bluuebunny/crossref_metadata_2025 huggingface dataset:
The relation between learning Mandarin Pinyin or Zhuyin and L2 (English) production
Authors: Yu Yan Helen , Bell-Berti Fredericka
Published: October 2013

This study investigates the relation between early written first language learning experience and the perception and production of speech in a person’s second langauge (L2). It compares the English pronunciation of native Mandarin speakers who have had different sound-annotating learning experiences (Pinyin versus Zhuyin). We predict that native Mandarin speakers who used the Pinyin system will produce some English sounds as their Pinyin counterparts if the same Roman letter is used as a pronunciation symbol both in English and in Pinyin system. However, because Pinyin and Zhuyin are not the primary written form for Mandarin, and are extensively used only in the first years of school, and because L2 learning involves exposure to speech as well as reading, we expect only moderate differences between the two groups’ perception and production abilities. We will examine the interaction for Pinyin and Zhuyin learners between (Mandarin) L1 learning experience, age effects, L2 experiences, and the establishment of English phonetic categories for the English monophthongal vowels and consonants /r/, /z/, and /l/.
Simulation and analysis of tremor in speech production
Authors: Farinella Kimberly A. , Story Brad H.
Published: October 2013

Tremor of the muscles used for voice and speech production creates frequency and amplitude modulations in the acoustic speech signal. Frequency modulation results primarily from changes in muscle activations that alter the mass and stiffness of the vocal folds, consequently altering the fundamental frequency (F0). The primary source of amplitude modulation comes from time-varying activation of the respiratory muscles (which alter alveolar pressure), from laryngeal muscles that modify the maximum glottal area, or from interaction of voice source harmonics with the vocal tract filter. The purpose of this preliminary investigation was to analyze acoustic signals generated with an articulatory speech synthesizer in which tremor was imposed separately at each of the three anatomical sites: the respiratory system, larynx, and upper airway (pharynx). The synthesizer consisted of a voice source model of the time-varying glottal area coupled to a wave propagation model of the airways upstream and downstream of the vocal folds. This allowed for complete control of F0, alveolar pressure, glottal area, vocal tract shape, and modulation frequencies of each. Frequency and amplitude contours of the resulting acoustic signals were extracted from the waveform and analyzed and compared using customized Matlab routines. Submitted For (Speech Communication) Young Presenter Award and (Speech Communication) Best Student Paper Award.
Broadband nearfield beamformer with compact size by using Nash genetic algorithm
Authors: Paik Soonkwon , Hixson Elmer L.
Published: October 2013

Though the acoustical array is effective in the reverberant field, its usage has been limited at low frequencies since the array with the length of more than 1 meter is difficult to install inside a vehicle. Furthermore, it is impractical to use circular coordinates especially inside vehicle since the sound source, a human mouth, stays at a fixed distance from and moves along the parallel line to the surface of the headliner. For the delay-and-sum beamformer in near-field, it is difficult to get the complex coefficients, amplitude weight and time delay, by analytical methods. In this paper, one numerical optimization method for a fixed microphone array is investigated which uses the Nash Genetic Algorithm (Nash GA) which was originally used in electromagnetism problems. By using Nash GA, first the optimal geometry of array element alignment inside a vehicle is found, then the complex coefficients are obtained. The results measured in an anechoic chamber correspond to that of computer simulation and satisfy the requirement of hands-free mobile telephony where the microphone array is installed in a vehicle’s headliner and the data is also measured in a reverberant field to investigate the signal to noise ratio.
Acoustical spectral analysis of a wake vortex cross-section using microphone-arrays
Authors: Wassaf Hadi S. , Ibe Oliver C. , Dougherty Robert P.
Published: October 2013

The ability to unambiguously identify the acoustic energy generated by airplane wake vortices using phased microphone-array intensity distribution maps is hampered by the lack of knowledge of the associated non-stationary spectrum throughout the wake’s duration. This ambiguity is especially pronounced when the low broadband signal to noise ratio renders the wake signal difficult to isolate from contaminating background noise. In this paper, a technique to isolate the acoustic spectral content of a cross sectional wake track (CSWT) is presented. First, image processing is used to generate a CSWT from vertical intensity distribution maps. In a second beamforming stage, the array’s main-lobe traces the track to amplify the acoustic signal along the CSWT and estimate its time-varying power spectral density PCSWT(f) using Short Time Fourier Transform. Simultaneously, the background noise frequency-dependent upper confidence limit CL(f) is estimated at each time increment by steering the array away from the wake source. The time varying CL(f) is then used as an adaptive threshold function on PCSWT(f) in order to dynamically segment out the wake frequency bands from those of the contaminating noise sources.
Acoustic to seismic ground excitation using time reversal
Authors: Libbey Brad , Fenneman Douglas J.
Published: October 2013

