bluuebunny/crossref_metadata_2025 huggingface dataset:
Relating physiology to perception: The case of the notched-noise masker
Authors: Carney Laurel H.
Published: May 2015

Sharpness of peripheral tuning is an essential factor in auditory signal processing. The notched-noise (NN) masking paradigm (Patterson, 1976, JASA) is an ingenious strategy used in numerous studies to estimate peripheral tuning bandwidths, filter shapes, and level-dependence in normal and impaired ears. Interpretation of NN results is based on the power-spectrum model of masking; however, the fact that NN thresholds are little influenced by a roving-level paradigm calls this interpretation into question (Lentz et al., 1999, JASA). Here, we explore neural cues for detection in NN in auditory-nerve (AN) and midbrain (inferior colliculus, IC) responses. Strong low-frequency fluctuations in AN discharge patterns associated with sharp spectral edges provide effective inputs for midbrain neurons tuned to low-frequency fluctuations. Addition of a tone target reduces the fluctuations in some frequency channels, creating a strong contrast in the fluctuation profile along the frequency axis. We explore the NN paradigm using computational models for AN and amplitude-modulation (AM) tuned IC neurons. Recordings from band-pass AM tuned neurons in the IC of awake rabbit support the hypothesis that the midbrain response profile can explain perception in the NN paradigm. Interpretation of NN masking results should include not only peripheral tuning but also central processing mechanisms.
Vibration isolation design of railroad tracks within Ankara high speed train station
Authors: Alan Salih , Caliskan Mehmet
Published: May 2015

Ankara serves as a hub for high speed railway operations within Turkey. A new station building of nine stories in total, which also incorporates a shopping mall and a hotel inside, is currently under construction. Need arises for controlling vibrations due to passing trains through the building. Finite element model of the building is developed by commercial software. The interaction of the building with the foundation is represented by a number of spring and damper combinations whose characteristics are obtained from the existing knowledge of soil-structure interactions. The dynamic stiffness characteristics of isolating layer under the railway slabs are sought. The FRF’s between several floors of the building and the base of the track are obtained from the finite element model, to be coupled with FRF’s of the train-track-isolating layer system. Vibration isolation design is carried with respect to vibration criteria in Turkish environmental noise regulations.
Refinements to the relaxation model for sound propagation in porous media
Authors: Wilson D. K.
Published: May 2015

The relaxation formulation for sound propagation in porous media [D. K. Wilson, J. Acoust. Soc. Am. 94(2), 1136–1145 (1993)] was intended to provide a phenomenologically correct model with relatively simple equations. This paper presents several refinements, which connect the relaxation model more clearly to others in the literature, and clarify interpretation of the parameters. In particular, the relaxation function is applied to the dynamic tortuosity (rather than the inverse of the complex density), and the vorticity and thermal relaxation times are related directly to the length scales of Allard and Champoux [J.-F. Allard and Y. Champoux, J. Acoust. Soc. Am. 91(6), 3346–3353 (1992)]. When formulated in this manner, the relaxation and Allard-Champoux models coincide exactly in the low-frequency/small-pore and high-frequency/large-pore limits, although interpolation between these limits differs somewhat. The revised relaxation model can be readily transformed into a causal time-domain model, involving convolutions between the acoustic fields and a relaxation response function. The basic formulation has five parameters: porosity, static flow resistivity, tortuosity, and two relaxation times. A sequence of model reductions is described, leading finally to two-parameter (porosity and static flow resistivity) equations for the impedance and complex wavenumber, which provide a useful generalization of the Delany-Bazley equations.
Acoustical Society of America Helmholtz-Rayleigh Interdisciplinary Silver Medal in Signal Processing in Acoustics, Underwater Acoustics, and Engineering Acoustics: Henry Cox
Authors: Penrod Clark S. , Spindel Robert C. , Kuperman William A. , Cable Peter G.
Published: May 2015

The Silver Medal is presented to individuals, without age limitation, for contributions to the advancement of science, engineering, or human welfare through the application of acoustic principles, or through research accomplishment in acoustics.
Acoustical Society of America Gold Medal: Gerhard M. Sessler
Authors: Reinhard Lerch , West James E.
Published: May 2015

The Gold Medal is presented in the spring to a member of the Society, without age limitation, for contributions to acoustics. The first Gold Medal was presented in 1954 on the occasion of the Society’s Twenty-Fifth Anniversary Celebration and biennially until 1981. It is now an annual award.
Investigating the effect of arrival time of diffuse reflections on listener envelopment
Authors: Cudequest Brandon , Pastore M. Torben , Braasch Jonas
Published: May 2015

