequency editing, and of special interest and importance, the detection and imaging of time-varying targets.
Three-dimensional reconstruction of sound fields based on the acousto-optic effect
Authors: Fernandez-Grande Efren , Torras-Rosell Antoni
Published: November 2013

The acousto-optic effect can be used to measure the pressure fluctuations in air created by acoustic disturbances (the propagation of light is affected by changes in the medium due to the presence of sound waves). This makes it possible to measure an arbitrary sound field using acousto-optic tomography via scanning the field with a laser Doppler vibrometer. Consequently, the spatial characteristics of the sound field are captured in the measurement, implicitly bearing the potential for a full holographic reconstruction in a three-dimensional space. Recent studies have examined the reconstruction of sound pressure fields from acousto-optic measurements in the audible frequency range, based on Fourier transforms and elementary wave expansion methods. The present study examines the complete reconstruction of the sound field from acousto-optic measurements, recovering all acoustic quantities, and compares the results to the ones obtained from conventional microphone array measurements.
Put your sound where it belongs: Numerical optimization of sound systems
Authors: Feistel Stefan , Olson Bruce C. , Jaramillo Ana M.
Published: November 2013

A new technology based on FIR filters in combination with room acoustic modeling allows optimizing steerable columns and line arrays to each specific venue in a matter of seconds. Both maximum SPL and maximum sound field uniformity can be prioritized to obtain an ideal sound distribution without losing sound pressure in the wrong directions thus avoiding unwanted reflections. Areas can also be excluded to minimize sound (i.e., stage area). Real-life test results support the theory.
Multipole, spherical harmonics and integral equation for sound field reproduction
Authors: Choi Jung-Woo
Published: November 2013

The quality of sound field reproduction depends on the way we use to represent a sound field. For example, the spherical harmonics expansion being used for the higher-order-Ambisonics attempts to represent a desired sound field as a sum of many spherical harmonics, and the method incorporating integral equations, e.g., wave field synthesis, identifies the sound field as a superposition of single or double layer potentials distributed on a boundary surface. In contrast, the multipole expansion converts the desired sound field into equivalent multipole distributions. In this work, we investigate the fundamental differences in these three representations when they are applied for the reproduction of sound fields. In particular, their advantages and disadvantages in representing the directivity of a virtual sound source, translation of a desired sound field, and their benefit in deriving time domain formula for the real-time application will be discussed.
The use of interpolated time-domain equivalent source method for reconstruction of semi-free transient sound field
Authors: Pan Siwei , Jiang Weikang
Published: November 2013

A semi-free transient sound field is reconstructed by extending the interpolated time-domain equivalent source method (ITDESM) in the free field to the semi-free field. In this approach, the time-domain equivalent sources are placed not only near the actual sound sources, but also in the vicinity of their mirrored sources with respect to the reflecting plane surface. Suppose that the number of equivalent sources distributed around the mirrored sources (virtual equivalent sources) is the same as that used near the actual sources (actual equivalent sources), with their locations symmetrical about the reflecting surface. The reflecting surface considered here can be perfectly rigid as well as impedance-effected. Furthermore, by reformulating the strengths of the virtual equivalent sources at each time instant with those of the corresponding actual equivalent sources, the computation load of solving the equivalent source strengths can be reduced by 50%. Numerical examples of reconstructing the semi-free transient sound field radiated from three monopoles under different reflection conditions demonstrate the feasibility of the proposed method.
The spectral profile estimation algorithm: a non-linear, non-a priori noise normalization algorithm
Authors: Ballard Jeffrey A.
Published: November 2013

Time-frequency analysis of acoustic signals often involves a background noise spectral estimation step to estimate the signal-to-noise ratio of the signals of interest. This step is typically accomplished with the application of a split mean normalizer (SPN) [Struzinski and Lowe, J. Acoust. Soc. Am. 76 1738–1742 (1984)]. These normalizers work well against tones and can be tuned with a priori information to normalize wider energy signals but can still suffer performance loss in these cases. For signal dense spectra that contain both tonal and broadband-like energy the SPN has difficulty separating noise from signal, and the signal energy unduly influences the background estimate. This work introduces a new normalization scheme called the Spectral Profile Estimation (SPE) algorithm, which operates with no a priori information to estimate the background noise of these signal dense spectra. The SPE algorithm assumes that the background noise has an f-m, m>0, shape, and that signals are superimposed on the noise and are associated with spectra maxima. The SPE algorithm then finds and connects local minima to estimate the background. The SPE algorithm is first explained and then applied to experimental data. Finally, SPE performance is compared to the performance of SPN.
A comparison of measured and predicted broadband acoustic arrivals in Fram Strait
Authors: Sagen Hanne , Worcester Peter F. , Sandven Stein , Beszczynska-Moeller Agnieszka , Dzieciuch Matthew A. , Geyer Florian , Dushaw Brian D. , Babiker Mohamed
Published: November 2013

