bluuebunny/crossref_metadata_2025 huggingface dataset:
A long-range, high-resolution Doppler sonar for fishery stock assessment
Authors: DeFerrari Harry A.
Published: October 2013

A new approach is developed for horizontal-looking active sonar that uses continuous bi-/multistatic transmission of very long period m-sequences. Compared to conventional monostatic ping rather than listen sonar, this approach improves the Doppler resolution by a factor of 20 and increases FOM by perhaps 13 dB by increasing the temporal coherent processing gain. The improved time/Doppler resolution helps to discriminate fish school from bottom reverberation, and improves the resolution of taxonomic parameters of fish assemblages. The improved FOM allows coverage of large areas of shallow oceans with source levels low enough to avoid environmental concerns for marine mammals. The principal obstacle to continuous transmission sonar operation is the masking of the target return by the time and frequency leakage of the direct path arrivals. Unique time-correlation property of m-sequences elimination time leakage and a process calls coordinate zeroing (CZ) eliminates all the Doppler leakage. A linear temporal Doppler search (LTDS) algorithm is used to shift the detection problem to a high-resolution pulse arrival-time/Doppler plane with a noise-limited background. Ultrafast Hadamard transforms lighten the computational burden. The combination of these ideas is presented including the theory, numerical experiments that demonstrate the concept, and verification with real ocean signals.
Development and application of high-frequency sonars for imaging naturally occurring plumes in the ocean
Authors: Palmer David R.
Published: October 2013

Hydrothermal plumes are formed when hydrothermal solutions are discharged from chimneylike vents on the ocean floor where adjacent tectonic platesare separating. Their study provides information on the transfer of heatand chemicals from the solid earth to the ocean. When high-frequency acousticswas proposed for imaging and studying hydrothermal plumes, Joe Blue contributedin a general way to the development of the effort. In this presentation the history of this effort is reviewed. After an introduction to hydrothermal venting, some of the problems addressed in the development and application of the sonar are discussed. These include sonar calibration, identification of the dominant scattering mechanism, estimating cross sections, and the intrinsic statistical variability associated with incoherent scattering. The results obtained from four sea trials are recalled. These trials involved either three-person, deep-diving submersibles or the JASON/MEDEA ROV system. The opportunities provided by the somewhat surprising progress that has occurredare discussed. Finally, an application of the developed technology is mentioned, acoustical imaging of the bubble plume emitted from the underwater volcano Kick em Jenny.
The art of merging physics and math with biology and psychology to study marine animal acoustics
Authors: Hastings Mardi C.
Published: October 2013

Joe Blue’s most recent contributions to marine animal acoustics resulted from successful collaborations with biologists and psychologists, each bringing their individual expertise to the table and working together to understand how the characteristics of the acoustic field generated by a moving vessel could provide critical insight into the observed behavior of right whales and manatees. Joe’s hands-on approach of going out and actually recording and measuring the sound fields provided data that not only verified his analyses, but also enhanced practical understanding of acoustics in the animal bioacoustics community. His work demonstrated the importance of physics and math in studying complex multidisciplinary acoustic problems and resolving perplexing dichotomies. Examples will be presented showing that Joe’s collaborative style is a model for everyone to follow.
Mastering music in a 5.1 world
Authors: Ayan Adam
Published: October 2013

The evolution of 5.1 surround sound in the world of popular music has changed the way artists, producers, and engineers conceptualize their recordings. Along with the artistic benefits of 5.1 surround production come the challenges of working in this relatively new format. Mastering engineers are responsible for making the final sonic enhancements to a recording, musically maximizing the recording, and making it compatible and competitive in the marketplace. 5.1 surround mastering shares many of the same techniques and philosophies as stereo mastering, but also presents a new set of concerns for the mastering engineer. This talk focuses on the specific production and engineering concerns that are unique to the world of 5.1 surround production, specifically as they relate to mixing and mastering techniques.
The influence of changes in diffusive acoustical treatment on spatial imagery associated with multichannel sound reproduction
Authors: Martens William L.
Published: October 2013

Listening experience in the newly constructed, largely diffuse small room at Blackbird Studios has led to the design of a new research space for the Sound Recording program in McGill University’s Schulich School of Music. The space was created to allow for experimental investigation of the influence of changes in diffusive acoustical treatment on variation in auditory imagery associated with multichannel sound selections while holding listener location and orientation constant relative to a fixed five-channel loudspeaker array. Preliminary tests suggest that a number of benefits result when low-amplitude indirect sound is provided by diffusive room acoustic treatment within the first 30 ms of the arrival of the loudspeaker signals. Both for conventional multitrack mixes, and for recordings made using multichannel microphone arrays, these benefits include greater Listener EnVelopment (LEV), improved segregation of simultaneously sounding musical sources, and more solid phantom images of virtual sources, especially those located to the listener’s extreme sides between front and rear loudspeakers (between 30 and 110 deg of azimuth to the left and right). This paper will summarize those results, and describe the specially designed system of variable acoustic treatment that enables such direct experimental investigation. [Work supported by Canada Foundation for Innovation.]
Low-frequency control options in surround-sound critical listening rooms
Authors: D’Antonio Peter
Published: October 2013

