bluuebunny/crossref_metadata_2025 huggingface dataset:
Shallow water performance of a moving time-reversing array
Authors: Sabra Karim G. , Dowling David R.
Published: October 2013

Future active sonar and underwater communication systems for use in unknown shallow ocean waters may be developed from the automatic spatial and temporal focusing properties of time-reversing arrays (TRAs). Previous simulation results suggest that stationary TRAs will work well with moving sources when the source Mach number is low. This presentation describes simulation results for the case when the TRA is moving and the source is stationary. When the array is moving, the forward and backward propagation necessary for TRA operations is influenced by the Doppler effect in an asymmetric manner. Here, numerical results for the characteristics of the retrofocused field will be presented for a range-independent sound channel based on wide-angle parabolic-equation (RAM by Dr. M. Collins of NRL) or wave number integration (OASES by Professor H. Schmidt of MIT) calculations. Different combinations of array motion and geometry for acoustic center frequencies of several hundred Hertz and nominal ranges up to 10 km will be included, as well as the influence of random bottom roughness. Issues concerning the implementation of a moving TRA in a realistic environment will also be addressed. [Work sponsored by ONR.]
Coastal zone management regulations in California and other coastal states
Authors: Delaplaine Mark
Published: October 2013

The California Coastal Commission is California’s designated coastal management agencies for the purpose of administering the federal Coastal Zone Management Act (CZMA) over Pacific Ocean waters offshore of California. Once a state’s coastal management program is certified by the federal government, the CZMA gives state coastal management agencies regulatory control (federal consistency review authority) over all federal agency activities and all federally licensed, permitted or funded activities (regardless of the location of the activity), if the activity affects the land or water uses or natural resources of the coastal zone. The regulations and the regulatory process under the CZMA (and under State law for activities in state waters) in California will be discussed, with an emphasis on the use of underwater acoustic devices (including seismic surveys, military sonar, and acoustic thermometry, and other research) and the evolution of policy development over the past 5–6 years. Comparisons and contrasts with procedural and policy positions taken by other states under the CZMA will also be made.
Audio system design for cruise ships
Authors: Edwards Alan
Published: October 2013

The design of audio systems for cruise ships introduce several acoustic challenges. The two leading challenges to overcome are ambient noise level and specular reflections. Ambient noise levels can reach 55 dBA and in many cases, higher. A majority of these noises are caused by engine vibrations, and HVAC which tends to be the leading cause of high noise floor levels. Audio systems are designed to compensate for such high ambient noise levels by distributing sound levels selectively throughout the facility. Another challenge to audio system design is specular reflections. This reflection is a delayed audible signal bounced off a surface at equal to or slightly less than the level of the direct sound with time as the variable. The problems caused by these reflections can vary from tonal coloration to echoes. Many surface materials not found in traditional showrooms can have very low absorption coefficients around the 1000 Hz–4000 Hz margin. Such surface materials include heavy plated glass windows, smooth tile flooring, etc. Interaction with the Interior Architect is crucial when designing the audio system. Many of these common problems can be minimized by room modeling through computer simulators for acoustics in the design phase.
Electro-acoustic design: The differences between land and sea
Authors: Rose Howard
Published: October 2013

For the past 5 years Jaffe Holden Acoustics has been consulting with Royal Caribbean Cruise Lines on the design of their theaters on board their latest three classes of cruise ships; Voyager Class (currently the worlds largest class of cruise ship), Millennium Class, and Radiance Class. Designing performance audio systems for cruise ships presents a variety of design and installation challenges. Some of the challenges we will discuss include: space restrictions, cabling practices, mounting methods, power requirements and restrictions, trade coordination, client politics, and budget. Given this multitude of challenges, we will discuss the success of these designs. We will present case studies for a few ships, some commissioned and some still under construction.
Regulating ocean noise: Limits and possibilities of existing legal frameworks
Authors: Reynolds Joel R. , Jasny Michael D.
Published: October 2013

This paper considers the framework that existing federal laws provide for regulating ocean noise and evaluates amendments that have been proposed with the intention of improving that framework. Particular attention is paid to the U.S. Marine Mammal Protection Act (MMPA), which establishes a moratorium on the ‘‘harassment’’ of marine mammals, and to changes in its language that have recently been recommended by scientific committees or advanced by administrative agencies through ad hoc rule making. The adverse consequences that some of these changes would have, as for example by hampering the agency’s ability to enforce the law, by restricting public notice, and by undermining the process of judicial review—not only with regard to ocean noise pollution but to other environmentally harmful activities that come under the purview of the MMPA—have not adequately been considered. Finally, this paper discusses alternatives to the existing regime, including steps that other governments have taken (such as setting noise limits in marine protected areas); and opportunities available for addressing ocean noise pollution under international conventions and protocols.
Hot topics in physical acoustics
Authors: Keolian Robert M.
Published: October 2013

