bluuebunny/crossref_metadata_2025 huggingface dataset:
Temporal, geographic, and density variations in the acoustic activity of snapping shrimp
Authors: Lammers Marc O. , Stieb Sara , Au Whitlow W.L. , Mooney T. Aran , Brainard Russell E. , Wong Kevin
Published: October 2013

The sounds produced by snapping shrimp (genus Synalpheus and Alpheus) are the main contributors to the ambient sound field of shallow-water tropical and subtropical marine habitats worldwide. Despite this, relatively little is known about the temporal and spatial variability of snapping shrimp activity. To investigate this issue further, ecological acoustic recorders (EARs) were utilized to obtain time-series records of the ambient sound field from multiple locations in Hawaii and American Samoa. Strong diel trends marked by sharp increases in acoustic activity during crepuscular periods were observed at all sites. However, sites varied greatly both in absolute sound levels and relative fluxes between day and night. In addition, fluctuations in snapping shrimp sound levels were found to track lunar cycles, with higher levels occurring during the new moon. To further investigate the reason for the higher levels observed during crepuscular periods, individual shrimp were localized using a three-hydrophone line array on both a coral reef and a mud and algae habitat in Kaneohe Bay, Hawaii. The density of acoustically active shrimp was found to be higher during the sunset period than during the day or at night.
Characteristics of the deep scattering layer in the Gulf of Mexico as they relate to sperm whale diving and foraging behavior
Authors: Azzara Alyson J. , Thode Aaron , Norris Tom , Benoit-Bird Kelly , Biggs Douglas C.
Published: October 2013

In June 2005 we used a 38-kHz ADCP and two Simrad fishery echosounders to collect backscatter data and passive acoustic array recordings of sperm whale sounds, as part of the Sperm Whale Seismic Study (SWSS). Dive profiles and presumed foraging depths of the whales were derived using a 3-D tracking technique [see abstract by Thode and Norris (this conference)]. Relationships are examined between dive profiles and acoustic backscatter intensity measurements from the main deep scattering layer (DSL) at a daytime depth of 400–600 m. Passive detections of creaks, believed to be associated with prey acquisition, are merged with dive profiles to provide insight between mid-water backscatter returns and foraging effort. Results to date indicate whales diving in three depth ranges: deeper than 800 m, between 500 and 800 m, and less than 500 m. Dive patterns indicate some whales dive through the main DSL into deeper secondary layers seen by the 38-kHz ADCP. There seems to be no difference in dive patterns between night and day. Calibration analysis of ADCP backscatter versus 70-kHz Simrad backscatter shows a positive functional relationship, with 4 units of relative acoustic backscatter intensity equal to 1 dB of Sv.
3-D tracking of sperm whale dive profiles from a towed hydrophone array in ray-refractive environments
Authors: Thode Aaron , Norris Tom , Azzara Alyson , Jochens Ann , Biggs Doug
Published: October 2013

During the past 3 years the U.S.-based Sperm Whale Seismic Study (SWSS) has supported the development of a mobile three-dimensional passive acoustic tracking system. Acoustic data were recorded on a single four-element wide-aperture hydrophone array, towed at 80–100-m depth. The array was subdivided into forward and rear two-element subarrays, separated by 200-m aperture. To fix a location of an impulsive sound, three quantities are measured: the time difference between direct-path arrivals on the forward and rear subarrays, the time difference between the direct and surface-reflected paths on the rear subarray, and the acoustic bearing measured on the rear subarray. These quantities, combined with independent measurements of hydrophone depths and cable inclination, are postprocessed using a matlab GUI into range-depth position fixes by implementing an efficient numerical procedure that uses precomputed look-up tables to account for ray-refraction effects caused by depth-dependent sound-speed profiles. The predicted time difference between the direct and surface-reflected paths on the forward subarray is compared with the measured data to adjust for array tilt and depth measurement error. A by-product of this processing is a semiautomated detector to detect distinctive creak sounds. [Work supported by the U.S. Minerals Management Service and the Industry Research Funders Coalition.]
Direct underwater visual and acoustic observations of echolocation behavior of sperm whales around a longline
Authors: Thode Aaron , Straley Jan , Folkert Kendall , O’Connell Victoria , Behnken Linda , Koltz Amanda
Published: October 2013

Sperm whales (Physeter macrocephalus) have learned to approach and depredate fishing vessels longlining for black cod in the Gulf of Alaska. In May 2006, off Sitka, Alaska, a video camera was placed inside an underwater housing with an external hydrophone mount, attached to a longline that had been partially hauled to the surface, and lowered between depths of 90 and 120 m, with black cod (Anoploploma fimbria) attached 2 to 4 m above the camera as bait. The camera was mounted facing towards the surface to exploit the ambient light and to eliminate the need for artificial lighting. An additional hydrophone was deployed at 17-m depth during the 40–60-m deployments, and a third autonomous acoustic recorder was usually mounted 1.3 m below the camera. During one encounter a whale investigated the line, producing characteristic creak sounds that were recorded on the three hydrophones, and which were subsequently time-aligned using vessel noise as a reference, in order to permit acoustic tracking. During the second encounter a whale interacted with two fish within 4 m of the camera, but only the camera hydrophone was available. Preliminary analysis of the echolocation behavior displayed by both animals is presented. [Work sponsored by the National Geographic Society and the North Pacific Research Board.]
Three-dimensional passive acoustic tracking of sperm whale behavior with widely separated vertical arrays in the Gulf of Alaska
Authors: Tiemann Christopher O. , Thode Aaron M. , Straley Jan , Folkert Kendall , O’Connell Victoria
Published: October 2013