Acoustically small rooms, which are typically used for critical listening, be it mono or surround, can potentially overwhelm the spatial and spectral textures that contribute to an enjoyable listening experience. The options to control potential modal and speaker boundary interference in rooms include optimal dimensional room ratios, optimal speaker/listener placement, optimal multiple subplacement and dedicated low-frequency absorbers, including quarter-wave traps, anechoic wedges, Helmholtz and membrane resonators, and a relatively new and potentially significant addition, the metal plate resonator, which absorbs efficiently down to 50 Hz with a thickness of only 4 in. The design theory, proof-of-performance evaluation testing methods, and optimal placement guidelines for all of these tools will be reviewed.
Simultaneous equalization of a loudspeaker and a room: Insights from a one-dimensional model
Authors: Chen Xi , Leishman Timothy
Published: October 2013

In recent years, many audio practitioners have concluded that a room excited by a loudspeaker cannot be effectively equalized. They argue that the free-field response of the loudspeaker may be equalized, but that the room response itself must be ignored. This paper presents a one-dimensional model to illustrate many of the difficulties encountered in past equalization methods that have led to this way of thinking. It explores the spatial-spectral variations of the reproduced sound field that make the methods problematic. It then uses the model to explain the benefits of using total energy density as a basis for equalization instead of acoustic pressure. Both the loudspeaker and the enclosed field can then be simultaneously equalized for nearly optimal results. The method is also implemented effectively using adaptive filtering techniques.
Attempting to define sound exposure metrics for fish
Authors: Hastings Mardi C.
Published: October 2013

One of the big issues in addressing the biological effects of sound on humans and animals is metrics. For fishes the issue is further complicated because their inner ear responds directly to acoustic particle motion and in some species, indirectly to pressure through multiple pathways. So, metrics based only on pressure can be misleading in developing sound exposure criteria. The decibel scale also confounds the problem because it is used to express not only levels of sound pressure, but also levels of sound power, intensity, and energy. Even for just sound pressure, decibels are used to express peak, peak-to-peak, and time-averaged values, which can hamper extrapolation of laboratory data to anthropogenic sources in the field. Add to that the changes in decibel reference values when going from air to water, more than 25000 different fish species, and the fact that a significant amount of sound exposure research on fish has been done in small enclosures at low frequencies, and one quickly realizes the difficulties in developing meaningful relationships between sound exposure and observed effects. This presentation will focus on relevant sound exposure metrics, their practical definitions, and their application to quantifying the biological effects of sound on fish.
Effects of high-intensity sonar on fish
Authors: Halvorsen Michele B. , Wysocki Lidia Eva , Popper Arthur N.
Published: October 2013

Studies investigated the effects of exposure to low-frequency active (LFA) sonar on rainbow trout, channel catfish, and pumpkinseed sunfish using an element of the SURTASS LFA. Animals were exposed to sounds that had a received peak level of 193 dB re: 1 uPa (rms) (188.5 dB re: 1 uPa2 s SEL). Measurements were made of hearing sensitivity using auditory brainstem response and of behavioral responses. Additional studies were done on pathology of the ear and other organ systems. Trout and catfish both showed temporary threshold shifts immediately after sound exposure, while sunfish showed no threshold shift. However, the amount of threshold shift and frequencies concerned varied. In addition, trout and catfish showed immediate behavioral responses to the sound onsets and in relative distribution during sound presentation. Details of the responses differed between species. There was no mortality in any species attributable to sound exposure during or after experiments. SEM examination of hair cell ciliary bundles of the inner ears did not show any damage. Similarly, there were no effects on the swim bladder or nonauditory tissues. Overall, the effects of LFA on fish depend upon species and appear to be temporary and relatively modest. [Work supported by Chief of Naval Operations.]
Effects of background sound on fish
Authors: Smith Michael E. , Wysocki Lidia E. , Popper Arthur N.
Published: October 2013

There is increasing awareness that underwater anthropogenic sounds may be detrimental to marine organisms. While most of this work has focused on marine mammals, recent studies have shown that sounds higher than background can have detrimental effects on fish as well. This presentation is a review of the current data available on the effects of increased background ambient sound on fish. Loud continuous sounds can cause temporary hearing loss in fish, with the extent of hearing loss increasing with noise exposure duration and intensity, and recovery of hearing occurring within a few days or weeks. The extent of hearing loss is also species specific—fish with more sensitive hearing thresholds are more prone to hearing loss, whereas nonsensitive fish are barely affected. The latter was shown in a long-term study on the effects of aquaculture noise in rainbow trout. A model termed the linear threshold shift hypothesis (LINTS) has been proposed to predict the extent of noise-induced hearing loss in fish, and this model should be beneficial in mitigating the effects of anthropogenic sound on fish. Other effects of noise include acoustical masking and physiological and behavioral stress responses, which also depend on species and noise type.
Applying optics in surface wave laser ultrasonic microscopy
Authors: Somekh Michael , Sharples Stephen , Clark Matthew
Published: October 2013