With the adoption of the 1996 Comprehensive Nuclear-Test-Ban Treaty, a global International Monitoring System of 321 monitoring stations is being deployed around the world. Three of the four types of sensors used by these stations are acoustical in nature. Seismic, hydroacoustic, infrasonic, as well as radionuclide sensors are used to detect banned underground, underwater, and atmospheric nuclear tests. The infrasonic sensors are arrays 1 to 3 kilometers across to lower their sensitivity to noise from the wind. They can detect nuclear blasts thousands of kilometers away, but they also detect some background events that are interesting too: meteorites, explosive volcanoes, supersonic aircraft, and reentering space debris.
Matched field processing and tracking with sparsely populated line arrays
Authors: Abawi Ahmad T. , Stevenson J. Mark
Published: October 2013

Data from the Shallow Water Cell Experiments SWellEx-96, which was performed in roughly 200 m of water, are used to assess the detection and localization performance of sparsely populated line arrays. The acoustic source in this experiment transmitted 13 narrow-band tones between 50–400 Hz. Data from this source was recorded on a 64-phone vertical line array with a vertical aperture of 118 m and a 240-meter long, 32-phone horizontal line array. Matched field processing and tracking using these data are performed and the detection performance of these arrays as a function of source level and the number of phones is investigated.
Acoustic considerations for speech intelligibility by special populations
Authors: Nelson Peggy
Published: October 2013

Increasingly the design of public spaces is complicated by the communication needs of multiple groups of users. Schools, places of worship, and community centers are used for meetings of children and adults, with and without hearing loss, who are native speakers of English or other languages. In this presentation, data concerning the acoustic needs of children, speakers of other languages, and listeners with hearing loss will be summarized. Data suggest that typically developing children require more favorable acoustic conditions than do adults. Listeners with hearing loss and those listening in a second language need even more favorable acoustics for speech intelligibility. Desired acoustic guidelines for public spaces will be described. Emphasis will be placed on the need for quieting noise and reducing reverberation, rather than amplifying sound.
Shallow water acoustics and marine mammals
Authors: Rogers Peter H.
Published: October 2013

Human activity is causing significant changes to the shallow water acoustic environment. A good understanding of the basics of shallow water acoustics is essential to a proper assessment of the impact of this activity on marine mammals. Misunderstanding of the relevant underwater acoustics can often lead to erroneous conclusions about the impact of such changes on marine mammal ecology. This paper will address some of the issues and misunderstandings. Shallow water regions present an acoustic environment which is typically much more demanding and complex than the deep water environment. Propagation is strongly influenced by the surface, water column, and sea bottom and will vary greatly from place to place, and time to time. Shallow water regions are highly reverberant and are often very noisy. Marine mammals rely on underwater sound for communication and detection of prey. Unlike fish, which evolved entirely in the sea, the marine mammals auditory system evolved from a terrestrial auditory system. This paper will also address the differences between shallow water acoustics and atmospheric and deep water acoustics, and how they effect the acoustic behavior of marine mammals. Specific adaptations of the dolphins echolocation system to the shallow water environment are highlighted.
Sound propagation in deep water
Authors: Kuperman W. A. , D’Spain G. L.
Published: October 2013

The basics of deep water sound propagation as related to marine mammal issues are reviewed. The spatial distribution of sound for a variety of source situations is qualitatively and quantitatively presented. Special care will be given to the details of the units describing sound levels. Acoustic signals will also be discussed in the context of natural and manmade ambient noise.
Recent progress in single crystal naval sonar transducer development
Authors: Powers James M.
Published: October 2013

Single crystals of lead magnesium niobate/lead titanate (PMN-PT) and lead zinc niobate/lead titanate (PZN-PT) are currently under investigation as high-performance piezoelectric transducer materials. In particular the high-strain (>1.0%) and high-coupling factor (k33>0.90) potentially allow the design of sonar transducers with greatly increased power density and bandwidth. In this talk the properties of single crystal material will be discussed as they pertain to sonar transducers, and some ongoing single crystal transducer developments will be reviewed. [Work supported by DARPA and ONR.]
Radiation patterns of novel one- and three-tine tuning forks
Authors: Blodgett Earl D. , McCann Lowell I. , Anderson Chelsea
Published: October 2013

Inspired by recent results [D. A. Russell, Am. J. Phys. 68, 1139–1145 (2000)] showing that the traditional two-tine tuning fork behaves as a linear quadrupole source, novel one-tine and three-tined tuning forks were constructed. The three identical tines on the three-tined fork were equally spaced around a circle and oriented so that each tine oscillated radially when exciting the fundamental mode. The angular dependence of the radiated sound from these forks was investigated as a function of distance from the symmetry axis of each fork. In the near field, the three-tined fork has three major maxima, one adjacent to each tine, and three minor maxima, one opposite each tine. The minor maxima disappear in the far-field measurements. These results were compared to a simple model wherein each tine behaves as an independent point dipole source [P. M. Morse and K. U. Ingard, Theoretical Acoustics, 2nd ed. (Princeton U.P., Princeton, NJ, 1986), p. 313]. The simple model shows good, but not perfect, agreement with the measured radiation patterns.
Prediction of aircraft flight tracks from noise measurements
Authors: Ikelheimer Bruce , Plotkin Kenneth , Lavallee Timothy
Published: October 2013