The Southeast Alaska Sperm Whale Avoidance Project (SEASWAP) was started in 2002 to study the increasing depredation encounters between sperm whales and longline fishermen near Sitka, Alaska. In 2005, the acoustic component of the study included passive acoustic data from four autonomous recorders attached to the anchor lines of two longlines spaced 3 miles apart, essentially turning them into temporary vertical arrays and allowing the monitoring of sperm whale vocal activity during fishing operations. Although the use of multipath arrival information from recorded sperm whale clicks has been a standard procedure for range-depth tracking, with the added knowledge of azimuthally dependent bathymetry relative to an array, a three-dimensional track of whale motion can be obtained from the same multipath information. The evolution of multipath arrival patterns is matched to range-, depth-, and azimuth-dependent modeled arrival patterns to generate an estimate of whale motion. The use of an acoustic propagation model can also account for all waveguide physics such as interaction with range-dependent bathymetry and ray refraction. Acoustic tracking results concurrent with whale encounters will be presented and compared to visual sightings.
Observation studies based on echolocation click signals of Irrawaddy dolphins in Chilika lagoon
Authors: Bahl Rajendar , Ura Tamaki , Inoue Tomoki , Sugimatsu Harumi , Sakamaki Takeshi , Kojima Junichi , Akamatsu Tomonari , Takahashi Hideyuki , Pattnaik Ajit , Khan Muntaz , Behera Sandeep , Kar Sudhakar
Published: October 2013

A resident population of Irrawaddy dolphins, Orcaella brevirostris, in Chilika lagoon in eastern India has been recently monitored based on their echolocation clicks. The free-ranging animals were monitored over several days in their natural habitat. A horizontal three-hydrophone line array was used for click data collection and off-line analysis of click trains to obtain underwater movements in shallow water of typical depth less than 3 m. The lagoon waters being placid provided a good surface echo that has been used to obtain depth information of the individual click sounds. This paper augments previous data on the broadband click characteristics [S. M. Van Parijs, G. J. Parra, and P. J. Corkeron, J. Acoust. Soc. Am. 108, 1938–1940 (2000)] and also provides a glimpse into the individual behavior of the dolphins. An estimate of the click lag time of the animal’s biosonar has also been obtained for the first time for a free-ranging animal.
High-frequency Acoustic Recording Package (HARP) for long-term monitoring of marine mammals
Authors: Wiggins Sean M. , Garsha Chris , Campbell Greg , Hildebrand John A.
Published: October 2013

Advancements in low-power and high-data-capacity computer technology during the past decade have been adapted to autonomously record sounds from marine mammals over long time periods. Acoustic monitoring has advantages over traditional visual surveys including greater detection ranges, continuous long-term monitoring in remote locations under various weather conditions, and lower cost. However, until recently, the technology required to autonomously record whale sounds over long durations has been limited to low-frequency ( ‘ 1000 Hz) baleen whales. The need for a broader-band, higher-data capacity system capable of autonomously recording toothed whales and other marine mammals for long periods has prompted the development of a High-frequency Acoustic Recording Package (HARP) capable of sample rates up to 200 kHz. The HARP design is described and data analysis strategies are discussed using examples of broadband recorded data. [Work supported by the U.S. Navy CNO-N45.]
Broadband backscatter measurements of individual Hawaiian mesopelagic boundary community animals
Authors: Au Whitlow W. L. , Benoit-Bird Kelly J.
Published: October 2013

Broadband simulated dolphin echolocation signals were used to measure the ex situ backscatter properties of mesopelagic boundary community animals. The signal had a peak frequency of 100 kHz, 3-dB bandwidth of 35 kHz, and duration of 80μs. Subjects were captured by trawling with a 2-m-opening Isaacs-Kidd midwater trawl. Backscatter measurements were conducted on the deck of the ship in a 2000-L seawater plastic tank with the transducer placed on the bottom, pointed upwards. Anesthetized animals were suspended in the transducer’s beam by nylon monofilament lines connected to a support device constructed out of dowels. Backscatter measurements were obtained in both the dorsal and lateral aspects for seven myctophids and only in the dorsal aspect for the other 13 myctophids, 6 shrimps, and 3 squids. The echoes from the myctophids and shrimps usually had two highlights, one from the surface of the animal nearest the transducer and a second probably from the signal propagating through the body of the subject and reflecting off the opposite surface of the animal. The squid echoes consisted mainly of a single highlight but sometimes with a low-amplitude secondary highlight. The target strength had a rippled pattern in the frequency domain showing a distinct null.
Acoustic measurements of volume backscattering strength from red tide phytoplankton, Cochlodinium polykrikoides
Authors: Bok Tae-Hoon , Paeng Dong-Guk , Kim Eunhye , Na Jungyul
Published: October 2013