Laser ultrasonics has many advantages compared to contacting ultrasonics, especially when both optical generation and detection are used. In addition to the obvious advantages of remote inspection there are several other benefits. In this paper we concentrate on the flexibility that can be conferred by employing both optical technology and optical concepts in our laser ultrasonic systems. The papers shows how spatial light modulators (SLMs) can be used to control the optical beam profile used to generate the ultrasonic waves. Initially, SLMs were introduced to improve the signal-to-noise ratio of the system. This is achieved by exciting the tone burst with a grating structure so that large signals can be generated without ablation. The SLMs can also be used to produce optical profiles that generate self-focusing surface waves; this also increases the ultrasonic amplitude. Our recent work has used SLM generation to overcome aberrations or distortions in the ultrasonic field during propagation. To this end an adaptive system using integrated electronics to overcome the phase aberrations during propagation has been developed. We also show how the SLM can be used to perform acoustic wavelength spectroscopy, which has proved invaluable in the characterization of texture in industrially important materials.
Laser pulse impact characterization using ultrasonic transducers
Authors: Jayaraman Subash B. , Bohenick Mark A. , Semak Vladimir , Tittmann Bernhard R. , Welsch Jill R. , Nicholas Nicholas C.
Published: October 2013

Experiments were conducted with an excimer laser (wavelength 248 nm) to cause damage to gelatinous materials, which have optical properties similar to skin tissue. The laser pulses, when they impact the specimen, generate an elastic wave that propagates through the material. A 150-MHz broadband ultrasonic transducer was placed underneath the specimen to observe the material response and the pressure generated by the laser pulse. Different incident laser energies and laser beam spot sizes were utilized to obtain a range of input parameters, and the corresponding transducer responses were recorded. Fourier analysis of the signals was performed to identify the frequency response from the laser pulse. Additional tests were carried out to observe the effects due to a train of laser pulses. Earlier tests were performed with 200-kHz hydrophone-calibrated transducer but due to the shortness of the laser pulses (∼20 ns), a higher frequency transducer was used to accurately characterize the laser impact. The initial results indicate that there is a dominant frequency response around the 25–30-MHz regime.
Dr. Blue at the Underwater Sound Reference Division
Authors: Zalesak Joseph F.
Published: October 2013

At the Underwater Sound Reference Division Dr. Blue had many varied interests including acoustic metrology, acoustic materials research, enginering acoustics, underwater transducers, and bioacoustics. He performed the first thorough study on the reproducibility of calibrations of standard hydrophones. He supported the development of traveling-wave tubes and large pressure vessels for calibrating Navy sonar transducers and for the measurement of acoustic materials. The Acoustic Pressue Tank Facility is a 30000-gal acoustic test vessel ideally suited for acoustic measurements at hydrostatic pressures up to 2700 psi and at frequencies as low as 1.0 kHz and can accommodate acoustic devices up to 6 ft in diameter. Dr. Blue supported research for improved measurement techniques for determining the properties of acoustic materials. Dr. Blue actively supported the development of new elastomeric materials used in the construction of underwater transducers. The Sonar Transducer Reliability Improvement Program was an extinsive program to properly specify a sonar transducer for Navy applications. He first suggested that coupler reciprocity might be used to perform ultra-precise calibrations of hydrophones. He also supported research in manatee vocalizations and dolphin echolocation clicks. Low-noise hydrophones with noise levels better than sea-state zero were developed for general use.
A perspective of Navy transducer calibration standards
Authors: Jenne Kirk
Published: October 2013

Research and development efforts to establish underwater electroacoustic transducer standards for use in a variety of environmental conditions, performed concurrently with research on calibration methodologies, began nearly 60 years ago. This research and development effort successfully generated a series of standards now made available under the auspices of the U.S. Navy’s Underwater Sound Reference Division in Newport, RI (a.k.a. USRD). Because of consistent and insightful investment of resources made over the years by Navy technical agents and advocates like Dr. Joseph Blue, scientists and engineers from government (U.S. and select foreign), academia, and industry can use Navy transducer calibration standards to perform accurate measurements of acoustic energy underwater. Definition and characteristics of a standard are considered. Performance characteristics of transducer standards currently used, along with some discussion of applications, are presented.
Joe Blue and nonlinear acoustic transduction: Lessons learned and forgotten, some even ignored; and practical issues to revisit, anew
Authors: Muir Thomas
Published: October 2013

