bluuebunny/crossref_metadata_2025 huggingface dataset:
Automatic recognition of working states of a rock breaker machine from acoustic signal processing
Authors: Aguilar Juan R. , Salinas Renato A. , Latorre Homero E.
Published: October 2013

In underground mining, there are risks involved in operating heavy machinery such as Load–Haul–Dump and rock breakers. In order to minimize those risks, that can be fatal, it was proposed to study the feasibility of employing both vision and sound to improve either human-based teleoperation or robotized machinery. Earlier attempts have considered only visual input data. In this work, recognition results carried out on acoustic emissions generated by a rock breaker during normal operating activities, are presented. These acoustic data were recorded in-situ and then analyzed using four different techniques: FFT, FFT-Wavelet, Cepstrum, and Time–Frequency. The results indicate that Power Cepstrum analysis provides the best performance both in terms of finding noticeable differences between the signals representing the operating states of the rock breaker as well as in terms of data compression capabilities. A back-propagation neural network was then trained to classify the signals into the different operating states of the machine. [Work partially supported by Project Dicyt 009913SS, University of Santiago, Chile.]
Novel physical interpretations of seafloor scattering leading to K-distributed clutter
Authors: Lyons Anthony P. , Abraham Douglas A.
Published: October 2013

Interest in describing and modeling envelope distributions of seafloor backscatter has increased recently, particularly with regard to high-resolution sonar systems. Seafloor scattering that can be described by heavy-tailed envelope distribution functions (i.e., non-Rayleigh distributions) is often the limiting factor in the performance of these types of sonar systems and in this context is referred to as acoustic clutter analogous to radar clutter. Modeling of clutter has traditionally entailed fitting various candidate distributions to time samples of the envelope of the scattered sonar (or radar) returns. This type of descriptive analysis yields little insight into the environmental mechanisms responsible for heavy-tailed distributions (e.g., distributions and clustering of discrete scatterers, patchiness in geo-acoustic properties, scattering strength of scatterers, etc.). In contrast, we derive the envelope distribution for the scattered returns starting from simple physical descriptions of the environment. It will be shown that several realistic descriptions of the environment lead to K-distributed clutter. This result explains, at least partially, the success of the K-distribution in the modeling of radar clutter and sonar reverberation at a variety of frequencies and scales. These results should prove useful in developing methods for modeling, predicting and mitigating clutter on high-resolution sonar systems. [Work sponsored by ONR under Contract No. N00014-01-1-0352.]
Determination of the character of sediments and model verification using frequency-dependent reflection coefficients
Authors: Isakson Marcia J. , Hood Egbert , Chotiros Nicholas P.
Published: October 2013

Several models exist for acoustic interaction with ocean sediments, including solid, fluid, and porous media representations, with and without interface roughness and volume scattering mechanisms. We present a method for model verification and determining the contribution from each mechanism by measuring the reflection coefficient. The method is self-normalizing and designed to minimize near-field effects. Data from smooth and roughened surfaces of unwashed river sand will be presented. Measurements were taken using a chirped signal from 50 kHz to 150 kHz at incident angles from 5 to 70 deg. Comparisons are drawn between models and experimental results. [Work supported by ONR, Ocean Acoustics.]
Hydrofoil singing on fast ferries
Authors: Matveev Konstantin I.
Published: October 2013

Hydrofoil singing phenomenon is sometimes observed on new and repaired fast ferries with hydrofoil systems. Hydrofoil singing is a tonal sound caused by interaction of the foil trailing edge with incoming flow. The intensity of the excited tone often dominates the total noise. Hydrofoil singing has very negative effects: first, the noise level is unacceptable for passenger transportation; second, vibration of the foil structure participating in singing leads to fatigue of the system and crack formation on foils and struts. The problem of hydrofoil singing first emerged on ferries with steel foils, but especially critically it was manifested on hydrofoil systems made from titanium. Experimental results obtained on a recent sea-going hydrofoil vessel are reported. Based on the structural peculiarities of the foil system, vortex shedding process and vibration of the trailing edge are discussed, and a lift-oscillator model is used for mathematical modeling. A new method of the special trailing edge profiling is considered; it allows elimination of the tone without degrading the hydrodynamic characteristics of the high performance vehicles.
Sub-critical insonification of buried spherical shells
Authors: Veljkovic Irena , Schmidt Henrik
Published: October 2013