This research is to measure the volume backscattering strength, Sv, of the Cochlodinium polykrikoides (the main species of red tide in Korea) in order to investigate the possibilities of early detection of red tide using high-frequency transducers (5, 10 MHz). First, the Sv from the cultured C. polykrikoides was measured with the population density in the laboratory. Next, ultrasonic transducers were attached to the side of a research vessel, and the Sv was measured over 9-km ship track near Yeosu in the Korean southern sea. Seawater at three stations was sampled, and the number of C. polykrikoides was counted to compare the theoretical Sv with the measured one. The results show that the measured Sv was in agreement with the theoretical one. The Sv when the light was on was measured to be higher than that when the light was off in the laboratory, probably due to the increase of size and density of C. polykrikoides during photosynthesis. In the field experiment, the Sv was measured in real time with the position information from the Global Positioning System data. This research proposes the use of underwater ultrasonic technology for early detection of red tide in real time.
Measurements of target strength spectra of metal spheres and fish by using broadband sonar signals of dolphin
Authors: Imaizumi Tomohito , Furusawa Masahiko , Akamatsu Tomonari , Nishimori Yasushi , Ogawa Shinji
Published: October 2013

Dolphins identify prey by using their broadband sonar signals. Considering that the spectrum of fish target strength (TS) leads to identification of objects, we measured the spectrum using dolphin’s sonar signals with a broadband system. The TS spectrum is obtained by dividing the echo spectrum by the incident spectrum while setting the projector and hydrophone face to face. First, we measured the broadband form function of a tungsten carbide and copper sphere in a water tank and confirmed good agreements with theoretical value. Second, we measured the spectra of TS of three species of anaesthetized fish in a water tank. Although the spectra showed nearly similar tendencies of past measurements, they changed according to the species, the individual, and the tilt angle. Third, we measured TS spectra of fish suspended by nylon monofilament line in the open sea in semi-in-situ. We tried to remove the directivity of transducers by a tungsten carbide sphere suspended near the fish. The change of the TS spectra should be important information for the fish identification.
Variations of echosounder transducer performance versus water temperature
Authors: Demer David A. , Renfree Josiah
Published: October 2013

Electroacoustic transducers are central components of multi-frequency echosounders used in remote target identification and acoustical surveys for fish and zooplankton. While these transducers, constructed from multiple materials such as piezoelectric ceramics, polyurethanes, and metals, are designed to be insensitive to performance changes versus time, pressure, and temperature, it has been shown that appreciable changes in echosounder system gains result from shifts in transducer resonant frequency, quality factor, and electrical impedance versus water temperature. Because it is standard practice to calibrate echosounder systems in one environment and apply the resulting gains to interpret data collected over a range of sea temperatures, the survey results may be significantly biased. The bias may be different for estimates derived from each echosounder frequency. The magnitudes of these frequency-dependent biases depend upon the temperature-dependent performances of the survey transducers, and the range of temperatures encountered during the survey. Here, the performance has been measured for ten commonly used survey transducers versus water temperature ranging from 1 to 18°C, using four different techniques. Temperature-dependent system gain corrections are proposed that can be used to minimize bias in multifrequency target identifications and biomass estimations. [Funding was provided by the NMFS Advanced Sampling Technology Working Group.]
Calibrating split beam transducers at depth
Authors: Ona Egil , Pedersen Geir
Published: October 2013

A new echo sounder probe for target strength measurements in deep water have been used to calibrate the depth performance of several pressure-stabilized split beam transducers. The probe carries three Simrad EK60 echo sounders and can be operated on 6500 m optical cable to about 1500-m depth. The transducers are mounted on a motorized, revolving platform. Digital angle sensors monitor transducer orientation, and an electronic compass also monitors transducer rotation. Calibration includes standard sensitivity parameters for split beam transducers, but also the equivalent beam angle and angle sensitivity at different depths. Examples of target strength data on marine animals will also be shown.
New scientific multibeam systems (ME70 and MS70) for fishery research applications
Authors: Andersen Lars Nonboe , Berg Sverre , Gammelster Ole Bernt , Lunde Even Borten
Published: October 2013

Fishery scientists have for many years been requesting calibrated multibeam systems specially designed for fishery research applications. Simrad AS, Norway, has, in cooperation with IFREMER, France, developed a new multibeam echo sounder (ME70) and with IMR, Norway, a new multibeam sonar (MS70) for fishery research applications. Both systems have 800 transmitting and receiving channels and are based on similar hardware and software platforms. The systems are characterized by calibrated narrow beams, low sidelobe levels, high instantaneous dynamic range, and operate in the frequency range 70–120 kHz. The echo sounder is designed for high operating flexibility, with a configurable fan of 1–45 roll/pitch stabilized split beams with opening angles ∼2 to ∼7. In addition, two configurable reference beams are available for comparison with standard echo sounder systems. The sonar is mounted on a drop keel, looking horizontally, covering a horizontal sector of 60 and a vertical sector of 45. This coverage matrix is generated using 500 roll stabilized beams, 25 beams horizontally with a resolution of ∼3, and 20 beams vertically with a resolution of ∼4. Both systems are designed for fish-stock assessment and fish-behavior studies. Results from system measurements will be presented.
First results with the new scientific multibeam echo-sounder ME70
Authors: Trenkel Verena , Mazauric Valerie , Berger Laurent
Published: October 2013

