bluuebunny/crossref_metadata_2025 huggingface dataset:
A ray-based blind channel estimation method in ocean sound channels. Application to high-frequency underwater telecommunications
Authors: Sabra Karim G. , Dowling David R. , Song H. C. , Kuperman W. A. , Hodgkiss W. S. , Akal T. , Stevenson J. M. , Guerrini Piero
Published: October 2013

A signal that travels through a sound channel is typically distorted when recorded by a remote listener because of interference arising from multiple propagation paths. We developed a ray-based blind channel estimation technique in ocean sound channels, i.e., using only records of the distorted signal along a transducer array. The technique yields broadband estimates of the source-to-array impulse response (or Green’s functions) synthesized directly from the recorded distorted signals. The technique relies on separating out the contribution of a propagating ray path having a phase that depends linearly on frequency. This technique was used to decode high-frequency underwater telecommunications sequences collected in 2005 off the West Coast of Italy, without any a priori knowledge of the channel impulse response. [Work supported by ONR.]
Are vowels in African American English affected by Southern vowel shift?
Authors: Holt Yolanda F. , Jacewicz Ewa , Fox Robert A.
Published: October 2013

There is a debate regarding whether the variety of speech called African American Vernacular English (AAVE) participates in any of the vowel shifts identified in today’s American English. Because pronunciation of vowels in AAVE has never been studied with sufficient experimental rigor, it is unknown whether the vowel system of AAVE differs from those of closely-related regional variants of American English. The present experiment examines the apparent resistance of AAVE to assimilation into Southern American English (SAE) and seeks to determine the presence or absence of Southern Vowel Shift in the speech of speakers of AAVE. Acoustic measures of AAVE vowels produced by male speakers born and raised in Statesville, NC (Piedmont region) are compared with the same measures of SAE vowels spoken by European-American male speakers living in western North Carolina. Acoustic measures (obtained from fourteen monophthongs and diphthongs in /h—d/ context) included dynamic formant pattern, extended vowel space area for each speaker, the amount of frequency change for F1 and F2 at two temporal points located close to vowel onset and offset (vector length), and vowel duration. These measures will establish both systemic and vowel inherent characteristics within these two varieties of English. Dialectal differences will be discussed. [Work supported by NIH NIDCD R01 DC006871.]
The combined effects of reverberation and fluctuating noise on sentence intelligibility
Authors: George Erwin L. J. , Festen Joost M. , Houtgast Tammo
Published: October 2013

Listening conditions in everyday life typically include a combination of reverberation and nonstationary background noise. It is well known that sentence intelligibility is adversely affected by these factors. To assess their combined effects, a model is introduced that combines two models of speech perception, the Extended Speech Intelligibility Index (E-SII), and the Speech Transmission Index (STI). First, the effect of reverberation on nonstationary noise—reduction of modulations—is determined. The E-SII is then used to evaluate the effect of this modified nonstationary noise, while the STI is applied to quantify the effects of reverberation and noise on speech quality. To validate this model, speech reception thresholds (SRTs) were measured for ten normal-hearing listeners, under various combinations of nonstationary noise and artificially created reverberation. After taking the characteristics of the speech corpus into account, results show that the model accurately predicts SRTs in fluctuating noise and reverberation for normal-hearing listeners.
Acoustic conversion of heat to sound at mid-audio frequencies
Authors: McLaughlin Bonnie , Symko Orest
Published: October 2013

A thermoacoustic prime mover was developed for conversion of heat to sound that is then directly converted to electricity. The acoustic device consists of a 2.7-kHz quarter-wave resonator with a stack of random material between a hot heat exchanger and a cold heat exchanger. It is loaded by a cavity that couples the sound to a piezoelectric device for generation of electrical power. Optimization of this device for energy conversion was based on studies of heat injection, temperature difference threshold for onset of oscillation, heat flow in the device, quality factor Q of the resonator, response time to heat input, and sound power output. Parameters for optimization included different mesh sizes for the heat exchangers, given stack filling factors, and levels of positive feedback from the acoustic cavity. Response time to heat injection was lowered by coupling the heat source directly to the hot heat exchanger. Device efficiency was doubled by reducing heat losses along the supporting structure of the stack. Temperature differences for oscillation were as low as 50°C, and sound levels of 130 dB were achieved. Thus device performance was enhanced substantially by optimizing geometric factors.
Numerical study of finite-amplitude source reconstruction
Authors: Shepherd Micah R. , Gee Kent L. , Wochner Mark S.
Published: October 2013

Since its inception in the 1980s, near-field acoustic holography (NAH) has been widely used to determine structural source properties. More recently, it has also been used to determine aeroacoustic source behavior. Although several alternate forms of NAH have been developed, all are based on the (linear) Helmholtz equation and would presumably not function correctly for a finite-amplitude pressure wave propagating nonlinearly. However, when nonlinear effects or reconstruction distances are small, NAH may still be a useful tool for determining radiation characteristics of finite-amplitude sources such as jets and rockets. A two-dimensional numerical propagation scheme has been used to simulate simple noise propagation from an extended source to study the effect of nonlinearities on source reconstruction using NAH. Results from the study and their implication regarding the use of NAH for high-amplitude acoustic sources will be discussed.
Acoustic noise produced by ship traffic in the Hudson River estuary
Authors: Roh Heui-Seol , Bunin Barry , Kamberov George , Sutin Alexander
Published: October 2013