Time reversal is a promising method of controlling the arrival of acoustic signals at receiver locations underwater and in biomedical tissues. This work applies the techniques in soil for landmine detection. The measurement of seismic vibrations between 50 and 300 Hz is problematic due to difficulties in transmitting energy into and through the soil from loudspeakers. The experimental setup consists of an array of loudspeakers capable of playing independent signals and a soil vibration sensor. The system response between the loudspeakers and the sensor are approximated, time reversed, and rebroadcast such that arrivals at the sensor are coincident. If the airborne and seismic paths are sufficiently complex, time reversal may help to control the energy distribution of a signal reaching the target region. However, the focusing ability is limited by an autocorrelation of the system impulse response that is inherent with time reversal processing. Simulations and experiments will be presented that demonstrate the advantages and limitations of using time reversal for controlling energy at a receiver. Results will compare vibration amplitude with and without the time reversal processing for target soil locations.
Influence of internal waves on vertical coherence of sound propagation in the East China Sea
Authors: Yang Jie , Rogers Peter H.
Published: October 2013

Literature of the last two decades has shown that internal waves are a major factor determining sound field fluctuations [Zhou et al., J. Acoust. Soc. Am. 90, 2042–2054 (1991); Lynch et al., ibid. 99, 803–821 (1996)]. Due to its time-dependent and anisotropic nature, internal waves can cause both temporal and spatial variations in the sound speed profile and hence, the acoustic field. In this paper, a model is built to study the range and azimuthal dependence of wave propagation in the presence of internal wave activity. The results are based on an in situ experiment ASIAEX in the East China Sea where intense tidal driven internal waves were recorded. The model explains the observed decorrelation after long range propagation (20 km) and in certain directions relative to the internal wave wavefront.
Prediction of the thermal conductivity of fiberglass insulation using propagation constant: A technique overview
Authors: Tinianov Brandon , Nakagawa Masami , Muñoz David
Published: October 2013

This paper describes a novel technique for the prediction of the thermal performance of low density fiber glass insulation and other related fibrous insulation materials using a non-invasive acoustic apparatus. The project motivation is to create an enabling technology for in situ quality control testing of such fiber glass batts during production. Experimental results obtained in the laboratory show excellent correlation between the thermal conductivity and both the real and imaginary components of the propagation constant. Correlation of calculated propagation constant magnitude versus measured thermal conductivity gave an R2 of 0.94 for the range of typically manufactured fiber glass batt materials. Given the promise of such highly correlated measurements, the acoustic technique could be used to continuously predict the thermal conductivity of the material during its production, replacing current off-line methods. The mechanisms for energy transfer through the materials are distinctly different for the acoustical propagation versus the heat transfer. The nature and behavior of the mechanisms will be reviewed and compared.
Impact of acoustic leakage on the absorption of mono-layer and two-layers porous material
Authors: Castel Franck , Sgard Franck , Atalla Noureddine
Published: October 2013

This paper discusses the effects of small lateral air gaps on the normal incidence absorption coefficient of mono layer and two layers porous materials. Such mounting conditions are responsible for changes in the absorption, leading to dramatic errors in the determination of the acoustics parameter with inverse characterization methods. As this type of mounting conditions is hard to control experimentally, a hybrid finite element-modal method is used to investigate the problem of the porous material inserted in a rectangular wave-guide. At the interface of the material and the waveguide, coupling between the different domains is accounted for accurately using a modal decomposition. An automatic meshing approach is employed to speed up and guarantee convergence of the method. A large set of materials spanning a wide range of flow resistivities is used for the simulations. The results are presented under the form of charts which makes them an easy to use tool suitable for both inspection and design. Firstly, these charts allow one to identify materials whose normal inci- dence absorption coefficient is sensitive to lateral air leaks. Secondly, these charts are a helpful tool for designing highly absorptive solutions based on the combination of porous materials and air gaps.
Controlled nucleation of microcavitation with laser-illuminated nano-particles
Authors: Roy Ronald A. , Farny Caleb H. , Wu Tianming , Murray Todd W. , Holt R. Glynn
Published: October 2013

The safe utilization of controlled cavitation in HIFU therapy requires the presence of nucleation sites for bubble formation. Effective cavitation nuclei do not exist in most tissues; nucleation thresholds pressures in excess of 4–5 MPa have been reported. We investigate the efficacy of transient vapor cavity generation from laser-illuminated gold nano-particles as a means for nucleating cavitation with high-intensity focused ultrasound. An acrylamide tissue phantom seeded with 82-nm diameter gold particle was exposed to 20 ns pulses from a 532 nm Nd:Yag laser. Laser firing was precisely synchronized with a pulsed 1.1 MHz HIFU pressure field. Acoustic emissions from inertial cavitation were detected by a 15 MHz focused transducer at a laser energy of 0.10 mJ/pulse and a HIFU peak-negative focal pressure as low as 0.92 MPa. In comparison, a peak-negative focal pressure of 4.50 MPa was required to nucleate detectable cavitation without laser illumination; nano-particles were present in both cases. Since the particles are durable, one can re-activate them as needed, essentially yielding cavitation nuclei on demand. [Work supported by the Dept. of the Army (award No. DAMD17-02-2-0014) and the Center for Subsurface Sensing and Imaging Systems (NSF ERC Award No. EEC-9986821).]
Nonlinear dynamics of gas bubbles in soft tissue
Authors: Yang Xinmai , Church Charles
Published: October 2013