The detection and classification of buried elastic targets presents a significant challenge to the shallow water mine countermeasures (MCM) community. Recent experimental and modeling studies have shown that in the case of subcritical isonification, significant evanescent field components can be converted into vertically propagating field components making the plane-wave, ray-tracing approach to the wave propagation inadequate. There has also been empirical evidence that the modal response of the target may be stronger than the direct backscattered return due to the evanescent nature of the sub-bottom field. The goats98 experiment had as one of its main objectives to explore the possibility of classifying features of the 3-D acoustics scattering by buried and proud objects using bistatic configurations such autonomous underwater vehicle (AUV) and horizontal line array (HLA). An unexpected physical phenomenon of a strong delayed flexural return of a flush buried spherical shell was observed in the AUV and the HLA data at frequencies much higher than predicted. A scenario similar to the goats98 experiment has also been modeled using oases−3d target modeling framework to further investigate scattering mechanisms of the flush buried spherical shell under evanescent isonification, as well as to validate the modeling capability of the package. [Work supported by ONR.]
An approximate Biot model for marine sediments with nonuniform pore sizes
Authors: Turgut Altan
Published: October 2013

The issue of attenuation and dispersion in marine sediments has been investigated by Hamilton [Geophysics (1972)] in detail. In his paper, Hamilton stated that an adequate model for marine sediments must be anelastic in which viscous damping and velocity dispersion should be considered if the pore water moves significantly relative to mineral structure. He introduced an attenuation parameter k which is empirically related to mean grain size and porosity. Based on the experimental measurements in frequencies within 14–100 kHz, he suggested a nearly elastic model with linear frequency dependency of attenuation and negligible velocity dispersion. Then, he explained the peak value of k for fine sands under the context of frictional energy losses between grains. In this study, an approximate Biot model is proposed. The new model includes both frame anelasticity and viscous damping in marine sediments with nonuniform pore sizes. For most marine sediments, the approximate model predicts similar frequency dependency of attenuation and velocity dispersion of compressional and shear waves to those of predicted by the Biot model. It has been shown that mean grain size and porosity dependency of parameter k can be also predicted by the new model without introducing an empirical relation. [Work supported by ONR.]
Evaluation of stage acoustics in a concert hall by measuring stage support
Authors: Jeon Jin Yong , Lee Byung Kwon , Barron Michael
Published: October 2013

Although stage acoustics is a very important characteristic in a concert hall in regard to the acoustical quality on stage and in the audience, it is the fact that there has not been much academic concern about stage acoustics. In this study, stage acoustics was evaluated by using real, scale and computer models of Seoul Arts Center Concert Hall. The stage acoustics were measured and evaluated at eight positions on the stage by ST1 (Stage Support) initiated by Gade [Acustica 65, 193–203 (1989)] as an early support from stage. The effect of diffusers on stage walls, the geometrical shape of the stage and the arrangement of performers on stage were investigated. In the results, it was found that the closer the receiving positions to stage walls, the higher the ST1 value, especially in the range of 3–5 m. The height of the stage ceiling or the ceiling reflector is also an influential aspect on stage support; the optimum height of the reflector started from 8 m.
Empirical relationships among sediment properties and acoustic properties of the continental shelf seafloor
Authors: Briggs Kevin
Published: October 2013

An extensive database of sediment properties has been developed from which empirical relationships are made among geological index properties and geoacoustic properties. All data are derived from surficial shelf sediments carefully collected by divers or by subcoring from undisturbed box cores. The chief problem encountered in regressing one parameter on another is due to the variability inherent in marine sediments. The variability may be due to vertical gradients as well as sediment sources. By using various statistical techniques including multiple regression, sediment sound speed, sediment sound attenuation, and sediment density are related to sediment grain-size parameters of mean grain size, grain sorting, percent gravel, percent sand, percent silt, and percent clay. From these empirical fits one can predict acoustic properties from sediment grain size with varying levels of confidence. [Work supported by ONR.]
Spectral models for musical sound synthesis: Expression issues
Authors: Serra Xavier
Published: October 2013

In order to obtain a naturally sounding musical instrument or voice, we require sound models that can both capture the microstructure characteristics of the acoustical source and that at the same time can be controlled by meaningful parameters, in a similar way as the performers do. The issue of how to generate these control parameters is one of the most interesting and open problems in the area of musical sound synthesis. This presentation will focus on the control question in the context of two recently developed synthesizers based on a spectral modeling approach: a singing voice synthesizer and a wind instrument synthesizer. The specific spectral models used in each case will be presented followed by a discussion on the expression controls employed and how they are obtained from actual performances. These controls are mainly at the note and the note-to-note articulation level and affect parameters such as pitch, dynamics, brightness, and vibrato. From actual performances, templates and models of the temporal evolution of these parameters are extracted and then used as the basic controls of the synthesizer on top of which the user interacts in real time.
Effects of acoustic impulses on hearing
Authors: Fleischer Gerald , Müller Reinhard , Heppelmann Guido , Bache Thomas
Published: October 2013

