bluuebunny/crossref_metadata_2025 huggingface dataset:
Time marching spectral analysis of a swept sine melody model
Authors: Bhat Rama B.
Published: October 2013

A melody is a progression of musical notes in a scale. Since the notes have identified frequencies, a melody rendering involves a quick sweep of frequencies between any two neighboring notes, and a dwell at the notes. A melody rendering is modeled as a dwell at the notes and a sinusoidal sweep in between. A time marching spectral analysis shows that the dwell time and the rate of sweep between notes have significant influence on the melody. Any two notes form the not-so-high harmonics of a periodic process which may or may not necessarily contain the fundamental and some of the lower harmonics. If a three-note combination of a first, a fifth, and an octave higher notes are taken, as the drone in Indian classical music, they have ratios of 1:3/2:2. The combination is a periodic process with half of the first note frequency as the fundamental which is missing, while the second, third, and fourth harmonics are present. A melodic rendering of seven notes or less may be construed as a periodic process with some of the harmonics varying or dancing with time. Results on a melody in pentatonic scale is presented and discussed.
Application of cochlear analysis techniques to finding percussive events in electro-acoustic music
Authors: Mills Anderson
Published: October 2013

Electro-acoustic music is a style of music for which often the pressure signal itself is the only consistent, objective representaiton of the music. A project has been undertaken at The University of Texas to automatically extract audio properties from recordings of electro-acoustic music, and the first property chosen to be extracted is a measure of the ‘‘single damped percussive events’’ (SPDEs) found in a piece of music. Because electro-acoustic music often contains sounds which are not considered musical in traditional contexts, the analysis of this type of music must begin by approaching the pressure signal without traditional musical foreknowledge, and therefore this analysis is focused on the extraction of any type of percussive event found in the pressure signal. The explored methods of analysis include bandpass filtering, spectrogram, and Patterson’s auditory image model (AIM) as front-ends. The results of these different methods are compared. A human experiment to determine the nature of an SPDE and to generate data to use as a measure for the algorithms is also discussed. Self-similarity at different time scales within the measure of SPDEs during a piece of music provides useful information to a music theorist and therefore is the next step in this analysis research.
Frequency tracking of ecclesiastical Byzantine music frequency intervals
Authors: Tsiappoutas Kyriakos M. , Ioup George E. , Ioup Juliette W.
Published: October 2013

Two Byzantine music (BM) pieces performed by two well-established traditional chanters are quantitatively analyzed using modern frequency tracking methods to estimate the tone frequencies of the diatonic scale, one of the three main scales of BM. The two experimental versions of the diatonic scale are compared with each other and with two of many theoretical diatonic scales proposed by traditional BM theorists. This constitutes a measure of how well theoretical scales model performance. Then a direct comparison between Byzantine and common European music scales is attempted. Statistical techniques are employed to reveal any significant differences among the different scales. The attraction effect (AE) or ‘‘elksis,’’ i.e., when a specific secondary tone intentionally takes on different frequency values (micro-sharpened or micro-flattened) depending on its direction in the musical script, is measured. This is part of a continuing attempt to quantify the AE empirically. Both main and secondary tones are independently examined to assess their reliance on the AE, but only secondary tones are found subject to it. A connection to the psychophysics of pitch perception illustrates whether the differences among scales are distinguishable by the human ear.
Synthesis and dynamic behavior of diffracted audio spectra
Authors: Eswaran C. , Vijayakumar V.
Published: October 2013

It is shown in this paper how the intensity and phase of the harmonics of a spectrum containing a discrete set of input frequecies of unit intensity is modified by diffraction through a circular aperture. The resulting spectrum further shows dynamic behavior which is discussed in terms of a modulation parameter. Examples of synthesized audio spectra which show similarity to known musical instruments are provided as illustration of the synthesis method.
The recent origin of human speech
Authors: Lieberman Philip , McCarthy Robert C. , Strait David
Published: October 2013

Studies of human development and swallowing show that a supralaryngeal vocal tract (SVT) capable of producing quantal vowels involves (1) facial restructuring yielding a short oral cavity; (2) a tongue that moves down into the pharynx carrying the larynx down with it; and (3) a long neck. The skeletal features of hominid fossils suggest the absence of fully human speech anatomy until 100000 years ago. With long faces and short necks, Neanderthals and early anatomically modern humans could not have possessed SVTs capable of swallowing and of producing fully human speech. Probable [i] SVT shapes were computer-modeled from perturbations of vocal-tract area functions obtained from MRIs of adult humans. When normalized to the length of an adult human SVT, F1/F2 patterns fall outside of the range of Peterson and Barney’s [‘‘Control methods used in a study of the vowels,’’ J. Acoust. Soc. Am. 30, 739–742 (1952)] data used by Lieberman and Crelin, ‘‘On the speech of Neanderthal man,’’ Linquistic Inquiry 2, 203–222 (1971) to assess Neanderthal speech), but at the extreme range for [i] as measured by Hillenbrand et al. [‘‘Acoustic characteristics of American-English vowels,’’ J. Acoust. Soc. Am. 97, 3099–3111 (1995)]. In neither case are the high-frequency spectra characteristic of human quantal [i]’s. F1/F2 patterns for unnormalized SVTs fall outside the human range for both plots.
Development of a binaural speech transmission index
Authors: van Wijngaarden Sander J. , Drullman Rob
Published: October 2013