Fram Strait is the only deep-water connection between the Arctic and the world oceans. On the eastern side, the northbound West Spitsbergen Current transports warm Atlantic water into the Arctic, while on the western side the southbound East Greenland Current transports sea ice and polar water from the Arctic to the Nordic Seas and Atlantic Ocean. Significant recirculation and intense small-scale mesoscale variability in the center of the Strait make it difficult to accurately measure ocean transports through the Strait. An acoustic system for tomography, glider navigation, and passive listening was installed in the central, deep-water part of the Strait during 2010–2012. The integral measurements of temperature provided by tomography and the spatial resolution of the glider data are complementary to the data from the long-term array of oceanographic moorings at 780 50’N. The oceanographic conditions and highly variable sea ice in Fram Strait provide an acoustic environment that differs from both the high Arctic and the temperate oceans and that results in complex acoustic propagation. Improved understanding of the measured acoustic arrivals through comparison with predictions based on available environmental data is important for development of tomographic inversion and assimilation techniques, for glider navigation, and for acoustic communications.
Observations at Ascension Island of T-phases from earthquakes in the Fiji-Tonga region
Authors: Prior Mark K. , Zampolli Mario , Heaney Kevin
Published: November 2013

Ascension Island in the Atlantic Ocean is the site of one of the hydrophone stations that make up part of the hydroacoustic network operated by the Comprehensive Nuclear-Test-Ban Treaty Organization. Hydrophones are deployed in two groups of three, known as triads; one to the north of the island and one to the south. Correlation processing across hydrophones allows signal azimuths to be determined and both triads show large numbers of signals arriving from the south-west. These signals are generated by earthquakes in the region between Fiji and Tonga in the Pacific Ocean and travel through Drake Passage between Antarctica and South America. Signal azimuths are studied and it is shown that some signals originate from earthquakes to which two-dimensional propagation modeling would suggest there is no direct path. The mechanisms by which sound from these “blocked” regions might reach Ascension Island are discussed.
leID1. Time-frequency analysis: Theory and applications
Authors: Cohen Leon , Loughlin Patrick
Published: November 2013

Time-varying spectra are one of the most primitive sensations we experience, since we are surrounded by light of changing color, by sounds of varying pitch, and by many other phenomena whose periodicities change. The development of the physical and mathematical ideas needed to explain and understand time-varying spectra has evolved into the field now called “time-frequency analysis.” Among the many signals whose frequency content has been shown to vary in time are speech and other animal sounds, biomedical signals (e.g., heart sounds, heart rate, the electroencephalogram (EEG), the electromyogram (EMG), and others), music, radar and sonar signals, and machine vibrations, among others. In this tutorial, we give an overview of time-frequency analysis, with a focus on its applications. We describe how these methods impinge on and clarify issues in biomedical and biological signal analysis, wave propagation, random systems, non-linear systems, and other areas. Of particular interest is the application of time-frequency analysis to pulse propagation in dispersive media. We show that time-frequency considerations lead to new approximation methods for dynamic systems and wave propagation. We describe how to transform wave equations into phase-space, where the resulting equation is often more revealing than the original wave equation. We also discuss the applications to random systems and in particular to the propagation of noise fields.
Acoustic diffusers, the effects of materials and finishes on diffusion efficiency and absorption coefficients
Authors: Lenz Richard L.
Published: November 2013

Over the years, many different theories about the effects of material mass, finishes, porosity, and other physical attributes of diffuser design have been put forth. These theories have included excess absorption and/or reduced diffusion being caused by different woods or other materials being used as well as different types of paints and finishes. This paper is a study on the veracity of those theories and the effects of assorted materials in the construction of acoustic diffusers. The study will include the use of a specific diffuser design utilizing a periodic design with specific frequency ranges as well as more simplified geometric designs such as pyramids and barrels. Tests will be conducted to look at specific absorption results and the correlation to diffusion efficiency, if any. Standard testing procedures will be used to derive the information presented in the paper.
Determining sound transmission through damped partitions: Challenges in theoretical prediction and laboratory testing
Authors: Shafer Benjamin
Published: November 2013

