bluuebunny/crossref_metadata_2025 huggingface dataset:
Geoacoustic inversion of ocean surface-wave noise with a littoral glider.
Authors: Jones Billy D.
Published: October 2013

Passive acoustics can be used to characterize the ocean bottom in a littoral environment. Ocean surface-wave noise acts as a natural directional source that can be measured to obtain bottom loss and subsequently inverted to obtain bottom density, sound speed, attenuation, and layering structure. A physical ocean surface noise model is introduced and its horizontal/vertical spatial cross-correlations is discussed. Acoustical energy conservation and its relation to bottom loss are discussed. The measurement method is a continuation of the ambient noise inversion work of [J. I. Arvelo, Jr., J. Acoust. Soc. Am. 123, 679–686 (2008)]. Aggressive adaptive beamforming is used for high-resolution bottom loss measurements with surface-wave noise as a source. Ambient noise measurements with an eight-element wire polyvinylidene fluoride vertical line array mounted in the bow of a littoral glider are presented. Results from summer 2008 measurements in Port Madison, WA are presented and compared against known bottom loss curves for the area. [Work supported by SPAWAR.]
Using the holographic property of synthetic aperture sonar images to enable real aperture sonar navigation.
Authors: Rikoski Richard , Fernandez Jose
Published: October 2013

Synthetic aperture sonar (SAS) images contain broadband multiaspect information about a scene; this leads to several holographic properties. The most commonly understood property is that a complete image can be reconstructed at lower resolution from any subband of the Fourier transform; this effect is used for speckle reduction. A less commonly understood property is that a SAS image contains all possible real aperture images over some range of angles and frequencies. This allows real aperture images to be coherently correlated with SAS images. The ability to coherently correlate sonar images permits the use of a broad class of probabilistic feature-based navigation algorithms. This paper describes the method of coherently correlating SAS and real aperture images for navigation, and presents results from St. Andrew Bay and the Gulf of Mexico using the small synthetic aperture minehunter.
Spatial coherence?
Authors: Cox Henry
Published: October 2013

The term spatial coherence is frequently used to summarize the impact of the propagation environment on array performance and to suggest a limitation on useful array aperture. A source of considerable confusion is that there is no single widely accepted precise meaning of the term. In general, coherence implies a fixed phase relationship and involves time as well as space. The time duration over which the measurement is made or for which the phase relationship appears fixed is central to the measurements of coherence. A number of different measurements types and associated data analyses are described and the results are interpreted in terms of the pertinent aspects of acoustic propagation, such as multipath, surface and internal waves, etc. The effects of source and receiver motion are also considered. The implications for array performance and the robustness of beamforming approaches in the face of environmental variability and uncertainty are also discussed. Examples are given from recent shallow water experiments. [Work supported in part by NAVSEA Contract No. N00024-07-C-5210.]
Robust processing techniques for underwater acoustics.
Authors: Zurk Lisa
Published: October 2013

The performance of sonar signal processing methods in shallow water waveguides is highly sensitive to the effects of the acoustic wave propagation, and the nature of this propagation is often critically dependent on the exact nature of the underwater channel. Signal processing formulations that exploit the structure of the channel have been shown to increase detection and localization performance when the channel properties are known. However, for many tactical situations, channel parameters are poorly unknown or “uncertain,” thus motivating the need for robust processing techniques that do not require exquisite knowledge of the environment but may still exhibit the increased performance of full field methods. The goal of devising robust processing approaches remains of high interest and is an ongoing topic for signal processing research. This presentation first provides some metrics of environmental uncertainty and the effect on the sonar signal processing then provides a review of several proposed approaches for achieving robustness. The algorithms are grouped into the following three categories: robust matched field processing algorithms, guide source calibration techniques, and invariance processing (both passive and active). The presentation concludes with a discussion of ongoing research and future areas for investigation.
Geoacoustic tracking.
Authors: Yardim Caglar , Gerstoft Peter , Hodgkiss William
Published: October 2013

This paper shows how to incorporate tracking techniques such as the extended Kalman, unscented Kalman, and particle filters into geoacoustic inversion problems. This enables not only the inversion of environmental parameters but also the spatial and temporal tracking of them, making geoacoustic tracking a natural extension to geoacoustic inversion techniques. Water column and seabed properties are tracked in simulation and using the MAPEX2000 experimental data for both vertical and horizontal line arrays. Filter performances are compared in terms of filter efficiencies using the posterior Cramér–Rao lower bound. Tracking capabilities of the geoacoustic filters under slowly and quickly changing environments are studied in terms of divergence statistics. The suitability of each filter in geoacoustic tracking is discussed in terms of the track quality, complexity of the probability density function of environmental parameters, nonlinearity of the geoacoustic propagation, and computational cost. The results show that geoacoustic tracking can provide continuously environmental estimates and their uncertainties using only a fraction of the computational power of classical geoacoustic inversion schemes. [Work supported by ONR-N00014-05-1-0264.]
Aural architecture: The missing link.
Authors: Blesser Barry
Published: October 2013