This paper presents results of measurements of acoustic noise in Hudson River Estuary near Manhattan in the frequency band 10–100 kHz. The Estuary has very complex sound propagation conditions due to the extremely shallow and high time- and space variability of the water characteristics. The acoustic noise was recorded by a set of hydrophones and the acoustic measurements were accompanied by ship traffic video recording using the video-based Surface Traffic Surveillance system. This video system allowed us to map various boats and ships and to find distances between them and the hydrophone system. The measurements provided acoustic noise data for different kinds of ships in Hudson River, their dependencies on frequencies, and distances. The measurements of noise for various distances were applied for estimation of sound attenuation in a wide frequency band. We calculated the sound attenuation coefficient showing the attenuation loss of an acoustic signal in addition to cylindrically spreading loss. The recorded levels of acoustic noise and estimation of transmission loss were used for estimations of detection distances of underwater threats that are presented in our other paper. [This work was supported by ONR Project No. N00014-05-1-0632: Navy Force Protection Technology Assessment Project.]
Investigation of voice stage support: A subjective preference test using an auralization system of self-voice
Authors: Yuen Cheuk Wa , Calamia Paul T.
Published: October 2013

The human voice plays an integral role in dramatic art. The performance of singers and actors, who perceive their voice through their ears as well as bone conduction, is highly related to the acoustic condition they are in. Due to the proximity of the sound source and the spectral difference in the transmission through the skull as compared to air, a support condition different from that for musical instrumentalists is needed. This paper aims at initiating a standardization of methodology in subjective preference testing for voice stage support in order to collect more data for statistical analysis. A proposal of an acquisition/auralization system for self-voice and a set of subjective test procedures are presented. The subjective evaluation of the system is compared to previous designs reported in the literature, and the implementation is validated. A small playhouse has been measured and auralized using the system described, and subjective-preference tests have been conducted with 13 professionally trained actors. Their preferred stage-acoustic conditions (in relation to locations on stage and head orientations) are reported. The results show potential directions for further investigations and identify the necessary concerns in developing an objective parameter for voice stage support.
Ultrasonic signatures of human motion
Authors: Ekimov Alexander , Sabatier James M.
Published: October 2013

Human footsteps generate periodic broadband frequency vibrations in the ground/floor and sound in the air from a few hertz up to ultrasonic frequencies due to repeatable cycles of surface loading by dynamic forces. The friction force of a footstep on the ground/floor produces broadband ultrasonic frequencies. Human motion can be characterized as a periodic, temporal process of a multi-degree of freedom mechanical system. The individual human body parts (torso, legs, arms, etc.) have different cross-sections and Doppler signatures that can be used for human recognition among other moving and stationary objects. A demonstration of human motion measurements using passive and active ultrasonic methods will be presented. The passive method employs ultrasonic measurements by a narrow band microphone that is sensitive to the sound from sliding contacts. The active method utilizes continuous wave Doppler ultrasound. Dynamic signatures of a walking person by the two methods will be demonstrated in real time during the presentation. [Work supported by Department of the Army, Army Research Office contract W911NF-04-1-0190.]
Computational thermoacoustics using a lattice Boltzmann simulation
Authors: Jensen Carl
Published: October 2013

Computational fluid dynamics is being used to investigate the thermoacoustic properties of stack materials with irregular pore geometries. Available models for stack materials with irregular geometries (such as wools and foams) are based empirically on parameters of the material that must be acoustically measured. A direct simulation of the thermohydrodynamic acoustic flow using a thermal lattice Boltzmann method provides a model of the acoustics from the base parameters of the materials make-up and provides insight into the mechanisms affecting that behavior. A particular focus is being placed on fibrous stack materials because their simple geometry is less challenging to replicate on a computer. Work will be presented on modeling a simple straight pore for verification of the numerical procedure as well as progress towards fully modeling a fibrous material. [Work supported by U.S. Army Space & Missile Defense Command.]
Phonemic contrast enhancement in clear speech production: The case of Korean stop production
Authors: Kang Kyoung-Ho
Published: October 2013