It is well known that acoustic impulses are especially dangerous to the ear. In order to understand the damaging mechanisms involved, cases of acute acoustic trauma in man were systematically collected and documented for many years. When possible, the damaging impulses were recreated and measured, to correlate the impulses with the auditory damage they caused. Detailed pure-tone audiometry up to 16 kHz was used to determine the effects on hearing. Together with epidemiological studies on various occupations, three different damaging mechanisms can be discerned. Relatively long and massive impulses (some explosions, some airbags) often lead to damage at low frequencies, from about 0.5 to 1.5 kHz. The typical notch at about 4 to 6 kHz typically is the result of strong peaks, lasting several milliseconds, or longer. There is another notch at 12 to 14 kHz, characteristic of very short, needle-like impulses that are caused by many hand weapons, toy pistols, and firecrackers. Probable mechanisms are discussed.
Perception time and movement time in dolphin pulsing and whistling
Authors: Ridgway Sam , Carder Donald
Published: October 2013

Auditory/vocal response time was separated into perception time (PT) and movement time (MT) in trials with bottlenose dolphins (Tursiops truncatus)—two males and one female. Pressure catheters accepted into the nasal cavity by each dolphin recorded the pressure increase that preceded sound production. Time from acoustic stimulus onset to onset of pressure rise was recorded as PT (range 57 to 314 ms) and pressure rise onset to dolphin sound onset was recorded as MT (range 63 to 363 ms). Blindfolded dolphins trained to report a target by whistling often responded before completion of their 200- to 800-ms echolocation click trains. Detection of the target, indicated by whistling, before termination of the animal’s own click train, suggests that dolphins do not voluntarily respond to each successive click but rather set a rhythm such that each click is emitted about 20 ms after the target echo arrives.
Control transducer locations for virtual acoustic imaging using binaural principle
Authors: Takeuchi Takashi , Nelson Philip A.
Published: October 2013

When binaural sound signals are presented with loudspeakers, the systems inversion involved gives rise to a number of problems such as loss of dynamic range, deterioration of control performance by small errors, and room reflections. A method of overcoming these fundamental problems is proposed. A conceptual monopole transducer is introduced whose azimuthal position varies continuously as frequency varies. This gives a minimum processing requirement of the binaural signals for the control to be achieved and all the above problems either disappear or are minimized. Among a number of practical solutions to realize such optimally distributed transducers is a discretization that enables the use of conventional transducer units. As for the elevation location of the control transducers, the analysis of the spectral cues and dynamic cues is performed. The frequency response of the plant that relates transducer outputs to ear-pressure signals suggests that control transducer positions will be promising at positions in the frontal plane above the listener’s head. The analysis of the dynamic cues induced by unwanted head rotation also strongly supports the use of transducer locations in the frontal plane. Subjective experiments are performed and the methods described here are proved to be advantageous.
Sound isolation performance of interior acoustical sash
Authors: Tocci Gregory
Published: October 2013

In existing, as well as new buildings, an interior light of glass mounted on the inside of a prime window is used to improve the sound transmission loss otherwise obtained by the prime window alone. Interior acoustical sash is most often 1/4 in. (6 mm) monolithic or laminated glass, and is typically spaced 3 in. to 6 in. from the glass of the prime window. This paper presents TL data measured at Riverbank Acoustical Laboratories by Solutia (formerly Monsanto) for lightweight prime windows of various types, with and without interior acoustical sash glazed with 1/4 in. laminated glass. The TL data are used to estimate the A-weighted insertion loss of interior acoustical sash when applied to prime windows glazed with lightweight glass for four transportation noise source types—highway traffic, aircraft, electric rail, and diesel rail. The analysis also has been extended to determine the insertion loss expressed as a change in OITC. The data also exhibit the reductions in insertion loss that can result from short-circuiting the interior acoustical sash with the prime window. [Work supported by Solutia, Inc.]
The concept of privacy in the social practice of the living environment through sonic phenomena (case of the old city of Constantine. Algeria)
Authors: Rabah Derbal Cobis , Hamza Zeghlache
Published: October 2013

The privacy of the different aspects composing the outside space and its social practice in the medinas and old islamic cities, is found to be often modulated by the quality of the physical criteria of the environment. Different activities in the medina have greatly modified the privacy suroundings. Privacy has been therefore, shaken up and greater permeability between inside and outside, particularly through sound phenomena, is one of the characteristics of such space. The exterior sound environment is fully perceived despite the supposed dispositions to preserve a certain degree of privacy. Underway studies on the old city of Constantine show already a great need to reconsider the concept of privacy in urban area throughout the sound environment. The noise acts, most of the time, not only by its disturbance, but by its information content as well, which is supposed to reduce and weaken significantly the concept of privacy in such old cities. More work is to be considered involving multidisciplinary approaches so that the notion of privacy can be worked out in reforming the discomfort of sonic environment into easy using soundscape with which privacy through social and historical mutations would fit in well.
Some validity issues in the theory and modeling of WPRM
Authors: Ewart Terry , Henyey Frank
Published: October 2013