Listener Envelopment (LEV) is a quality of diffuse sound fields, and a highly sought after attribute of performance venues. However, the ability for an enclosure to achieve ideal, diffuse sound field is often difficult, and varies from space to space. Thus, a rigid transition time between early and late energy is an insufficient way of evaluating LEV. Current theories on listener envelopment focus on the arrival time of the reflections within the impulse response, but typically disregard the diffusivity of these reflections, building on the fact that the impulse response generally becomes more diffuse over time. An alternative model is proposed, where the listener envelopment is determined by both the diffusivity and the arrival time of reflections. The model disregards the current 80-ms criterion and also allows reflections earlier then this to contribute to LEV. A 64-channel wave field synthesis system is used to perceptually evaluate the effects of spatially and temporally diffuse sound components as a function of arrival time.
Marketing architectural acoustics to non-acousticians (a.k.a. the unwashed masses)
Authors: Diaquila Samuel V.
Published: May 2015

Architects understand aesthetic issues: color, texture, glare, serenity, excitement, as well as mechanical issues; fire suppression, air changes, and restroom requirements. Their thought process rarely considers the intangible world of acoustics. Their clients (the “owner”) is even further removed. In today's construction environment, how does the acoustical consultant market his or her services successfully to decision makers who are faced with ever decreasing budgets and an ever increasing bombardment of information? Even more challenging is ensuring that the acoustical consultant's recommendations are implemented. Learn ways to awaken your potential client’s sensitivity and awareness of acoustics. Changing your sales presentation from a technical (acoustical consultants are generally “blind”), relying on computer generated acoustical reports that resemble mathematical thesis papers to an emotion based technique (potential clients are generally “deaf”), that brings the science of acoustics to life at a tangible human level. Everyone reacts to bad acoustics, with the exception of concert halls and restaurants, acoustics is rarely discussed and often not one of the end user’s priorities until there is a problem needing a retrofit.
Practical desktop full-wave architectural acoustic solutions
Authors: Murray Patrick , Cipolla Jeff , Hapij Adam
Published: May 2015

An explicit, time-domain, finite-element method is shown to calculate the reverberation time in realistic acoustic spaces using desktop computing resources. The reverberation time is defined as the time required for reflections of direct sound to decay 60 dB, and is also the principal quantity in architectural acoustics across the frequency ranges of interest. Current industry practice for calculating the reverberation time involves empirically derived formulae which cannot account for the architectural complexity of modern acoustic spaces or the detailed placement of acoustic treatments. Computing advances over the past several years have made it possible to calculate the reverberation time using finite element models in the time domain. Explicit finite-element codes are distinct from traditional ones because they operate by integrating the governing equations of mass, momentum, and energy in the time domain, avoiding the need for matrix generation, storage, and factorization. The feasibility of this full-wave approach is demonstrated using the configurations of real example acoustic spaces. Comparison is made with empirical calculations and experimental measurements. It is also shown how the enhancements can be made to a space by the addition of acoustic damping material.
Beyond ISO3382—Measuring acoustics with live sound
Authors: Griesinger David H.
Published: May 2015

Current acoustic measurements techniques typically require time and heavy equipment. The effort and expense would be justified if the results accurately predicted the sound quality from a performance at an individual seat, but they do not. If one believes that it is possible to hear and accurately report sound quality from live sound in different seats, then it must be possible to measure it this way. This paper describes a model of human hearing that promises to provide this ability, at least for quality aspects relating to clarity. The model is based on the ease with which information is carried from one or more sources to a listener. For speech, this involves both reverberant masking from late reverberation, and interference to the direct sound from early reflections. To make such a measurement, we need to model how the ear and brain system precisely localizes sound sources, and separates their sound from each other and acoustic interference without added information from context, grammar, or prior knowledge. A description of such a model will be presented, along with results obtained from live sound.
Acoustic adventures over continents, among cultures: Under tides of academia and profession
Authors: Sü Gül Zühre
Published: May 2015

After obtaining a Bachelor of Architecture and an MFA with an emphasis in amphitheater acoustics, I was accepted into Rensselaer Polytechnic Institute’s unique Graduate Program in Architectural Acoustics. There I completed an MS degree focusing on architectural acoustics in coupled spaces and was honored to receive the Robert Newman Award, a TCAA Student Paper Award and an ASA commendation for student design. Since 2006 I have applied my academic focus to design projects, first at RBDG Inc. in Dallas, and later at home in Turkey at MEZZO Stüdyo, the firm I co-founded in 2009. Turkish governmental supports have afforded MEZZO the opportunity to become a critically recognized “R&D incubator.” We’ve also completed over one hundred design projects, both in-house and teamed with architectural-engineering groups around the world and are proud members of NCAC (National Council of Acoustical Consultants). During the restricted times of not managing my firm—and my 3-year-old son!—I enjoy giving university lectures to inspire future generations about exciting diversities in the field of acoustics. Luckily, I just completed my PhD degree on Architectural Acoustics again, and I am much proud and happy to share this whole adventure.
Strategies for guiding undergraduate acoustics students through independent research projects
Authors: Ronsse Lauren M.
Published: May 2015