This study explores the code enhancement aspect of clear speech production. Younger (n=11, 20–29 years old) and older (n=11, 40–60 years old) speakers of Korean produced the three series of Korean stops (aspirated, lenis, fortis) in three different speaking styles: conversational, citation-form, and clear speech. The production of Korean stops was analyzed for three acoustic properties differentiating the Korean stops, voice onset time (VOT), amplitude difference between the first and the second harmonics (H1-H2), and fundamental frequency (F0). For both of the younger and older groups, the VOT difference between the aspirated and lenis stops was enhanced in clear speech, in addition to enhanced difference between the aspirated/lenis and fortis stops for H1-H2. The two groups differed in that only the younger speakers showed a substantial increase in F0 for the production of the aspirated stops in clear speech. Also, there was a substantial degree of interspeaker variability in the size and direction of the acoustic adjustment in clear speech. The results of this study support Silva’s [Phonology 23, 287–308 (2006)] proposal that younger and older Korean speakers may use different strategies in order to maintain a distinction between the three types of Korean stops.
Frequency band-importance functions for auditory and auditory-visual sentence recognition
Authors: Grant Ken W. , Bentstein Joshua G.W.
Published: October 2013

For consonant recognition, the frequency band-importance function (FBIF) for audio-alone (A) and auditory-visual (AV) speech recognition are significantly different. The relative importance of very low speech frequencies is greater for AV than for A conditions, whether individual frequency bands with different center frequencies are presented in isolation or simultaneously. However, sentences filtered into different frequency bands of approximately equal intelligibility yield no difference between the A and AV FBIFs [Grant and Braida, J. Acoust. Soc. Am. 89, 2952–2960 (1991)]. A correlation method designed to estimate frequency weighting functions for spectral profile analysis, but applied to speech, yields very different FBIFs under broadband versus isolated-band conditions [Turner et al., J. Acoust. Soc. Am. 104, 1580–1585 (1998)]. The present study sought to reexamine the A and AV FBIFs for sentences using broadband speech. IEEE sentences were filtered into three simultaneously presented non-overlapping frequency bands adjusted for equal A intelligibility. Stimuli were presented in noise filtered into the same bands as the speech, with the signal-to-noise ratio (SNR) selected randomly and independently for each band. The FBIF was estimated by calculating a correlation coefficient between performance and the SNR in each band. Implications for hearing-aid design and fitting will be discussed.
Fresnel approximations for acoustic fields of rectangularly symmetric sources
Authors: Mast T. Douglas
Published: October 2013

A general approach is presented for determining the acoustic fields of rectangularly symmetric, baffled, time-harmonic sources under the Fresnel approximation. This approach is applicable to a variety of separable source configurations, including uniform, exponential, Gaussian, sinusoidal, and error function surface velocity distributions, with and without focusing in either surface dimension. In each case, the radiated field is given by a formula similar to that for a uniform rectangular source, except for additional scaling of wave number and azimuthal distance parameters. The expressions presented are generalized to three different Fresnel approximations that correspond respectively to diffracted plane waves, diffracted spherical waves, or diffracted cylindrical waves. Numerical results, for several source geometries relevant to ultrasonic applications, show that these expressions accurately depict the radiated pressure fields, except for points very near the radiating aperture. Highest accuracy near the source is obtained by choice of the Fresnel approximation most suited to the source geometry, while the highest accuracy far from the source is obtained by the approximation corresponding to diffracted spherical waves. The methods are suitable for volumetric computations of acoustic fields including focusing, apodization, and attenuation effects.
An etude in hearing-aid directivity measurement and benchmarking
Authors: Green Matthew J. , Burns Thomas
Published: October 2013

In this study, a three-dimensional, automated scanning system is used to measure the directional performance of hearing aids mounted on a test manikin. A diffuse field is simulated in an anechoic environment by sequentially positioning a loudspeaker along the surface of a 1-m-radius sphere circumscribing the manikin and device under test. Particular attention is given to the type of stimulus, the spatial resolution of loudspeaker positions, and postprocessing of the impulse responses; each affects the measurement precision of the Directivity Index and the 3D polar responses. The purpose of this research is to describe the recipe that yielded minimal measurement bias and variance for ITEs, BTEs, and OTEs of varying directivity.
Modifications to the diffusion model for room-acoustic prediction
Authors: Jing Yun , Xiang Ning
Published: October 2013

Recently, a diffusion model has drawn attention in room-acoustic predictions. This paper proposes possible modifications to the diffusion model to predict the reverberation times and sound pressure distributions in enclosures. While the original diffusion model [Ollendorff, Acustica 21, 236–245 (1969); J. Piacut et al., Acustica 83, 614–621 (1997); Valeau et al., JASA 119, 1504-1513 (2006)] usually has a good performance for low absorption surfaces, the modified diffusion model, including a new boundary condition and a higher order approximation of a transport equation, yields more satisfactory results for both low and high absorption surfaces. Examples of cubic rooms, flat rooms, and long rooms with various absorption coefficients are presented for comparisons between the modified model, the original model, a geometrical-acoustics model, and several well-established theories in terms of reverberation times and sound pressure level distributions. This paper will discuss improved prediction accuracies by the modified diffusion model.
Excitation of a vertical liquid capillary jet waveguide by modulated ultrasonic radiation pressure
Authors: Lonzaga J. B. , Thiessen D. B. , Marston P. L.
Published: October 2013