Multibeam echo-sounders and sonars are increasingly used in fisheries acoustics for studying school structure and behavior and for abundance estimation. However, data quality and a poor signal-to-noise ratio obtained with the existing multibeam echo-sounders preclude quantitative biomass estimation as carried out with the traditional single beam echo-sounders. In order to overcome these shortcomings, Ifremer and Simrad AS started in 2003 the development of the new and highly flexible calibrated multibeam echo-sounder ME70 designed for studying a wide range of scientific questions. This paper will present the full functionalities of the ME70 and preliminary results obtained with the system installed onboard the research vessel Thalassa. It will also provide first indications of its performance. Data have been collected on small pelagic fish species in the bay of Biscay, using simultaneously the traditional single beam echo-sounders and the ME70 with different beam configurations. Preliminary comparisons of fish school descriptors and biomass estimates based on single- and multibeam data allow us to quantify the effect of the gain in sampling coverage and the high angular resolution of the new system.
Development of a quantitative scanning sonar system and sea trial for a fish school of herring
Authors: Nishimori Yasushi , Iida Kohji , Mukai Tohru , Tang Yong , Ogata Masaki , Tokuyama Kohzoh , Okazaki Emi
Published: October 2013

A quantitative sonar system enabling data recording, calibration, and numerical analysis of fish schools was developed based on the commercial scanning sonar. This system is equipped with a newly developed algorithm for estimation of the abundance of a fish school using three-dimensional echo integration. Estimation was made on the condition that the target strength of all fish is identical and known and the weight of a single fish is known. The field recording was performed to evaluate the algorithm. The school of spring spawning herring were scanned three-dimensionally and recorded using two different scanning methods. Two methods were applied in different distances between the school and vessel. The volume and three-dimensional echo integration for these two recorded dates were calculated and compared to each other. It was found that the variance of three-dimensional echo integration is smaller compared with the variance of volume. A compensation of abundance estimation using average target strength was tried and its effectivity was examined.
Advances in the evaluation of acoustic beamformed backscatter data for fisheries applications
Authors: Malzone Chris , Wilson Matthew , Iampietro Pat
Published: October 2013

Single-beam echosounders are well-established tools for fisheries research. However, single-beam echosounder geometry is limited to a very small ensonification volume located within a 3 to 15-deg cone directly beneath the vessel. Recent advances in multibeam echosounder technology provide the option to collect backscatter and water-column data during an IHO order 1 hydrographic survey. Such comprehensive data sets are valuable for scientific and management purposes since they expand the volume in which water-column data are collected, and they provide as well a potential method to link the biology to the habitat. However, water-column information collected with multibeam echosounders poses several challenges, including increased data storage requirements, a need for data decimation, and survey methodology considerations. In this paper, concurrently acquired backscatter data from a split-beam scientific echosounder and multibeam echosounder are analyzed for relative abundance, spatial distribution, and avoidance behavior of pelagic organisms, primarily the market squid Loligo opalescens and various finfish. Aspects of the data sets are then explored, compared, and contrasted. Proposed solutions to some of the challenges posed by multibeam sonar water-column analysis are then reviewed and placed within a overall framework for fisheries applications.
Mapping fish schools with a high-resolution multibeam sonar
Authors: Trevorrow Mark
Published: October 2013

In late 2002 an evaluation of a high-resolution multibeam sonar (RESON SeaBat 8125) for mapping mid-water fish schools was performed in Knight Inlet, BC. The ship-mounted multibeam sonar operated at 455 kHz and provided 240 one-half-degree beams in the across-track plane with one-degree along-track beam width. Simultaneous measurements were made with a conventional 200-kHz echo-sounder. Acoustic calibrations of this multibeam sonar will be discussed, showing some range- and angle-dependent variations in sensitivity. The multibeam sonar was able to provide well-resolved mid-water images of fish schools (likely juvenile herring), sampling many fish schools missed by the echo-sounder and revealing cross-track fish school shape. Comparison of near-vertical volumetric scattering strengths between the multi-beam sonar and echo-sounder show reasonable agreement. Discussions on the combined use of conventional and multibeam sonars for fish surveys will be given.
Multibeam assessments of Australian seabed habitats
Authors: Parnum Iain , Gavrilov Alexander , Siwabessy Paulus , Penrose John
Published: October 2013