Understanding the behavior of cavitation bubbles driven by ultrasonic fields is an important problem in biomedical acoustics. The previous studies are largely limited by availability of experimental data on soft tissue. To approach this problem, we combine the Keller-Miksis equation for nonlinear bubble dynamics with the linear Voigt model for viscoelastic media. Using experimentally determined values of viscoelastic properties of soft tissue as a guide, the effects of elasticity on bubble oscillations are studied. The inertial cavitation thresholds are determined using a criterion of Rmax/R0=2, and subharmonic emissions from an oscillating bubble are calculated. The results show that the presence of the elasticity increases the threshold pressure for inertial cavitation, and subharmonic signals only can be detected in a certain region of radii and driving pressures at a given frequency. These results should be useful in cavitation detection and bubble-enhanced imaging work. The model also could be used to determine values for the viscoelastic properties of soft tissue.
Use of complex source points to simplify numerical Gaussian beam synthesis
Authors: Forsythe Stephen
Published: October 2013

It is often desirable to generate the acoustic field due to a so-called Gaussian beam. One way to do this is to use the free-space Greens function for the acoustic field and to sum small area sources over a circular plate with the appropriate shading for the desired Gaussian beam. For very high frequencies and narrow beams, the computation time to give an accurate sum can be large when calculating the sum for many points in the acoustic field. An alternate approach comes from the use of a single point source with complex coordinates R=[Xr+iXi,Yr+iYi,Zr+iZi]. When this complex source point is used in the free-space Greens function, the formal expressions for pressure and particle velocity can be used if careful attention is paid to the interpretation of the complex distance, r, that arises in the exp(ikr)/r term. The singularity is no longer a single point in the case of a complex source, but a circular disk. The far field of a complex source point is a good approximation to a Gaussian beam. Several computational uses of the technique will be demonstrated. Extension to the shear wave Greens function will be explored.
Fast calculations of time-harmonic near field pressure distributions produced by triangular sources
Authors: Chen Duo , McGough Robert
Published: October 2013

An analytical expression is derived for the near field pressure response to a sinusoidal excitation for a triangular piston. The analytical expression eliminates a numerical singularity from the impulse response and therefore achieves much more rapid convergence than the impulse response. This results in shorter computation times relative to the impulse response for a given peak error value. These fast-converging expressions are represented by three integrals, where each integral expression corresponds to an edge of the triangle. Pressure fields are evaluated within a grid that includes the face of the triangular source, and computation times are compared with the impulse response for given values of the peak error. For a specified peak error of 1%, the rapidly converging expressions are at least 50% faster than the impulse response for equilateral triangles with sides ranging from one-half wavelength to 8 wavelengths. For a specified peak error of 10%, the rapidly converging expressions are at least 120% faster than the impulse response when applied to the same group of equilateral triangles. Different reductions in computation time are achieved by other piston and grid geometries.
Individual differences in the masking level difference (MLD) with a narrowband masker at 500 or 2000 Hz
Authors: Buss Emily , Hall Joseph W. , Grose John H.
Published: October 2013

The MLD for a narrowband masker is associated with marked individual differences. This study examines factors that might account for these individual differences, including binaural temporal resolution and sensitivity to interaural cues based on time or level. MLD data were collected for 50-Hz wide maskers at 500 and 2000 Hz, gated on for 400-ms. The signal was a pure tone at the center frequency of the masker, of either brief (15-ms) or long (200-ms) duration. Brief signals were coincident with either a local minimum or maximum in the pattern of inherent amplitude modulation. Sensitivity to interaural time and level cues was assessed using similar stimuli, with the exception that the long-duration signal was a 50-Hz band of noise, generated to provide just interaural time cues, just interaural level cues, or both types of cues. Binaural temporal windows were estimated based on pure tone detection thresholds for a brief 500-Hz tone presented at different points in time relative to an abrupt interaural phase transition in a masking noise, bandpass filtered between 100 and 2000 Hz. Relationships between MLD results and those of binaural temporal windows and interaural cues of time and level will be discussed.
A biologically inspired binaural approach to monaural modeling
Authors: Shub Daniel E. , Colburn H. Steven
Published: October 2013

The auditory system is often discussed as having monaural and binaural neurological pathways; similarly models are classified as either monaural or binaural. Psychophysical evidence of contra-aural interference (when performance with one ear is better than performance with two ears) suggests that the information used on monaural tasks (e.g., N0S0 and NmSm detection) may be carried by a binaural pathway. Binaural models often require monaural channels to predict the results of monaural tasks, but these monaural channels prevent the models from predicting contra-aural interference. This modeling work investigates the monaural information carried by a processor which is inherently binaural. The processor design makes the inclusion of monaural channels unnecessary and contra-aural interference is predicted under certain conditions. The performance of the model matches results from a variety of traditional psychophysical tasks (including discrimination of differences in overall intensity; discrimination of differences in interaural level, time and coherence; as well as detection under monaural and binaural masking conditions). Results suggest that binaural neurons contain sufficient information to explain performance on both binaural and monaural tasks. [Work supported by NIH grants R01 DC 00100 and 1 F31 DC006769-01.]
The spatial distribution of sound pressure within the human ear canal
Authors: Stinson Michael R. , Daigle Gilles A.
Published: October 2013