In many publications in the recent to older litererature on the theory and modeling of wave propagation in random media, WPRM, in ocean and atmospheric environments there are serious validity issues that arise. The issues discussed will include the following. (1) The validity of using the Markov approximation in theoretical treatments must be established for specific environments before theories based on that approximation can be used. Parameters that are required to be small must be shown to be so before the applicabilty to specific environments can be assured. (2) Most publications that purport to model the pdf’s of intensity do not include the standard ‘‘goodness of fit’’ parameters. The Kolmogorov–Smirnov GoF test emphasizes the center of the distribution and often the pdf’s of WPRM are characterized by very high tailed distributions where the fitting of that component can be important to understanding the scattering physics. GoF tests that include the full range of received intensity are needed. (3) Signal processors invariably require that the quadrature components of their receptions have Gaussian pdf’s. It has been shown by simulations of WPRM that this is often not even close to the case. What significance this effect has on signal processing algorithms is a difficult and unresolved issue.
Recent results from basin-scale ocean acoustic wave propagation: Implications for the general theory of the approach to saturation
Authors: Colosi John A.
Published: October 2013

Long-range ocean acoustics as a problem in wave propagation through random media is unique in several ways. First the propagation takes place in the ocean sound channel (a waveguide), and second, a primary source of sound speed fluctuations are the anisotropic and inhomogeneous ocean internal waves (not turbulence). Recent observations of 75 Hz, broadband transmissions over several thousand kilometers have revealed fascinating results on the approach to saturation. Two distinct propagation regimes are observed in the same pulse: a fully saturated regime characterized by Rayleigh statistics, and an unsaturated regime in which the probability density function for intensity is nearly log-normal. The transition between these two regimes is extremely rapid. The saturated region of the pulse is composed of acoustic energy traveling near the waveguide axis, while the unsaturated region is composed of acoustic energy strongly refracted by the waveguide. This fact suggests a fundamental stabilizing influence by the waveguide. Application of path-integral theory, which was successful in describing shorter-range ocean experiments, cannot describe these two regimes. Recent efforts using semiclassical and ray chaos theory have led to new insights into the observational results and to the failure of the path-integral theory, yet a complete theoretical description remains elusive.
Physiological modeling for hearing aid design
Authors: Bruce Ian C. , Young Eric D. , Sachs Murray B.
Published: October 2013

Physiological data from hearing-impaired cats suggest that conventional hearing aid signal-processing schemes do not restore normal auditory-nerve responses to a vowel [Miller et al., J. Acoust. Soc. Am. 101, 3602 (1997)] and can even produce anomalous and potentially confounding patterns of activity [Schilling et al., Hear. Res. 117, 57 (1998)]. These deficits in the neural representation may account at least partially for poor speech perception in some hearing aid users. An amplification scheme has been developed that produces neural responses to a vowel more like those seen in normal cats and that reduces confounding responses [Miller et al., J. Acoust. Soc. Am. 106, 2693 (1999)]. A physiologically accurate model of the normal and impaired auditory periphery would provide simpler and quicker testing of such potential hearing aid designs. Details of such a model, based on that of Zhang et al. [J. Acoust. Soc. Am. 109, 648 (2001)], will be presented. Model predictions suggest that impairment of both outer- and inner-hair cells contribute to the degraded representation of vowels in hearing-impaired cats. The model is currently being used to develop and test a generalization of the Miller et al. speech-processing algorithm described above to running speech. [Work supported by NIDCD Grants DC00109 and DC00023.] a)Now with the Dept. of Electrical and Computer Engineering, McMaster Univ., 1280 Main St. W., Hamilton, ON L8S 4K1, Canada.
Localization judgments are sensitive to late-arriving sound
Authors: Stecker G. Christopher , Hafter Ervin R.
Published: October 2013

In a study of temporal aspects of sound localization, free-field listeners localized trains of 2–32 spatially distributed clicks (4-kHz narrow-band impulses) in a pointing task. Multiple regression coefficients estimated the perceptual ‘‘weight’’ listeners applied to each click in a train when making location judgments. Temporal weighting functions (TWFs) obtained in this way exhibited two dominant features: First, at high stimulus rates (>80 Hz), weight for the first click in a train was significantly larger than that for later clicks, as observed previously in studies measuring TWFs for ITD-based lateralization [K. Saberi, Percept. Psychophys. 58, 1037–1046 (1998); R. Dizon et al., Assoc. Res. Otolaryngol. Abs. 21, 42 (1998)]. Second, in several conditions, clicks near the end of a train received larger weights than earlier clicks. This presentation focuses on the latter finding, which affected the last few clicks in a train despite manipulations of train length (overall duration) and predictability, and which appeared independently of increased weight on the first click. The effect cannot be explained as a release from temporary suppression, but may relate to effects of temporal integration, apparent motion, or the influence of non-ITD spatial cues. [Work supported by NIDCD 00087.]
Simple neuron models of ITD sensitive neurons
Authors: Dasika Vasant , White John A. , Colburn H. Steven
Published: October 2013