Although the speech transmission index (STI) is a well-accepted and standardized method for objective prediction of speech intelligibility in a wide range of environments and applications, it is essentially a monaural model. Advantages of binaural hearing to the intelligibility of speech are disregarded. In specific conditions this leads to considerable mismatches between subjective intelligibility and the STI. A binaural version of the STI was developed, based on interaural cross correlograms, which shows a considerably improved correspondence with subjective intelligibility in dichotic listening conditions. The new binaural STI is designed to be a relatively simple model which adds only few parameters to the original standardized STI, and changes none of the existing model parameters. For monaural conditions, the outcome is identical to the standardized STI. The new model was validated on set of 39 dichotic listening conditions, featuring anechoic, classroom, listening room, and cathedral environments. For these 39 conditions, subjective intelligibility (CVC-wordscore) was measured, as well as the binaural STI. The relation between binaural STI and CVC-wordscores in dichotic listening conditions closely matches the STI reference curve (standardized relation between STI and CVC-wordscore) for monaural listening. The monaural STI performs poorly in these cases.
New directions for a speech-based speech transmission index
Authors: Drullman Rob , van Wijngaarden Sander J.
Published: October 2013

The standardized method for determining the speech transmission index (STI) involves the use of a specific intensity-modulated test signal. The STI is obtained from measurements on the transmission channel, usually showing reductions of the modulation depths in the received test signal. Instead of using an artificial signal, various approaches have been suggested in the literature to use speech as a test signal [cf. Payton et al., J. Acoust. Soc. Am. 111, 2431 (2002)]. Such a speech-based STI has several advantages, e.g., predicting intelligibility differences due to speaking style and enabling the evaluation of vocoders. As we encountered shortcomings and inaccuracies in the existing speech-based STI methods, we propose a new procedure for estimating the speech-based modulation transfer function (MTF) which approaches the accuracy of conventional STI implementations. The new procedure uses the cross spectrum between the transmitted and received speech signals, with special phase weighting to address the relative importance of shifted modulations of the temporal envelope. Evaluation of the algorithm on a vocoder database showed promising results, yielding an average correlation coefficient of 0.93 between the subjective CVC scores and the speech-based STI for male speech. Details of this new speech-based STI algorithm will be discussed.
Statistical characterization of target-to-interferer ratio of co-channel speech
Authors: Smolenski Brett
Published: October 2013

Recent research in speaker identification technology suggests that it can operate in co-channel environments provided the system can have access to only the less-corrupted segments of speech. In order to identify the uncorrupted speech segments as accurately as possible, it is necessary to fully characterize the statistics of the random processes generating the uncorrupted segments. In a co-channel environment the uncorrupted speech segments are produced when one speaker’s voiced speech overlaps with the other speaker’s silence or unvoiced speech. Hence, if one has a statistical model of voiced, unvoiced, and silence segments, one can use this information to obtain a model of the uncorrupted speech segments. To accomplish this, statistical models that account for the observed voiced, unvoiced, and silence segment lengths are first developed. Markov models are used to account for dependencies between voiced, unvoiced, and silence segments. In addition, a model of the sampling distribution of the segmental target-to-interferer ratio (TIR) is developed and the short- and long-term correlation present in the segmental TIR signal is also explored.
Not all feedback is created equally: The role of multisensory feedback in the perceptual learning of speech under a novel acoustic transformation
Authors: Webster Kevin T. , Lachs Lorin
Published: October 2013

Previous research has investigated the perceptual learning of speech modified by the frequency-inversion transformation, in which the spectral content of an acoustic pattern is rotated about an arbitrary frequency. The resulting transformed speech is almost completely unintelligible. However, given appropriate training, individuals can learn to perceive the linguistic content of the transformed spoken message. Recent work by Webster and Lachs has indicated that providing multisensory feedback during training appears to enhance the rate at which individuals adapt to the transformation. Furthermore, different types of multisensory feedback give rise to different patterns of learning. For example, learners presented with concurrent visual displays of a talkers lip movements (i.e., articulatory information) demonstrate better learning of training materials than learners presented with concurrent visual displays of text. The goal of the present experiment was to refine the technique for training perceivers in order to exaggerate differences between feedback groups in overall learning. A new control condition was also included to test the hypothesis that nonarticulatory but dynamic visual displays yield qualitatively different patterns of learning that those exhibited by perceivers trained with articulatory displays. The results provided interesting insights into the methodology necessary to test perceptual learning of frequency-inverted speech under multisensory conditions.
Optimal detection with vector sensors and vector sensor line arrays
Authors: D’Spain Gerald L. , Luby James C. , Wilson Gary R. , Gramann Richard A.
Published: October 2013