A method has been developed to estimate an aircraft’s flight path based on noise measurements at a number of positions within a study area. Two-second time histories of A-weighted sound levels were recorded on 38 digital sound level meters (SLMs) distributed by Geo-Marine Inc. through a mountainous region of approximately 400 square miles. Six of these SLMs recorded one-third octave spectra. Aircraft pass through this area at low altitude along straight tracks (no turns). Determining the aircrafts position from SLM data is difficult because of the complexity of sound propagation over precipitous terrain and the size of the data matrices. The computational core of Wyle Laboratories’ noise simulation model NMSIM is used to perform the propagation calculations. A least mean square method is used to curve-fit the flight track to the SLM data. The accuracy of this approach depends on the time intervals of the SLM data, the speed of the aircraft, and the accuracy of the NMSIM propagation algorithms. The NMSIM predicted flight path will be compared to available radar flight track data. Once a flight track has been established, NMSIM modeled time history and spectral data will be compared with measured data.
Noise pollution in the city of Curitiba, Brazil
Authors: Diniz Fabiano B. , Zannin Paulo H. T.
Published: October 2013

A study carried out in 2000 in the city of Curitiba, Brazil, showed that the noise levels generated by the traffic have decreased when compared to the levels obtained in a similar survey conducted in 1992. Noise levels were measured in 350 points spread through the city considering the same criterium adopted in 1992. A study conducted by Maschkle showed that levels higher than 65 dB(A) are likely to cause health disturbances. The current survey showed that 80.6% out of the measured points presented noise levels over 65 dB(A), whereas in the previous survey 93.4% out of the measured points presented levels over that value. In spite of this, the 2000 levels are still too high considering the local legislation, putting the city in a high risk category to health impairments. Among the possible reasons that caused such a reduction on the noise levels some can be cited: better conditions of the new road vehicles circulating in the Brazilian cities and in Curitiba as well, installation of electronic speed controllers, and the establishment of speed limits for some urban streets and avenues.
Further investigations on the effects of salts on SBSL
Authors: Khong Anthony , Doschek Elizabeth , Apfel Robert , Ketterling Jeffrey
Published: October 2013

This current report extends earlier work done introducing lithium halide salts in the SL medium. A positive relationship between increasing salt concentrations in solution and bubble dynamics was noted. The radius versus time plots showed near perfect inelastic collapse of the bubble in lithium chloride solution as the salt concentration was increased to 3%. It appears that damping in the bubble is appreciably reduced in a solution with a high-salt saturation than in pure water. This observation seems in line with theories that considered the presence of water vapor molecules in the bubble as attenuating its collapse energy. However, any correspondence between the experimental and the theoretical C curves in the phase diagram plots could not be established. In this report, the following is examined: the effects of further increase in salt concentrations, gas saturations, and gas ratios in solution; of counterions other than lithium; and of lowering the temperature have on bubble dynamics. The aim, ultimately, is to have conditions streamlined for studies with salts in deuterated water, from which it is hoped to observe interesting products brought about by SL in this case. [Work supported by DARPA through a subcontract from University of Washington.]
Laser induced cavitational luminescence in a bipolar acoustic pulse wave
Authors: Sankin Georgii N. , Mettin Robert , Lindau Olgert , Wolfrum Bernhard , Lauterborn Werner , Teslenko Vyacheslav S.
Published: October 2013

Laser induced bubble dynamics (200–300 μs life time) under the influence of a convergent bipolar acoustic pulse (100 bar, 2 μs) in water is investigated experimentally. The amplitude of both an emitted shock and luminescence from the bubble collapse are recorded by a pvdf pressure probe and a photomultiplier tube (which integrates the spectral range from 260 to 530 nm). Different delay time (phase) between collapse and pressure pulse is found to influence the luminosity. For certain phases the average amplitude of the luminescence signal is increased by an order of magnitude in comparison with the average signal from an undisturbed collapse (i.e., outside the additional pressure pulse). Photorecordings show that bubbles re-expand after the first collapse nonspherically if an acoustic pulse was applied. They form a nose on the shadow side of the pulse wave which is possibly indication for jetting. Results for a collapse of a laser cavitation bubble and a bubble produced by shock cavitation are compared. [Work supported by DAAD and RFBR.]
Measurements of the frequency- and size-dependent response of single, acoustically driven bubbles suspended in a polymer gel
Authors: McCormick Ryan D. , Roy Ronald A.
Published: October 2013