Neurons which show sensitivity to interaural time delay (ITD) exist in both mammalian medial superior olive (MSO), and bird nucleus laminaris (NL). In this study, we examine simple mathematical models of single MSO and NL cells which respond probabilistically to a pair of isolated inputs with a response probability that depends on the input interpulse interval. Inputs are either isolated pulse pairs or pairs of periodic trains, with or without random jitter added to their event times. Refractoriness is incorporated in the input description and/or in the cell model in specified simulations. We find that periodic rate-ITD shapes are shaped by three interacting factors: the cell’s temporal response (described by the paired-pulse response), input frequency, and the degree of input synchrony. Paired-pulse responses are able to predict the widths of rate-ITD curves obtained from deterministic periodic input simulations. Reduced input synchrony predictably smears rate-ITD curves. Larger numbers of weaker inputs yield stronger rate-ITD modulation than a few strong inputs. Model response is compared with in vivo and in vitro MSO and NL physiological data. Comparisons with published analytical models as well as more complex and realistic physiological cell models are examined.
Estimation of size at three sites on the face
Authors: Verrillo Ronald T. , Bolanowski Stanley J. , McGlone Francis P.
Published: October 2013

The subjective size of steel balls was judged by nine subjects using the method of Absolute Magnitude Estimation. The balls were rolled (‘‘scripted’’) over three areas of the face (forehead, cheek, and lower lip) using the right index distal finger pad. The areas were stimulated under three conditions; (1) the subjects upon themselves (intra-active touch); (2) the subjects upon another person (interactive touch); and (3) another person upon the face of the subject (interactive touch). There were significant differences among the three facial sites in the intra-active condition. When another person’s face was scripted by the subject, there were no differences among the sites. The results were mixed when another scripted upon the faces of the subjects. The results are considered in terms of tissue mechanics, mode of stimulation and representation of the sites on the somatosensory cortex. [Work supported by NIH.]
Pyrotechnic devices and their applications
Authors: Himelblau Harry
Published: October 2013

Pyroshock is mechanical shock transmitted through structures from explosive devices, sometimes accompanied by structural impact. These devices are designed to cause the intentional separation of structures, or to cause the deployment of various mechanisms or subsystems required for mission operation. Separation devices usually fall into two categories: (a) line sources, such as linear shaped charges, and (b) point sources, such as explosive bolts, pin puller and pushers, and gas generators. The advantages of these devices are high reliability (especially when redundantly activated), low cost and weight, high activation speed, and low structural deformation a short distance from the source. The major limitation is pyroshock, a severe high-frequency transient capable of causing failure or malfunction to small nearby elements, especially electronic and optical components located close to the source. This pyroshock tutorial, which is intended to summarize recent improvements to the technology, is initiated with a review of explosive and companion devices.
Interaction of cues to vowel identity and consonant voicing: Cross-language perception
Authors: Morrison Geoffrey Stewart
Published: October 2013

Canadian English has two high front vowels differing in spectral and duration properties, Spanish has one high front vowel, and Japanese has two high front vowels differing in duration only. Vowel duration is a major cue to post-vocalic consonant voicing in English, but not in Japanese or Spanish. Canadian English, Japanese, and Mexican Spanish listeners identified members of a multidimensional edited speech continuum covering the English words bit, beat, bid, bead. The continuum was created by systematically varying the spectral properties of the vowel, and the durations of the vowel, the consonant closure, and the carrier sentence. English listeners had a categorical cutoff between /i/ and /I/ based primarily on the spectral properties of the vowel. Half the English listeners identified consonant voicing using vowel duration. Japanese listeners had a categorical cutoff between the English vowels based primarily on the duration of the vowel. The location of the cutoff was the same as the categorical cutoff between Japanese long /i:/ and short /i/. Japanese listeners identified consonant voicing at random. Spanish listeners identified the English vowels using vowel duration but did not have a categorical cutoff. Half the Spanish listeners identified consonant voicing using the spectral properties of the vowel.
Segmental and coarticulatory timing in Ikalanga prenasalized stops
Authors: Beddor Patrice S. , Onsuwan Chutamanee , Letsholo Rose
Published: October 2013

The temporal characteristics of prenasalized stops in Ikalanga, a Bantu language of Botswana, are investigated. Eight speakers were recorded producing Ikalanga words with VNCV (NC=/mb nd ŋg), VNV (N=/mnŋ), and VCV (C=/b d g/) sequences. Acoustic measures of 3 speakers’ productions showed that oral closure durations (from vowel offset to closure release) were only slightly longer for NC than for N or C (94, 83, and 83 ms, respectively). When analyzed separately, the N and C portions of VNCV were somewhat shorter than their counterparts in VNV and VCV, but nearly all of the shortening occurred in the C portion (in VNCV, N=78 ms and C closure=16 ms). The durations of vowels preceding the medial consonants did not differ across the three consonant types. Thus, for segmental durations, the main difference between Ikalanga VNCV and VNV was the presence of a brief oral occlusion in the former. However, measures of coarticulatory nasalization point to another systematic difference: while both sequences exhibited comparable anticipatory vowel nasalization, VNV (but not VNCV) sequences showed carryover nasalization extending through more than 70% of the post-nasal vowel. Findings will be compared with previous work on Bantu prenasalized stops. [Work supported by NSF.]
An acoustical study of the voicing distinction in Dutch plosives
Authors: van Alphen Petra M.
Published: October 2013