The sound field inside a human ear canal has been computed using 2 approaches. A simple model, a modified Webster horn equation approach, can accommodate the curvature and varying cross section of the ear canal. Calculations using the horn equation demonstrate the formation of standing waves within the canal. The pressure may be interpreted as either the pressure along the center axis of the canal or the average pressure within a cross-sectional slab. To investigate possible spatial variation through a cross section, the sound field has also been computed using the boundary element method (BEM). Over 2000 triangular mesh elements, 1 mm or less in size, were used to represent the canal geometry. For a plane piston source at the canal entrance and both a rigid and a resistive impedance condition at the eardrum position, the computed sound pressures along the center axis of the ear canal are in good agreement with the horn equation calculations, up to 15 kHz. The BEM approach, though, reveals spatial variations of sound pressure through each canal cross section, increasingly significant as frequency increases. Further, for source configurations that are more realistic than a simple piston, large transverse variations in sound pressure are anticipated.
Achieving pseudo-degeneracy in handbell modes
Authors: Buschert John R. , Cha Sungdo , King Daniel A. , Horst Daniel B.
Published: October 2013

Degenerate modes in handbells are split by nonuniformity in the bell. By adding small masses to the bell, the modes can be shifted in position and frequency. Interesting things happen when one attempts to recreate a degeneracy that has been split. Holographic photos of the modes will be shown which can be used to follow the effects of the added mass on individual modes. By moving and varying the mass, one can bring the modes back to a pseudo-degeneracy. Holographic interferometry photos and graphs of the position and frequency of the modes show the stages of this transition.
Recognition of English phonemes in noise
Authors: Benkí José R. , Felty Robert
Published: October 2013

Native speakers of American English identified the consonants and vowels of American English CV and VC syllables and the vowels of hVd syllables. The CV and VC syllables, consisting of all of the English consonant phonemes, were selected from recordings described by Shannon et al. [J. Acoust. Soc. Am. 106, L71–L74 (1999)], and the hVd syllables were selected from recordings described by Hillenbrand et al. [J. Acoust. Soc. Am. 97, 3623–3641 (1995)]. All syllables were presented binaurally in signal-correlated noise. The resulting confusion matrices and feature analyses will be presented along with a position (initial versus final) analysis for the consonant results. The consonant and vowel results will be used to derive empirical measures of similarity of English words. [Work supported by NIH/NIDCD.]
Articulatory influences on the categorization of speech sounds
Authors: Yeung H. Henny , Gick Bryan W. , Werker Janet F.
Published: October 2013

This cross-modal study investigates whether production of speech gestures can influence auditory speech perception. Participants made categorization judgments on a continuum between /ba/ and /da/, while making concurrent motor gestures. Ten participants categorized synthesized sounds from a /ba/-/da/ continuum while (a) simply listening, (b) concurrently making a /ba/, /da/, or /ga/ gesture without vocal fold vibration, or (c) making a nonspeech gesture (i.e., tongue protrusion). Preliminary data indicate that making /ba/ and /ga/ gestures, or tongue protrusions, will shift the perceptual boundary away from the /da/ end of the continuum (i.e., towards the /ba/ end of the continuum), compared to a passive listening condition. Making /da/ gestures did not shift the perceptual boundary, compared to this same listening condition. These data offer support for the idea that auditory categorization of speech tokens on a continuum can be influenced by conflicting information in other modalities—specifically articulatory gestures. Further studies will be conducted to examine the influence of (a) other speech gestures on these synthesized sounds, and (b) speech gestures on the perception of naturally-produced speech tokens.
Enhancement of visual perception of speech via tactile input
Authors: Gibraiel Diana , Gick Bryan , Ikegami Yoko , Johannsdottir Kristin , Muehlbauer Jeff
Published: October 2013

Motor theories of speech perception predict that perceptual information from modalities other than sound enhance speech perception directly by informing the perceiver of the speaker’s gestures [A. Lieberman and I. Mattingly, Cognition 21, 1–36 (1985)]. Acoustic theories predict that perceptual information from modalities other than sound will only enhance speech perception if there is a learned mapping between the acoustic speech signal speech and that modality [R. Diehl and K. Kluender, Ecol. Psych. 1, 121–144 (1989)]. As normal subjects are unlikely to have learned a mapping between visual and tactile speech information, this study tests whether and how tactile input enhances visual speech perception. In the control condition, perceivers in noise repeat syllables pronounced by a speaker who they can see clearly. Accuracy is judged on the basis of the repeated syllables. In the experimental condition, subjects additionally have their hand on the speaker’s face in the Tadoma position. Results show that subjects are significantly more accurate at perceiving speech when they have both visual and tactile input then when they have visual input alone. In particular, tactile input enhances perceptual accuracy of voice and manner features. [Work supported by NSERC.]
Variability of oronasal coupling in children and adults
Authors: Venkatesh Lakshmi , Moore Christopher A.
Published: October 2013