Students in the B.S. Acoustics Program at Columbia College Chicago must successfully complete an independent research project as part of the curriculum. Since this is the first independent research experience for most of the students, measures are taken to guide them through the research process. Also, an electronic research notebook tool has been developed, providing a structured format for the students to document their research. The teaching techniques employed to prepare and guide the undergraduate acoustics students through the research process will be described. Recent student research projects that utilized the electronic research notebook reporting format will also be highlighted.
Cultureshock Los Angeles: A midwesterner’s guide to acoustics, food trucks, and surfing
Authors: Rawlings Samantha
Published: May 2015

Samantha Rawlings & Joshua Magee were awarded a Student Paper Award at the Fall 2007 Acoustical Society of America conference in New Orleans for undergraduate research on sound radiation from footfall noise. This student project paved the way for Samantha to move to Los Angeles to join Veneklasen Associates, which was a wholly un-looked for opportunity for someone who once laughed outright at a Hardees commercial showing a hamburger wrapped in lettuce. Since moving to LA, Samantha has become a LEED AP and Project Manager and has had the chance to work on projects of all size and scope; everything from the “mystery noise” cold call to landmark project such as City Creek Center in Salt Lake City and Wilshire Grand in downtown Los Angeles. Additionally, Samantha has participated in research projects that have been presented at ASA, NoiseCon, and Internoise conferences. In this presentation, Samantha reflects on the surprising events of the past seven years and the adventure of learning to fit in and love Southern California.
Parallels in scattering research between architectural and underwater acoustics
Authors: Olson Derek R.
Published: May 2015

Acoustical scattering is a central area of research in the fields of underwater and architectural acoustics. Although the mathematical formulation of the scattering problem is common to both fields, their goals and environments have motivated divergent analysis techniques, and quantities associated with the pressure field due to scattering. One of the primary differences is the role of statistical averaging. Ensemble-averaged quantities can often be used in ocean acoustics because the seafloor may have statistically homogeneous roughness and geoacoustic properties over large areas. In the built environment, the acoustic field can interact many times with a single acoustic diffusor, and deterministic properties of the scattered field are of greater import. Acoustical quantities such as the scattering cross section, scattering coefficient, and the diffusion coefficient will be defined and compared. Examples will be given that highlight cases when ensemble-averaged quantities can aid or hinder design of acoustical diffusors, depending on the design constraints.
Effects of conductor verbal and nonverbal instructions on changes in singer voicing behaviors: A survey of recent research
Authors: Manternach Jeremy N.
Published: May 2015

Vocal and choral music professionals seek to guide their singers to efficient and beautiful vocal production. They do so using a multitude of techniques, some of which have been passed along from one generation of teachers to the next. These techniques include giving singers a particular focus of attention and displaying varied conducting gestures designed to evoke specific voicing behaviors. Despite the prevalence of these techniques, few researchers have investigated whether they consistently change the acoustical output or the muscle engagement used by individual singers or choristers. This presentation provides an overview of recent research that has sought to quantify the voicing behaviors of individual singers as they (a) sang a short melody while focusing on various internal or external foci, (b) viewed varied conductor preparatory (inhalation) gestures prior to singing a short melody, and (c) viewed varied conductor final release (cutoff) gestures at the end of a short melody. The resulting acoustical, biomedical, and perceptual data inform the pedagogical implications that are discussed throughout.
An approach to communicating in-field acoustical performance to architects as it relates to end user experience
Authors: Lesser Ari M. , Wells Adam P.
Published: May 2015

A study was conducted within an industry leading architecture firm to benchmark the noise isolation class, background noise level, and reverberation time throughout the firm’s spaces. Testing was conducted in accordance with the general guidelines of ASTM E336-14, ANSI S1.13, and ASTM E2235-04. Acoustical test results were compared to employee subjective satisfaction survey responses in an effort to bridge the gap between acoustical design recommendations and end users’ expectations and experiences of their environment. [Work supported by Cerami & Associates, Inc.]
Application of time-warping to passive acoustic remote sensing
Authors: Godin Oleg A. , Ball Justin S. , Brown Michael G. , Zabotin Nikolay A. , Zabotina Liudmila Y. , Zang Xiaoqin
Published: May 2015

Interferometry of ambient and shipping noise in the ocean provides a way to estimate physical parameters of the water column and the seafloor without employing any controlled sound sources. With noise interferometry, two-point cross-correlation functions of noise serve as the probing signals and replace the Green’s function measured in the active acoustic remote sensing. The amount of the environmental information, which can be obtained with passive remote sensing, and robustness of the estimates of the water column and the seafloor parameters are expected to increase, when contributions of individual normal modes can be resolved in the noise cross-correlation function. Using the data obtained in the 2012 noise-interferometry experiment in the Straits of Florida [M. G. Brown et al., Geophys. Res. Lett. 41, 5555–5562 (2014)], this paper demonstrates the feasibility of normal mode decomposition of the noise cross-correlation function measured by two hydrophones. The normal modes are resolved by using time-warping, a signal processing technique that has been previously successfully employed to separate normal modes generated by a wide-band compact sound source in shallow-water waveguides. The passively measured dispersion curves of acoustic normal modes are inverted for geoacoustic parameters of the seafloor. [Work supported by NSF and ONR.]
Spectrum of sound intensity fluctuations due to mode coupling in the presence of moving nonlinear internal waves and bottom parameters estimation
Authors: Katsnelson Boris , Grigorev Valery , Lynch James
Published: May 2015