Dutch has two voiced plosives, namely /b/ and /d/. They are said to have a negative VOT (i.e., are prevoiced), while the voiceless plosives /p/ and /t/ have a small, positive VOT. A production study was designed to investigate two questions. First, how does prevoicing vary in spoken Dutch? Second, what other cues in the acoustic signal might contribute to the perceptual distinction between voiced and voiceless plosives? Ten subjects were asked to produce a list of monosyllabic words which were chosen to study the following factors: place of articulation (labial versus alveolar), following phoneme (vowel versus consonant), lexical status of the carrier stimulus (word versus nonword), and lexical competitor environment of the carrier stimulus. Results will be reported on the relative contribution of various durational, spectral, and energy measures to the voiced–voiceless distinction. The data showed that 25% of all tokens were produced without prevoicing. The prevoicing of the voiced plosive was omitted more often when the plosive was followed by a consonant than when it was followed by a vowel. Although both spectral and energy cues signal the voicing distinction, and although prevoicing is often omitted, VOT appears to be the primary cue to this distinction.
Time reversal in a layered medium
Authors: Chambers David H. , Meyer Alan W.
Published: October 2013

We investigate using a time reversal array to detect voids between two layers of materials. The array is positioned on the surface of a layered material so that acoustic pulses propagate in a direction roughly normal to the layers. These pulses are reflected from both the layer interface and small voids in the interface. The reflected pulses are time-reversed and sent back into the material. This process is iterated until it converges into an eigenstate of the time reversal operator associated with either a void or the interface. The eigenstates associated with the interface can be understood in terms of interactions between the array and its image in the interface. We look at the problem of detecting eigenstates associated with voids in the presence of the interface eigenstates. Strategies for classifying the eigenstates are derived by considering the simplified problem of a time reversal array on a single layer slab. [Work performed under the auspices of the Department of Energy by the Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.]
Investigation of near-axial interference effects in long-range acoustic propagation in the ocean
Authors: Grigorieva Natalie S. , Fridman Gregory M.
Published: October 2013

The observed time-of-arrival patterns from a number of long-range ocean acoustic propagation experiments show early geometrical-like arrivals followed by a crescendo of energy that propagates along the sound-channel axis and is not resolved into individual arrivals. The two-dimensional reference point source problem for the parabolic index of refraction squared is investigated to describe in a simple model case the interference of near-axial waves which resulted in forming the so-called axial wave and propose a formula for the axial wave in more general cases. Using the method proposed by Buldyrev [V. Buldyrev, Tr. Mat. Inst. Steklov 115, 78–102 (1971)], the integral representation for the exact solution is transformed in such a way to extract ray summands corresponding to rays radiated from the source at angles less than a certain angle, the axial wave, and a term corresponding to the sum of all the rays having launch angles greater than the indicated angle. Numerical results for the axial wave and the last term are obtained for parameters corresponding to long-range ocean acoustic propagation experiments. The generalization of the obtained formula for the axial wave to the case of an arbitrary range-independent sound speed is given and discussed. [Work supported by VSP Grant No. N00014-01-4003.]
A new numerical method for wave propagation through assemblies of cylinders and spheres
Authors: Yano Takeru , Prosperetti Andrea
Published: October 2013

PHYSALIS is a new method for the numerical solution of a variety of problems (potential theory, Navier-Stokes equations, and others) involving cylindrical or spherical internal boundaries [A. Prosperetti and H. N. Oguz, J. Comput. Phys. 167, 196–216 (2001)]. At the heart of the method is the use of an exact analytical solution to transfer the boundary conditions from the surface of the inclusions to the neighboring grid nodes. This step avoids the difficulty deriving from the complex geometrical relationship between the internal boundaries and the underlying regular grid, with the added benefit that fast solvers can be used. In this work the method is adapted to two-dimensional acoustic scattering by cylinders as governed by the Helmholtz equation. As in prior applications, the method reveals itself highly efficient and of a relatively simple implementation. These features are illustrated on several problems. In particular, it is shown that the computational time grows much less than linearly with the number of cylinders, which permits the simulation of complex multiple scattering problems without large computational resources. [Work supported by The Japan Ministry of Education, Culture, Sports, Science and Technology, and by ONR.]
Acoustic wave propagation in atmospheric boundary layer above a rough terrain
Authors: Liu Lanbo , Moran Mark L.
Published: October 2013