Oronasal coupling in young children remains poorly understood primarily because of experimental challenges associated with non-invasive techniques for transducing velopharyngeal movement. Productions of the word [bama] were studied in children with normal speech acquisition (NSA) and children with speech delay (SD; 3-to-5 years of age) with respect to adults. Nasal vibration was transduced using a small, lightweight accelerometer affixed to the lateral alar cartilage of the participant’s nose. The variability in the nasal acceleration signals obtained for multiple productions of the stimuli for each participant was described using the spatiotemporal index (STI) and functional data analysis (FDA). The spatiotemporal index served as a composite method of variability following linear time normalization of the signals. The FDA technique involving nonlinear time normalization allowed for independent evaluation of amplitude and phase variability. The two groups of children with NSA and SD were more variable than the adults on both measures of STI and amplitude variability, while the amount of phase variability was similar between children and adults. These methods have complementary merits and potential in revealing the properties of development and disruption of oronasal coupling in children and adults. [Work supported by NIH-NIDCD.]
Final devoicing in Russian: Acoustic evidence of incomplete neutralization
Authors: Dmitrieva Olga
Published: October 2013

A number of acoustic and perceptual studies conducted on German, Polish, Catalan, and Dutch found evidence of incomplete neutralization of the voicing contrast of obstruents in word-final position. The present study investigates the acoustic correlates of word-final stops and fricatives in Russian. 34 minimal pairs differing in the underlying voicing characteristics of the final segment were incorporated into the body of filler items organized as a stream of associations. This word list was presented to 14 native speakers of Russian. Measurements were obtained for the duration of the vowel preceding the final obstruent, the closure/frication portion of the final obstruent, the burst for the final stops, and duration of the voicing into closure/frication of the final obstruent. Statistical analysis revealed that the effect of underlying voicing, as well as manner of articulation, was significant for all parameters measured. The results strongly suggest that final devoicing in Russian represents a case of incomplete neutralization, at least in the experimental conditions employed.
Haptic-auditory interference from air flow in speech perception
Authors: Ikegami Yoko , Gibraiel Diana , Gick Bryan , Johannsdottir Kristin
Published: October 2013

Previous work on haptic interference in auditory perception has shown McGurk-like effects from manual-tactile contact with the face [Fowler and Dekle, JEP:HPP 17, 816–828 (1991)]. The present study investigates whether indirect haptic input affects auditory perception. A novel method was developed in which one experimenter blew puffs of air onto a subject’s neck while another produced English plosives, creating possible mismatches between the sensation of aspiration and its acoustic presence. Subjects were blindfolded and wore headphones playing white noise. For 50% of the trial, one experimenter, whose presence was hidden from the subjects, blew puffs of air on subjects’ necks lightly enough to be perceived but not noticeable as unnatural. Simultaneously, a second experimenter produced syllables with bilabial plosive onsets (aspirated /p/ or unaspirated /b/) and subjects were asked to repeat what was heard. Sessions were videotaped and three observers rated successful simultaneity of stimuli. Results indicate cross-modal interference. Subjects showed higher accuracy of speech perception when appropriate haptic stimuli accompanied the auditory stimuli. Moreover, when presented with mismatched tactile and auditory stimuli, subjects demonstrated the fusion of the two modes. Subjects perceived /pa/ when auditory stimulus /ba/ was presented with emulating aspiration. [Work supported by NSERC.]
The development of laryngeal coarticulation: Comparison of women, 5-year-olds, and 10-year-olds
Authors: Koenig Laura L.
Published: October 2013

Past work has indicated that adult speakers show effects of laryngeal coarticulation in voice source measures taken in vowels flanking voiceless consonants. In a recent pilot study, we presented time-varying voice source measures from 5-year-old girls producing VCV sequences with varying consonants. The results suggested that, on average, the children produced laryngeal coarticulation over a duration at least as long as adults, but extensive token-to-token variability complicated interpretation of the results. The present analysis extends that work by comparing normal women with normally-developing 5-year-old and prepubertal 10-year-old children. Speakers were recorded producing multiple repetitions of intervocalic /b p h/ in simple carrier phrases such as ‘‘Poppa Hopper’’ while oral airflow signals were collected using a Rothenberg mask. After software-inverse filtering, pulse-by-pulse measures of DC airflow, open quotient, and f0 are made from the transition out of the consonant into the following vowel. Results will be intepreted in terms of age effects and, for the children, possible gender differences. These data have implications for our understanding of laryngeal motor control in children and, more generally, for theories of the development of coarticulation. [Work supported by NIH.]
Acoustic methods for tactical surveillance
Authors: Ferguson Brian G. , Lo Kam W.
Published: October 2013