The detection performance of single vector sensors and vector sensor line arrays is degraded by nonacoustic self-noise and spatial coherence of the noise between vector sensor components. Results based on optimizing the directivity index for a single vector sensor show that the particle motion channels should always be included in the processing for optimal detection, regardless of self-noise level, assuming these levels are properly taken into account. The vector properties of acoustic intensity can be used to estimate the levels of nonacoustic noise in ocean measurements. Application of conventional, minimum variance distortionless response, and white-noise-constrained adaptive beamforming methods with ocean acoustic data collected by a vector sensor illustrates increase in spatial resolution but corresponding decrease in beamformer output and introduction of bias with increasing beamformer adaptivity. Expressions for the spatial coherence of all pairs of vector sensor components in homogeneous, isotropic noise show that significant coherence exists at half-wavelength spacing between particle motion components. For angular intervals about broadside, an equal spacing of about one wavelength for all components provides maximum directivity index, whereas each of the component spacings should be different to optimize the directivity index for angular intervals about endfire. [Work supported by ONR.]
Vector sensor processing results using data from the Makai experiment
Authors: Hursky Paul , Porter Michael B. , Siderius Martin , Abraham Bruce M.
Published: October 2013

Interest in small mobile platforms such as AUVs and gliders, and fixed autonomous systems, whose small size and power budget severely limit their ability to deploy larger arrays, has stimulated interest in vector sensors (that sense both pressure and particle velocity). Such combined sensors provide performance that can only be duplicated by larger pressure-only hydrophone arrays. In September 2005, during the Makai experiment, we deployed a four-element vector sensor array in waters off the coast of Kauai in Hawaii. We will present comparisons of processing a towed source and acoustic communications packets recorded on the four-element vector sensor array and a comparable pressure-only sensor array. We will also discuss modifications to propagation models based on Gaussian beams and normal modes to predict particle velocity, showing comparisons between model predictions and our experiment data.
Imaging marine geological environments with vector acoustics
Authors: Lindwall Dennis A.
Published: October 2013

Using vector acoustic sensors for marine geoacoustic surveys instead of the usual scalar hydrophones enables one to acquire 3D survey data with instrumentation and logistics similar to current 2D surveys. The addition of a collocated hydrophone allows the signal to be rectified, removing the ghost images. This concept was tested by a scaled experiment in an acoustic water tank that had a well-controlled environment with a few targets. Using vector acoustic data from a single line of sources, the three-dimensional tank environment was imaged by directly locating the source and all reflectors. [Office of Naval Research program element 61153N.]
Sediment sound speed measurements using buried vector sensors
Authors: Lyons Anthony P. , Osler John C. , Chapman David M. F. , Hines Paul C.
Published: October 2013

As part of the SAX04 sediment acoustics experiment conducted off the coast of Florida in the Gulf of Mexico, vector sensors containing three-axis accelerometers and pressure sensors were buried in the seabed. These sensors were used as the receivers to measure sediment sound speed dispersion from 300 to 3000 Hz a band in which it has been particularly difficult to make these measurements. The acoustic intensity measured by the vector sensors was combined with the experimental geometry and propagation conditions, to relate the angle of arrival to sediment sound speed as a function of frequency. Lower frequency measurements, 300 to 1200 Hz, used noise radiated from a moored research vessel as the acoustic source. Higher frequency measurements, 800 to 3000 Hz, used transmissions from an acoustic projector in a three-point mooring in the water column that could be adjusted to change the angle of ensonification. Results from the two techniques are compared with each other and previous measurements of dispersion in sandy sediments. [Work performed under ONR Grants N00014-04-1-0013 and N00014-03-1-0883.]
Forming first- and second-order cardioids with multimode hydrophones
Authors: McConnell J. A. , Haberman R. C. , McCormick T. A. , Rudzinsky J.
Published: October 2013

Most everyone in sonar signal processing is familiar with forming a first-order cardioid using scalar and vector sensors, which are defined as the reciprocal analog of a monopole and dipole radiator, respectively. The second-order cardioid can be formed using scalar, vector, and dyadic sensors, in which the latter sensor is defined as the reciprocal analog of a quadrupole radiator. Multimode hydrophones configured as piezoelectric cylinders and spheres with segmented electrodes have the ability to form the both types of cardioids. This paper compares and contrasts the use of multimode hydrophones to produce each beam pattern and presents the results of several sensors that were developed. Topics relating to the sensitivity, bandwidth, noise floor, beamwidth, beam steering, and directivity index will be covered. [Work supported by C. M. Traweek at the Office of Naval Research Code 321MS and L. Shumway at the Department of Homeland Security.]
Development of a miniature uniaxial pressure-acceleration probe for bioacoustic applications
Authors: McConnell J. A. , Jensen S. C.
Published: October 2013