While acoustic architecture focuses primarily on the acoustic physics of objects and geometries, aural architecture emphasizes the experience of space in terms of behavior and emotions. Because auditory spatial awareness, which is the basis for aural architecture, depends on a social value system, the role of acoustics varies among individuals and cultures. When evaluating the aural experience of space, two independent phenomena must be simultaneously considered: Space changes our experience of sound and sound changes our experience of space. Sound sources and spatial acoustics are inseparable. This bilateralism creates an interdisciplinary complexity that fuses physical and social sciences. Hearing is a means by which people acquire a sense of where they are, connecting them to dynamic events and spatial geometry. Auditory spatial awareness allows people to sense the elegance of a plush office, the emptiness of an uninhabited house, the depth of a dark cave, the quiet of a city covered in snow, the vastness of a railroad station, and the openness of a beach front. Each of these situations can be described in the language of aural architecture, which includes at least five types of experiential spatiality: navigational, social, aesthetic, symbolic, and musical.
Uncertainty in ocean acoustics.
Authors: Finette Steven
Published: October 2013

When modeling ocean-acoustic systems, the environmental information necessary to compute the acoustic field properties is assumed to be accurately specified by various parameters, fields, and boundary conditions. However, in real world applications, these quantities are subject to uncertainties due to our incomplete knowledge of the waveguide environment. This form of uncertainty involves errors that are quite distinct from the numerical errors that can arise when a mathematical model is discretized, implemented on a computer, and solved with finite precision arithmetic. In effect, the environmental uncertainty introduces spurious degrees of freedom into the system. In order to make reliable simulation-based predictions, this uncertainty needs to be quantified and incorporated in the simulation process itself. The idea of embedding uncertainty into the simulation framework and elevating its status to a subject worth studying on its own merits represents a paradigm shift that has stimulated research in several disciplines. This talk will overview recent approaches to this problem in an ocean-acoustic context and give examples of computations that have incorporated environmental uncertainty in the numerical computation of acoustic field properties. [Work supported by the Office of Naval Research.]
Hot topics in physical acoustics.
Authors: Gladden Joseph
Published: October 2013

The field of physical acoustics touches a broad range of technical areas important to fundamental science and society. This “Hot Topics” presentation will reflect the breadth of this impact by discussing the following three topics: sound waves in the early cosmos, acoustics in slip-stick friction systems, and acoustic metamaterials. The early universe, composed of hot ionized matter, was able to support acoustic waves until the temperature cooled enough to allow the formation of neutral atoms. The imprint of these relic acoustic waves is still evident in the cosmic microwave background and yields new information about key cosmological constants and dark matter. Earthquakes are perhaps the most destructive of natural disasters, as was painfully demonstrated by recent events in China. Studies on the effects of acoustic vibrations in slip-stick friction systems have begun to shed light on triggering mechanisms for earthquakes and may lead to better early warning systems. Metamaterials are man-made materials in which precise geometric arrays of structures are engineered to produce coherent scattering effects on scales much larger than the structures themselves. These systems can exhibit such exotic properties as a negative index of refraction, band gaps, and a negative effective elastic modulus.
Case study: Leadership in Energy and Environmental Design Platinum office building with innovation credit for acoustic design.
Authors: Roy Kenneth , Costello Amy , Snader Anita
Published: October 2013

During the fall of 2006, an existing corporate office building in Lancaster, PA was registered with USGBC for Leadership in Energy and Environmental Design (LEED) certification. In the spring of 2007, this building was awarded the highest achievement, a LEED-EB Platinum rating, only the sixth such award nationwide at that time. This level of performance was due in part to the achievement of an Innovation Credit 1.3 for superior acoustics. The building IEQ postoccupancy survey was evaluated by using the UC Berkeley, Center for the Built Environment, on-line survey tool. The survey results indicated problems with speech privacy performance in the open plan spaces, and a balanced design approach was taken to resolve that issue. Since this was the first such application for an innovation credit on the basis of acoustic design, it was first necessary to provide USGBC with proof that the acoustic environment does affect the health and performance of occupants and that a superior acoustic design can be developed compared to what is generally considered a typical design.
Leadership in Energy and Environmental Design for schools: Designing mechanical system noise control to be green, affordable, and meet requirements.
Authors: Bridger Joseph F. , Stulgin Steven S. , George Mathew M.
Published: October 2013