The excitation of a liquid capillary jet issuing from a nozzle is investigated using internally applied modulated ultrasonic radiation pressure. The transducer used here is more efficient than one used in prior studies [J. B. Lonzaga et. al., J. Acoust. Soc. Am. 116, 2598 (2004)] and is suitable for nozzle velocities as low as 25 cm/s. At low velocities, the liquid jet is significantly tapered. As a consequence of the taper, the acoustic cutoff frequency increases with increasing distance from the nozzle. For ultrasound propagation down the jet from the nozzle, finite-element calculations of the radiation pressure show that the radial stress at the cutoff location is significantly larger than at any other region of the jet. Two distinct capillary modes exist and are conjectured to be excited near the cutoff location by modulated radiation pressure: one traveling upward and the other traveling downward. In a certain range of modulation frequencies, the latter is an exponentially growing mode and leads to the forced disintegration of the jet into liquid drops. Excitation of the growing mode at the nozzle is achieved for low-speed jets by using carrier frequencies close to or below the nozzle cutoff frequency. [Work supported by NASA.]
Active sonar classification using perceptual signal features from musical acoustics
Authors: Young Victor W. , Hines Paul C. , Pecknold Sean
Published: October 2013

Because of the relatively low frequencies at which they operate, navy active sonars are often plagued by false-alarm returns resulting from geological structures. In the lexicon of sonar operators these false returns are referred to as geoclutter or simply clutter. Despite mounting evidence that human operators can aurally discriminate target returns from clutter, attempts to develop robust automatic classification algorithms have, as yet, met with limited success. This paper investigates the possibility of improving the performance of automatic classifiers by exploiting the signal processing employed in the human auditory system. This amounts to replacing the statistical signal features used by conventional automatic classifiers with perceptual signal features that reflect the way a human listener would perceive a given return. Drawing an analogy between active sonar returns and percussive musical timbre, this paper considers perceptual signal features—like loudness centroid, sub-band attack/decay, and sub-band correlation—that have previously been identified as underlying the perception of timbre. Values for each of these timbre features are measured for a series of target and clutter returns recorded during an experimental sea trial. The effectiveness of these perceptual features as target-clutter discriminators is then evaluated using a Gaussian linear discriminant classifier.
Calibrating parametric sonars for backscattering applications
Authors: Foote Kenneth G.
Published: October 2013

The status of parametric sonar calibration is reviewed. For backscattering applications, the standard-target method, which is widely used in calibrating ultrasonic scientific echo sounders and multibeam sonars that provide the water-column signal, can be adapted. Two problems generic to parametric sonars are addressed. (1) The virtual nature of the array may require controlled measurements at a number of ranges, spanning the near field in the general case. (2) Calibration at rather low difference frequencies requires a suitably powerful target. Both measurement protocols and target design are considered for a particular parametric sonar based on primary frequencies in the band 15–21 kHz, with difference frequencies in the band 0.5–6 kHz and sum frequencies in the band 30–42 kHz. Solid elastic spheres are specified for both frequency bands. For the lower band, this is an aluminum sphere of diameter 280 mm, with immersed weight of 190 N.
Optimal source localization in the presence of interfering sources
Authors: Michalopoulou Zoi-Heleni
Published: October 2013

Source localization in shallow-water ocean environments is hindered by the presence of loud interfering sound sources. To remediate these nuisance sources, one needs to back out the true signal from the received mixed acoustic field by estimating a most likely interference scheme. In this work the focus is on resolving problems introduced by an unknown number of interfering signal sources. A statistical model for the sensed acoustic field is estimated using Gibbs sampling in which one obtains through iteration an approximation to the full joint posterior probability description of the model and data. From this joint probability description, the impact of canceling undesirable field components is readily seen on the estimated uncertainty that characterizes the localization process. [Work supported by ONR.]
Customization of acoustic output in lithotripsy using a piezoelectric transducer array
Authors: Chitnis Parag V. , Cleveland Robin O.
Published: October 2013

A piezoelectric array was employed to examine the role of waveform shaping on stone fragmentation in lithotripsy. The array consisted of 170 elements placed on the inner surface of a 15-cm-radius spherical cap. Each element was driven independently using 170 individual pulsers—each capable of generating 1.2 kV. The acoustic field was characterized using a fiber optic probe hydrophone with a bandwidth of 30 MHz and a spatial resolution of 100 μm. When all elements were driven simultaneously, the focal waveform was a shock wave with peak pressures p+=65±3 MPa and p−=−16±2 MPa and the focal region was cigar shaped: 13 mm long and 2 mm wide. The firing of group of elements was adjusted so that each groups focused to different locations in the geometric focal plane. This method allowed the width of the focal region to be broadened albeit with decrease in peak pressure: for a 3-mm-wide region p+=32 MPa and for a 4-mm focal region p+=25 MPa. Waveform shaping was used to enhance or suppress cavitation effects where cavitation activity was observed using a dual passive cavitation detector consisting of two 1-MHz focused transducers. Stone fragmentation was assessed by treating artificial stones with fixed number of shock waves. [Work supported by NIH.]
Lagrangian description of the interaction of a bubble with a particle
Authors: Hay Todd A. , Hamilton Mark F.
Published: October 2013