The 20th century was ripe with major advances in the understanding of nonlinear acoustics and its practical applications, in the American as well as the European and Soviet schools of thought. Some of us were privileged to study this art and contribute to its science, guided by the world’s finest educators and mentors. The results originated in physics and were applied to aircraft acoustics and underwater sound, and later to biomedical acoustics, and other arenas, with great success. Joe Blue was a contributor and long-time advisor in many of these endeavors. Some early nonlinear acoustics topics will be reviewed, to refresh memories and introduce newcomers to the field. This includes parametric transmitters, the effects of shock formation and harmonic generation, parametric receivers, various theoretical models, classic experiments in air and water, as well as practical applications. In the early days, ideas for new nonlinear acoustic applications were often met with the comment, ‘‘That’s crazy.’’ Perhaps many of these ideas were not crazy enough. At the present time, there appears to be some lack of boldness and innovation, coupled with abundant mistakes, in what is proposed and reported. Some comments on the state of the art are offered. [Work supported, throughout the years of the mid to late 20th century, by the U.S. Navy.]
The application of acoustic standards to sound sources and the subsequent levels in the ocean
Authors: Carey William M.
Published: October 2013

The American National Standards on Acoustics are applied to common sound sources used in both acoustics research and in naval sonar systems operation. Metrics are quantified for both continuous and transient sources of sound. The standard definitions are reviewed with theoretical sound source models and applied to examples of energy sources of sound such as transients from a small omni explosive, an air gun, a light bulb, and a dolphin. A qualitative model of a typical surface ship sonar system is discussed and active sonar transmissions are analyzed with the requisite quantitative metrics required to characterize these emissions. The relative role of peak pressure, time spread, intensity, and energy flux is discussed for deep- and shallow-water environments. These results should be useful in environmental assessments, biological experiments, and in the system design.
Evaluating the significance of interface nonlinearity for shallow-water parametric array sonar
Authors: Waxler Roger , Muir Thomas G.
Published: October 2013

Difference frequency generation in shallow water is considered for the case in which wave steepening in the primary beam is not significant. A general formula for the effective difference frequency source strength is presented. The Pekeris shallow water model, in which sound speeds and densities in both the water column and sediment are assumed to be constant and both interfaces are assumed to be planar, is considered. In this model, the propagating difference frequency pressure field is computed. Contributions from the interface nonlinearity are compared to those from nonlinearity in the water column.
High frequency acoustic wave propagation
Authors: Badiey Mohsen
Published: October 2013

A program studying high frequency acoustics was established in the mid-1990’s by the Office of Naval Research that is still going on and has evolved into a substantial basic and applied research initiative to study many areas, including underwater communication. This abstract explains the genesis of that program, and Joe Blue’s involvement in making it happen. During the course of the initial experiments under that program, a series of issues were raised dealing with the effects of acoustic transmissions on marine mammals. Again, Joe was a key person in resolving those issues, which could have brought the program to a halt. His insight into the technical problems, as well as, his calm nature helped to bring an excellent new program in acoustic research into being.
Ship strike acoustics: A paradox and parametric solution
Authors: Gerstein Edmund , Blue Joseph , Forsythe Steve
Published: October 2013

Marine mammals are vulnerable to ship collisions when are near the surface. Here, acoustical laws of reflection and propagation can limit their ability to hear and locate the noise from approaching vessels. Defining the physics of near-surface acoustical propagation as it relates to ship noise and hearing is central to understanding and mitigating ship strikes. Field data from controlled ship passages through vertical hydrophone arrays demonstrate a confluence of acoustical factors that poses detection challenges including (i) downward refraction; (ii) spreading loss; (iii) Lloyd’s mirror effect; (iv) acoustical shadowing; and (v) masking of approaching ship noise by ambient noise and distant ships. A highly directional, dual-frequency parametric sonar has been developed to mitigate these challenges and alert marine mammals of approaching vessels. The system projector is a planar array, comprised of 45 elements, band centered to transmit a high carrier frequency along with a lower sideband signal. The nonlinearity of water is used to demodulate the mixed high-frequency carrier into a lower-frequency waveform audible to both manatees and whales. The bow-mounted arrays project a narrow beam directly ahead of vessels, and fill in acoustical shadows in an effort to alert marine mammals of the approaching danger. [Research supported by DOD Navy Legacy Program.]
Finite-element calculation of a bass drum
Authors: Bader Rolf
Published: October 2013