Leadership in Energy and Environmental Design (LEED) for schools has added classroom acoustics (based on ANSI S12.60) to the prerequisite for all K-12 schools seeking the U.S. Green Building Council LEED certification and several points for achieving additional measures. The Background Noise Level requirements of LEED for schools (U.S. Green Building Council) have several different compliance paths to meet the requirements. This paper explores the pros and cons of each and shares experience on how to design the HVAC noise system to meet the requirements for typical green building designs.
What can we learn from studying manatee vocalization patterns?
Authors: Miksis-Olds Jennifer L.
Published: October 2013

Vocalizations are assumed to form the basis of most long range communication in manatees, so studying how animals naturally use their vocalizations can provide insight into many aspects of the manatee acoustic communication system. Vocalizations were recorded from manatees in Sarasota Bay, FL over two nonwinter seasons. Recordings were made under a variety of conditions spanning different habitats, social groupings, behavioral states, environmental sound levels, and observation methods. Analysis of vocalization patterns indicates that manatee vocalization usage is highly context dependent. Patterns were observed to be a function of calf presence, behavioral state, and environmental sound levels. Additionally, vocalizations tended to separate into two distinct call types. Observed patterns will be discussed in the context of communication theory. Further analysis of the dataset has the potential to offer information relating to signal evolution, call function, and impacts of noise on manatee communication and behavior.
Source-height and frequency dependence in sensitivity analysis of near-ground sound propagation.
Authors: Pettit Chris , Wilson D. Keith
Published: October 2013

Computational forecasts of the near-ground sound pressure level (SPL) are key features of proposed frameworks for designing acoustic sensor networks. In many cases the local weather and terrain will not be known precisely enough to justify high confidence in forecasts of the probability of detection. The sensitivity of SPL forecasts to parameter variations therefore must be known in order to assess the probability of detecting acoustic disturbances in poorly characterized environments. To facilitate these assessments, we have expanded a recent framework for full-field sensitivity analysis (FFSA) throughout the parameter space. This new version continues to employ sampling methods, proper orthogonal decomposition, and cluster-weighted models to develop robust surrogate models for sensitivity analysis. Enhancements shown here include (i) locally linear functions in the cluster-weighted models, (ii) analytical differentiation in place of local response surfaces for computing sensitivities, and (iii) estimation of the forecast uncertainty in the sensitivities. These capabilities are used for FFSA of the near-ground SPL due to a harmonic point source operating at several frequencies. The governing parameters and source height are assumed to vary across wide but physically realistic ranges. The dependence of the forecast uncertainty on various factors is examined.
Comparison of three wind noise reduction strategies.
Authors: Raspet Richard , Webster Jeremy , Yu Jiao
Published: October 2013

Wind noise is a serious adverse factor in acoustic detection/location systems. Three types of wind noise reduction devices have been used in the past: streamlined probes, spherical wind screens, and surface mounted devices. When these systems are used outdoors near the surface of the ground, the largest contribution to the wind noise is the interaction of the device or surface with the atmospheric turbulence. The goal of our research program is to develop theories to relate measured wind and turbulence properties to the measured wind noise so that wind noise reduction methods can be optimized for any particular application. In this paper we will present measurements of wind noise reduction with devices using the three strategies listed and compare the reduction achieved. Advantages and disadvantages in a variety of applications will be discussed based on the theoretical predictions.
Cross-linguistic acquisition of vowels: English, Korean, Greek, and Cantonese.
Authors: Chung Hyunju , Edwards Jan , Weismer Gary
Published: October 2013

It has been widely claimed that vowels are acquired earlier than consonants. This is why relatively few studies have focused on investigating acquisition patterns of vowels. However, the acquisition patterns of consonants are not separable from those of vowels and a few studies [e.g., work of MacNeilage (1990)] suggest that vowel acquisition is more complicated than previously assumed. Furthermore, there is relatively little cross-linguistic research on how children master language-specific characteristics of vowels. While children show preferences for native-language vowels by 6 months of age, language-specific patterns in production emerge considerably later. This study examines cross-linguistic variation in the location of shared vowels in the vowel space across four languages: English, Korean, Greek, and Cantonese for 2-year-old, 5-year-old, and adults. The vowels /i/, /u/, and /a/ were elicited in familiar words using a word repetition task. Productions of target words were recorded and transcribed by native speakers of each language. First and second formant frequencies were measured for correctly produced vowels. Language-specific differences in the location of shared vowels were observed in the formant values of both children and adults. [This work was supported by a Fulbright Fellowship to H.C., and NIDCD Grant 02932 and NSF Grant 0729140 to J.E.]
Finite difference time-domain simulation of Scholte wave generation and propagation along a shallow waterway bottom containing an anomaly.
Authors: Muir Thomas , Lafleur Dwynn
Published: October 2013