Smart acoustic sensor systems can be deployed for the automatic detection, localization, classification and tracking of military activities, which are inherently noisy. Acoustic sensors are appealing because they are passive, affordable, robust, and compact. Also, the propagation of sound energy is not limited by obstacles that block or obscure the clear line of sight that is required for the effective operation of electromagnetic systems. Methods, with examples, for extracting tactical information from acoustic signals emitted by moving sources (air and ground vehicles) are provided for both single sensor and multiple sensor configurations. The methods are based on processing either the narrowband or broadband spectral components of the sources’ acoustic signature. Weapon firings generate acoustic impulses and supersonic projectiles generate shock waves enabling source localization and classification by processing the signals received by spatially-distributed sensors. The methods developed for land-based acoustic surveillance using microphone data are also applied to hydrophone data for passive acoustic surveillance of the underwater environment.
The effects of orthokinetic collision and the acoustic wake effect on acoustic agglomeration of polydisperse aerosols
Authors: Dong Shaozeng , Lipkens Bart , Cameron Timothy
Published: October 2013

A new concept of effective agglomeration length, which measures the maximum particle separation distance for effective collisions, is proposed for acoustic agglomeration of polydisperse aerosols with respect to the separate and combined effects of orthokinetic collision and acoustic wake in a horizontal acoustic wave. Particle gravity is found to be significant for the acoustic wake effect while the particle collision efficiency is important for the orthokinetic collision. Results indicate that orthokinetic collision dominates at low frequencies for intermediate size ratios while the acoustic wake effect is more significant at higher frequencies for all particles. The optimum frequency for orthokinetic collision is confirmed but shifts downward with the increase of sound power. For the acoustic wake effect, the agglomeration increases monotonically with sound frequency. Results also show that the orthokinetic collision is not effective for agglomeration of sub-micron particles because of low particle collision efficiency.
Moving ship tomography a first look at BASSEX 04
Authors: Heaney Kevin D. , Baggeroer Arthur B.
Published: October 2013

During the Basin Acoustic Seamount Scattering Experiment (BASSEX04) a line array was towed between two source moorings in the North Pacific separated by 500 km. The moorings were part of the SPICE04 test led by Scripps Institution of Oceanography. Each mooring had two broadband sources (center frequency 250 Hz) at depths of nominally 800 m and 3000 m. Thirty transmissions were recorded as the ship passed south along the line bisecting the two source moorings. The sources transmitted simultaneously (for each source). In order to break the conical ambiguity of the arrivals from each source, the array was turned 20 degrees for each reception. One set of sources used coded m-sequences with different laws, permitting separation of the signals by signal processing. Comparisons of the received signals will be compared with initial propagation model results using the measured sound speed field from the ship. An approach to Nx2−D tomography (where N=30) will be investigated. [Work supported by ONR Ocean Acoustics.]
Tone-burst otoacoustic emissions and loudness
Authors: Epstein Michael , Florentine Mary
Published: October 2013

Several models of cochlear mechanics lead to the conclusion that the amplitude of tone-burst otoacoustic emissions (TBOAEs) is proportional to basilar-membrane (BM) motion. Buus and Florentine [Fechner Day 2001 (Pabst, Berlin), 236 (2001)] showed that the square of loudness, derived from measurements of spectral and temporal integration, closely matched basilar-membrane velocity at the best frequency. Buus et al. [Physiological and Psychophysical Bases of Auditory Function, 373 (2001)] examined the relationship between distortion-product otoacoustic emissions (DPOAEs) and BM motion. Follow-up work by Epstein et al. [J. Acoust. Soc. Am. 117, 263 (2005)] showed in a direct comparison that TBOAEs and psychoacoustical measures, of loudness and of pulsation threshold, on six subjects with normal hearing led to very similar estimations of basilar-membrane motion. These outcomes suggest that otoacoustic emissions could serve as an excellent tool–one that is objective, non-invasive, and rapid–for estimating in subjects with normal hearing both relative basilar-membrane motion and relative loudness. [Work supported by NIH/NIDCD Grant R01DC02241.]
Acoustic archeology at the lost city of Helike
Authors: Lehman Sean K.
Published: October 2013

In 373 BC an earthquake and tsunami destroyed and submerged the classical Greek city of Helike (HELL-E-KEY) on the north Peloponnese shore of the Gulf of Corinth. In June 2004, surface seismo-acoustic surveys were performed in the area of present Helike in order to collect non-invasive tomographic data to guide the archeological excavations. Prior to tomographic inversion and imaging, the raw data time series must be preprocessed to estimate ground acoustic velocity, and to remove the ground roll signal. We present a generalized cross-correlation technique which appears successful in solving both problems. We describe the technique as applied to the data and present tomographic inversions.
Effect of clinical diagnostic ultrasound pressure amplitude and pulse repetition frequency on echogenic liposome destruction
Authors: Smith Denise A. B. , Porter Tyrone M. , Holland Christy K. , Huang Shao-Ling , MacDonald Robert C. , McPherson David D.
Published: October 2013