The bioacoustics community has recently expressed an interest in using collocated measurements of the acoustic pressure and the particle velocity to categorize how certain species of marine life transmit and receive sound. For most applications the frequency range of interest spans from tens of hertz to a few kilohertz. Because the test specimens and the test facilities can be relatively small, a miniature pressure-acceleration (b−a) probe was developed. The probe conforms to the geometry of a cube having a principal side length of 31.75 mm (1.25 in.) and contains flexural mode piezoelectric transducers to measure the acoustic pressure and one component of the acoustic particle acceleration vector. The cube also houses a low-noise two-channel preamplifier and is compliantly suspended inside a light frame. This paper highlights the design evolution of a few prototypes and addresses issues associated with the electronic noise floor of the accelerometer, mechanical cross talk between the transducers, damping of the external suspension system and transducers, and the dynamics of the signal cable. [Work supported by Acoustech Corporation IR&D.]
Position-invariant close-talking microphone array
Authors: Meyer Jens , Elko Gary W.
Published: October 2013

Close-talking microphones are commonly used for speech pick-up in high-noise environments since they can significantly improve the signal-to-noise ratio (SNR) relative to conventional pressure microphones. Increased SNR is based on the assumption that unwanted noise sources are in the far field. However, close-talking microphones have to be carefully positioned or otherwise they can have reduced SNR improvement. A new close-talking microphone array is proposed that is orientation invariant with respect to the attenuation of far-field noise sources. It is shown that by appropriate processing of the close-talking microphone array signals, one can adaptively compensate for the distance and orientation of the microphone for a near-field source. The proposed close-talking array is based on a spatially orthonormal decomposition of the sound field for a near-field source. It consists of four or more pressure microphones that are mounted in the surface of a small rigid sphere. Finally, it is shown that decomposing the sound field into spatially orthonormal modes leads to a computationally efficient implementation. The orientation compensation is applicable not just to close-taking microphones but to directional microphones in general, e.g., podium microphones or hand-held vocal microphones.
Intensity processing of vector sensors in the bistatic regime
Authors: Naluai Nathan K. , Lauchle Gerald C. , Gabrielson Thomas B.
Published: October 2013

Acoustic intensity processing of signals from directional frequency analysis and recording (DIFAR) acoustic subsystems is used to enhance the detection of submerged bodies in bistatic sonar applications. In some directions, the scattered signals may be completely dominated by the incident blast from the source, depending upon the geometry, making the object undetectable by traditional scalar pressure measurements. Previous theoretical derivations suggest that acoustic vector intensity sensors, and the associated intensity processing, are a potential solution to this problem. Deep-water experiments conducted at Lake Pend Oreille in northern Idaho are described. A large body of revolution is located between a source and a number of SSQ-53D DIFAR sonobuoys positioned from 5 to 30 body lengths away from the scattering body. Scalar pressure measurements change by less than 0.5 dB when the scattering body is inserted in the field. However, the phase of the acoustic intensity component formed between the omnipressure and directional channel orthogonal to the direction of incident wave propagation varies by as much as 75. This metric is shown to be a repeatable and strong indicator of the presence of the scattering body. [Work supported by ONR, code 321MS.]
Comparative beamforming studies employing acoustic vector sensor data
Authors: Smith Kevin B. , Richards Roger T. , Duckett Philip V.
Published: October 2013

Data obtained from a vector-sensor line array (VSLA), while deployed vertically at Lake Pend Oreille during calibration, are examined in the context of propagation phenomena. Both broadband (FM sweep) and cw signals are analyzed. Only linear plane-wave beamforming is considered, based on well-established array processing techniques for vector sensors [Cray and Nuttall, J. Acoust. Soc. Am. 110, 324 (2001)]. Normalization is addressed, as is the determination of the vertical plane of propagation for proper steering of the vector components. Results show that the vector sensor array can be properly scaled and steered using a strong, single, cw source. Peak-to-sidelobe improvements of several dB were observed using vector beamforming rather than pressure-only beamforming. Arrival direction resolution using cardioid null is also presented. The vertical configuration allowed testing of predicted multipath interference behavior. As expected, arrival angle determinations with a single vector sensor is possible with the broadband signal. The difficulty of similarly resolving multipath arrival angles with one vector sensor and a single cw tone is shown. An array of vector sensors will resolve these angles. [Work completed with the support of Michael Traweek, Thomas Curtin, and Ellen Livingston, all from the Office of Naval Research, and by Daniel Deitz of NAVSEA-PMS403.]
Acoustic mode at low frequencies in marine sediments: Derivation from first principles using the method of homogenization
Authors: Pierce Allan D. , Carey William M. , Barbone Paul E.
Published: October 2013