The bass drum of a drum kit used with rock or jazz music is modeled as a 3D geometry in a transient finite-element formulation. The geometry was taken from a Gretch drum set called ‘‘Vinnie Colaiuta’’ with no cushion damping within the drum or at the resonance membrane. The 12 cross layers or wood used for the drum body was assumed to result in an isotropical Young’s modulus all over the wood. The drum was modeled with air enclosed, with the beating and resonating membranes being coupled to the air and to the wooden rim of the drum body. Also, as a starting point of the transient calculation, the strain of the wooden body caused by the tension of the membranes was taken into consideration. The transient model started with a beating on the front membrane and the radiation of the system was integrated over the radiating area. The results are compared to recordings of a real bass drum of this Gretch drum set.
Future directions in loudness standardization: Time-varying loudness
Authors: Davies Patricia , Marshall Andrew
Published: October 2013

The loudness of many sounds varies with time and the temporal processing of the human hearing system affects loudness perception. Existing loudness algorithms that are standardized address loudness of stationary sounds. Two algorithms that predict time-varying loudness have been developed: Zwicker’s, and Moore and Glasburg’s time-varying loudness; variants of the former are available in most sound-quality analysis systems. For continuous sounds with repetitive impulses or beating tones loudness exceeded 5% of the time correlates well with perceptions of overall loudness. The focus here is on predictions of time-varying loudness algorithms for isolated impulsive sounds caused by supersonic aircraft, because recent developments in supersonic aircraft design could result in aircraft producing much quieter booms that may be more acceptable to the general public. Loudness is a major factor in community response; thus, the research focus is to understand how sound modifications (amplitude reduction, signal shaping) affect the loudness of transients. Also, playback systems involve signal filtering; how this may affect loudness perception is of interest. The predictions of the two algorithms are compared for a series of sonic-boom recordings and modified recordings to determine how filtering and signal modification affect loudness predictions.
A frequency-domain algorithm for the propagation of finite-amplitude acoustic signals
Authors: Falco Lauren E. , Morris Philip J. , Atchley Anthony A.
Published: October 2013

It has been shown that the quantity Qp2p, the cross-spectral density of the square of the pressure and the pressure, is related to the strength of nonlinear effects in a propagating acoustic signal. Morfey and Howell [AIAA J. 19, 986–992, (1981)] derive from the Burgers equation an expression that relates Qp2p to the rate of change of the power spectral density (PSD) of a signal. They suggest a propagation scheme based on this expression that makes assumptions about the Gaussian nature of the signal. These assumptions are invalid for many finite-amplitude signals, so a new propagation scheme is proposed and validated. This scheme uses an expression for the rate of change of the phase of the signal as well as its amplitude. These two expressions are combined into a finite-difference equation that is used to step the signal to the desired propagation distance. The method is shown to compare favorably with the Fubini solution for lossless plane waves. Comparisons are also made with a numerical split-step algorithm for the nonlinear propagation of a broadband source, and with experimental data obtained in a plane wave tube. [Work supported by ONR, GE.]
Thermal gradient effects on the propagation of nonlinear pressure waves in a gas
Authors: DiZinno Nicholas , Vradis George , Otugen Volkan
Published: October 2013

A numerical study of wave propagation through gases with nonuniform temperature distributions will be presented. The main objective of this study is to determine the impact of temperature gradients on high-intensity, initially sinusoidal pressure waves. Particular emphasis is paid to wave reflection, transmission, and any influence a high-temperature region may have on nonlinear behavior. Ultimately, the performance of thermal barriers in attenuating nonlinear waves is evaluated. The concept of using regions of hot gas inside an ambient environment has potential in aeroacoustic applications, such as jet screech mitigation. This analysis considers one-dimensional compressible unsteady Euler equations with an ideal gas state equation, applied over a uniform domain. The domain is composed of two regions with uniform and equal gas properties (ambient conditions) separated by a third region with higher gas temperature and, accordingly, lower density. Pressure is uniform throughout the domain. We introduce a high-intensity sinusoidal wave into this medium. The shape and extent of the high-temperature zone is varied to study the effect of this region on wave propagation. Further, wave reflection and transmission are studied for a range of wave and thermal field parameters. Results for nonlinear pressure waves are compared to linear acoustic waves.
Spatial audio target acquisition in the frontal horizontal plane: Effects of feedback, mobility, and index of difficulty
Authors: Marentakis Georgios , Brewster Stephen
Published: October 2013

The results of an empirical study investigating the effect of feedback, mobility, and index of difficulty on a deictic spatial audio target acquisition task in the horizontal plane in front of a user are presented. Audio feedback marked display elements are found to enable usable deictic interaction that is performed with high accuracy and can be described using Fitts’ law. Feedback does not affect perceived workload or preferred walking speed compared to interaction without feedback. Without audio feedback, spatial audio is not found to support adequately the corrective submovements necessary for high selection accuracies. Interaction with the display becomes therefore highly inefficient. Mobility is found to degrade interaction speed and accuracy by 20%. Participants were able to perform deictic spatial audio target acquisition when mobile while walking at 73% of their preferred walking speed. The proposed feedback design is examined in detail and the effects of variable target widths are quantified. Deictic interaction with a spatial audio display is found to be a feasible solution for future interface designs.
Effect of roving on spatial release from masking for amplitude-modulated noise stimuli
Authors: Kopčo Norbert , Jacobson Jaclyn J. , Shinn-Cunningham Barbara G.
Published: October 2013