Temporal fluctuations of intensity of sound pulses (300±30 Hz) are studied in the presence of nonlinear internal waves (NIW) moving at the some angle with direction of an acoustic track providing mode coupling. In the episode of Shallow Water 2006 experiment, considered in the work, angle between wave front of NIW and source-receiver direction is about 10 degrees. It was shown that there is main maximum in the spectrum measured at fixed depth ~8 cph and set of smaller peaks ( ~15 cph, ~25 cph, and ~35 cph) in accordance with the theory proposed by authors earlier. Besides, there is maximum in the spectrum of total intensity (summarized over depth or over all hydrophones of vertical line array) at the frequency ~15 cph. In authors opinion, the last one is determined by coupling of propagating modes (excited by the source) having maximal difference in modal attenuation coefficients (in given case modes 2 and 4). Role of horizontal refraction is small. Using the spectrum speed of NIW and bottom attenuation coefficient (in our case ~0.2 dB/wavelength) are determined. Mentioned parameters are in a good agreement with estimations obtained by other methods. [Work was supported by BSF.]
Direct inversion for sediment sound speed in ocean acoustics
Authors: Lin Tao , Michalopoulou Zoi-Heleni
Published: May 2015

A fast direct approach for estimating sediment sound speed is presented, building on a previously developed technique. The algorithm inverts for the seabed sound speed employing low frequency measurements. The Deift-Trubowitz integral equation is solved by using sound pressure after a Hankel Transform. A modified Born approximation is implemented that improves on previously obtained results, followed by an interpolation method which provides a further improvement. Although the approaches initially rely on assumptions about the sound speed at infinity, we show that the assumptions can be relaxed without affecting the performance. The methods are stable with noise-free data, but problems arise when noise is added to the acoustic field. It is demonstrated that a regularization technique remedies the problem. [Work supported by ONR.]
Change-point detection for recursive Bayesian geoacoustic inversions
Authors: Tan Bien Aik , Gerstoft Peter , Yardim Caglar , Hodgkiss William S.
Published: May 2015

In order to carry out geoacoustic inversion in low signal-to-noise ratio (SNR) conditions, extended duration observations coupled with source and/or receiver motion may be necessary. As a result, change in the underlying model parameters due to time or space is anticipated. In this paper, an inversion method is proposed for cases when the model parameters change abruptly or slowly. A model parameter change-point detection method is developed to detect the change in the model parameters using the importance samples and corresponding weights that already are available from the recursive Bayesian inversion. If the model parameter change abruptly, a change-point will be detected and the inversion will restart with the pulse measurement after the changepoint. If the model parameters change gradually, the inversion (based on constant model parameters) may proceed until the accumulated model parameter mismatch is significant and triggers the detection of a change-point. These change-point detections form the heuristics for controlling the coherent integration time in recursive Bayesian inversion. The method is demonstrated in simulation with parameters corresponding to the low SNR, 100–900 Hz LFM pulses observed in the Shallow Water 2006 experiment.
Plane nonlinear shear waves in relaxing media
Authors: Cormack John , Hamilton Mark F.
Published: May 2015

Due to very low shear moduli for soft tissue or tissue-like media, shear waves propagate very slowly, on the order of meters per second, making it relatively easy to produce shear waves exhibiting waveform distortion and even shock formation. Finite amplitude effects in plane shear waves result from cubic nonlinearity, compared with quadratic nonlinearity in compressional waves. Both attenuation and dispersion also significantly affect propagation of shear waves in tissue. Here we account for these complex viscoelastic effects by considering a medium with one relaxation mechanism. An analytical solution similar to that of Polyakova, Soluyan, and Khokhlov [Sov. Phys. Acoust. 8, 78 (1962)] for a compressional wave with a step shock in a relaxing medium is obtained for a shear wave with a step shock in a relaxing medium. The wave profile with cubic nonlinearity closely resembles that with quadratic nonlinearity. For weak nonlinearity the solution reduces to an expression obtained by Crighton [J. Fluid Mech. 173, 625 (1986)] for a Taylor shock in a viscous medium with cubic nonlinearity. Numerical simulations are presented comparing shock formation with quadratic and cubic nonlinearity for other wave profiles in relaxing media. [Work supported by the ARL:UT McKinney Fellowship in Acoustics.]
Sensors, dynamics, and control: Program overview and relevance to acoustics research
Authors: Ruzzene Massimo
Published: May 2015