The original low-frequency Biot model factors into three characteristic modes, one being the acoustics mode, having only three significant aggregate parameters: apparent density and bulk modulus, and a numerical coefficient relating attenuation to ω2. This prediction, although from a heuristic multiparametered model, finds an independent basis in a modification of the derivation by Burridge and Keller [‘‘Poroelasticity equations derived from microstructure,’’ J. Acoust. Soc. Am. 70 1140–1146 (1981)] of the poroelasticity equations from microstructure, using only the equations of elasticity and of those for a fluid with viscosity, with no exotic mechanisms. The overall mathematical procedure is the method of homogenization. Isolation of the acoustic mode is achieved by introducing a reference velocity scale, cref, the intrinsic sound speed in the fluid alone, with the macroscopic length scale H taken as cref/ω. Mass densities of fluid and elastic media are assumed comparable, and the elastic modulus is assumed comparable to bulk modulus of fluid. The nature of sediments suggests that one needs two inner scales, the larger of which is a representative grain dimension, and the smaller of which is associated with the contact areas of adjacent grains caused by gravitational compression.
Seabed sediment properties from single-channel seismic profiling data
Authors: Leurer Klaus C. , O’Connell Brian , Brown Colin
Published: October 2013

An acoustic model is presented for the calculation of velocity and attenuation of compressional waves in unconsolidated marine sediments. The model uses the concept of a standard sediment structure that assumes spherical grain shapes and a bimodal grain-size distribution in which the small particles represent the clay fraction. The description of the acoustic response of this bimodal sediment model is based on Biot’s poroelastic theory and includes two viscoelastic extensions to the original formulation to enable the resulting combined model to cover a wide range of unconsolidated marine sediments. The first extension, an effective-grain model, is introduced to include the fine-grained spectrum of these sediments and the second, a viscoelastic grain-contact model, to account for their unconsolidated granular nature. The acoustic model provides the basis for a neural-network (NN) inversion scheme to extract sediment physical properties from measured single-channel seismic reflection profiling data. Input parameters for the NN are travel times, attenuation, and reflectivities, which are determined from the seismograms. Preliminary application to real reflection data has provided reasonable results within the framework of our standard sediment model for sediment thickness, density, porosity, sound velocity, and concentration of fine-grained material.
Ultrasonic velocity measurements for synthetic gas-hydrate samples
Authors: Zhang Hailan , Wang Dong , Zhao Haibo , Lin Weijun , Wang Xiuming
Published: October 2013

Laboratory ultrasonic methods offer a way of studying acoustic velocity of a gas-hydrate bearing formation. By measuring ultrasonic velocities of the gas-hydrate samples in various temperature and pressure conditions, more effective inversion techniques can be developed to quantitatively evaluate gas-hydrate concentration and distributions. Low-temperature laboratory measurements of compressional velocities in compacted samples are conducted. These gas-hydrate samples are synthesized by using various densities at various pressures and temperatures. At −10°C, the compressional velocities of the compacted gas-hydrate samples are from 2440 to 3570 m/s with the density range from 475 to 898 kg/m3. Compressional velocity measurements are made where the temperature and pressure can be controlled. When the pore pressure increases from 10 to 40 MPa, the compressional velocities of the sample increases from 2340 to 2600 m/s at 1.5°C. When the temperature decreases from 10° to −13°C, the compressional velocity will increase from 3600 to 3800 m/s at a pore pressure of 6 MPa. Our experimental results are qualitatively in agreement with those of weighted average model and the Biot-Gassmanns model when the gas-hydrate concentration in a sediment bearing sand is about 20%. [Work supported by National Natural Science Fundation of China, No. 10534040.]
The effect of multi-path on synthetic aperture sonar image statistics
Authors: Johnson Shawn F. , Lyons Anthony P. , Abraham Douglas A. , Williams Kevin
Published: October 2013

The K-distribution shape parameter has been shown to be a useful metric of seafloor reverberation statistics. Using this metric, synthetic aperture sonar (SAS) data collected during the Office of Naval Research sponsored SAX04 experiment in the Gulf of Mexico during October 2004 has been processed to examine image statistics as a function of range from the sonar. SAS images are unique in that the resolution cell size does not increase with range as for traditional sonar. Analysis of the SAX04 data has shown that in spite of the fixed resolution cell size, shape parameter estimates were found to increase with range from the sonar. The increase can be attributed to multi-path propagation. At increasing distance from the sonar, scattered returns arising from additional propagation paths arrive in a specified time window, with the result that two or more resolution cells are contributing, which leads to a larger estimate of the shape parameter than would be expected when only the direct path contributes. Model results using the sonar system geometry and seafloor scattering theory will be used to demonstrate this effect. [Work supported by ONR Codes 321 and 333. First author supported by a National Defense Science and Engineering Graduate Fellowship.]
Time evolution of acoustic scattering from a bioturbated seafloor
Authors: Gerig Anthony L. , Lyons Anthony P. , Pouliquen Eric
Published: October 2013