A previous study investigating detection of broadband signals embedded in broadband noise showed that detection thresholds depended both on the temporal structure of the target and masker and their simulated spatial locations [Kopco and Shinn-Cunningham, J. Acoust. Soc. Am. 117, 2396 (2005)]. The current study extends this work by introducing a rove in overall intensity to reduce the reliability of overall intensity cues for detecting the target. Detection thresholds were measured for a broadband noise target spectrally and temporally centered within a broadband noise masker. Thresholds were measured for all combinations of six spatial configurations of target and masker and five modulation conditions (all combinations of target modulated and unmodulated and of masker modulated and unmodulated; when both target and masker were modulated, the modulation could either be equal or π out of phase). The amplitude modulation, if present, had a rate of 40 Hz and depth of 0.5. The masker level was roved by ±5 dB between intervals within a trial. Results suggest that the cues underlying target detection depend on both the spatial configuration of target and masker and their temporal structure, but that, when available, overall intensity cues also contribute to a target detection. [Work supported by NSF and ONR.]
Experiments in speech localization using headphones and loudspeakers
Authors: Canfield Casey , Vu Michelle , Busch-Vishniac Ilene J. , West James E.
Published: October 2013

This experiment studies the ability of humans to localize sound as recording and playback methods are varied. Further, because subjects are asked to indicate personal preference, we are able to determine the importance of localization in setting personal preference. The stimulus used in this experiment was speech (6 stanzas of a poem, each recorded at a different location). Three recording methods were used: monaural, stereo, and stereo through an artificial head. Two playback methods were used: stereo speakers and stereo headphones. Results of the work are applicable to the design of conference facilities and the design of headphones and speakers. [This work is a Wise Women project. Wise Women partners high school students from Garrison Forest School with Johns Hopkins engineering faculty.]
Evaluating the principal spectral components positioning a virtual sound source on a cone of confusion
Authors: Benson David H. , Martens William L.
Published: October 2013

Although many studies have attempted to identify spectral cues to sound-source direction for the entire sphere of possible incidence angles, few studies have focused their attention on directional hearing for virtual sources positioned on cones of confusion. These regions of space, defined by relatively constant interaural time and intensity differences, provide an ideal subset of incidence angles for testing the importance of the spectral cues to direction allowing for up/down and front/rear distinctions between sources at constant angular distance from the median plane. In this study, head-related transfer functions (HRTFs) measured on a well-lateralized cone of confusion were decomposed into principal spectral components putatively responsible for positioning a virtual sound source, and their related angle-dependent scores that describe the relative contribution of each shape to the total spectral variation. The findings can be summarized as follows: For the set of ipsilateral HRTFs the most significant set of scores shows sinusoidal variation with angle, and could potentially encode a front-back cue, though with the extrema rotated by about 30 deg. The most significant score from an analysis of interaural spectral differences seems to capture a head-shadowing effect which is most extreme in the lower rear.
Learning of interaural-level-difference discrimination with a 0.5-kHz tone in human adults
Authors: Zhang Yuxuan , Wright Beverly A.
Published: October 2013

Sound-source location on the horizontal plane is primarily determined by two cues: interaural time differences (ITDs) for low-frequency sounds and interaural level differences (ILDs) for high-frequency sounds. Though not available in natural listening environments, ILDs in low-frequency sounds, when artificially delivered to listeners through headphones, also can be used to lateralize sounds. Little is known about the neural processing of such low-frequency ILDs. Here, the modifiability of this processing was examined by training human adults on ILD discrimination with a 0.5-kHz tone on the midline. After nine 1-h daily training sessions, trained listeners (n=6) improved significantly more than untrained controls (n=8) on the trained condition. This learning generalized to a 4-kHz tone and a 0.5-kHz tone amplitude modulated at 30 Hz, but appeared not to generalize to a 1-kHz tone, an off-midline position, or ITD discrimination with the trained tone. This overall learning pattern differs from those previously obtained for ILD at 4 kHz and ITD at 0.5 kHz using the same training paradigm [Wright and Fitzgerald, Proc. Natl. Acad. Sci. U.S.A. 98, 12307–12312 (2001)], suggesting that the processes involved in low-frequency ILD discrimination differ from those encoding high-frequency ILDs and low-frequency ITDs, at least at the neural site(s) affected by training. [Work supported by NIH/NIDCD.]
Unsteady surface pressures on a ship hull
Authors: Goody Michael , Farabee Theodore , Lee Yu-Tai
Published: October 2013