Sound propagation through bubbly liquids is a topic of interest to a variety of communities. However, characterization of the bubbly medium itself has proven difficult as bubbles either move with a flow or rise too quickly for precise observations. To bypass this problem, a gel has been devised using the food-thickening polymer xanthan gum to hold bubbles stationary pending dissolution [Hwang et al., J. Atmos. Ocean Tech. 12, 1289–1302 (1995)]. The gel has the same salinity as seawater, but possesses a much higher viscosity and is probably more elastic. Using this material, it is possible to unobtrusively ‘‘levitate’’ bubbles without reliance on an acoustic standing wave. The frequency-dependent driven response of a single bubble of known size can then be measured via laser scattering. Experimental results will be presented for an acoustically forced bubble driven at frequencies spanning the fundamental resonance frequency, and compared with model predictions. [Work supported by ONR.]
A model for the ultrasonic modulation of optical path in acousto–photonic imaging
Authors: Manneville Sebastien , Roy Ronald A. , DiMarzio Charles C. , Boas David A.
Published: October 2013

Diffusive optical tomography (DOT) is a well-established technique for measuring blood volume and oxygen concentration in a variety of tissues. In acousto–photonic imaging (API) a focused ultrasound beam is used to modulate the diffusive photon density wave, resulting in a ‘‘virtual source’’ of modulated photon density waves emanating from within the tissue. There are two primary mechanisms for this interaction: index of refraction perturbations and induced particle motion. In this talk, we propose a simple model for the ultrasound-induced motion of a particulate suspension in a fluid. The model accounts for first order oscillatory particle translation and second-order effects such as steady streaming and primary radiation force. Coupled to numerical simulations of the pressure field and of the steady streaming field, this model yields quantitative estimates for the particle motion as a function of space and time, for both continuous wave and pulsed wave insonations. The results are fed into a Monte Carlo simulation of the photon migration/scattering process to yield predictions of the API virtual source strength as a function of acoustic parameters and propagation medium properties. [Work supported by the Center for Subsurface Sensing and Imaging Systems, under the NSF ERC Program (award ♯EEC-9986821).]
An efficient algorithm for the simultaneous solution of exterior acoustic problems over a frequency band
Authors: Wagner Marcus M. , Pinsky Peter M. , Malhotra Manish
Published: October 2013

A method for solving time-harmonic exterior acoustics problems in a frequency band over selected regions of the computational domain is presented. The partial fields of interest include surfaces enclosing the sound source, as well as distinct points in the near-field of the source. The discretization of the boundary-value problem is based on finite elements. Replacing the infinite domain problem with an equivalent formulation in a bounded domain leads to the incorporation of a Dirichlet-to-Neumann (DtN) map, which accounts for the analytical asymptotic behavior of the solution. By interpreting the discretized DtN operator as a low-rank update of the system matrix, a standard shifted form of the inverse of this matrix, which is incorporated in the expression for the partial fields, is obtained. Due to the complex frequency dependence of this inverse, a direct evaluation is prohibitive. Hence, a matrix-valued Padé approximation of the inverse operator is employed via a two-sided block Lanczos algorithm, which provides a stable and efficient representation of the Padé approximation. A numerical example illustrates the performance and advantages of the outlined method.
Exploring underlying pitch targets in English statements
Authors: Xu Yi , Xu Ching X.
Published: October 2013

This study investigates F0 contours and their potential association with underlying pitch targets in English statements with and without narrow focus. Eight native speakers of American English read aloud 21 sentences at 2 speaking rates with 7 repetitions. The initial, middle, and final words in these sentences vary in focus status (focus or no focus) and word length (monosyllabic, disyllabic, or trisyllabic). F0 curves are extracted using a method that combines automatic vocal cycle detection and manual rectification. Preliminary results show that F0 peaks occur earlier when the vowel of the accented syllable is phonologically long than when it is phonologically short. This seems to suggest that a nonfinal pitch accent in an English statement is probably associated with a high static target. Preliminary analyses also show that F0 contours of nonaccented syllables are influenced more by the preceding accent than by the following accent. Furthermore, the influence of the accented syllable on the F0 of the following (but not the preceding) nonaccented syllable is found to reduce over time. These patterns seem to suggest that inter-accent F0 contours in English probably also result from certain underlying pitch targets rather than from linear or nonlinear interpolation between adjacent pitch accents.
Stress effects on voicing and frication in voiced obstruents in north-central Spanish
Authors: Gonzalez Carolina
Published: October 2013

In Spanish /b, d, g/ are usually realized as voiced approximants in all sylllabic contexts unless following a stop—a phenomenon called spirantization. However, in North-Central Peninsular Spanish (NCS) voiceless fricatives rather than voiced approximants are produced. In the majority of cases this occurs in stressed syllables. This study examines whether stress is a factor in the likelihood of frication and devoicing of coda /b, d, g/ in this dialect. Nine native speakers of NCS were recorded producing nonce words with /b, d, g/ in coda position in both stressed and unstressed syllables. Measurements were made of vowel and consonant duration, presence and absence of frication and voicing, and voicing duration. The results indicate that frication is more likely in stressed syllables than in unstressed syllables. This suggests that in stressed syllables a higher subglottal pressure produces higher airflow across the glottis, favoring frication. In turn, frication inhibits voicing due to conflicting aerodynamic requirements between the two. It is concluded that stress is a factor in spirantization and that it may indirectly affect the voicing properties of /b, d, g/. [Work supported by Del Amo and the Basque Government.]
Positional and planning effects on the durational structure of repetition strings
Authors: Bell Alan , Girand Cynthia
Published: October 2013