Knowledge of the structure, composition, and time evolution of the seabed is essential to modeling acoustic seafloor scattering. The purpose of this work is to quantify the change in a bioturbated seafloor profile with time, and use the results to predict concomitant changes in a backscattered acoustic wave. To accomplish this task, digital stereo photograph pairs of an approximately 0.5-−m2 patch of bioturbated seafloor were taken every 10 min over the course of several days at several different locations off the Florida coast as a part of the Office of Naval Research sponsored SAX04 experiment. Photographs were captured, calibrated, and processed according to standard photogrammetric methods to produce surface height fields of the seafloor. The time sequence of fields was then used to estimate height decorrelation with time. Fields were also used to calculate height spectra for the seafloor, and to estimate spectral decorrelation with time. These estimates were subsequently compared for differences in decorrelation time between frequencies. Finally, quantitative results were used as input for the small perturbation surface scattering model to predict the time evolution of acoustic backscatter. Preliminary results indicate that seafloor decorrelation occurs on the scale of hours. [Work supported by ONR.]
Backscattering by layered elastic seafloors: The equivalent input backscattering strength approach
Authors: Guillon Laurent
Published: October 2013

In low-frequency experiments, an acoustic signal may penetrate with great depth into the seafloor and interact with submerged structures. Consequently, for many applications, there is need for a model to predict the backscattering strength (BS) of a layered seafloor containing elastic layers. A few models exist; however, two problems exist for their use: first, as most of them are based on specific configurations they are poorly adaptable, and second, very few deal with both layered and elastic seafloors. This paper proposes to extend to the case of elastic layers the equivalent input backscattering strength (EIBS) approach defined for a fluid layered seafloor [L. Guillon and X. Lurton, ‘‘Backscattering from buried sediment layers: The equivalent input backscattering strength model,’’ J. Acoust. Soc. Am. 109, 122–132 (2001)]. The BS is calculated as follows: each layer BS is defined with a specific model, then each local BS is modified to take into account the various effects of stratification, and finally the different modified BS are added to provide the total BS. Two different local models for the individual BS are tested within this general frame. The numerical results obtained show the flexibility of the EIBS approach and its ability to reveal specific effects of layering on the global BS. [Work supported by IFREMER.]
How can bell vibrations affect the sound of brass instruments?
Authors: Moore Thomas , Jiawon Vishal , Zietlow Daniel
Published: October 2013

It has recently been shown that the vibrations of the bell of a trumpet affect the spectra of the sound produced during play. The manner in which these vibrations produce this effect is still under investigation, but two possibilities have been proposed: (1) the vibrations of the bell feedback to the lips and change their motion, and (2) the bell vibrations change the radiation impedance of the instrument. The former explanation appears to be the most plausible; however, we will present results of recent experiments that indicate at least some of the effect is due to a change in radiation impedance.
Scholte-Stoneley wave generation by means of diffraction on a corrugated surface: Influence of corrugation shape
Authors: Declercq Nico F. , Sarens Bart
Published: October 2013

Because of the growing number of applications of phononic crystals and other periodic structures, there is a renewed and growing interest in understanding the interaction of ultrasound with periodically corrugated surfaces. A theoretical investigation is presented of the transformation of ultrasound incident from the solid side onto a solid-liquid periodically corrugated interface. It is shown that it is possible to tailor the shape of a corrugated surface with given periodicity such that there is a more significant amount of energy transformed into Scholte-Stoneley waves than if pure saw-tooth or sine-shaped surfaces were used. This permits the fabrication of periodic structures that can be patched on or engraved in body parts of a construction and enables efficient generation of Scholte-Stoneley waves. The study is performed for incident homogeneous plane waves as well as for bounded beams. Incident longitudinal waves are studied and also incident shear waves.
American Institute of Architects/Continuing Education System (AIA/CES) provider registration and reporting requirements
Authors: Brooks Bennett M.
Published: October 2013

The Technical Committee on Architectural Acoustics (TCAA) is a Registered Provider in the American Institute of Architects (AIA) Continuing Education System (CES). The TCAA has developed a standardized introductory short course for architects. The TCAA short course is called Architectural Acoustics and attendance at this one-hour long course can earn an architect one continuing education unit (CEU). This paper will cover the administrative requirements of the AIA/CES, to prepare potential presenters. These requirements include the proper handling of paperwork, so that AIA members may receive credit for the course. Also, the manner in which the course is given is dictated by AIA requirements. TCAA membership and attendance at this workshop are required to qualify as an authorized presenter for this AIA/CES short course.
Geoacoustic inversion using the data nullspace projection method
Authors: Lin Ying-Tsong , Newhall Arthur E. , Lynch James F.
Published: October 2013