Unsteady surface pressure measurements at locations distributed on the surface of a ship model hull and flow visualization of the bow wave and free surface are discussed. The measurements were performed in the David Taylor Model Basin using a ship model that is approximately 40 ft. long and representative of a naval combatant at Froude numbers from 0.14 to 0.44. The pressure measurement locations are distributed over the hull surface from 15 surface pressure spectrum and limited spatial coherence measurements are discussed. Additionally, the measured surface pressure spectra are compared to predictions done using an RANS-based formulation and predictions done using an empirical formulation that is based on historical, flat-plate, surface pressure spectra. [Work sponsored by Office of Naval Research, Code 334.]
Power flow and wave propagation characteristics of surface ship inner-bottom structure
Authors: Haberman Robert C.
Published: October 2013

The construction of the inner bottom of a surface ship consists primarily of deck plating connected to hull plating by longitudinal vertical plates. Foundations supporting equipment typically line up with the vertical plates, thereby providing a direct path of mechanical excitation to the hull resulting in forced acoustic radiation. The purpose of this paper, therefore, is to provide an overview of the physics that controls wave propagation in surface ship inner-bottom structure along with a description of the power flow associated with direct force excitation of the vertical plating. Two theories will be presented: (1) an approximate theory based on the vertical plate modeled as a beam coupled to the deck and hull modeled as plates containing flexural waves and (2) an exact theory based on all three structures modeled as plates containing flexural, compressional, and shear waves. Numerical results will be presented that show the importance of full wave coupling along with some interesting phenomena associated with power flow and leakage of energy into deck and hull plating. The implication of these results in statistical energy analyses modeling will be briefly discussed. [Work partially funded by ONR, Code 334 Dr. S. Schreppler.]
Radiated acoustic power of model ship hull sections estimated from scanning laser Doppler vibrometer vibration response measurements
Authors: Carroll Gerard P.
Published: October 2013

This paper will present radiated acoustic power estimates for ship hull models which are based entirely on scanning laser Doppler vibrometer measurements of the underwater vibrating surface.The radiated power estimates are compared to direct measurements of the radiated acoustic power obtained using hydrophones in the reverberant tank. These radiation estimates are based on Rayleigh integral formulations, one for which the vibrating surface is assumed to be baffled, and the other for which it is unbaffled. For the latter case, the pressure in the plane of the vibrating surface is assumed to be zero outside the vibrating surface. This corresponds to a mixed boundary condition in which the velocity is known on the plate and the pressure is known off the plate. An iterative application of the Rayleigh integral is used to determine the velocity and the pressure over the entire plane. For the purposes of calculating the radiated power, this formulation is shown to iterate much more quickly by iteratively calculating the surface intensity. This is possible since the pressure and therefore the surface intensity is zero outside the plate boundary. Utilizing these surface radiation intensity calculations, it is possible to then investigate the sources and mechanisms of the hull radiation.
Numerical investigation of small-scale surface ships by energy finite-element analysis
Authors: Wu Kuangcheng , Vlahopoulos Nick
Published: October 2013

Experimental investigations have been performed to understand the structural acoustic characteristics of two small-scale surface ship models representing sections of conventional and advanced double-hull ship designs [Craun et al., ‘‘Experimental and analytical investigation of surface shiphull structure acoustics using physical models,’’ J. Acoust. Soc. Am. 116, 2569 (2004)]. Recently, new developments have been added to the energy finite-element analysis (EFEA) for surface ships [Wu and Vlahopoulos, ‘‘Vibratory response of surface ships predicted by energy finite element approach,’’ J. Acoust. Soc. Am. 116, 2569 (2004)]. The presentation will compare hull responses from EFEA predictions to test data for the two small-scale models to validate the new development in EFEA. Furthermore, the impact of the hull responses due to the different model designs will be discussed. [Support for this research is provided by ONR code 334.]
The role of structural acoustics in the space shuttle flowliner crack investigation
Authors: Allen Michael J. , Haberman Robert C.
Published: October 2013

During normal inspection of the Space Shuttle main propulsion fuel line system small cracks were identified in a slotted flowliner just upstream of the main propulsion engines. The cause is believed to be resonance excited by pressure fluctuations originating from the downstream fuel pump. This presentation highlights the analyses that were performed to characterize the structural acoustic environment surrounding the flowliner during waterflow and liquid hydrogen laboratory experiments, as well as in-flight conditions. Analyses employed a combination of analytical and finite-element methods to model fluid structure interaction and inverse methods to reconstruct equivalent acoustic sources representative of the fuel pump. Numerical results will be presented that compare experimental strain and pressure data with theoretical counterparts. Implications will be drawn regarding the applicability of the theory to the actual shuttle fuel line system. [Work was sponsored by NASA Marshall Flight Center.]
A strain energy approach to the flexural damping of layered plates
Authors: Deigan Richard J. , Ng Kin
Published: October 2013