Liposomes are submicron-sized phospholipid vehicles that contain both gas and fluid. Entrapped microbubbles within the liposome cause them to be echogenic. With antibody conjugation and thrombolytic drug incorporation, such as rt-PA, these liposomes can be used as novel targeted diagnostic ultrasound echo contrast agents to deliver a drug locally. In this study, the echogenicity of unconjugated liposomes suspended in distilled water was assessed by measuring the decay rate of backscattered intensity using a Philips HDI5000 diagnostic ultrasound scanner with a 12-5 MHz linear array. Pulses of ultrasound with a 7-MHz center frequency and derated peak rarefaction pressure amplitudes of 0.16, 0.35, and 0.61 MPa were used to expose the liposomes. Pulse repetition frequencies in the range of 6.7 kHz to 13.3 kHz were employed at frame rates between 16 and 35 Hz, respectively. The average backscatter intensity was determined from a 20 mm2 region-of-interest in each image frame. An exponential decay was fit to each data set. Ultrasound pulses with higher acoustic pressures and higher pulse repetition frequencies destroyed the liposomes at a faster rate.
Perception of speaker size and sex of vowel sounds
Authors: Smith David R. R. , Patterson Roy D.
Published: October 2013

Glottal-pulse rate (GPR) and vocal-tract length (VTL) are both related to speaker size and sex—however, it is unclear how they interact to determine our perception of speaker size and sex. Experiments were designed to measure the relative contribution of GPR and VTL to judgements of speaker size and sex. Vowels were scaled to represent people with different GPRs and VTLs, including many well beyond the normal population values. In a single interval, two response rating paradigm, listeners judged the size (using a 7-point scale) and sex/age of the speaker (man, woman, boy, or girl) of these scaled vowels. Results from the size-rating experiments show that VTL has a much greater influence upon judgements of speaker size than GPR. Results from the sex-categorization experiments show that judgements of speaker sex are influenced about equally by GPR and VTL for vowels with normal GPR and VTL values. For abnormal combinations of GPR and VTL, where low GPRs are combined with short VTLs, VTL has more influence than GPR in sex judgements. [Work supported by the UK MRC (G9901257) and the German Volkswagen Foundation (VWF 1/79 783).]
Native and non-native perception of phonemic length contrasts in Japanese: Effects of speaking rate and presentation context
Authors: Wilson Amanda , Kato Hiroaki , Tajima Keiichi
Published: October 2013

Japanese words can be distinguished by the length of phonemes, e.g., ‘‘chizu’’ (map) versus ‘‘chiizu’’ (cheese). Perceiving these length contrasts is therefore important for learning Japanese as a second language. The present study examined native English listeners’ perception of length contrasts at different speaking rates and in different contexts. Stimuli consisted of 20 Japanese word pairs that minimally contrasted in vowel length, and 10 synthesized nonwords. The nonwords were created by modifying the duration of the second vowel of the nonword ‘‘erete’’ along a continuum (from ‘‘erete’’ to ‘‘ereete’’). Stimuli were presented with or without a carrier sentence at three rates (fast, normal, slow). Rate was either fixed or randomized trial by trial. Sixteen native English and 16 native Japanese listeners participated in a single-stimulus, two-alternative forced-choice identification task. Results suggest that native Japanese listeners’ identification boundaries systematically shifted due to changes in speaking rate when the stimuli were in the context of a sentence with mixed rates of presentation. In contrast, native English listeners show a shift in the opposite direction, suggesting that they did not follow the variation in speaking rate. These results will be discussed from the viewpoint of training second-language phoneme perception. [Work supported by JSPS.]
Sequential grouping constraints on across-channel auditory processing
Authors: Oxenham Andrew J. , Dau Torsten
Published: October 2013

So/ren Buus was one of the pioneers in the study of across-channel auditory processing. His influential 1985 paper showed that introducing slow fluctuations to a low-frequency masker could reduce the detection thresholds of a high-frequency signal by as much as 25 dB [S. Buus, J. Acoust. Soc. Am. 78, 1958–1965 (1985)]. So/ren explained this surprising result in terms of the spread of masker excitation and across-channel processing of envelope fluctuations. A later study [S. Buus and C. Pan, J. Acoust. Soc. Am. 96, 1445–1457 (1994)] pioneered the use of the same stimuli in tasks where across-channel processing could either help or hinder performance. In the present set of studies we also use paradigms in which across-channel processing can lead to either improvement or deterioration in performance. We show that sequential grouping constraints can affect both types of paradigm. In particular, the perceptual segregation of off-frequency from on-frequency components, using sound sequences preceding or following the target, leads to results similar to those found in the absence of the off-frequency components. This suggests a high-level locus for some across-channel effects, and may help provide a functional distinction between within- and across-channel mechanisms. [Work supported by NIH R01DC03909 and Danish Research Council.]
Highway noise levels in a suburban environment under inversion conditions
Authors: Chambers James , Saurenman Hugh , Bronsdon Robert , Sutherland Louis , Gilbert Ken , Waxler Roger , Talmadge Carrick
Published: October 2013