The Lagrangian formalism used previously to describe pulsations and translations of interacting bubbles [Ilinskii et al., Proc. 17th ISNA, Penn State, edited by Atchley and Sparrow (AIP, New York, 2006)] has been extended to model interactions of bubbles and elastic particles. The bubbles and particles are assumed to be spherical. Of eventual interest is interaction of a cavitation bubble cluster with fragments of kidney stones produced during shock-wave lithotripsy. Here, we discuss only the interaction of a single gas bubble with a single rigid particle. Numerical simulations illustrate change in separation distance in the presence of an applied sound field. Using the averaging procedure employed by Harkin et al. [J. Fluid Mech. 445, 377 (2001)] for two bubbles, we develop approximate equations for the translation under the conditions of weak excitation and weak interaction. Radiation force between the bubble and particle is fifth order in terms of the separation distance, as found previously by Coakley and Nyborg [in Ultrasound: Its Applications in Medicine and Biology, edited by F. Fry (Elsevier, Amsterdam, 1978), pp. 77–159]. Numerical and analytical results are compared with results obtained by others using different approaches. [T.A.H was supported by an NSF Graduate Research Fellowship.]
Scattering by surfaces with sub-Bragg structure
Authors: Henyey Frank , Tang Dajun
Published: October 2013

The scattering from a rough pressure release surface, where the spectrum of the surface only contains wavelengths considerably shorter than half the acoustic wavelength, is considered. The amplitude of the surface may be larger than that for which perturbation theory would be appropriate. We show that the surface can be replaced by an effective surface containing waves longer than half the acoustic wavelength. This effective surface is close to the envelope of the actual surface; this effective problem is likely to be much easier to solve than the original problem. We investigate the relationship between the problems and adjust parameters of the effective surface, by solving both problems with the integral equation.
Study of parametric excitation of nonlinear vibrations in strings
Authors: Brown David A. , Yan Xiang
Published: October 2013

The vibration of a string apparatus can easily be modified to demonstrate and study the parametric excitation of nonlinear acoustic vibrations. As faculty at Brown University were pioneers in both the study of nonlinear acoustic phenomena and introducing clever teaching apparatus to illustrate the principles of this science, it seems fitting to present the results of our study in this special session. The direct drive inductive transducer generates an alternating force, which drives a fixed-free aluminum thin beam that is tuned at resonance with the addition of mass. The string is attached to the free end of the beam and a dual pulley system and micro-positioning rail allows for the continuous adjustment of tension. The orientation of longitudinal vibrations in the string modulates the tension and excites transverse resonance modes that match the condition of half the drive frequency. The classic results of highly bent tuning curves are illustrated in this system by adjusting the tension (sound speed) in the string such that the resonance versus wave number spectra can be observed. Thus such a system may be useful in introducing the student to the study of parametric excitation of nonlinear vibrations in simple systems.
Dynamic time warping for automatic classification of killer whale vocalizations
Authors: Brown Judith C. , Miller Patrick J. O.
Published: October 2013

A large number of sounds from the captive killer whale population at Marineland of Antibes, France have been classified perceptually into call types. [A. Hodgins-Davis, thesis, Wellesley College (2004)]. The repetition rate of the pulsed component of five or more examples of each call type was calculated to give a set of melodic contours. These were compared pairwise using dynamic time warping to give a dissimilarity or distance matrix. The distances were then transformed into a component space using multidimensional scaling, and the resulting points clustered with a k-means algorithm. In grouping 57 sounds into 9 call types, there was a single discrepancy between the perceptual and automated methods. Preliminary measurements on a second set of 74 sounds from northern resident killer whales have been made. Both the high-frequency and low-frequency contours have been measured and classified perceptually into 7 groups. Errors for the automatic classification of this group are over 10%. [Sound recording supported by grants from WHOI’s Ocean Life Institute and the Royal Society to Patrick J. O. Miller.]
Informational masking: Effects of similarity and uncertainty for detection of a high-frequency amplitude-modulated tone
Authors: Gallun Frederick J. , Mason Christine R. , Kidd Gerald
Published: October 2013

Detection of a 3-kHz target tone with 125-Hz amplitude modulation (AM) was measured in the presence of maskers that varied in their similarity to the target. Spectro-temporal similarity was varied in that maskers were tones, narrow-band noises, or AM tones. Similarity in terms of interaural configuration was varied by presenting maskers diotically while target was presented (1) diotically, (2) monotically, or (3) with its envelope delayed at one ear. All maskers had four narrow-band components with center frequencies (CFs) between 1 and 5 kHz. Masker CFs were varied on every block, trial, or interval of a 2IFC procedure, resulting in three levels of masker-frequency uncertainty. As expected, the spectro-temporally similar AM maskers caused greater masking than pure-tone or noise maskers. Surprisingly (and at variance with previous results), varying similarity by interaural configuration had no effect. Increasing masker uncertainty resulted in more masking only for the AM masker. These results suggest that (1) the effects of uncertainty are most pronounced in conditions where maskers and targets are similar and (2) more study is needed of the factors responsible for binaural release from informational masking. [Work supported by NIH/NIDCD and AFOSR.]
Perceptual judgments of breathy voice quality using rating scale, magnitude estimation, and matching tasks
Authors: Patel Sona , Shrivastav Rahul , Eddins David A.
Published: October 2013