In the period 2003–2006 a major program of shallow seabed habitat assessment has been undertaken in Australian coastal seas. As part of the Coastal Water Habitat Mapping (CWHM) project of the national Cooperative Research Centre for Coastal Zone, Estuary and Waterway Management, research into optimal use of acoustic techniques for habitat assessment has been undertaken. Echo sounder, side scan, and multibeam acoustic systems have been used and evaluated in this program. Multibeam systems have been primarily employed with particular attention being given to combining topography data with associated measures of backscatter intensity. The emphasis on shallow waters, generally 50-m depth or less, and high-frequency multibeam systems with up to 240 beams has provided data sets with relatively high levels of spatial resolution. Measures of backscatter variation with incident angle have been incorporated into the interpretation process and a new angular dependence correction algorithm developed for production of backscatter imagery. The processing techniques developed in the CWHM project have been evaluated using towed video data for a variety of tropical and temperate coastal environments around Australia.
Measurement of fish school abundances in shallow sea using omnidirectional multibeam sonar
Authors: Tang Yong , Iida Kohji , Mukai Tohru , Nishimori Yasushi
Published: October 2013

Previous studies had been constructed in the use of commercial scanning sonar to estimate the abundance of pelagic fish school. However, a relatively narrow dynamic range and lack of linear signal processing limited the application of sonar. In this research, quantitative omnidirectional multi-beam sonar (FSV30 research version, 24 kHz, Furuno) was used to investigate a fish school in a shallow area. The raw volume backscattering strength signal (RSV, output signal with 20logr TVG and coefficient of multiple echo) of the fish school echoes were recorded and then its biomass was confirmed using purse seine capture. In postprocessing, the fish school echoes were extracted from the sonar echogram using the image processing method (polygon and a low-pass filter). The relationships between a school’s biomass, its echo area, the maximum, and the average RSV of each ping were considered for various species. Results showed a positive correlation between the sonar-measured school area and school biomass, but no correlation between the RSV and school biomass. Also, the echo integration method for sonar survey using RSV in broad area and methods for averaging the target strength (TS) in three dimensions with respect to echo integration method were also discussed.
Precise measurement of travel time difference for reciprocal transmission of Central Equatorial Pacific tomography
Authors: Hachiya Hiroyuki , Nakamura Toshiaki , Fujimori Hidetoshi , Nakano Iwao
Published: October 2013

We present the estimation results of the travel time difference in reciprocal transmission data collected during the tomography experiment performed by Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in the Central Equatorial Pacific. A precise estimation of travel time is essential for measuring ocean current using ocean acoustic tomography. We estimate the variation of the correlation of reciprocal propagated sound transmissions. Generally, reciprocal propagation sound waveforms that are transmitted at the same time are similar mutually, and it is considered that their correlation is high. However, it is found that reciprocal sound waveforms sometimes become different in the experiment. The vertical arriving angle of ray is measured using the phase differences between the receivers of a 30-m-long receiving array. The theoretical analysis of phase deviation using the Rice distribution is presented. From the ray identification results, the travel time difference between corresponding rays of reciprocal transmissions can be estimated. Since the phase of a ray signal is very stable, the precision of the travel time difference using phase difference is 6 times higher than the conventional estimation. The combination of the amplitude and phase information is effective for observing the ocean structure change.
An overview of BASSEX (Basin Acoustic Seamount Scattering Experiment)
Authors: Baggeroer Arthur B. , Heaney Kevin D. , Worcester Peter F. , Dzieiuch Matthew , Mercer James , Andrew Rex , Howe Bruce
Published: October 2013

BASSEX exploited the signals transmitted from the SPICEX, LOAPEX, and NPAL Kauai sources to examine the forward scattering from the Kermit-Roosevelt Seamounts near the Mendocino Fault in the northeast Pacific. The receiver was the FORA (four octave research array) from Pennsylvania State University. This array was towed at 300 m and had approximate resolutions of 2 and 6 deg for the 250- and 75-Hz signal transmissions. These were beamformed and pulse compressed for analyzing the multipath receptions from the sources. Source-receiver ranges covered from 250 to 1600 km provide a very rich data set. Data for forward- and backscattering from the slope near the NPAL source north of Kauai were also obtained. The analysis so far has demonstrated forward-scattering shadow convergence zones as well as diffraction from the seamounts. The upslope/downslope path structure near the Kauai source has also been analyzed. Both ray path and full wave acoustic modeling have been used for path identification as well as a theoretical model for modal scattering from a cone within an acoustic wave guide. [Work supported by ONR Code 321, Ocean Acoustics.]
Mixed layer effects on acoustic arrival structure
Authors: Van Uffelen Lora J. , Worcester Peter F. , Dzieciuch Matthew A. , Rudnick Daniel L.
Published: October 2013

Oceanic mixed layers develop as the summer sun warms the upper layer of the water column and turbulence from early autumn storms stirs this heat downward, forming a well-mixed layer with constant temperature and salinity. The mixed layer is therefore thinnest in summer, when the surface is warm and the winds are relatively weak, and deepest in late winter. Receptions from moored 250-Hz acoustic sources at ranges of 500 and 1000 km in the North Pacific were recorded on vertical line array receivers from June through November 2004, spanning the early development of the winter mixed layer. The time-evolving character of the acoustic arrival structure throughout this transmission period will be investigated to explore the effect of a changing mixed layer environment on long-range acoustic propagation. Particular consideration will be given to variability in the early branches of the acoustic timefronts, which correspond to steep rays interacting with the upper ocean.
Seamount geo-acoustic inversion from an acoustic scattering experiment (NPAL-04)
Authors: Heaney Kevin D. , Baggeroer Arthur B. , Worcester Peter F. , Dzieciuch Matthew A.
Published: October 2013