Results are presented on a two-dimensional simulation of the generation and propagation of a Scholte wave pulse along a water-sediment interface in a shallow water waveguide, consisting of 12.5 m of water, overlying a like depth of sand sediment. An underwater sound source, 2.5 m above the sediment, generates a low-frequency Ricker wavelet, which propagates as “modal tone bursts” in the waveguide and the sediment. Some of the energy is partitioned into a propagating Scholte wave mode at the sediment interface, a planar surface containing an “anomaly,” i.e. a moundlike feature. Acoustic leakage into the elastic sediment is demonstrated, as is the propagation of the Scholte wave impulse moving along the interface and traveling over the anomaly, at a much slower velocity than its acoustic mode counterpart in the water column. The results are presented as a movie sequence, composed of snapshots of the spatial amplitude distribution of the Scholte wave as it propagates. Also presented are the modeled seismometer signals, yielding a two-dimensional particle velocity (hodographs) in the vertical plane at the anomaly, and somewhat beyond it. The significance of low-frequency Scholte waves in the acoustics of extremely shallow water is discussed.
A model of distant shipping noise.
Authors: Clark Cathy Ann , May Randall T. , Moore Kristy A.
Published: October 2013

Shipping noise from high-density areas is believed to migrate down the coastal shelf and propagate to long ranges via the deep sound channel, resulting in an increase in noise level at low angles for submerged receivers. A propagation calculation, which is applicable when a high degree of cycle mixing results in nearly random summation of path effects, is introduced and used to predict low-frequency (1–300 Hz), long range shipping noise. The vertical directionality of the noise is computed by fitting a source distribution within the deep sound channel by the method of least squares. Comparisons to a limited number of low-frequency measured data sets are presented.
Mitigating low-frequency sound with tunable acoustic chimneys.
Authors: Schnitta Bonnie , Freeedman Roy
Published: October 2013

A way to absorb and filter low-frequency sound that is generated by sound sources in one or more enclosures is described. A sound generating room is encapsulated within an outer acoustic absorbing room that contains various openings to several acoustic ducts. The acoustic ducts function as an acoustic waveguide to the open air. At each end of the acoustic duct is an impedance matching tapered acoustic horn. In the sound generating room the horn serves as an acoustic absorber that tapers sound into the acoustic duct. At the opposite end, the horn serves as an acoustic radiator of sound energy to the open air. Both radiator and absorbers may be tuned to transmit frequencies past a certain cutoff. The effect is similar to a pressure release valve. The acoustic waveguides may be coupled to tunable passive or active noise mitigation devices such as Helmholtz resonators and low-frequency noise sources that utilize phase information.
Microphone calibration.
Authors: Rasmussen Gunnar
Published: October 2013

Microphone calibration accurate acoustical measurements are desirable for legal reasons and for research and development. The uncertainty in acoustic measurements may cause uncertainty in determining improvement in design and development of products. International standards may still be improved for calibration of the measurement technique at low frequencies and at high frequencies especially. The absolute calibration of measurement microphones is dominated by reciprocity calibration. This has been dominating in acoustic metrology for many years and rightly so for the middle frequency range 100–1000 Hz. Other methods are very useful at low frequencies and at high frequencies with a good overlap to the reciprocity technique and may offer lower uncertainty especially for calibration in the field where the major part of acoustical measurements take place. Microphone comparison, piston phone calibration, scaling in microphone size at high frequencies, electrostatic actuator, and directionality are some of the techniques used in practical calibration work.
Frequency limitations of coupler-based calibrations of the pressure sensitivity of measurement microphones.
Authors: Zuckerwar Allan J. , Shams Qamar A.
Published: October 2013

Calibration of the pressure sensitivity of measurement microphones in a coupler requires by definition that the incident pressure be uniform over the surface of the microphone diaphragm. This requirement is readily satisfied at frequencies up to the cut in frequencies of the radial modes and, if the microphone is not azimuthally symmetric, the spin modes. Above the lowest natural frequency of either of these modes, the uniformity of the pressure distribution will be destroyed. This effect is alluded to in current standards, ANSI S1.15-2005/Part 2 and IEC 61094-5:2001, but the suggested countermeasure “to use more than one coupler with different dimensions” or to compare “calibrations performed in a variety of other jigs and couplers” does not resolve the problem. Specification of the maximum excitation frequency to preserve pressure uniformity in a coupler is presented for several laboratory standard and working standard microphones.
Standing waves on a string and electromagnetic induction.
Authors: Gladden Joseph
Published: October 2013