Experiments to study voice quality have typically used rating scales to obtain listener judgments. Recent research has questioned the validity of this data due to poor agreement between listeners [Kreiman et al., J. Acoust. Soc. Am. 87, 820–857 (1993)]. However, Shrivastav et al., J. Acoust. Soc. Am. 117, 2622 (2005) showed that such variability was partly related to the experimental methodology and could be minimized by multiple presentations of each stimulus to each listener. The nature of this averaged data, whether ordinal or interval, needs to be determined since it is necessary to develop appropriate perceptual scales for voice quality. The present experiment used three different psychophysical methods to obtain perceptual estimates of voice quality. These include a rating scale (with single and multiple presentations of stimuli to each listener), a direct magnitude estimation task, and a matching task. The experiment sought to determine if these three methods provided equivalent information. Perceptual judgments of breathiness were obtained for ten synthetic vowel continua that varied in terms of their aspiration noise, open quotient, or both. Preliminary results show that perceptual judgments using the magnitude estimation task and rating scale task (with multiple presentations of each stimulus) give very similar information. Results of the matching task will also be discussed. [Research supported by NIH/R21DC006690.]
Electromagnetic-to-seismic conversion: A new direct hydrocarbon indicator
Authors: Thompson A. H.
Published: October 2013

In electroseismic (ES) exploration, electromagnetic (EM) energy converts to seismic energy at depth in the Earth. The amplitude of the converted seismic wave is large at porous, permeable, resistive bodies such as hydrocarbon reservoirs. ES is the only known exploration tool that, applied from the surface of the Earth, may discriminate between water, gas, and oil in the pores of reservoir rock. ES measures rock electrical properties with seismic resolution. The seismic conversion may be linear, at the same frequency as the EM stimulus. Electrokinetic effects, involving the relative motion of the rock solids and fluids, describe linear ES well. Nonlinear conversion may create all harmonics of the EM stimulus. Conventional descriptions of ES and SE conversion do not account for nonlinear conversions. New models, that couple EM and seismic energies through modulation of electrochemical potentials in the Earth, do explain the observations. ES field tests detected the hydrocarbon-sensitive, linear response to 1000 m and the nonlinear response to 1500 m deep. The results suggest that greater depth penetration, to 7000 m, is feasible.
Acoustic noise in microphones from the thermal boundary layer resistance in enclosures
Authors: Thompson Stephen C. , LoPresti Janice L.
Published: October 2013

Many types of acoustic sensors include a small enclosure as an integral part of the device. For example, a condenser microphone has a volume enclosed behind its diaphragm so that the acoustic pressure drives only the front of the diaphragm. In other sensors the enclosure may exist mainly to protect the sensitive components or to provide electrostatic shielding to the high impedance parts of the electrical circuitry. Whatever their reason, these volumes can play a significant role in the performance of the sensor. The adiabatic compliance of the enclosure is commonly included in device models. However, these enclosures are often small enough that the thermal boundary layer thickness can consume a substantial fraction of the enclosed volume at low frequencies. Thermal effects modify both the real and imaginary parts of the cavity impedance in ways that may be important in determining the sensitivity and internal noise of the device. This paper examines these effects. One interesting consequence is a thermal noise source that has a power spectral density proportional to 1/f throughout a substantial frequency band.
Broadband sound velocity and attenuation in sandy seabottoms in shallow water
Authors: Zhou Ji-Xun , Zhang Xue-Zhen
Published: October 2013

A previous paper analyzed and reviewed low-frequency (LF) field measurements conducted at 17 locations in different coastal zones around the world, and indicated that the effective acoustic attenuation curves for sandy seabottoms, derived from different field characteristics at these locations, exhibited similar magnitude and nonlinear frequency dependence in a frequency range of 50–2000 Hz. [Zhou and Zhang, ‘‘Nonlinear frequency dependence of the effective seabottom acoustic attenuation from low-frequency field measurements in shallow water,’’ J. Acoust. Soc. Am. 117, 2494 (2005)]. This paper aims to report the sound velocity in sandy bottoms, derived from the LF field measurements. The resultant LF velocity ratio in the sandy bottom and in the water (at the water/bottom interface) is in a range of 1.04–1.08. Combining the LF field-derived sound velocity and attenuation with the benchmark data of bottom acoustic parameters at mid- to high frequency, obtained from the SAX99 [Williams et al, IEEE J. Ocean. Eng. 27, 413–428 (2002)], offers a reference data set of sound velocity and attenuation in sandy bottoms for a broadband of 50–300000Hz. The broadband sound velocity data show a significant amount of dispersion. The attenuation data are robust enough to cast doubt on a universal assumption of a linear dependence of attenuation on frequency. [Work supported by ONR and CAS.]
3-D acoustic analysis based on magnetic resonance imaging of a ‘‘retroflex’’ and ‘‘bunched’’ American English rhotic sound
Authors: Zhou Xinhui , Espy-Wilson Carol , Tiede Mark , Boyce Suzanne
Published: October 2013