It is thought that the deep ocean has thick, soft sediment due to millennia of build up from detritus. An open question is the sediment thickness on vast seamounts that rise many km from the ocean floor. Acoustic scattering from the Kermit-Roosevelt seamount (39.2O N 146.3 O W) in the central Pacific during the Basin Acoustic Seamount Scattering Experiment (BASSEX-04) in August of 2004 is used to address this question. The Kermit-Roosevelt seamount rises from a floor of 5400 m to a maximum height of 977 m below the surface. Broadband transmissions (100 Hz bandwidth, 250 Hz center frequency, 12.276 s period length) from two sources suspended (800 m depth, ranges of 521 and 625 km) were received on towed array (300 m depth, 200 m aperture) in the vicinity of the seamount. Combining array gain and time-bandwidth gain from the matched filter it is possible to clearly identify energy that has scattered from the seamount in 15 transmissions. These receptions are used to infer the sediment thickness and type as a function of the water depth. An efficient PE computational approach is applied as well as a reflection-coefficient ray-based approach.
Image reconstruction using eigenfunctions of a scattering operator
Authors: Waag Robert
Published: October 2013

A multiple-frequency iterative inverse scattering method is reviewed. In the method, scattered acoustic fields are described using a scattering operator with eigenfunctions that correspond to far-field patterns of an effective source distribution. Incident-wave patterns determined using the eigenfunctions focus on the distribution. The focusing properties of the eigenfunctions are employed to reconstruct an object by using products of numerically calculated fields defined by weighted products of the eigenfunctions. The full range of frequencies present in an incident pulse waveform is employed. Iteration using a linearized version of the method and calculated scattering from an estimate of the object permits reconstruction of large-scale high-contrast objects. The method is illustrated using calculated and measured data. In the calculations, an exact solution for scattering from nonconcentric lossy cylinders with parallel axes was employed to obtain the scattered field. In the measurements, a novel ring-transducer system was used to obtain the incident and total fields. The results of simulations and experiments show that the method converges and is accurate for high-contrast large-scale tissue-mimicking objects. Reconstructions using measured scattering from random media have considerably less speckle than conventional b-scan images, implying that the inverse scattering method can clearly demonstrate small high-contrast inclusions.
Linear sampling method for acoustic inverse scattering in breast microcalcification detection
Authors: Lewis Matthew A. , Liu Peiying , Richer Edmond , Antich Peter P. , Johnson Stuart G.
Published: October 2013

In women under age 40, the breast may be too dense for mammographic screening and microcalcification detection. A nonionizing method would be preferred for frequent screening in patients with significant risk factors for developing breast cancer. Ultrasonic detection of microcalcifications has been problematic since frequencies above 10 MHz suffer from appreciable attenuation in soft tissues. Transmission diffraction tomography is by construction a low-pass filter and insensitive to scattering caused by small, hard inhomogeneities. A more general form of acoustic inverse scattering is therefore needed for microcalcification detection and localization by ultrasound. An advanced scalar inverse scattering theory developed by Colton, Kirsch, and others [D. Colton, J. Coyle, and P. Monk. SIAM Review 42(3), 369–414 (2000)] in the electromagnetic inverse scattering community for determining the location and shape of scatterers with size on the order of the wavelength (the so-called resonance region) has been simulated in the context of breast microcalcification detection. This method was shown to be related to both multiple signal classification and time-reversal algorithms [M. Cheney. Inverse Problems 17, 581–585 (2001)] [S.K. Lehman and A.J. Devaney J. Acoust. Soc. Am. 113(5), 2742–2753 (2003)]. Translation of this method to a heterogeneous soft-tissue background is a significant challenge.
Chirp seismic surveying of shallowly buried fluvial systems on the outer New Jersey continental shelf: Mapping channel morphology and internal stratigraphy in 3D
Authors: Goff John , Nordfjord Sylvia , Austin James , Schock Steven
Published: October 2013

The outer New Jersey continental shelf has been the focus of Office of Naval Research-sponsored acoustic studies for more than a decade. As part of this effort, ONR has funded a number of field programs to characterize the geologic history and sedimentary properties of the shallow seabed. We report here on a chirp seismic campaign conducted in 2001, with particular focus on characterizing the morphology and internal stratigraphy of shallowly buried fluvial channel systems that are widespread in this region. These channels were formed during the last glacial lowstand, and then filled and buried by sediments during sea level rise. Mapping the channel morphology in 3D presented a significant challenge. Although coverage (200-m line spacing) was dense, application of standard interpolation techniques resulted in poor representation of channel continuity along sinuous pathways. We developed a technique for transforming the seismic horizon data into a channel-oriented reference frame, wherein the channel is effectively straight and simple interpolation techniques can be used to maintain channel continuity. Seismic units within the channel fill could be discerned based on bounding reflectors and acoustic character and mapped throughout the 3D channel systems. These units provide a record of sea level change and drowned-river estuary development.
Nonlinear optimization for beamforming a geometrically deficient vertical line array: Application to sediment tomography
Authors: Crocker Steven E. , Miller James H. , Potty Gopu R. , Lynch James F.
Published: October 2013