Gaining time to resolve some difficulty in the production of upcoming speech is the primary function of unplanned repetitions. Understanding their duration structure is thus crucial to modeling their production, which surely differs greatly from fluent phrases. When the duration structure of the entire repetition string of unplanned repetitions is examined, strong global dependencies are found. Repetition strings are words/phrases repeated once or more, together with silent and filled pauses optionally occurring next to them. The main effects are that durations of first and second string items, whether repeated words or pauses, are positively correlated with the duration of the rest of the string; items, whether words or pauses, are shorter as they occur later in the string; and strings that begin with a pause average longer than strings that do not. The study is based on an analysis of 503 disfluent repetitions taken from the ICSI phonetically transcribed sample of the Switchboard conversation corpus, extensively checked and recoded. The results help explain local durational dependencies of the repeated words [Bell and Girand, LabPhon 7 (2000)] and imply that the articulation of repetitions is influenced from the onset by the nature and degree of difficulty they address.
Resolution of left–right ambiguity in towed array sonars
Authors: Kaouri Katerina , Allwright David J.
Published: October 2013

A method is proposed for resolving the left–right ambiguity in passive sonar systems, a problem that arises in source localization when the array is straight. In practice, the array is not straight and a statistical analysis within the Neyman–Pearson framework is developed for a monochromatic signal in the presence of noise, assuming that the exact array shape is known. For any given array shape, an expression for the probability of correct resolution (PCR) is derived as a function of two parameters: the SNR and an array-lateral-displacement parameter. The first parameter measures the strength of the signal relative to the noise and the second the curvature of the array relative to the acoustic wavelength. The PCR is calculated numerically for a variety of array shapes of practical importance. The model results are found to agree with intuition; the PCR is 0.5 when the array is straight and is increasing as the signal is becoming louder and the array more curved. It is explained why the method is useful in practice and the effects of correlation between beams are discussed. [Research partially supported by Thomson Marconi Sonar Ltd.]
Acoustic noise suppression for speech enhancement
Authors: Anderson David V. , Whitehead Phil Spencer , Clements Mark
Published: October 2013

Removal of noise from a single channel audio signal is becoming an increasingly important problem due to the proliferation of portable communication devices. Early methods of single channel noise suppression introduced artifacts that could be as annoying as the original noise. Substantial effort has been focused on more effective noise suppression with fewer artifacts, but many difficulties remain and the problems seem far from being solved. For example, nearly all noise suppression techniques actually reduce the intelligibility of the processed signal. This paper investigates the sources of some of the artifacts common with Wiener filtering and proposes a structure to mitigate or eliminate these artifacts and effectively reduce noise without adversely affecting intelligibility. Results of one implementation of such a structure demonstrate significant improvements both in speech recognition performance and perceived speech quality.
Personal computer and frequency analyzer measure reverberation time
Authors: Arcas Guillermo , Martn Alberto , Asensio Cesar
Published: October 2013

This paper shows how a frequency analyzer (such as Brüel and Kjaer’s Model 2144) can be used to perform reverberation time measurements with the help of some extra software. Although a particular solution is presented, the concept can be applied to any frequency analyzer that has a programmable interface. Brüel and Kjaer’s Model 2144 is a powerful frequency analyzer, but it does not measure reverberation time. On the other hand, the analyzer has a programmable interface (GPIB) that permits us to control the instrument from a personal computer. This paper shows how a software application has been developed that gives the B&K2144 connected to a computer, the capacity of measuring reverberation time. The application has been developed using LabVIEW and it makes reverberation time measurements easy and reproducible.
Variation of attenuation constant and absorption coefficient of fiberglass with altitude
Authors: Hastings Mardi C.
Published: October 2013

ASTM C 423-99a specifies requirements for air temperature and relative humidity during decay rate measurements, but does not address variations in air density even though this parameter decreases with increasing altitude. The effect of changes in air density on absorption of fiberglass was investigated using approximations for characteristic impedance and complex propagation constant [M. E. Delany and E. N. Bazley, NPL AERO REPORT Ac37, March 1969], and design charts for absorbers in diffuse sound fields [F. P. Mechel, J. Acoust. Soc. Am. 83, 1002–1013 (1988)]. At constant temperature and relative humidity, air density decreases by 17% from sea level to 5000 ft altitude, resulting in a 17% decrease in its acoustic impedance and a 12% increase in the attenuation constant of fiberglass. Using measured flow resistivities of four different fiberglass boards and an empirical correction factor to account for diffraction effects at sample edges, NRC values for the same board were found to vary within ±0.04 between sea level and 5000 ft. Transmission measurements, such as those used to qualify aircraft insulation, will be overstated at higher altitudes because transmission loss is proportional to the attenuation constant. Thus correction factors should be developed for data taken substantially above sea level for comparison with data taken near sea level.
Temporary threshold shift (TTS) in bottlenose dolphins (Tursiops truncatus) exposed to tonal signals
Authors: Finneran James J. , Carder Donald A. , Ridgway Sam H.
Published: October 2013