The data nullspace projection method is developed to reduce the effect of water-column fluctuations on geoacoustic inversions. The basis of this method is to project the bottom information contained in acoustic data onto a data nullspace that is insensitive to the variations of water acoustic properties. To capture more bottom information, the data nullspace needs to be enlarged, which can be done by employing the empirical orthonormal function (EOF) analysis to efficiently decompose the fluctuating acoustic properties in the water column to only few dominant EOF modes. A model resolution matrix is derived to display the preservation of bottom information. The trade-off between preserving bottom information and reducing the effect of water-column fluctuations is discussed. The acoustic data collected from the SW06 experiment, which was conducted on the Mid-Atlantic Bight continental shelf off New Jersey in the summer of 2006, are used to invert for the bottom acoustic properties in the surveyed area. Specifically, the oceanography measurements during the experimental period will provide us with accurate EOF modes for the data nullspace projection method. The efficiency of this projection method is compared with another method that simultaneously solves for bottom and water column properties.
Qualitative analysis of concert hall acoustics with multiple directional sources
Authors: Kwon Youngmin , Siebein Gary W. , Gold Martin A.
Published: October 2013

Following the previous work on quantitative analysis of concert hall acoustics with multiple directional sources (16 directional loudspeakers) [Kwon and Siebein, J. Acoust. Soc. Am. 120, 3263(A) (2006)], this paper discusses qualitative assessments of concert hall acoustics by means of psycho-acoustical listening tests of room acoustical qualities such as loudness, reverberance, clarity, warmth, spaciousness, envelopment, etc. The music signals binaurally recorded in a performance hall with the same multiple directional source array were evaluated in comparison to those recorded with the single omni-directional source. Results showed that some of the room acoustical qualities of the music signals recorded with multiple directional sources were perceived noticeably different from those recorded with a single omni-directional source. In the main orchestra area at 95% significance level, the music recording with multiple directional sources was perceived more in reverberance and clarity but less in warmth. Some results from these qualitative assessments were, however, found to contradict their quantitative measures.
Some speculations on source localization in uncertain ocean environments
Authors: Finette Steven
Published: October 2013

Incomplete environmental knowledge is a factor that can adversely affect the prediction capability of physics-based signal processors to localize acoustic sources in ocean waveguides. Environmental uncertainty effectively introduces unwanted additional degrees of freedom into the signal processing scheme. Including a quantitative measure of this incomplete information into the processor can be accomplished by considering the influence of alternative environments, each weighted by their probability of occurrence. An approach is outlined to account for environmental uncertainty in matched field processing by the use of polynomial chaos basis expansions to represent the replica vectors in terms of stochastic Green’s functions. These bases are interpreted as representing the effect of introducing additional degrees of freedom due to environmental uncertainty, because the pressure field replicas are specified as random processes. In this manner, a processor correlates the measured pressure field with a set of statistically weighted propagators between a replica source location and a sensor array. [Work sponsored by ONR through NRL base funding.]
Analysis of observer-based measures of infant hearing
Authors: Arora Raman , Lutfi Robert A.
Published: October 2013

In the clinical evaluation of hearing, behavioral audiometry remains the gold standard. Yet behavioral measures are not easily obtained from those who stand to benefit most from early diagnosis of a hearing loss; infants and young children. In such cases behavioral assessment requires an observer-based method wherein a judge must decide whether the child has in some way responded to a sound. In the present paper observer-based measures are analyzed within the framework of a two-stage (infant-judge) detection model involving a minimum number of assumptions. Based on the results of this analysis, several recommendations are made for improving estimates of the hearing sensitivity of infants obtained from these measures. They include: (1) using multiple judges, (2) providing judges with prior knowledge of the stimulus on each trial, and (3) estimating the performance of judges at high signal levels. The last of these approaches, moreover, provides a means of empirically evaluating the former two and other procedural variations designed to improve estimates. [Work supported by NIDCD grant R01 DC01262-15.]
Scattering of a Bessel beam by a sphere: Geometric interpretation and resonance excitation
Authors: Marston Philip L.
Published: October 2013

The exact solution for the scattering of sound by an isotropic sphere centered on a Bessel beam in an inviscid fluid was recently given [P. L. Marston, J. Acoust. Soc. Am. 121, 753–758 (2007)]. The solution gives insight into the scattering by a broader class of beams and provides a benchmark for the testing of finite-element based scattering algorithms. An important parameter in the Bessel beam solution is the cone angle of the Bessel beam which is related to the ratio of the beam size to the sphere radius and to the wave-number-radius product. For an impenetrable sphere there is a simple geometric interpretation of the scattering pattern verified by quantitative ray theory. The modification of the partial wave series due to Bessel beam illumination may be interpreted using the Van de Hulst localization principle. In the scattering by elastic spheres, specific partial-waves may be suppressed by appropriate selection of the cone angle of the beam. Compared with the plane-wave case, this suppression of partial waves may increase or decrease the backscattering, depending on the situation. [Work supported by the Office of Naval Research.]
Axial radiation force of a Bessel beam on a sphere, direction reversal of the force, and solid sphere examples
Authors: Marston Philip L.
Published: October 2013