The 1996 Shelfbreak PRIMER experiment included broadband acoustic transmissions in the vicinity of a shelfbreak front collected using a geometrically deficient vertical line array (VLA). The broadband signals were used to tomographically image sediment sound speed and attenuation. The VLA spanned the lower half of the water column. Hence, the orthonormal properties of the underlying normal modes cannot be guaranteed for any replica vector based on the local modal structure. This produces modal sidelobes in the output of the geometrically deficient VLA. Various methods of extracting the normal modes from VLA data have been developed including a generalized least squares method shown to improve the performance of a geometrically deficient VLA processing phase encoded tomography signals [Chiu et al., IEEE J. Ocean. Eng. 22, 522–533 (2005)]. The present study seeks to enhance the modal resolution for the reception of high-amplitude, impulsive signals transmitted over a wide variety of source receiver paths in shallow water where ensemble averaging is not an option. The method uses nonlinear optimization techniques to compute a set of array element coefficients that enhance suppression of modal sidelobes, while maintaining adequate spatial matching with the desired mode. [Work supported by Office of Naval Research.]
Models of musical timbre using cortical spectro-temporal receptive fields and temporal codes
Authors: Elhilali Mounya , Pressnitzer Daniel , Shamma Shihab
Published: October 2013

It has been customary to propose several ‘‘descriptive’’ definitions to quantify timbre as one of the basic attributes of sound. Multidimensional scaling techniques have proposed several acoustic dimensions to characterize the timbre of subsets of sounds. Yet, in the general case, timbre is an intricate percept difficult to relate to concise acoustic cues. Timbre probably reflects the dynamic interactions between spectral and temporal characteristics of sound that play a crucial role in identifying natural sources and convey a wealth of information about the environment. Recent physiological investigations revealed possible neural mechanisms to extract and represent the spectral and temporal information in complex sounds. At the level of the primary auditory cortex, spectro-temporal receptive fields exhibit a multiscale representation that captures many aspects of dynamic sound spectra. In the current study, we explore the potential correspondence between these cortical properties and the identification of musical instruments. We investigate the use of such representation as a quantitative descriptor of musical timbre, as validated by behavioral data from human subjects. Additionally, we examine biologically plausible coding strategies in this multidimensional cortical mapping involving spike-timing information.
Perception of Japanese pitch accent: Examination of minimal accent pairs
Authors: Sugiyama Yukiko
Published: October 2013

Perception of Japanese pitch accent was examined using 20 bimoraic/disyllabic minimal accent pairs. A minimal accent pair refers to a pair of words that is identical except for their accent types. For example, /hana/ ‘‘flower’’ and /hana/ ‘‘nose’’ have the same phonemic sequence and the pitch pattern of low-high yet they differ in that ‘‘flower’’ has accent on the word-final mora while ‘‘nose’’ has no accent (unaccented). A preceding production study that utilized the same 20 pairs of words found that the maximum F0 in the word-final mora was reliably higher for the final-accented words than the unaccented words and the F0 rise from the initial mora to the final mora was reliably larger for the final accented words than the unaccented ones when they were produced sentence-medially followed by a particle. However, the two accent types did not show any reliable difference when they were produced by themselves in isolation. This perception study accesses if the properties found to be related to Japanese pitch accent in production are actually used by listeners when they identify accent types. The relation between the production and perception of Japanese pitch accent will be discussed.
The phonetic and phonological triggers for downstep in Japanese: Evidence from perception
Authors: Shinya Takahito
Published: October 2013

In Japanese the F0 peak of a word is downstepped after a lexically accented word. Lexical accent can be characterized by its phonological specification in the lexicon or by its phonetic F0 pattern. A perceptual experiment was conducted in order to observe how these two properties interact with each other as downstep triggers. The experiment tested whether listeners compensate for downstep exclusively based on the phonological information of lexical accent or on the phonetic cues available. Participants were asked to judge the relative prominence between two F0 peaks. Results suggest that in order for two words to be perceptually equal in prominence, the second F0 peak must be lower than a given first F0 peak. This difference between the two F0 peaks was significantly greater when the first word was phonetically accented than when it was phonetically unaccented, which suggests that the downstepped F0 peak is perceptually compensated. A similar effect was observed for the phonologically accented first peak, but the effect size was much smaller than the effect observed for the phonetically accented first peak. These results suggest that the primary trigger of downstep in Japanese is the F0 pattern of accented words. Lexical specification plays, at best, a secondary role.
Pitch values in prominent and nonprominent sentence enders in Japanese
Authors: Enyo Yumiko
Published: October 2013