A variety of articulatory configurations can produce an American English /r/. Common across all configurations is a large front-cavity volume that results directly or indirectly in the characteristically low third formant. Earlier work [Zhang et al., ICASSP2005 1, pp. 893–896] using 2-D finite-element modeling of the front cavity with stylized bunched and retroflexed shapes showed that, even at 2000 Hz, cross modes are generated in the front cavity. Thus, the front cavity should be modeled as a single tube with a side branch, regardless of whether there is space underneath the tongue. This paper extends the earlier work by (a) considering the full 3-D vocal tract geometry reconstructed from magnetic resonance images, (b) performing 3-D finite-element analysis, and (c) using contrasting tongue shapes from similar-sized subjects. Harmonic analysis showed the frequency response is comparable to the spectrum of the acoustic signal, suggesting good agreement between the actual and reconstructed vocal tracts. As before, wave propagation in the front cavity is not planar. 3-D vocal tract analysis shows that the cross modes have 3-D properties. Application of the 3-D wave propagation property to area function extraction and simple-tube modeling of the vocal tract will be discussed. [Research supported by NIH.]
Gassy sediment acoustics: Low-frequency sound-speed measurements paired with computed x-ray tomography imaging in reconstituted natural sediments
Authors: Wilson Preston S. , Reed Allen H. , Wood Warren T. , Roy Ronald A.
Published: October 2013

Various models of sound propagation in gas-bearing sediments have appeared in the literature but they are largely unverified by experiment. This is primarily due to the difficulty of assessing the bubble-size distribution and global void fraction in optically opaque sediments. We successfully measured the sound speed in reconstituted natural mud and kaolinite sediments containing varying fractions of biogenic gas bubbles. We used a one-dimensional acoustic resonator technique to determine the low-frequency (100–2000 Hz) sound speed of sediment samples contained within cylindrical acrylic core liners. High-frequency (400 kHz) time-of-flight sound-speed measurements were obtained on a subset of the samples. The sediment samples were contemporaneously imaged with a computed X-ray tomography system that yielded independent estimates of the void fraction and bubble-size distribution. Measured sound speeds ranged from 1520 m/s for gas-free mud to as low as 280 m/s for gassy mud and 110 m/s for gassy kaolinite. CT-derived mud void fractions ranged from 0.001 to 0.002, and the kaolinite void fraction was 0.005. The results of these measurements will be compared to existing theory, but a preliminary analysis shows reasonable agreement between measurement and Wood’s suspension model. [Work supported by NRL and the UT College of Engineering.]
Radiated noise measurements with vector sensor arrays
Authors: Clark Joseph , Tarasek Gerald
Published: October 2013

The use of arrays of vector sensors to measure source levels of radiated noise from submarines is currently being studied. Ambient noise limits the accuracy of these measurements. The directional character of the ambient noise field (anisotropy) has been found to affect measurement accuracy differently for alternative kinds of processing. In this talk, two types of vector sensor processing, linear matrix and intensity processing, will be compared theoretically and experimentally. Theoretical comparisons of achievable measurement accuracies will be developed in terms of the fourth moment of the measured signal amplitude (the variance of the sound power). Experimental comparisons will be based on data obtained during recent testing at SEAFAC, the U.S. Navy acoustic signature measurement facility in Behm Canal, Alaska.
Learning to categorize lexical tones in sentences with variable narrow focus: A neural network approach
Authors: Gauthier Bruno , Shi Rushen , Xu Yi
Published: October 2013

The surface F0 patterns of lexical tones contain variability from many different sources, which raises questions as to how infants can learn tones based on such highly variable input. A recent modeling study showed that the velocity profiles of F0 (i.e., first derivatives, or D1) enable naive learners to successfully categorize the four Mandarin tones despite cross-speaker and contextual variations [Gauthier, etal. ‘‘Recognising tones by tracking moments—How infants may develop tonal catagories from adult speech input,’’ in Proceedings ISCA workshop on plasticity in Speech Perception, edited by V. Dellwo (UCL Publications, London, UK, 2005) pp. 72–75]. The present study explores the robustness of D1 for categorizing Mandarin tones in sentences said with different focus conditions. As a contrastive communicative function, narrow focus within a multi-word utterance introduces extensive variability to F0, making tone learning a more challenging task. Using multi-speaker productions of utterances with systematically varied tones and focus [Xu, ‘‘Effects of tone and focus on the formation and alignment of contours. J. Phonet. 27, 55–105 (1999)], self-organizing neural networks were trained with both syllable-sized D1 and F0 as input, with no special treatment for different focus conditions. In the testing phase, novel tokens were tested for tonal categorization. The results revealed that D1 yielded overall excellent categorization, far superior than F0. Detailed analyses showed that with D1, performance of tonal recognition dropped only in post-focus regions. These findings indicate that successful tone learning can be achieved with velocity profiles as input despite variability introduced by focus.
Use of low-frequency marine seismo-acoustics in understanding earthquake processes: Applications to the Great Sumatra-Andaman earthquake
Authors: Tolstoy Maya , Bohnenstiehl DelWayne R.
Published: October 2013