Noise levels were measured in Scottsdale, AZ during a two week period in March, 2004 to identify the reasons for increased noise levels near a major highway during early morning hours. The noise levels were accompanied by meteorological measurements as well as traffic counts to fully describe the problem. The noise levels were measured in one-third octave bands and ranged 100 ft to 2620 ft (30–800 m) from the highway and included data on both sides of the highway. The meteorological data indicated inversion conditions or downward refraction during the times of interest and model results from a Parabolic Equation (PE) calculation indicated good results with the data. The data and model indicated an approximately 10–15 dB increase in levels during inversion conditions which rapidly transitioned to neutral and lapsed conditions shortly after sunrise. The results of the modeling effort as well as the data will be presented. [Work supported by Arizona Dept. of Transportation.]
Uncertainty propagation in ocean acoustic waveguides
Authors: Finette Steven
Published: October 2013

This presentation discusses a general method for representing uncertainty in numerical models that describe acoustic field propagation within partially specified ocean waveguide environments. The approach treats uncertainty within a probabilistic framework, representing both the sound speed distribution and acoustic field as stochastic processes. In this talk, environmental uncertainty is linked to incomplete knowledge of the volume sound speed field and is directly incorporated into the mathematical formulation for acoustic propagation in a stochastic ocean waveguide. As an example, equations describing the propagation of uncertainty [Finette, J. Acoust. Soc. Am (in press)] are solved analytically for the special case of a point source in a random, but spatially uniform sound speed field bounded by a pressure release surface and a rigid bottom. Results for the first two moments of the acoustic field are calculated using this approach and compared with an independent estimate of the same moments obtained from Monte Carlo based realizations that are computed from a deterministic parabolic wave equation. [Work supported by ONR.]
Forward scattering from the Kermit-Roosvelt Seamount complex during the SPICEX-LOAPEX-BASSEX experiments
Authors: Baggeroer Arthur B. , Sikora Joseph , Heaney Kevin , Scheer Edward K. , von der Heydt Keith , Becker Kyle
Published: October 2013

The SPICEX-LOAPEX-BASSEX expermiments were executed in the Northeast Pacific to examine several long range, low frequency propagation phenomena. Low frequency sources centered at 68 and 75 Hz with nominal bandwidth of 30 Hz and a source at 250 Hz with 100 Hz bandwidth were deployed transmitting orthogonal M seqeunces and FM chirps. A 64 element towed array cut for 250 Hz from Penn State Univ. was the primary multichannel receiving system. This presentation concerns the BASSEX study of low frequency scattering around the Kermit-Roosevelt Seamount complex which shoals to 900 m near 39 N and 145 W. We examine (i) the forward scattering shadow, (ii) any patterns of horizontal refraction as a function of source and receiver range from the seamounts, (iii) any backscattering from the seamounts, and (iv) the modal content of the signals by travel time methods. In addition, directional spectra of ambient noise were measured.
Surface wave tomography from seismic ambient noise in Southern California
Authors: Sabra Karim , Gerstoft Peter , Roux Philippe , Kuperman Willliam , Fehler Michael
Published: October 2013

It has been demonstrated experimentally that an estimate of the Green’s tensor between two seismic stations can be obtained from the long-time average of the cross-correlation of ambient noise at the two stations. This result provides a means to image Earth structure using the ambient noise field only, without the use of active seismic sources or earthquakes. Seismic noise data from 148 broadband seismic stations in Southern California were used to extract the surface wave arrival-times between all station pairs in the network in the frequency band 0.05–0.4 Hz. In this frequency band, ambient noise (originating from ocean microseisms) propagating over long distances is typically dominated by surface waves. A record section of the waveforms as a function of increasing receiver separation shows clearly that the recovered signals are propagating wavetrains. The seismic data were then used in a simple, but densely sampled tomographic procedure to estimate the surface wave velocity structure for a region in Southern California. The result compares favorably with previous estimates obtained using more conventional and elaborate inversion procedures. This demonstrates that coherent ambient noise between station pairs can be used for seismic imaging purposes.
A binary masking technique for isolating energetic masking in speech perception
Authors: Brungart Douglas S. , Simpson Brian D. , Chang Peter S. , Wang DeLiang
Published: October 2013

When a target speech signal is obscured by interfering speech, two distinct types of masking contribute to the resulting degradation in the intelligibility of the target talker: energetic masking caused by overlap in the time-frequency distribution of energy in the two voices, and informational masking caused by the listener’s inability to correctly segregate the acoustic elements of the two voices into distinct streams. This study attempted to isolate the effects of energetic masking on multitalker speech perception with ideal time-frequency binary masks that retained those spectro-temporal regions of the acoustic mixture that were dominated by the target speech but eliminated those regions that were dominated by the interfering speech. This procedure removed the same phonetic information from the target speech that would ordinarily be lost due to energetic masking, but eliminated the possibility for the kinds of target-masker confusions that are thought to produce informational masking. The results suggest that energetic masking may play a surprisingly small role in the overall masking that occurs in certain types of multitalker speech signals. They also indicate that the number of competing talkers has a much greater influence than target-masker similarity on the amount of energetic masking that occurs in a multitalker stimulus.