The flexural damping factor of multilayered plates is developed using a strain energy approach. The derivation is based on the exact, steady-state solution for a plate subjected to boundary conditions that are harmonic in time and position along the plate. The distribution of elastic strain energy contained within the individual layers of the plate is developed, from which an effective, flexural damping factor is determined. Comparisons to the widely used RKU analysis [D. Ross, E. E. Ungar, and E. M. Kerwin Jr., ‘‘Damping of Plate Flexural Vibrations by Means of Viscoelastic Laminae,’’ ASME, Section 3, pp. 49–87 (1959)] are made for selected cases of constrained and unconstrained layer damping. Good agreement with RKU theory is demonstrated for the selected cases. Advantages of the present analytic approach include: (1) The ability to model the effect of fluid loading; (2) Unlimited number of plate layers; and (3) The handling of compressible layers and associated loss mechanisms. Analytical estimates of damping factors are compared with measurements made on steel bars treated with an unconstrained damping layer. Stress-state assumptions are shown to be a major factor affecting theory-data agreement.
Dynamic modulus measurement using the Dynamic Mechanical Analyzer
Authors: Ng Kin , Deigan Richard , Koch Samedi
Published: October 2013

The Navy has used the Dynamic Mechanical Thermal Analyzer (DMTA) as a tool to characterize material properties over the last 20 years. It is now evaluating the Dynamical Mechanical Analyzer (DMA) as a replacement for the DMTA, with the goal to insert it into operation in 2006 with minimal disruption to current acquisition programs. This paper compares the two instruments with regard to their capabilities and looks at some of the transition issues.
Finite-element simulations of self-oscillation mechanisms in human phonation
Authors: Cook Douglas , Mongeau Luc , Smith Paul
Published: October 2013

The fluid-structure interactions which occur during human phonation were investigated using a commercially available finite-element program. Both lumped mass and continuous structural models were coupled with viscous fluid flow. The simulated behavior was analyzed. The addition of viscous flow was not sufficient to induce self-oscillation of a single degree-of-freedom lumped mass model but did contribute to the steady vibration of the continuous model. This observation reinforces the conclusion that structural complexity is an essential mechanism of self-oscillation. The influence of false folds on the oscillation patterns of the continuous model was also examined.
Patterns of interarticulator coordination within the syllable
Authors: Bonaventura Patrizia , Sand Joseph
Published: October 2013

Interarticulatory coordination patterns were observed in movements of the crucial articulator for the production of place in selected syllables containing labiodental and alveolar consonants. The coordination of the lower lip with upper lip and tongue tip, and the coordination of the tongue tip with tongue blade and lower lip have been observed. The goals of the study were (a) to verify whether stable patterns of speed with respect to excursion of movement [Fujimura, O., ‘‘Temporal organization of articulatory movements as a multidimensional phrase structure,’’ Phonetica, 38, 66–83 (1981a); ‘‘Icebergs revised,’’ ASA meeting, 2aSC (1996b)], were found in concurrent articulators to the crucial one for place, under different prosodic conditions; (b) whether such stable portions would vary proportionally to the increase in amplitude of the vertical jaw movement, selected as a measure of the magnitude of the syllable; (c) to observe relative timing at the iceberg thresholds in the selected consonantal movements with respect to the center of the syllable. Analyses were performed on articulatory recordings from cinefluorographic data, based on read dialogues [Erickson et al., ‘‘Articulatory correlates of prosodic control: Emotion and emphasis,’’ Lang. Speech, 41, 399–417 (1998)]. Iceberg patterns were found in the concurrent articulator movements, showing a linear dependence of slope on the total excursion of the demisyllabic movement. Timing of concurrent articulator movements with respect to the center of the syllable is shown to be relatively stable.
Modulation of frication noise in a dynamic mechanical model of the larynx and vocal tract
Authors: Barney Anna , Jackson Philip J. B.
Published: October 2013

A dynamic mechanical model of the larynx and vocal tract was used to investigate the aerodynamics and acoustics of voiced fricatives. The model had typical dimensions for a human adult male. Glottal excitation arose from driven shutters representing the vocal folds; sinusoidal and square-wave driver functions were investigated. Glottal amplitude, fundamental frequency (f0), and volume velocity were independently controlled. Frication noise was produced by an orifice plate with a sharp-edged obstacle on its downstream side. Two different positions of constriction within the vocal tract, each coupled with a different constriction-obstacle distance, were investigated. Vocal-tract wall pressure was measured at three locations and a microphone at the vocal-tract exit measured radiated sound. The sound radiated from the open end of the vocal tract was found to have both harmonic and noise components. The noise was modulated by the f0 of the glottal vibration. The depth of modulation was independent of the shape of the glottal excitation. It showed an overall decreasing trend with increasing f0 in the range 20 to 150 Hz, but with a local maximum of modulation depth around 80 Hz. The noise bursts had maxima coincident with the middle of the glottal open phase.