A behavioral response paradigm was used to measure underwater hearing thresholds in two bottlenose dolphins (Tursiops truncatus) before and after exposure to intense tones. The fatiguing sounds were 3 kHz, 1 s tones. Hearing thresholds were measured at 3 and 4.5 kHz using a vocal response technique and a modified version of the Method of Free Response. Tests were conducted in a 6 m diam, 1.5 m deep vinyl-walled swimming pool. Ambient noise spectral density levels in the pool were approximately 44 dB re: 1 Pa2/Hz. Postexposure threshold measurements normally began within two minutes of exposure and continued for 1015 min following exposure. A temporary threshold shift (TTS) was defined as a 6 dB or larger increase in threshold compared to the corresponding pre-exposure level. Preliminary results indicate no TTS at 4.5 kHz for either subject at received SPLs of 200 dB re: 1 Pa. These data, as well as the test paradigm, absolute hearing thresholds, and observed behavioral reactions, will be presented and compared to existing TTS data for odontocetes.
Oil-filled cymbal panels for acoustic projection applications
Authors: Howarth Thomas R. , Carney Walter L. , Tressler James F. , Carney Walter L.
Published: October 2013

The U.S. Navy is developing cymbal-based elements arranged in a closely packed configuration for future underwater applications. This presentation concerns the design and experimental data of 49 elements placed within an oil-filled frame to form a 101 mm by 101 mm aperture. Experimental data shows a tunable low-frequency resonance between 5 and 10 kHz. The projector continues to increase in sound output to 100 kHz and then remains flat to 220 kHz. Higher overtones have been observed at 400 and 600 kHz. The units were tested under hydrostatic pressure from ambient to 800 psi and back. Laser Doppler vibrometry was performed over this frequency range to observe the modal behavior. The presentation will include a discussion of the results as well as planned future endeavors. [Work sponsored by ONR 321SS and ONR 321TS.]
Prototype high-sensitivity triaxial pressure gradient acoustic accelerometer
Authors: Brown David A. , Aronov Boris , Reinhart Lawrence , Volkema Glenn , Oishi Tetsuro
Published: October 2013

We present the results of the development of a high-sensitivity (400 mV/g) triaxial pressure gradient sensor of the acoustic motion type for underwater applications. The device uses piezoelectric flexural plates arranged symmetrically and mounted in a near neutrally buoyant case. The sensor is operated below resonance in the accelerometer mode. Hydrophones are attached to the case to realize a vector sensor that can produce a cardiod steerable in all azimuth and elevation. The four channels have a common acoustic center. Results of sensitivity and measured directivity beam patterns will be presented. [Work supported in part by BTECH and ONR 321SS.]
The influence of wavelets on music research
Authors: Spiegelberg Scott
Published: October 2013

Starting in the late 1980s, wavelets have been used for a variety of purposes in music research. The earliest and still most prevalent use of wavelets has been time–frequency representations of musical signals, as a superior alternative to Fourier analysis. Computer music specialists interested in sound synthesis have also used wavelets as a means of dynamic filtering and separating monaurally superimposed sounds. One researcher has explored the use of wavelets in detecting patterns of whole pitches or rhythms, with varied results. And researchers at Yale University have used wavelets for noise reduction of a 1889 recording of Johannes Brahms performing his Hungarian Dance Number 1. In this paper the different types of wavelet transforms used in the music research mentioned above are explained, and future uses in timber research and sound synthesis is explored.
Simultaneous performance of musical and verbal tasks
Authors: Acker-Mills Barbara E.
Published: October 2013

Allport, Antonis, and Reynolds [Q. J. Exp. Psych. 24, 225–235 (1972)] demonstrated that pianists could sight read piano music and perform a verbal shadowing task. However, although widely cited in the multiple resource attention literature, the study has never been replicated. The current work provides a more detailed evaluation of the verbal component of the task and thorough statistical analyses. Effects of part and whole practice also are explored. Pianists completed a baseline phase where a Mozart minuet was performed and note/timing mistakes were recorded. A text passage from a SAT review book then was presented over headphones and reading comprehension questions were answered. In the dual task sessions, participants performed similar musical passages while listening to similar text passages. Reading comprehension questions were completed at the end of each dual task performance. Finally, half of the pianists practiced the musical and verbal tasks together for 10 min, while the other half practiced each individual task for 5 min each. Both groups repeated the dual task and the types of performance improvements were analyzed. Similarity to the Allport et al. results and effects of part and whole practice will be discussed.
Mitigation of structureborne noise nuisance
Authors: Ko Wing P.
Published: October 2013