The exact solution for the axial radiation force on an isotropic sphere centered on an acoustic Bessel beam in an inviscid fluid was recently given [P. L. Marston, J. Acoust. Soc. Am. 120, 3518–3524 (2006)]. Following a review of the physical relevance of such radiation force calculations for acoustic plane waves, the Bessel beam radiation force derivation and results will be summarized. In the ordinary case, the direction of the axial force is parallel to the propagation direction of the beam. Among the predictions given in the publication is the possibility of an axial radiation force on certain fluid spheres for which the force is directed opposite to the propagation direction. In a recent extension of the published work, conditions have been identified for such a force reversal on solid spheres and elastic shells. These calculations give insight into situations where the radiation force of acoustic beams may be used to pull (instead of push) spherical objects. [Research supported in part by NASA.]
Large-area acoustic field characterization in shallow water by using broadband ship noise measured on the New Jersey Shelf
Authors: Turgut Altan
Published: October 2013

Acoustic signals emitted by ships of opportunity (merchant ships) are simultaneously recorded on three vertical line arrays (VLAs) during the New Jersey Shelf RAGS03 experiment. Although the single-receiver correlation between the VLAs (separated by ∼10 km) was very low, a Bartlett correlator between each VLA produced well-defined striation patterns. Waveguide invariant theory has been applied to Bartlett correlator output to obtain range ratios of the noise source to the receiver arrays [A. Turgut, J. Acoust. Soc. Am. 118, 1857 (2005)]. Trajectories of striations are identified by the Hough transform that converts a difficult global detection problem in the image domain into a simpler local peak detection problem. The striation patterns are also observed when the Bartlett correlator is applied to different time segments of the noise data. This provided an opportunity of obtaining reference acoustic field data for winter conditions if the location of the noise source is known a priori. Analysis of the RAGS03 data indicates the feasibility of source localization and acoustic field characterization by using broadband noise signals emitted by distant surface ships. [Work supported by ONR.]
Generation of shear motions by radiation force in a nonlinearly distorted ultrasonic beam
Authors: Ostrovsky Lev
Published: October 2013

A new possible mechanism for shear wave generation in biological tissues by focused ultrasound is described. In our previous work it was shown that, besides the classical, dissipative mechanism for this effect, medium inhomogeneity can result in a non-dissipative generation of shear displacements. In this presentation, it is shown that even in a homogeneous water-like medium such as tissue, nonlinear distortions (i.e., harmonic generation) of a focused ultrasonic wave can generate shear motions even without dissipation (i.e., prior to the shock wave formation). Estimates made for biological tissues show that the effect can be significant.
The effect of depth-dependent distribution of bubbles on internal waves
Authors: Ostrovsky Lev A. , Grimshaw Roger H. J. , Khusnutdinova Karima K.
Published: October 2013

A new type of gravity waves associated with the subsurface layers of bubbles existing ubiquitously in the ocean is considered. Due to bubble compressibility, such a layer creates a vertical density gradient. Although the density changes due to bubbles are small, the corresponding gradient can be significant, at least comparable with or even exceeding the natural density gradient due to the temperature or salinity variations. As a result, the bubbles may affect propagation of short-period internal waves or even be exclusively responsible for the internal modes in otherwise homogeneous water. These modes can be strongly localized near the surface and thus contribute to ripple modulation, affect sound propagation, etc. The dispersion equation for the bubble-affected internal waves is derived, and the corresponding modal structures are plotted. Some estimates are made and limitations of the simple model considered under real conditions are discussed.
Performance of a high-frequency acoustic forward-scatter barrier in a dynamic coastal environment
Authors: Sabra Karim G. , Conti Stephane , Roux Philippe , Kuperman W. A. , Stevenson J. Mark , Tesei Alessandra , Guerrini Piero , Bonni Piero , Akal Tuncay
Published: October 2013

This paper investigates the performance of a high-frequency ‘‘barrier’’ or ‘‘tripwire’’ surveillance system based on forward scattering for shallow water (<20 m depth) choke points, such as harbor entrance. Harbor entrances are usually regions of very high ambient noise and often are reverberation-limited environments, making them challenging for some traditional ASW techniques, i.e., techniques inherited from blue-water ASW. Detecting a target by measuring its forward-scattered field is of interest because sound scattered in the forward direction is generally higher than in the backward direction. We will present a series of proof-of-concept experiments to test the feasibility of an acoustic tripwire based on forward scattering using two vertical source and receive arrays operated over a 135-m range at a center frequency of 15 kHz with about 8 kHz of bandwidth. The signal of interest was the aberration (in space and time) caused by the acoustic forward scattering field of a crossing object (scuba tank, 2-m-long steel cylinder and 1-m-diam steel sphere). Autonomous signal processing techniques based on the spatio-temporal coherence of the signals measured across the vertical receive array were applied to enhance the signal of interest, yielding a usable detection threshold of several dB.