Standing waves on a string are a popular classroom demonstration which helps students understand such fundamental acoustic concepts as wavelengths, interference, and resonances. The close connection between this demonstration and stringed musical instruments helps bridge the gap between the science classroom and other interests they may have. In this version of the demonstration, we replace the string with a copper wire and add a permanent magnet. This allows the vibrations in the string to be directly translated into an electrical signal which can be broadcast through a standard stereo amplifier and speakers similar to an electric guitar pickup. The effects of string tension and length can then be explored. Alternatively, an ac can be driven through the wire creating a periodic driving force from the magnetic field of a precise frequency allowing standing waves to be established on the string. More advanced students can also examine the Fourier transform of the signal produced when the wire is struck and find peaks at the resonant frequencies.
Progress update from S12 working group 46: Relocatable classrooms.
Authors: Hardiman Tom
Published: October 2013

The purpose of forming working group 46 was to develop an amendment to ANSI S12.60-2002 that specifically focuses on the challenges and unique circumstances surrounding the design, construction, use, and relocation of relocatable classrooms. S12/WG46 is currently drafting an addendum to S12.60-2002 Guideline for Classroom Acoustics. This presentation will provide an update on the progress being made by S12 working group 46.
Exploration of alternative means to evaluate exterior noise loss.
Authors: Good Kenneth
Published: October 2013

The outdoor-indoor transmission class measurement can be problematic to execute due to many environmental and logistical issues. This leads to the following question: Can the measurement be made from the inside to the outside? This presentation will explore a technique to evaluate a building’s ability to block exterior sound by placing the source signal inside and measurement device on outside.
Turbulent boundary layer shear stress transmitted through a viscoelastic layer.
Authors: Capone E. , Bonness William K.
Published: October 2013

Transfer functions are developed for the transmission of unsteady shear stress, generated by a turbulent boundary layer in water, through a viscoelastic layer backed by a rigid plate. Existing analytical models are used to estimate the unsteady wall pressure and shear stress from 10–1000 Hz for a flat plate boundary layer with zero pressure gradient. A new model is developed for the transmission of unsteady shear stress through the viscoelastic layer. The model is used to predict the unsteady pressure fluctuations, or flow noise (due to the unsteady shear stress), which would be seen by a finite size sensor embedded under the elastomer layer. The calculated unsteady pressure and shear stress levels are in good agreement with recent experimental measurements. The unsteady shear stress transfer functions are found to have a peak at the acoustic wavenumber.
Diffuse field interferometry for experimental Green’s function estimation and damage detection.
Authors: Duroux Adelaide , Sabra Karim , Ayers James , Ruzzene Massimo
Published: October 2013

Structural health monitoring systems often rely on propagating elastic waves through complex structures, which can result in the formation of diffuse-fields over a long reverberation time. Recent theoretical and experimental studies have demonstrated that Green’s functions between a pair of monitored points can be extracted from cross-correlation of the recorded diffuse-fields (e.g., scattered fields or ambient noise). Knowledge of the Green’s functions between large numbers of points can be used to successfully identify and localize damage in complex structural components. In this work, Green’s functions are first estimated experimentally from full-field measurements obtained with a scanning laser vibrometer. This provides the wealth of a priori information necessary to detect and localize “secondary” sources, such as damages, when only a limited number of sensors are actually mounted on the structure. The proposed approach relies on the detailed knowledge of the structural response, which is exclusively obtained through experimental measurements performed on the actual component under consideration.
Recent improvements to the University of California, Los Angeles’ voice synthesizer.
Authors: Antonanzas-Barroso Norma , Kreiman Jody , Gerratt Bruce R.
Published: October 2013

A number of enhancements have recently been added to the UCLA voice synthesizer. Additions have been made to add functionality and to address several theoretical issues that arose during development and application. New functions include the ability to manipulate the source spectrum directly by changing the slope and/or amplitude of a user-defined group of harmonics or by manipulating individual harmonics directly. The synthesizer also allows users to add zeros to the vocal tract transfer function, improving the modeling of many pathological voices. A number of other enhancements improve the ability to create and systematically vary stimuli for perceptual experiments. Theoretical development has focused on the importance of pitch-synchronous Fourier analysis in modeling the voice source, particularly with respect to measuring and manipulating the amplitudes of H1 and H2. Issues surrounding spectral effects of upsampling, downsampling, and pulse stretching, which are needed for precise manipulation of F0, will also be discussed. This synthesizer is available with documentation as open source shareware at www.surgery.medsch.ucla.edu/glottalaffairs/, and copies will be available at the conference. [Work supported by NIH/NIDCD Grant No. DC01797.]
Hemisphere lateralization underlying auditory feedback control of voice F0.
Authors: Liu Hanjun , Meshman Michelle , Larson Charles
Published: October 2013