Noise is radiated directly from the vibrating structure as structureborne noise. A structureborne noise case in a domestic building is described in this paper. The pipes were installed and mounted vertically with little or no insulation between the pipes and the walls. The result was that, every time a toilet was flushed or fresh water was used in one of the units in the building, the water flow and pump noise was heard clearly in the unit directly above the pump room. The family in the unit was very annoyed with the noise, especially in the middle of the night. The measured noise level inside the unit was found to exceed the statutory requirement of 45 dBA (Leq. 30 min) in the night time period (23:00–07:00 h). The solution to this problem was to isolate the pipes and pumps from the walls and floors with resilient materials or hangers to break the vibration channel. Also, the pump operation was limited to only one time within any 30 min in the nighttime period. Finally, the noise level inside the unit was found to meet the statutory requirement.
Survey and assessment of noise in coal preparation facilities
Authors: Vipperman Jeffrey S. , Bauer Eric R. , Spencer Ellsworth R. , Babich Daniel R.
Published: October 2013

Noise induced hearing loss (NIHL) has been found to be a significant problem in the mining industry. Between 70% and 90% of miners are reported to have enough NIHL to be classified as a disability (NIOSH, Publication No. 76-172, 1976; Franks, NIOSH Internal Report, 1996). In response to this problem, the National Institute of Occupational Safety and Health (NIOSH) is conducting a cross-sectional mining noise survey. Objectives for this survey include determining if various mining environments are within compliance with the recent mining noise regulation: 30CFR, Part 62 and if not, what engineering or administrative controls might be instituted. The preliminary results from the study of four coal preparation plants will be presented. Measurements included noise dosimetry in conjuction with time-at-task studies, 1/3-octave sound level measurements throughout each floor of the plants, and T20 reverberation time measurements. Results generally reflect fairly uniform A-weighted overall noise levels throughout the plant, which are capable of creating overexposures for a full 8-hour shift. The potential for administrative controls exists but the use of engineering controls is hindered by the size and number of the noise sources, the frequency content of the noise, accessibility requirements for the equipment, and industrial harshness of the environment.
Nonlinear acoustic techniques for landmine detection: Experiments and theory
Authors: Korman Murray S. , Sabatier James M.
Published: October 2013

A nonlinear acoustic technique for detecting buried landmines has been suggested by Donskoy [SPIE Proc. 3392, 211 (1998); 3710, 239 (1999)]. Airborne sound at two primary frequencies f1 and f2 undergo acoustic-to-seismic coupling and a superimposed ‘‘slow’’ compressional wave interacts with the compliant mine and soil. The nonlinear mechanism involves a simple model of the top surface of the mine–soil planar surface separating two elastic surfaces. During the compression phase of the wave, the surfaces stay together and then separate under the tensile phase due to a relatively high compliance of the mine. This ‘‘bouncing‘‘ soil–mine interface is thought to be a bimodular oscillator that is inherently nonlinear. Geophone measurements scanning the soil’s surface (at the difference frequency) profile the mine, but off the mine some nonlinearity exits. Amplitude-dependent frequency response curves for a harmonically driven mass-soil oscillator are used to find the nonlinearity of the soil acting as a ‘‘soft’’ spring. Finally, a layer of soil in a large tube, terminated by a thin elastic plate, is used to model the bimodular nonlinearity. [Work supported by the United States Army Communications-Electronics Command Night Vision and Electronic Sensors Directorate.]
Modeling tongue shapes with conic arcs
Authors: Iskarous Khalil , Whalen D. H. , Mattingly Ignatius
Published: October 2013

Quantifying the changing shape of the tongue has been a longstanding challenge for experimental phonetics. One approach is to track the location of points on the tongue using x-ray microbeam or EMA. This leads to a precise numerical quantification, but is limited to information from a few points. Cinefluorography, MRI, and ultrasound remove the limitation by imaging entire sections of the tongue, but it is difficult to derive quantitative information from the scans. The present work illustrates a new method for quantifying an ultrasound tongue image by automatically fitting a conic arc to the midsagittal edge of the tongue. These arcs can vary continuously in shape from elliptic to parabolic to hyperbolic, and the variation is parametrized by two phonetically meaningful geometric parameters: one correlates with constriction location and the other with constriction degree. Quantification of tongue shape change is then measured by tracking the change in these 2 unique descriptors. One arc is sufficient for most tongue shapes, but some require two. Also, the general conic arc is a better model of the tongue dorsum than the circle, which has been used in articulatory synthesis systems. We will present data comparing these two models. [Work supported by NIH Grant DC-02717.]
A distinctive region model based on empirical vocal tract area functions
Authors: Story Brad H.
Published: October 2013