The sound transmission loss through traditional wall and ceiling building partitions can currently be predicted using software programs and/or laboratory test data. There is, however, a great divide that separates the theoretical prediction of sound transmission loss from the laboratory-measured values. Some of the most common prediction software packages do not account for dynamic (frequency- and temperature-dependent) material properties and are, therefore, incapable of predicting sound transmission accurately for some common solutions. The most accurate and precise software prediction tools available become impractical because the cross-correlation between laboratory testing facilities is so poor that it is not possible to replicate predicted performance dynamics in a laboratory setting. Using the structural properties of damping materials as an example, the divide between theoretical prediction and laboratory testing will be illustrated and possible solutions for closing such a divide will be presented.
Laboratory measurement of the acoustic absorption coefficient based on the modal dispersion
Authors: Prisutova Jevgenija , Horoshenkov Kirill , Groby Jean-Philippe , Brouard Bruno
Published: November 2013

This work presents a novel method of measurement of the absorption coefficient of large material samples in an acoustic waveguide in a broad frequency range. The material sample is deployed at one end of an acoustic waveguide the other end of which is excited with a point source. The sound pressure data are obtained using a long horizontal microphone array deployed in this waveguide. The optimization analysis is then applied to the sound pressure data to calculate the modal reflection coefficients, which are then combined to determine the overall absorption coefficient of the material sample placed at the end of this waveguide. It believed that this method will be able to extend significantly the frequency range attained with the current ISO 10543-2 impedance tube method and be applied to those materials which have a corrugated surface or complex surface morphology such as acoustic diffusers or living plants. It is also believed that this method will provide the means to estimate efficiently the diffusivity of materials with complex surface morphology with a relatively simple laboratory setup.
Studying acoustic communication in pilot whale social groups
Authors: Jensen Frants H. , Tyack Peter L.
Published: November 2013

Many cetaceans are gregarious animals with a complex group structure, and they depend on acoustic signals for mediating social interactions among individuals. However, the marine lifestyle and closed sound production system makes it difficult to study social signaling in groups of wild cetaceans. Acoustic and movement logging tags offer new possibilities for sampling the sounds and behavior of individuals, but themselves provide new challenges in determining the source of acoustic signals. Here, we draw on experiences from studies of short-finned and long-finned pilot whales to discuss how social signaling can be investigated in wild marine mammals. We discuss how specific social contexts, especially separations from the social group, can aid the interpretation of individual tag data to test whether calls of short-finned pilot whales are important in mediating social contact with group members, while emphasizing the pitfalls of using such methods. Specifically, we highlight the advantages of simultaneously instrumenting multiple closely associated pilot whales with acoustic and movement recording tags. This has improved our understanding of acoustic interactions through ready identification of the sender and simultaneously monitoring the reaction of other group members, and we use this dataset to discuss ongoing challenges of studying social dynamics using simultaneous tag deployments.
Challenges in identifying (or not) focal animal sound production in baleen whale acoustic tag datasets
Authors: Stimpert Alison K. , Nowacek Doug P. , Friedlaender Ari S. , Straley Jan , Johnston David W. , Goldbogen Jeremy A. , Chiu Ching-Sang
Published: November 2013

Ascribing sounds on animal-borne tag recordings to individual sound producers is integral to understanding social behavior of animal groups. Previously, sounds recorded on tags have been assigned to the tagged individual (focal animal) based on proximity of other conspecifics, angle of arrival, low frequency artifacts in the sound, or a combination of signal-to-noise ratio (SNR) and received level (RL). However, most acoustic-based methods do not translate well to baleen whales producing low frequency sounds, as the tag often resides in the near field of the sound source. In addition, for social species that spend time in groups with conspecifics in close proximity, sounds produced by nearby animals may have comparably high SNR and RL. Here we discuss the challenges of determining if a tagged whale is calling in baleen whale datasets, using acoustic records from two humpback whales, one fin whale, and one blue whale as examples. The datasets include intense song or feeding calls and are from several locations. We compare SNR, RL, harmonic content, and behavioral sensor data in these cases, and discuss the implications of confirming sound production by a tagged individual for measuring communication, behavior, and responses to external stimuli in baleen whales.
Classification of behavioral state using hidden Markov model analysis of animal-attached tag data: Applications and future prospects
Authors: Miller Patrick J. , Isojunno Saana
Published: November 2013