The talk will provide an overview of the sensors, dynamics, and control program, its goals, its funding levels, and its priorities. Specifically, the talk will address topics and research directions that are relevant to the acoustics community at large. Such topics include vibration and noise control, dynamic-based structural health monitoring, wave propagation in complex media, nonlinear dynamics, and acoustic metamaterials. Examples of currently funded projects and ideas for future investigations will be provided to facilitate the discussion. The SDC program supports fundamental research on the analysis, measurement, monitoring, and control of dynamic systems, including development of new analytical, computational and experimental tools, and novel applications to engineered and natural systems. Dynamics is the science of systems that change in time. Control concerns the use of external influences to produce desired dynamic behaviors. Diagnostics concerns the use of observation to infer information about a dynamic system. Objectives of the SDC program are the discovery of new phenomena and the investigation of innovative methods and applications in dynamics, control and diagnostics. The intellectual merit of proposals submitted to the SDC program will be evaluated on the basis of fundamental innovation in foundational areas, on alignment with the core disciplines of the CMMI Division, and on potential for transformative impact within and across disciplinary boundaries.
Understanding the social media medium
Authors: Pyzdek Andrew T.
Published: May 2015

With social media platforms like Twitter, Facebook, and Tumblr largely dictating how information is viewed and shared online, Marshall McLuhan’s famous statement that “The medium is the message” has never been more true. While it is possible to share the same message over multiple platforms with minimal variation, success is borne when a unique approach is tailored to each one. This talk will focus on the affordances of each social media platform and how those should inform not only your use of social media but also your choice of platform. Special attention will be payed to common uses for social media in acoustics: disseminating original research, establishing connections within the field, advocating science, and educating a general audience on acoustics. Also presented is my personal experience educating a lay-person audience about acoustics as a moderator of the AskScience subreddit and the curator of the Listen To This Noise blog on Tumblr, and how these platforms differ both in content and form.
Professional development with social media
Authors: Rundquist Andy
Published: May 2015

I was lonely. I realized that my colleagues didn't always share my particular passions about teaching and research. Reaching out online using twitter, the Global Physics Department, and blogs has helped me find a community that supports me, challenges me, entertains me, and teaches me. Prompts like “Help! I teach normal modes tomorrow and I need better examples” and “how fast do whistlers settle on a frequency” draw me into the community where I hear several, sometimes conflicting, views that then motivate me to learn. My requests about things like whether minimizing the area between a sound wave and a particular sine wave is akin to finding a Fourier coefficient (it isn't) connect me with experts who don't roam my hallways. I'll talk about how I engaged with my various learning communities and how I've developed various workflows to leaverage them.
Using Twitter to disseminate acoustics information: Planning and measurement using marketing science and sociophysics
Authors: Norris Lawrence
Published: May 2015

While many people use Twitter for many different purposes, it is an amazing tool for disseminating scientific information. There are several serious tools for marketing products, information, and people via Twitter. Indeed, a body of science in marketing and sociophysics is available to plan campaigns on Twitter and to measure their efficacy. In this talk, I will discuss tools and methods that the acoustics community can use to engage science students at all levels, their teachers, and parents, as well as other acousticians, policy-makers, and the general public.
Infrasonic analysis of the October 28, 2014 Antares rocket failure at Wallops Island, Virginia, using video recordings as ground truth
Authors: Pulli Jay J. , Kofford Aaron
Published: May 2015

We used close-in video recordings of the October 28, 2014 Antares rocket failure at Wallops Island, VA to establish an event timeline to aid in the analysis of infrasound recordings made at nearby stations of the IRIS Transportable Array. Our timeline is ignition at 22:22:38 UTC, liftoff at + 4 s, bright plume and first explosion at an altitude of 300 m at + 15 s, second large explosion as the rocket hits the ground at + 25 s, followed by the excess fuel burn lasting some 400 s. Both explosions and the fuel burning events are seen in the infrasound data recorded at IRIS station S61A at a distance of 23 km, and the two explosions can be seen out to distances of 130 km. High resolution time frequency analyses of the infrasound signals at the distant stations show a dispersed signal from 0.5–8 Hz with a peak at 1.7 Hz and corresponding group velocity of 360 m/s. This dispersion curve corresponds to a low velocity duct at the surface with a thickness of approximately 1.2 km. The relatively fast group velocity can be attributed to the prevailing winds. Explosion yield estimates using the BOOM model indicate equivalent TNT yields of 20 and 200 tons for the two explosions. Co-located seismic and infrasound sensors at two stations allow us to estimate the acoustic-to-seismic spectral ratio at 1–10 μm/s/Pa. However, low coherence between the acoustic and seismic signals implies a non-linear transfer function at the sites.
Infrasound propagation and model reduction in randomly layered media
Authors: MILLET Christophe
Published: May 2015