The development of the Distinctive Region Model (DRM) [Mrayati et al., Speech Commun. (1988)] is based on theoretically derived acoustic characteristics for a tube of uniform cross-sectional area assumed to approximate a neutral vocal tract configuration. Formant sensitivity functions calculated for the uniform tube are used to divide the vocal tract into distinctive regions that, when constricted or expanded, will cause the formant frequencies to change in a predictable pattern. This study compares the original DRM (based on a uniform tube) with a new version created from a neutral vocal tract area function derived from published MRI data. Because it is subject to physiologic constraints, this neutral area function is nonuniform in cross-sectional area variation but exhibits formant frequencies similar to a uniform tube. Sensitivity function calculations for F1, F2, and F3 also show similarities to those of a uniform tube, but the zero-crossing points that divide the vocal tract into distinctive regions are shifted toward the lips. The result is distinctive regions that are not symmetric about the vocal tract mid-point but rather the back and front regions occupy about 60% and 40% of the total tract length, respectively. [Work supported by NIH R01-DC04789.]
Three-dimensional reconstruction of vocal fold geometrical deformation induced by formalin fixation
Authors: Kimura Miwako , Tayama Niro , Chan Roger W. , Titze Ingo R.
Published: October 2013

In our previous study [Kimura et al., J. Acoust. Soc. Am. 109, 2413 (2001)], we showed that significant tissue deformation and distortion of vocal fold geometry is induced by the commonly used histological procedure of formalin fixation. Significant shrinkages of the vocal fold body (thyroarytenoid muscle) and considerable distortion of the vocal fold cover (particularly the free edge) were observed. In mid-membranous coronal sections of canine tissues, there was an average of 20% shrinkage in vocal fold thickness and 40% shrinkage in vocal fold depth. This paper reports a three-dimensional (3-D) follow-up to these two-dimensional measurements. Vocal fold coronal sections every 2 mm along the anteroposterior direction were prepared from the same canine tissue samples, allowing for 3-D reconstruction of geometrical deformation. Results showed that the free edge of the vocal fold cover was significantly deformed, as emphasized by 3-D images.
Three-way contrast in breathiness in Ju—’hoansi
Authors: Miller-Ockhuizen Amanda
Published: October 2013

I present results of an acoustic study investigating three female and three male speakers’ productions of a three-way contrast in breathiness in the Khoisan language Ju—’hoansi, with the spectral slope (H1–H2) occurring at the release of the stop resulting in aspirated consonants, or the peak H1–H2 reached over the first part of the vowel in partially breathy vowels, or the peak H1–H2 maintained over the entire vowel in fully breathy vowels. H1–H2, and gamnitude of the first rahmonic peak were measured throughout the course of the vowel using a window of 46.5 ms, with a sampling rate of 22050 Hz, starting from the first computer-recognized glottal pulse, with a step-size of 10 ms. Results show extremely similar patterns for both H1–H2 and gamnitude of the first rahmonic peak for aspirated consonants and partially breathy vowels. These sounds are distinguished on the basis of VOT, but not by fundamental frequency (F0). Aspirated consonants and partially breathy vowels are extremely similar in H1–H2, gamnitude of the first rahmonic peak, and F0, being differentiated only by voice onset time (VOT).
Prosodic differences in tracheoesophageal speech: Perception and production
Authors: Rosenbauer Kimberly , Trudeau Michael
Published: October 2013

Prosody plays an important but often unrecognized role in a listeners interpretation of an utterance. The potential for significant prosodic limitations is often found in speakers who use tracheoesophageal speech due to extirpation of the larynx from cancer. This is because many prosodic features in the normal speaker are controlled by the use of laryngeal muscles [Kent, The Speech Sciences (1997)]. Previous studies showed inconsistencies in intonation and word stress perception and production levels regarding tracheoesophageal speech [Gandour and Weinberg, J. Speech Hear. Res. 26, 142–148; Trudeau et al., J. Commun. Dis. 21, 21–31]. The present study was designed to reevaluate listeners perceptions of tracheoesophageal speech and then describe the production components or limitations leading to these perceptions. Listeners unfamiliar with tracheoesophageal speech listened to normal and tracheoesophageal speakers saying the sentence Put the dishes away as a declarative, query, and exclamation—both in and out of sentential context. Listeners then heard a recording of all speakers and categorized the sentences as to sentence types. Intonation patterns of normal and tracheoesophageal speakers were then compared and contrasted. A more detailed analysis of tracheoesophageal tokens identified as correct nearly all or none of the time was also done.
Multi-wavelet detection and denoising of low-frequency chirp signals using adaptive wavelet methods
Authors: Wheatley Joseph S. , Ioup Juliette W. , Ioup George E.
Published: October 2013

The detection and classification of underwater acoustic signals embedded in noise is a fundamental problem of interest to the signal processing community. The use of wavelet transforms is a recent development in digital signal processing which has been applied in many different areas. A particular type of wavelet is the chirplet, which includes frequency variation as well as time shift and scaling. Both linear and polynomial chirp signals are present in underwater acoustic signals generated by such sources as biologics, ships, and submarines. Distinguishing the features of these chirps relative to other ambient noise shows promise as an initial step in classification of underwater acoustic signals. Removal of unwanted broadband signal components via wavelet methods has been shown to outperform other noise removal processes such as low-pass and high-pass filtering and Weiner filtering. Examples of low-frequency simulated chirp signals with additive noise have been generated. A multi-wavelet packet method for detection and denoising low-frequency signals containing multiple chirps embedded in noise using a specific wavelet designed for polynomial chirp signals is shown. [Research supported in part by ONR.]