Data from high-resolution animal-attached tags enable quantification of behavioral responses to anthropogenic noise. However, the duration of such detailed tag records on marine divers are typically too short to allow evaluation of the biological significance of such effects. To explore whether and how sperm whale behavior changed during exposure to sonar, we developed a discrete-time hidden activity state model that describes how observed parameters derived from measured Dtag data (depth, pitch, and clicking behavior) arise from five behavioral modes (surfacing, descent, bottom phase, ascent, resting, and silent active). Although the model assumed simple Markovian state-transitions, the state classification matched well with expert judgment of dive state. During experimental exposures to 1–2 kHz sonar, all four sperm whales tested reduced foraging time, increased silent active behavior, and buzz rates during foraging states decreased. None of those effects were found during 6–7 kHz experimental exposures of the same four whales, nor for three other whales exposed to distant sonar. Hidden classification of behavioral state using quantitative analysis of data collected by the animal attached tag is a procedure that has the potential to be processed autonomously on-board tags. This would enable collection and satellite telemetry of longer-term behavioral data sets with biologically significant interpretations.
Statistical analysis of data from acoustic tags: Methods for combining data streams and modeling animal behavior
Authors: DeRuiter Stacy L. , Harris Catriona , Sadykova Dina , Thomas Len
Published: November 2013

Statistical analysis of data from multi-sensor acoustic tags presents several characteristic challenges. Datasets generally include time-series of many measurements on a small number of individuals; different data streams often have distinct temporal resolutions and precisions. The MOCHA project (Multi-study Ocean acoustics Human effects Analysis) is a three-year effort focused on developing innovative statistical methods for such data. Here, we present several approaches for appropriate, effective statistical analysis of such datasets, with an emphasis on quantitative assessment of changes in marine mammal behavior in response to acoustic disturbance. Issues to be addressed will include: combining data streams from multi-sensor tags (and also concurrent visual observation data) for statistical analysis; statistical methods to characterize or summarize normal behavior and detect departures from normal; methods for analysis of call-production-rate data from acoustic tags; and methods for combining analysis of data from multiple tags, individuals, and species. Specific statistical methods to be presented will include Mahalanobis distance as a summary of multivariate data, state-switching models, random effects, and other extensions of generalized linear models appropriate to tag data.
Acoustic and foraging behavior of tagged sperm whales under natural and depredation foraging conditions in the Gulf of Alaska
Authors: Mathias Delphine , Wild Lauren , Thode Aaron , Straley Jan , Calambokidis John , Schorr Greg S.
Published: November 2013

Sperm whales have been depredating black cod (Anoplopoma fimbria) from demersal longlines in the Gulf of Alaska for decades, but the behavior has now become pervasive enough that it may be affecting government estimates of the sustainable catch, motivating further studies of this behavior. Over a three-year period, 11 B-Probe bioacoustic tags have been attached to seven adult sperm whales off Southeast Alaska, permitting observations of the animals’ dive profiles and acoustic behavior during natural and depredation foraging conditions. Two rough categories of depredation were identified: “deep” and “shallow.” “Deep depredating” whales consistently surface within 500 m of a hauling fishing vessel, have maximum dive depths greater than 200m, and display significantly different acoustic behavior than naturally foraging whales, with shorter inter-click intervals, occasional bouts of high “creak” rates, and fewer dives without creaks. “Shallow depredating” whales conduct dives that are much shorter, shallower, and more acoustically active than both the natural and deep depredating behaviors, with median creak rates three times that of natural levels. Occurrence of slow clicks and the behavioral context in which these vocalizations are produced were also investigated. These results provide insight into the energetic benefits of depredation behavior to sperm whales. [Work conducted under the SEASWAP program, supported by the North Pacific Research Board and the National Geographic Society.]
Acoustic radiation force on gas bubbles and soft elastic scatterers in tissue
Authors: Yoon Sangpil , Aglyamov Salavat R. , Karpiouk Andrei B. , Emelianov Stanislav Y. , Ilinskii Yurii A. , Zabolotskaya Evgenia A. , Hamilton Mark F.
Published: November 2013

Acoustic radiation force on a scatterer in tissue depends on the compressibility and shear modulus of both the tissue and the scatterer. This force is related to the monopole and dipole scattering coefficients. The finite shear modulus of the tissue decreases the radiation force in comparison with the force exerted on the same scatterer surrounded by liquid. Shear moduli for soft tissue range from several kilopascals (breast, liver) to tens of kilopascals and higher for cornea, cartilage, and cancerous tissue. As reported previously, the radiation force on a bubble in tissue having 100 kPa shear modulus is 50% less than if the bubble is in water. This difference decreases for scatterers with finite shear moduli, examples of which are reported here. Additionally, displacement of a scatterer due to radiation force is inversely proportional to the shear modulus of the tissue, which permits measurement of the latter. Experiments demonstrating this technique are reviewed. In these experiments, the radiation force is applied to a gas microbubble produced by laser-induced optical breakdown, while displacement of the microbubble is measured by high-frequency ultrasound as a function of time. Results are reported for tissue-mimicking phantoms and animal crystalline lenses in vitro.