Reflexive compensation for unexpected pitch changes in auditory feedback for stabilization of voice fundamental frequency (F0) has been demonstrated using the frequency perturbation technique. However, neural mechanisms of the pitch-shift reflex are still unclear. This study investigated hemisphere lateralization in the auditory processing of pitch changes by using event-related potentials. During vocalization of sustained vowels, subject's voice pitch feedback was randomly shifted upward or downward 100, 200, or 500 cents with 200 ms duration. Simultaneously, brain activity was recorded through surface electrodes located on the scalp bilaterally referenced to linked earlobes. The results showed larger brain potentials (peak difference between P200 and N100) in the C3 (left) than in the C4 (right) site, indicating left hemisphere dominance in the central motor area, while right hemisphere dominance was found in the lateral frontal area with larger potentials in the F8 (right) than in the F7 (left) site. Furthermore, these patterns were maintained regardless of stimulus magnitude and stimulus direction. This preliminary study suggests that, although both left and right hemispheres are involved in voice production, functional lateralization of the brain may exist for voice F0 control. Results also suggest that lateralization varies along the anterior-posterior dimension of the neural axis.
Experimental study and theoretical simulation of stress relaxation behavior of vocal fold lamina propria tissue.
Authors: Zhang Yu , Keuler Megan , Jiang Jack
Published: October 2013

The viscoelastic properties of vocal fold lamina propria tissue play an important role in tissue modeling, as well as in clinical studies of the effects of carcinoma, scarring, atrophy, or edema on dysphonia. Although the impact of these properties has been well studied, quantification of viscoelastic behaviors such as creep and stress-relaxation continue to be important in the research. The current study examined the stress-relaxation curves of ten canine vocal fold cover samples by stretching the tissue to 5%, 10%, 15%, and 20% of the sample reference length. The force on the lamina propria tissue was then recorded for 5 mins, and graphed so the stress-relaxation response could be seen. The curves obtained were what we hypothesized, with the lamina propria tissue exhibiting exponential relaxation initially, and very slow decay at the end of the trial. These results are consistent with our previous studies on stress-relaxation predicted by the biphasic theory of vocal fold tissue [Zhang et al., J. Acoust. Soc. Am. 123, 1627–1636 (2008)]. Finite element simulation has also been given to investigate the stress distributions within the vocal fold epithelium and lamina propria tissues.
Tongue body movements in speech: Straight or curved paths?
Authors: Lfqvist Anders
Published: October 2013

This paper examines tongue body movements between two vowels with particular emphasis on the shape of the movement paths. Earlier work on tongue movements in speech has mostly focused on movements for consonants. The movements analyzed are from the first to the second vowel in a sequence of vowel-bilabial consonant-vowel. Native speakers of Japanese and Italian served as subjects. The linguistic material consisted of words with a long or short labial consonant. Recordings were made using a magnetometer. To assess the movement path, the movement magnitude was calculated in two ways as a straight line, the Euclidean distance, and as the actual path, obtained by summing the individual Euclidean distances between successive samples from movement onset to offset. The ratio between the path and the Euclidean distance is 1 when the movement is a straight line and greater than 1 when the path is curved. For most of the movements, the ratio was less than 1.1, thus suggesting that these movements are almost a straight line. There was no clear difference between movements during long and short labial consonants. [Work supported by NIH.]
The effects of roughness on the frequency dependence of specular scattering.
Authors: Isakson Marcia , Yarbrough R. Abe , Chotiros Nicholas
Published: October 2013

Specular scattering data were collected at grazing angles from 7 to 77 deg grazing and frequencies from 5 to 50 kHz at the experimental validation of acoustic modeling techniques (EVA) sea test near Isola in October 2006. High resolution microbathymetry data taken using a laser line scan system were also collected. The amplitude and phase of the specular scattered data exhibit a distinctive frequency dependence. This frequency dependence may be due to Bragg scattering from small interface ripples on the ocean bottom indicated by peaks in the measured interface roughness power spectrum. This study simulates the scattering using realizations of interface roughness in a finite element model to determine if the frequency dependence is due solely to scattering or if other mechanisms such as layering are important factors. Results will be compared to analytic approximations such as the Kirchhoff approximation as well as exact integral equations. [Work sponsored by the ONR, Ocean Acoustics.]
Scattering from an ocean bottom layer using steady-state and transient radiative transfer.
Authors: Quijano Jorge E. , Zurk Lisa M.
Published: October 2013

Research on volume scattering from a layered ocean bottom containing random media is usually conducted through methods based on the wave equation. Radiative transfer (RT) theory is an alternative formulation based on the conservation of energy and empirical laws that has the potential of being computationally more efficient and yet can provide considerable insight into the scattering phenomena. The RT theory has been successfully used in electromagnetic remote sensing and characterization of materials using ultrasound. In this work, the RT equation is applied to ocean acoustics to obtain the volume scattering from a layer of sand with flat boundaries overlying a limestone half space. Steady state results are presented to discuss the main processes that contribute to volume scattering and the transformation of energy between shear and longitudinal waves at the boundaries of the layer and at the scatterers. The transient solution of the RT equation as a function of frequency is outlined by introducing an incident pulse of infinitesimal duration that approximates an impulse. The time domain response for a broadband pulse of finite duration is then obtained by convolution with the computed impulse response, which would allow comparison with experimental chirp sonar data. [Research sponsored by the Office of Naval Research, Grant No. N000140510886.]
Model for scattered field from a vertically extended target in a range-dependent ocean waveguide.
Authors: Küsel Elizabeth , Ratilal Purnima
Published: October 2013