In this paper we will present the latest development in the numerical simulation of acoustic wave propagation in the lowest atmospheric boundary layer above a rough terrain with a finite difference time domain (FDTD) algorithm. It is of great interest to investigate the effect of dynamic turbulent boundary layer meteorology coupled with surface terrain on acoustic wave propagation in frequency bands relevant to battlefield sensor systems. Turbulent mixing in the vicinity of the earth–air boundary layer is the key factor contributing to acoustic signal fluctuations such as upward refraction, scattering, high attenuation, and coherence degradations. Using first principles acoustic wave equation expressions for a moving fluid will allow us to couple acoustic models with time varying, 3-D large eddy simulation (LES) results. The specific meteorological parameters are vector wind velocity, temperature, pressure, and density as a function of space and time. Our acoustic simulation uses a coupled system of first-order temporal and spatial differential equations relating wind velocity, pressure, and density variations. This system of equations was evaluated with an explicitly time-stepping finite difference numerical approach. The coupling of LES and acoustic FDTD simulation will allow us to directly identify spectral portions of turbulent boundary layer meteorology contributing to short- and long-term acoustic signal variations.
Optimization of speech in noise with three signal processing algorithms for normal-hearing and hearing-impaired subjects
Authors: Franck Bas A. M. , Dreschler Wouter A. , Lyzenga Johannes
Published: October 2013

In this study a three-dimensional Simplex procedure was applied to optimize speech in noise by a combination of signal processing algorithms for different acoustic conditions and hearing losses. The algorithms used to span the three dimensions are noise reduction, spectral tilting, and spectral enhancement, respectively. Additionally, we studied the algorithms for their main effects and interaction effects within the optimization process. The subjects were asked to evaluate two consecutive, differently processed sentences on listening comfort. Three different noise types and two signal-to-noise ratios (S/N) were used. Three groups of subjects participated: normal hearing, normal hearing with simulated impaired auditory filtering (by spectral smearing), and sensorineurally hearing-impaired subjects. For the normal-hearing group we applied S/N=0 dB. For the hearing-impaired and the simulated hearing-impaired subjects we applied S/N=5 dB. We will discuss the similarities and differences in the response patterns of the three groups. Also, the individual preferences will be related to the hearing capacity, and to the type of interfering noise. Finally, we will discuss differences in the perceptual features that are used to judge listening comfort of the fragments by normal-hearing and hearing-impaired subjects.
Further investigations into performance metrics for underwater communications
Authors: Whitney Scott L. , Edelson Geoffrey S. , Thammakhoune Ned B. , Richman Michael S.
Published: October 2013

Determining the relationship between the performance of an underwater acoustic data communications system and the operating environmental conditions is a problem that continues to plague researchers. The complexity of the time-varying channel is difficult to measure and model. Therefore an approach that uses metrics measured from data collected at sea to characterize the channel is attractive. As expected, preliminary assessments on limited data have shown that performance depends not only on environmental conditions, but also on system implementation. By extracting a variety of metrics, a better understanding of the subset that discriminate between good and bad performance can be developed. Also, by analyzing the relationship between certain metrics and performance, system limitations can be identified for re-evaluation. For example, a surprising result of the initial assessment of performance using a multichannel decision feedback equalizer on real data showed that sparseness of multipath arrivals may be an arbiter of performance [M. S. Richman et al., J. Acoust. Soc. Am. 110, 2619 (2001)]. Therefore changes to the algorithm that allows for sparse arrivals may improve performance. In this paper, a larger number of metrics from greater quantities of real-data and system configurations are measured and evaluated against equalizer results.
A comparison of algorithms and the development of a new fast convergence and reduced computational load algorithm for multichannel active noise control
Authors: Bouchard Martin , Norcross Scott
Published: October 2013

In this presentation, the three main factors that affect the convergence speed of learning algorithms for adaptive FIR filters used in multichannel active noise control are described. Based on these three factors, a comparison of several adaptive FIR filter algorithms for multichannel active noise control is done, including several existing algorithms and a few unpublished algorithms. Of the unpublished algorithms, one algorithm has the potential for optimal convergence speed, and this algorithm is described in more detail in the presentation. The algorithm combines the use of recursive-least-squares algorithms with the use of an inverse model of the multichannel acoustic plant between the actuators and the error sensors. The resulting algorithm is called the multichannel inverse delay-compensated filtered-x RLS algorithm for active noise control. This algorithm can not only provide fast convergence, but for multichannel systems it also provides a significant reduction of the computational load compared to the previously published algorithm with the fastest convergence speed. Simulation results are presented to validate the convergence behavior of the new proposed algorithm.
Evaluation of an autoregressive spectral estimation technique for determining horizontal wave-number content in shallow water
Authors: Becker Kyle M. , Frisk George V.
Published: October 2013