A consensus has emerged within the infrasound research community that gravity waves are filtered out in the available atmospheric models. Apart from occasionally strong lower-atmospheric effects, the major wave influences occur in the middle atmosphere, between 10 and 110 km altitudes. In the present approach, the unresolved gravity waves are represented as a random field that is superimposed on the average background state, and the wave equation is solved using a reduced-order model, starting from the classical normal mode technique. The reduced model is obtained by retaining a few propagating modes, with the aim of simplifying the acoustic model to the point that the predicted statistics of waveforms are correct, even though some small irrelevant details is lost. We focus on the asymptotic behavior of the transmitted waves in the weakly heterogeneous regime, for which the coupling between the wave and the medium is weak. The statistics of a transmitted broadband pulse are computed by decomposing the original pulse into a sum of modal pulses that can be described by a front pulse stabilization theory. Specifically, it is shown how reduced-order models can be used to explain some aspects of the variability of large infrasound datasets.
Hamiltonian ray tracing in an arbitrary curvilinear coordinate system—Amplitude estimation
Authors: Blom Philip , Arrowsmith Stephen J.
Published: May 2015

Acoustic ray tracing is known to be an efficient and robust numerical method to compute propagation paths of acoustic energy through the atmosphere and ocean. Over large propagation distances, a Cartesian formulation of ray tracing is known to be inadequate and a spherical or spheroidal formulation is required in order to obtain accurate propagation paths. An overview of the ray tracing equations in an arbitrary curvilinear coordinate system will be presented and compared with the known spherical coordinate formulation. Typically, coaxial ray paths are used to compute ray tube density and provide an estimation of the amplitude along the ray path. Here, the method of auxiliary parameters is used to identify the exact geometric spreading factor along individual ray paths. The implementation of the resulting ray tracing methods will be discussed including methods used to decrease computation time and planned additions to the propagation scheme.
Localizing sound sources when the listener moves: Vision required
Authors: Yost William , Zhong Xuan
Published: May 2015

In an article under review at JASA, we showed that when the listener rotates, determining the rotational direction of sound moving from loudspeaker to loudspeaker or if the sound is fixed at one loudspeaker location requires two forms of information: information provided the auditory spatial cues (e.g., interaural differences) AND information about the position of the head/body. Primary head/body position cues are provided by vision (and to some extent by the vestibular system and probably by other sensory and cognitive systems). In this paper, we address a very simple question which, as far as we know, has not been asked before: What is sound source localization accuracy when the listener moves? A sound source localization identification task was used to measure root-mean-square-errors (rms) in degrees in the full azimuth plane. Different stimuli were used and listeners were either rotated at a constant velocity or were stationary. They listened with their eyes open or closed. When listeners had no visual or others forms of information about head/body position (e.g., eyes closed) and, thus, all they had were the auditory spatial cues (e.g., interaural difference) sound source localization accuracy was very poor. [Research supported by an AFOSR grant.]
Auditory illusions arising from lack of visual clues
Authors: Waller Steven J.
Published: May 2015

Auditory illusions arising from lack of visual clues will be discussed and related to prehistoric cave art and Stonehenge. In the ancient past, when the wave characteristics of sound were not understood, virtual sound effects arising from complex sound wave interactions (echoes, reverberations, interference patterns, etc.) were misinterpreted as invisible beings (echo spirits, thunder gods, sound absorbing bodies, etc.) as described in ancient myths around the world. Scientifically conducted experiments involving blindfolded participants show how various ambiguous sounds can be interpreted in more than one way—like optical illusions. The blindfold in this case is a metaphor for ignorance of the wave nature of sound. It is proposed that ancient peoples were looking at the apparent source of sound and not seeing anything, and so concluded that the sounds emanated from beings that could not be seen. These experiments thus can help in understanding our ancestors’ perceptions and reactions to sounds they considered mysterious and spooky. These discoveries are just a few examples of research findings that are springing from the new field of Archaeoacoustics. See https://sites.google.com/site/rockartacoustics/ for further examples.
The role of articulatory cues in the establishment of perceptual categories
Authors: Cibelli Emily
Published: May 2015

This study investigates the interaction of perceptual and articulatory information in the acquisition of non-native phoneme categories. There is evidence that perceptual learning can improve production of target sounds in a new language, but the reverse—improvement of perceptual discrimination from articulatory learning—is less well-studied (for one example, see Catford and Pisoni 1970). In this experiment, native English speakers learned Hindi coronal stop contrasts (dental vs. retroflex; 4-way VOT contrast) in a pre-test/training/post-test paradigm. Training involved production training, where subjects got explicit instruction about place of articulation and voicing of the target sounds, and practiced producing them. Comparison of pre- and post-test performance on an AX discrimination task indicated greater accuracy (β = 0.486, t = 2.763) and faster responses (β = −0.215, t = −3.396) for most target contrasts after training. (Those contrasts which did not improve tended to map onto English phonemic distinctions, and were well-discriminated at pre-test.) This result supports the hypothesis that articulatory information can contribute to the early development of novel perceptual categories under certain conditions. More generally, it suggests that information from one speech domain can be used to support representations in another speech domain.
Articulatory and acoustic correlates of English front vowel productions by native Japanese speakers
Authors: Mehta Sonya , Katz William F.
Published: May 2015