A model for the scattered field from a vertically extended target in a range-dependent ocean waveguide is developed by application of Green’s theorem. The model is implemented with the parabolic equation (PE) method for a vertically extended pressure-release cylinder, such as the BBN target. The local scattered field at the surface of the target is approximated by the sum of Hankel functions. The total scattered field is calculated using Kirchhoff’s integral approximation to Green’s theorem. Results of calculations for a Pekeris waveguide show good agreement with the Ingenito normal-mode-based model for target scattering in a waveguide. A limitation with the Ingenito scattering model is that the target has to be located within an isospeed layer. The PE-based scattering model developed here, on the other hand, is able to take into account sound speed variations along the vertical extent of the target. We show that using the Ingenito model in a layered waveguide with the vertically extended target can lead to inaccuracies in estimating the scattered field. Illustrative examples are also provided for range-dependent environments.
Classroom acoustics: Moving toward needed regulation.
Authors: Thibault Lois
Published: October 2013

This year, the U.S. Access Board voted to pursue regulation of classroom acoustics. The initiative born just a decade ago from Mike Nixon’s advocacy for adequate listening conditions in schools can now move forward toward enforceability with a new ADA standard based on ANSI/ASA S12.60-2002, the voluntary standard recently reballotted by ASA. Today, Connecticut requires its new schools to meet the S12.60 standard; the LEED sustainability credential rewards good acoustics in its school evaluations, and California’s High-Performing Schools movement recognizes acoustical performance. Armed with data Nixon collected and shared and connected by the classroom acoustics LISTSERV he established, stakeholders have been able to influence scores of jurisdictions to require new school designs to address classroom acoustic performance. Nixon’s work in improving public understanding of the need for good classroom acoustics has made today’s regulatory agenda possible: he provided both the tools and the energy used to build an effective constituency for quiet classrooms. The community of support Nixon encouraged among parents, educators, audiologists, acousticians, and advocates is a necessary underpinning for progress toward regulation. This paper will document the history and anticipate the future of classroom acoustics regulation, focusing on building and access code process and provisions.
Investigation and analysis of urban noise for sustainability.
Authors: Orozco-Medina Martha G. , Figueroa-Montao Arturo , Garca-Velazco Javier
Published: October 2013

The concept of urban sustainability involves complex issues such as civil services, social participation, resilience, productivity, health, and development into a multilevel approach of environmental, social, and productivity sectors. Viewing environmental noise as part of urban dynamics is essential. However it is almost absent or underestimated in most current environmental, social, and health policies in the developing world. Efforts to investigate noise pollution toward analysis, regulation, fulfillment, inspection, and fines contribute in a positive way to improve acoustic quality within urban communities. Therefore the ultimate goal for decision makers is to consider noise as a key issue when establishing or discussing management policies of urban areas and to transfer the approach to lower levels with preventive and educational measures, rather than restrictive or prohibited, in order to attain sustainability of urban communities.
Characteristics of porous-hose infrasonic wind-noise-reducing filters.
Authors: Hetzer Claus , So Jin , Talmadge Carrick , Raspet Richard , Webster Jeremy , Shields Douglas
Published: October 2013

Spatial wind-noise-reducing filter technologies are widely used in infrasound recording because wind is the primary source of noise in this frequency band. While permanent infrasound arrays often make use of large solid-pipe rosette spatial filters, portable or temporary arrays must use other materials, the most popular of which is porous garden hose. While undeniably effective at reducing wind noise, porous hoses have distinct frequency-dependent effects on signal amplitudes and by changing the phase response of the microphone can have deleterious effects on bearing accuracy. In this presentation the effects of the use of porous-hose wind-noise-reducing filters are discussed, both in terms of the effectiveness of noise reduction and the effects on signal characteristics.
On the relationship between the perception and learning of Hindi voicing and place contrasts by native speakers of American English.
Authors: Harnsberger James D.
Published: October 2013