Low-frequency (1–100 Hz) hydroacoustic recordings can provide a wealth of information on earthquake characteristics in the shallow marine environment. This frequency band, considered low frequency for acousticians, is actually high frequency for regional or global seismologists who commonly work with frequencies of a few Hz and below. In some cases this higher frequency data may provide higher resolution of some earthquake characteristics than traditional seismic methods. The 2004 Great Sumatra-Andaman earthquake provides an example where detailed analysis of the T-wave arrival has allowed detailed characterization of changes in rupture velocity that have not proven easy to resolve in traditional seismic data. Our single-station interpretation of the T-wave data shows that the fault ruptured northward from the epicenter in at least two phases with lower rupture velocity in the north. The methods behind this single station approach will be discussed along with possible future uses of this type of data for improving our understanding of earthquake rupture processes, as well as providing a rapid assessment of the size, location, and geographic extent of large submarine earthquakes, and hence their tsunamigenic potential.
Emergence of the Green’s function from ambient noise in moving media
Authors: Godin Oleg A.
Published: October 2013

A rather general proof of a connection between two-point correlation function of ambient noise and the elastodynamic Green’s function relies on the reciprocity principle [K. Wapenaar, Phys. Rev. Lett. 93, 254301 (2004)]. In this paper, the flow reversal theorem [O. A. Godin, Wave Motion 25, 143–167 (1997)] is applied to extend this result to moving, inhomogeneous fluids and problems involving flow-structure interactions. In the motionless case, the time derivative of the cross-correlation function of ambient noise gives an estimate of the sum of the causal and acausal time-dependent Green’s functions between the two receivers. In the moving medium, the result is shown to be similar, but the acausal Green’s function corresponds to sound propagation in a medium with reversed flow. Therefore, instead of redundant information, combination of the causal and acausal Green’s functions contains additional useful data on flow velocity field in the medium. The data contained in the two-point cross-correlation function of ambient noise are analogous to the data that would be obtained in a reciprocal transmission experiment employing acoustic transceivers located at the two points. Possible applications of the theoretical results obtained to passive remote sensing of ocean and atmosphere are discussed. [Work supported in part by ONR.]
Acoustic source measures for documenting outcomes of combined modality treatment of adductor spasmodic dysphonia
Authors: Silverman Erin , Shrivastav Rahul , Sapienza Christine
Published: October 2013

Spasmodic dysphonia (SD) is a voice disorder of neurogenic origin, wherein one or more intrinsic laryngeal muscles exhibit irregular and uncontrollable spasms. These spasms interfere with the production of perceptually normal voice. This paper presents a prospective, randomized, and placebo-controlled study to examine the effects of phonatory retraining (voice therapy) following Botox injections for ADSD. Thirty subjects were randomly assigned to 1 of 3 experimental groups: Botox only, Botox plus voice therapy, and Botox plus sham therapy. The sham therapy group was included in order to examine nonspecific treatment effects which may emerge as a result of close patient-therapist interaction during voice therapy for ADSD. Dependent variables of interest include acoustic source measures as well as voice-related quality of life, subject self-rating of voice, and duration of benefit between initial and repeat Botox injections. Source measures were typed according to National Center for Voice and Speech and signal typed into type 1, 2, and 3 signals. Voice breaks and frequency shifts were also measured. Preliminary results indicate that the combined modality treatment of voice therapy plus Botox has the more significant positive effect on source measures with trend toward more normal phonation or type 1 signal.
Sensitivity to across-frequency detection cues in binaural hearing
Authors: Hall Joseph W. , Buss Emily , Grose John H.
Published: October 2013

The detectability of an Sπ signal in a narrow-band No masking noise can be improved by the addition of comodulated No flanking noise bands [Hall and Cokely, J. Acoust. Soc. Am. 83, 1839–1845(1988)]. This effect is relatively unreliable, however, occurring in only about 50% of listeners. The present study examined whether the effect can be made more reliable by slightly reducing the interaural correlation of the masking noise. For such a masker, interaural correlation fluctuates as a function of time. For the stimuli used here, the on-signal and the comodulated flanking bands shared the same pattern of interaural correlation as a function of time. The rationale was that the flanking bands could potentially be used as templates to help the auditory system distinguish the ongoing interaural differences of the slightly decorrelated on-signal noise band from the interaural differences introduced by the Sπ signal. Results from all six of the listeners tested showed improved Sπ detection in conditions where the on-signal and flanking bands had the same pattern of interaural correlation. This effect can be considered a form of binaural profile analysis wherein signal detection is aided by an across-frequency analysis of binaural cues. [Work supported by NIH NIDCD R01 DC00397.]