Speakers of languages having a relatively small vowel inventory (e.g., Japanese) may experience interference effects when attempting to produce novel vowels from a language with a larger vowel inventory, such as English. Studies of English vowels produced by native Japanese speakers have shown formant frequency and duration differences between native and accented productions. Less is known about the exact articulatory processes underlying second language vowel learning. The current study examines tongue position during native Japanese speakers’ productions of American English vowels. Ten speakers produced the front vowels /i/, /ɪ/, /e/, /ε/, and /æ/ while seated in a 3D electromagnetic articulograph (EMA) system that tracked the position of the tongue (tongue tip, TT, tongue dorsum, TD, and tongue back, TB) and lower lip during vowel productions in the consonant environment /hVd/. Kinematic and acoustic measures were taken at the midpoint of each vowel steady-state portion. Differences in tongue position for tense-lax vowel pairs were determined by calculating the Euclidean distance between vowel centroids. Preliminary results suggest more spatial overlap in vowels produced by Japanese talkers than those produced by monolingual English speakers. The relationship between these articulatory distances and acoustic measures (formant frequency and durational changes) will be explored.
On the fricative vowels in Suzhou Chinese
Authors: Hu Fang , Ling Feng
Published: May 2015

Apical vowels are widely distributed in Chinese dialects, whereas fricative vowels or strident vowels are less known. This paper is an acoustic and articulatory study of fricative vowels in the Suzhou dialect of Wu Chinese. The acoustic data from 20 speakers show that the fricative vowels have formant patterns between their plain and apical counterparts. Linguographic data from four speakers reveal that more laminal part of the tongue is involved in the production of the fricative vowels than their plain counterparts, which are basically anterodorsal. And the EMA study from three speakers confirms a comparatively advanced lingual configuration in the production of the fricative vowels. Although the production of fricative vowels is characterized by visible turbulent frication from the spectrograms, and a significantly lower harmonics-to-noise ratio, the results suggest that spectral characteristics of fricative vowels and apical vowels play a more important role in defining the vowel contrasts. That is, plain high vowels, fricative high vowels, and apical vowels distinguish in place of articulation, namely, being anterodorsal, laminal, and apical, respectively. And frication could be treated as a concomitant and redundant feature in the production of fricative or apical vowels.
Phonation type contrasts and vowel quality in Marathi
Authors: Berkson Kelly , Politzer-Ahles Stephen
Published: May 2015

Phonation-type contrasts in consonants and vowels are typically associated with a number of acoustic differences. Phonemic breathy phonation, for instance, is fairly consistently associated with lower Cepstral Peak Prominence values than modal sounds, and with higher values for spectral measures such as H1-H2 and H1-A3. The effect of breathy phonation on vowel quality, however, is less consistent: lower first formant (F1) values have been found for breathy vowels in some languages, while others do not show consistent F1 differences based on phonation type. Furthermore, at present little work has investigated the effect of breathy voiced consonants on formant values in subsequent vowels. The current study presents data from Marathi, an Indic language with phonemically breathy-voiced obstruents and sonorants. Ten native speakers (five males and five females) produced real words that included the vowels [a] and [e] after both modal and breathy consonants. The effect of consonant phonation type on F1 and F2 values in subsequent vowels is reported in order to augment our understanding of the relationship between voice quality differences and vowel quality.
Persian speakers of English: Acoustics of vowel epenthesis
Authors: Akbari Christina C. , Aoyama Katsura , Dembowski James
Published: May 2015

This study results from the need to develop further understanding into the process of vowel epenthesis which is often observed with second language learners. The purpose of this study was to examine the epenthetic vowels produced by Persian speakers of English to determine the acoustical characteristics and to ascertain if these vowels were acoustically different or similar to the main vowels. Past research indicated that at times the vowels could be copies of the main vowels but at other times they were different. However, no acoustical data were provided in regards to the acoustical characteristics of the epenthetic vowels (durations, F1, and F2 frequencies). Twenty Persian speakers of English took part in the study. All participants arrived in the United States after the age of 22. All of the participants demonstrated limited English proficiency on a standardized measure. The results indicated that the epenthetic vowels produced were qualitatively different from the main vowels in terms of duration, F1, and F2 frequencies.
Phonetic context effects in second-language phonetic category discrimination
Authors: Ogden Dave C.
Published: May 2015

In an exemplar-based model, effects of linguistic experience in L2 acquisition are explained as the conspiracy of experienced tokens in reshaping phonetic category representations (Goldinger, 1998; Johnson, 1997). Such a model predicts that acquisition of a new category is facilitated in phonetic contexts, which are highly dissimilar to L1 experience. This prediction was tested for English-speaking learners’ acquisition of the prevoicing-short lag bilabial stop contrast in French. In a phoneme-monitoring task, French learners heard French CV words and responded whenever they heard “the sound p.” Word-initially, [p] exemplifies the category /b/ in English but /p/ in French. French vowels included English-like [i u e o] and front rounded non-English [y ø]. If learners' stop category representations retain experienced stops in context, stop tokens preceding [y ø] fall only in the French pre-voicing [b] to short-lag [p] VOT range, while stops preceding [i u e o] include tokens of both languages’ categories ([b], [p], and [ph]). This should lead to faster identification of unaspirated [p] as an instance of /p/ before French-only [y ø] than before shared vowels. Identification of [p] as /p/ was significantly faster before French-only vowels; representations of phonetic segments appear to include information about phonetic context.
The production of Korean coronal obstruents by inexperienced English-speaking learners of Korea
Authors: Park Hanyong
Published: May 2015