Many non-native speech sounds are challenging to perceive and, ultimately, to acquire. Predicting specific learning outcomes from perceptual data has been hampered by (1) problems in quantifying acoustic-phonetic similarity between non-native and native sounds, (2) calculating the perceptual weighting of acoustic cues in the native language, and (3) the high-variability commonly observed in the perceptual assimilation of non-native contrasts to multiple native categories. This variability may reflect long-term persistent patterns in learning or it may represent only a brief early stage prior to fossilization. To examine these two possible accounts, the perceptual assimilation by 15 American English listeners of 7 voicing and place contrasts produced by 6 Hindi speakers was examined before and after training in a paired-associate word learning task. Training utilized tokens from four of the six talkers used in perceptual assimilation tasks. The purpose of the study was to determine whether or not assimilation patterns could be greatly modified and simplified by very limited experience in acquiring the contrasts via word learning. The results showed that limited laboratory training significantly reduced talker and token variability in perceptual assimilation and allowed for non-native contrasts to be categorized more cleanly in terms of their predicted difficulty in learning.
Effects of childhood exposure to a second language on the production of voice onset time and closure duration.
Authors: Harada Tetsuo
Published: October 2013

This study compares the production of voice onset time (VOT) and closure duration for singletons and geminates in Japanese by English-speaking university students who were exposed to Japanese in an immersion program in childhood and those regular university students who had no previous exposure to Japanese. 20 informants enrolled in a third-year Japanese were asked to repeat several target words including initial /p, t, k/ for VOT, and medials /p, t, k/ and /pp, tt, kk/ for singletons and geminates in a sentence frame. Both VOT of the initial stops and closure duration of the medial stops were measured. The results show that the immersion graduates’ VOT values in Japanese were shorter (i.e., more Japanese-like) than those of the learners who had had no exposure to Japanese in childhood (p<0.05). For the production of closure duration, although the learners of Japanese without childhood L2 experience did not distinguish singletons from geminates, the immersion graduates did (p<0.005). The findings may suggest that long-term benefits of L2 experience in childhood in the naturalistic setting, which were found in the work of Knightly et al. (2003), may also apply to the instructional setting like immersion education.
An epenthetic vowel between consonantal sequences in perception and production by Japanese.
Authors: Sperbeck Mieko , Strange Winifred
Published: October 2013

Native Japanese have a strong tendency to epenthesize a vowel when producing consonantal sequences in English. This study investigated how Japanese learners of English perceive and produce word-initial CCV versus CəCV contrasts (e.g., sport versus support). Two types of tasks were employed: a categorial ABX task for perception and a delayed imitation task for production. Nonsense words of the form /C1C2ani/ (e.g., spani) and /C1əC2ani/ (e.g., sepani) served as the stimuli where C1C2 combinations were /s-p/, /s-t/, and /s-k/. In the ABX task, participants heard three short sentences that contained the target words and answered whether the third target word was the same as the first or the second one. In the delayed imitation task, participants heard the production of a native speaker in a carrier sentence (e.g., say sepani now) twice and produced the target word in isolation and then in the carrier sentence. Japanese participants made both perception and production errors. Interestingly, the majority of errors in the production task were vowel deletion for the CəCani contexts rather than vowel epenthesis for the CCani contexts. The relationship between perception and production among L2 learners as well as influence of L1/L2 phonotactic differences will be discussed.
The perception of English lexical stress by native Thai speakers.
Authors: Jangjamras Jirapat
Published: October 2013

This study investigates the influence of L1 stress patterns and stress cues on the perception of L2 lexical stress. Thai and English were examined due to their prosodic differences such as the stress pattern and native perceptual correlates of stress. Thai, being a tone language, has a fixed stress pattern and employs the duration contrast as the primary stress cue. In contrast, English has a variable stress pattern and employs a combination of acoustic cues such as F0, duration, intensity contrast, and vowel reduction. Perceptual difficulties by listeners from a fixed-stress background have been reported in L2 stress discrimination and identification tasks. In this study, two groups of listeners, 35 Thai and 10 American English (AE), identified the stress location of disyllabic English nonwords produced by a trained phonetician using the above stress cues except vowel reduction. The preliminary results show similar mean scores between the two groups with a bias toward initial stress in misidentified tokens by AE listeners. Further analysis will report the reaction time analysis and the interaction between the syllabic structure and stress location.
A shape variable acoustic panel system for multipurpose rooms
Authors: Andria Ken , Kleiner Mendel
Published: October 2013

This work proposes an acoustically effective alternative to current passive acoustic solutions. Typical systems involve moving panels to one of either reflective, absorptive, or diffusive surface states. By varying the shape of an array of ceiling reflectors, acousticians can achieve more precise control of the room response to better serve a wider range of acoustic scenarios. The results of scale model testing show how a single system can direct, absorb, or diffuse sound energy so that the room will be appropriate to four distinct programmatic events: lectures, gathering, simultaneous sources, and flat effect. By including microphones and a digital signal processing system the panel system may be designed to adaptively change its behavior to suit that of the current room use.