Modal-based techniques for geoacoustic inversion require estimates of discrete horizontal wave numbers corresponding to the propagating modes in a shallow-water waveguide. For range-dependent waveguides, local wave-number content can be extracted as a function of range using methods analogous to short-time Fourier transform techniques as applied to non-stationary time series data. A limiting factor in these techniques is the aperture length, L, required to resolve closely spaced horizontal wave-number content. Using classical spectral estimation methods, the limit of resolution is proportional to 1/L. In order to increase the spatial resolution of local horizontal wave-number estimates, the use of a high-resolution autoregressive spectral estimator was investigated for determining horizontal wave-number content. The performance of the estimator was evaluated numerically using both time-series and spatial data. Results are presented of estimator performance for various aperture lengths using signals with increasing levels of additive noise and signals with closely spaced wave-number components. Comparisons are made with results of classical methods as well as other high-resolution methods. The results show the AR method to be well suited for wave-number estimation in shallow-water waveguides. [Work supported by ONR.] a)Presently with the Acoustics Group, The Pennsylvania State Univ., Appl. Res. Lab., P.O. Box 30, State College, PA 16804, kmb166@psu.edu.
The development and use of the diffusion scattering coefficients in room modeling software: The effect of diffuse reflections on reverberation time
Authors: D’Antonio Peter , Cox Trevor J.
Published: October 2013

In the last 20 years, much progress has been made in the measurement and characterization of sound diffusing surfaces. This presentation describes how this research might improve the accuracy of computer based geometric room modeling. To model diffuse reflections, one needs to know the scattering distribution and the portion of scattered energy that is diffusely reflected. AES Working Group SC-04-02 recently published an information document AES-4id-2001, which describes a measurement procedure to determine the polar balloons from scattering surfaces. This allows programmers to use actual measured or calculated distributions instead of Lamberts law, which applies to incoherent optical diffusion. ISO WG 25 is currently addressing a measurement procedure to determine the random incidence scattering coefficient. This scattering coefficient is used directly in geometrical modeling programs. The two measurement procedures will be contrasted. It will then be demonstrated by example how the use of diffusion data can affect the predicted reverberation time.
General principles involved in the effect of noise on hearing and vocal communication in birds
Authors: Dooling Robert J. , Dent Michael L.
Published: October 2013

Birds provide very useful models for understanding the effects of noise on hearing and acoustic communication. They are excellent subjects for laboratory studies of hearing in which signals and noise can be precisely defined and delivered and behavioral responses can be unambiguously interpreted. For this reason, a huge amount is already known about their hearing. Acoustic communication is critically important for most species of birds and some even acquire their communication signals through vocal learning. For this reason, a lot is already known about how birds perceive complex acoustic signals such as vocalizations. Drawing from both field and laboratory studies, we review what is known about the effects of noise on hearing and vocal communication in birds. This includes the effects of intense noise on the ear, the effects of background noise on the detection and discrimination of both simple sounds and complex vocalizations, and the spatial effects of signal detection in noise in the free-field. As a whole, these studies show that birds are resistant to damage and interference from noise and have developed a variety of strategies to effectively communicate.
Acoustic communication by ants
Authors: Hickling Robert
Published: October 2013

Many ant species communicate acoustically by stridulating, i.e., running a scraper over a washboard-like set of ridges. Ants appear to be insensitive to airborne sound. Consequently, myrmecologists have concluded that the stridulatory signals are transmitted through the substrate. This has tended to diminish the importance of acoustic communication, and it is currently believed that ant communication is based almost exclusively on pheromones, with acoustic communication assigned an almost nonexistent role. However, it can be shown that acoustic communication between ants is effective only if the medium is air and not the substrate. How, then, is it possible for ants to appear deaf to airborne sound and yet communicate through the air? An explanation is provided in a paper [R. Hickling and R. L. Brown, ‘‘Analysis of acoustic communication by ants,’’ J. Acoust. Soc. Am. 108, 1920–1929 (2000)]. Ants are small relative to the wavelengths they generate. Hence, they create a near field, which is characterized by a major increase in sound velocity (particle velocity of sound) in the vicinity of the source. Hair sensilla on the ants’ antennae respond to sound velocity. Thus, ants are able to detect near-field sound from other ants and to exclude extraneous airborne sound.
Prosodic persistence in music performance and speech production
Authors: Jungers Melissa K. , Palmer Caroline , Speer Shari R.
Published: October 2013

Does the rate of melodies that listeners hear affect the rate of their performed melodies? Skilled adult pianists performed two short melodies as a measure of their preferred performance rate. Next they heard, on each trial, a computer-generated performance of a prime melody at a slow or fast rate (600 or 300 ms per quarter-note beat). Following each prime melody, the pianists performed a target melody from notation. The prime and target melodies were matched for meter and length. The rate of pianists’ target melody performances was slower for performances that followed a slow prime than a fast prime, indicating that pianists’ performances were influenced by the rate of the prime melody. Performance duration was predicted by a model that includes prime and preferred durations. Findings from an analogous speech production experiment show that a similar model predicts speakers’ sentence rate from preferred and prime sentence rates. [Work supported by NIMH Grant 45764 and the Center for Cognitive Science.]