This study uses naturally occurring interview data to investigate properties of intonational prominence in Japanese sentence enders (SEs). Since Japanese intonation patterns generally observe downstep (Venditti, 2005), a sentence-ending AP (accentual phrase) is likely to have the lowest F0 in an utterance if it does not receive prominence. Data from one interviewee’s responses, SEs in long IPs (more than 5 APs) and short IPs (one or two APs), are used for this analysis. Within the group of 28 short IPs, there were eight cases of the SE nandaroo ‘‘what is it, I wonder.’’ Measurements of highest and lowest F0 within nandaroo indicate two distinctive F0 patterns, determined by whether the SE is prominent or nonprominent. (Prominence appears to be placed on an SE when its content is focused.) In prominent SEs, the intonation contour contains peaks that exceed three standard deviations of the speakers F0 average. However, prominent and nonprominent utterances are similar in their F0 minima. As a result, SEs with prominence typically show wider pitch range than those without prominence. Similar results are found for other SEs contained in both long and short IPs.
Phrasal length and complexity effects on interphrase pause duration
Authors: Krivokapic Jelena
Published: October 2013

This study examines the effect of prosodic structure and phrase length on pause duration and the speech planning processes that such pauses can reveal. Subjects read sentences varying in two ways. First, each sentence included a pause bounded either by long intonational phrases both before and after it, medium phrases before and after, or short phrases before and after. Second, the prosodic complexity of the phrase on each side of the pause, i.e., before it and after it, was varied as to whether it was a branching intonational phrase or a nonbranching intonational phrase. Fourteen speakers read sentences synchronously in dyads so as to minimize variability due to speech rate and individual differences [Cummins, ARLO (2002), Cummins, J. Phonetics: (2003); Zvonik and Cummins, ICSLP (2002)]. The results for the dyads analyzed to date indicate that preboundary branching phrases are followed by longer pauses than nonbranching preboundary phrases. Further, surrounding long phrases lead to longer pauses than surrounding medium phrases, which in turn give rise to longer pauses than surrounding short phrases. Interaction effects of phrasal length and complexity will also be discussed. [Work supported by NIH.]
Voice F0 responses to actual versus consciously perceived auditory feedback pitch shifts
Authors: Burnett Theresa , Madonia Dana
Published: October 2013

The purpose of this study was to determine the effect of pitch shift discrimination ability on production of voice F0 responses to auditory feedback pitch shifts. Subjects repeatedly vocalized /u/ into a microphone while listening to their voice fed back over headphones. During each trial, auditory feedback pitch was experimentally shifted upward or downward (randomly determined) by 50 cents for 100 ms. Subjects subsequently pressed a button labeled up or down to indicate their perceived direction of voice feedback pitch shift. Voice output was recorded, F0 extracted, smoothed, time aligned to the onset of the pitch shift, and averaged. Button response accuracy was found to be at chance expectancy among the majority of subjects. Nevertheless, all subjects responded vocally to the pitch shifts by changing voice F0 in the opposite direction, indicating that the direction of the shift was indeed processed by the auditory system. These results are consistent with the existence of preattentive mechanisms of audio-vocal control, and provide evidence for a mismatch between conscious and preattentive auditory processing of voice pitch feedback for the control of voice F0. [Work supported by NINDS.]
Frequency and amplitude derivatives as syllable-level F0 features
Authors: Liberman Mark , Yuan Jiahong
Published: October 2013

Most descriptions of tone and intonation focus on the alignment of F0 rises, falls, and inflection points relative to the phonetic unfolding of associated syllables. In this context, it is suggested that the relationship between proportional changes in F0 (treated modularly to eliminate the effects of period doubling and halving) and proportional changes in amplitude (within the frequency bands typically dominated by energy from voicing) provides an interesting characterization of F0 trajectories in relation to syllabic structure. Using data from conversational and broadcast speech in English and Chinese, parameters of this type (in combination with other acoustic measures) are used in identifying relevant features of tone and intonation.
Declination of subglottal pressure during speech and its relation to tone distribution
Authors: Hanson Helen M. , Slifka Janet , Shattuck-Hufnagel Stefanie , Kobler James B.
Published: October 2013

The subglottal pressure contour Ps for speech is considered to have three phases: initiation (rapid rise), working (level or slightly declining), and termination (rapid fall). The current work focuses on characterization of the working phase in terms of the distribution of pitch accents and of phrase and boundary tones. In particular, the degree of Ps declination is studied. A measure of Ps declination has proven difficult to define [cf. Strik and Boves, J. Phonetics 23, 203–220 (1995)]. Therefore, in pilot work, subjective ratings of degree of declination are made on a subset of a corpus in which the tone distribution is controlled. Significant variation in the degree of declination is observed among speakers. For example, Ps for one speaker is relatively constant to slightly declining, while for another it is almost always sharply declining. For some speakers utterances with an early-occurring nuclear pitch accent (NPA) show greater degree of declination than utterances with a late-occurring NPA, as do utterances ending with high tones. Data for additional subjects and objective measures will be presented. The results have implications for models of speech production, and for applications such as computer speech synthesis and recognition. [Work supported by NIH Grants DC00075 and DC04331.]