English-speaking learners of Korean often experience difficulty in learning Korean laryngeal categories (i.e., fortis, lenis, and aspirated). We examine whether the degree of difficulty in producing these laryngeal categories generalizes across the whole coronal obstruent system (i.e., stops and fricatives) and two different prosodic locations (i.e., CV and VCV). In our experiment, English-speaking college students taking first semester Korean course read a list of Korean frame sentences with target stimuli. The target stimuli consist of three coronal stops /t t’ th/ and two coronal fricatives /s s’/ combined with the vowel /a/ in CV and VCV. To assess production accuracy, native speakers of Korean are asked to identify the consonants from the learners’ productions. Results indicate that lenis categories are the most difficult across stops and fricatives in the two prosodic locations, suggesting that the learners develop production skills for laryngeal contrast applicable across the entire obstruent system. However, the degree of difficulty patterns are not similar in CV and VCV: the learners were more accurate producing /th/ in VCV than in CV. Thus, these findings suggest that the learners develop the production skills separately for different prosodic locations.
Articulatory targets for coronals in Taiwan Mandarin: A study of EMA, palatography, and linguagraphy
Authors: Chen Wei-rong , Chang Yuen-chin
Published: May 2015

Coronal consonants hold a special status for their crowded space for articulatory contrasts. Mandarin and its variants are known to have rich inventories of coronal consonants, where a three-way coronal place contrast is usually maintained. Nonetheless, previous studies have reported a (partial) neutralization of coronal places of articulation in Taiwan Mandarin, while other acoustic studies contend that the three-way contrast remains. The aim of this study is to evaluate the purported coronal neutralization from an articulatory perspective. Five native speakers of Taiwan Mandarin participated in a set of electromagnetic articulographic (EMA), palatographic and linguagraphic experiments in order to investigate the articulatory targets of coronal consonants in Taiwan Mandarin. Our articulatory results are in general consistent with the acoustic results in previous studies, in that the three-way coronal place contrast does exist in Taiwan Mandarin, and the so-called “retroflexes” in Taiwan Mandarin were produced with constrictions being at “alveolar” zone, rather than “postalveolar” zone as in Beijing Mandarin.
Articulatory similarity in rhotic sounds: A cross-linguistic comparison
Authors: Boyce Suzanne , Hamilton Sarah M. , Rivera Campos Ahmed , Nair Varsha
Published: May 2015

The question of what phonetic quality defines rhotics as a natural class has been debated. Clinical reports indicate that in many languages, rhotics are developmentally late to emerge and subject to errors that are resistant to remediation, suggesting that rhotics may be distinguished by “complexity in articulation.” In American English, the complexity of articulation may derive from its doubly articulated nature; simultaneous palatal and pharyngeal tongue constrictions are consistent features across variants. For other languages with a rhotic liquid, however, it is unclear if this pharyngeal constriction gesture is also an articulatory feature. Using ultrasound, this study compares rhotics from different language families to describe the presence or absence of pharyngeal constriction. Results indicate that pharyngeal constriction is observed across languages in rhotic allophones that have been described as difficult for children to acquire.
A kinematic analysis of Japanese /r/: Effects of syllable position and vowel context
Authors: Katz William F. , Mehta Sonya , Berglund Amy
Published: May 2015

Japanese /r/ is claimed to vary substantially as a function of context. Greater stricture is thought to occur after pauses and at initial syllable position when compared with intervocalic position. The environment of certain vowels is thought to result in changes to the degree of lateralization of /r/. However, few studies have investigated the articulatory processes involved in realizing the varieties of Japanese /r/ production. To address this issue, we obtained speech recordings for ten native talkers of standard Japanese using an Electromagnetic Articulography (EMA) system. Each talker produced 12 repetitions of /ra/, /ri/, /ru/, /re/, /ro/ in a carrier phrase designed to contrast syllable boundaries: /sore wa VCV VCV desu # CV/ (e.g., “This is ara ara [pause] ra”). Kinematic data were recorded with sensors placed on the tongue tip (TT), tongue body (TB), tongue left lateral (TL), tongue right lateral (TR), and lower lip (LL) positions. Results to date suggest syllable-initial (post-pausal) /r/ has the greatest stricture, followed by the first VCV production. Productions also showed vowel-dependent differences, with /a/ and /o/ showing noticeable lateral movement patterns. The kinematic data will be compared with perceptual ratings of /r/ quality by native English speakers.