bluuebunny/crossref_metadata_2025 huggingface dataset:
Propagation of nonlinear acoustic plane waves in an elastic gas-filled tube
Authors: Bednarik Michal , Cervenka Milan
Published: October 2009

This paper deals with modeling of nonlinear plane acoustic waves propagating through an elastic tube filled with thermoviscous gas. A description of the interactions between gas and an elastic tube wall is carried out by the continuity equation of a wall velocity. Simplification on the basis of the local reaction assumption enables to model an acoustic treatment on the tube wall by using a wall impedance. Because there are considerable losses due to wall friction, the influences of the acoustic boundary layer were also considered. Using certain assumptions a special form of the Burgers equation was derived which enables to describe the propagation of nonlinear waves in the elastic tube. This model equation takes into account nonlinear, dissipative, and dispersion effects which compete each other. Characteristic lengths of the supposed effects and numerical results with respect to the source frequency were used for a qualitative analysis of the model equation. Applicability of this model equation was demonstrated by series of measurements. By application of the long-wave approximation the Korteweg–de Vries–Burgers and Kuramoto–Sivashinsky equations were derived from the modified Burgers equation.
Diotic and dichotic detection with reproducible chimeric stimuli
Authors: Davidson Sean A. , Gilkey Robert H. , Colburn H. Steven , Carney Laurel H.
Published: October 2009

Subject responses were measured for individual narrow-band reproducible stimuli in a low-frequency tone-in-noise detection task. Both N0S0 and N0Sπ conditions were examined. The goal of the experiment was to determine the relative importance of envelope and fine-structure cues. Therefore, chimeric stimuli were generated by recombining envelopes and fine structures from different reproducible stimuli. Detection judgments for noise-alone or tone-plus-noise stimuli that had common envelopes but different fine structures or common fine structures but different envelopes were compared. The results showed similar patterns of responses to stimuli that shared envelopes, indicating the importance of envelope cues; however, fine-structure cues were also shown to be important. The relative weight assigned to envelope and fine-structure cues varied across subjects and across interaural conditions. The results also indicated that envelope and fine-structure information are not processed independently. Implications for monaural and binaural models of masking are discussed.
Effect of boundary slip on the acoustical properties of microfibrous materials
Authors: Umnova Olga , Tsiklauri David , Venegas Rodolfo
Published: October 2009

A variety of new porous materials with unusually small pores have been manufactured in the past decades. To predict their acoustical properties, the conventional models need to be modified. When pore size becomes comparable to the molecular mean free path of a saturating fluid, the no-slip conditions on the pore surface are no longer accurate and hence the slip effects have to be taken into account. In this paper, sound propagation in microfibrous materials is modeled analytically, approximating the geometry by a regular array of rigid parallel cylinders. It has been shown that velocity and thermal slip on a cylinder surface significantly changes the model predictions leading to lower attenuation coefficient and higher sound speed values. The influence of material porosity, fiber orientation, and size on these effects is investigated. Finite element method is used to numerically solve the oscillatory flow and heat transfer problems in a square array of cylindrical fibres. Numerical results are compared with predictions of the analytical model and the range of its validity is identified.
Fractal ladder models and power law wave equations
Authors: Kelly James F. , McGough Robert J.
Published: October 2009

The ultrasonic attenuation coefficient in mammalian tissue is approximated by a frequency-dependent power law for frequencies less than 100MHz. To describe this power law behavior in soft tissue, a hierarchical fractal network model is proposed. The viscoelastic and self-similar properties of tissue are captured by a constitutive equation based on a lumped parameter infinite-ladder topology involving alternating springs and dashpots. In the low-frequency limit, this ladder network yields a stress-strain constitutive equation with a time-fractional derivative. By combining this constitutive equation with linearized conservation principles and an adiabatic equation of state, a fractional partial differential equation that describes power law attenuation is derived. The resulting attenuation coefficient is a power law with exponent ranging between 1 and 2, while the phase velocity is in agreement with the Kramers–Kronig relations. The fractal ladder model is compared to published attenuation coefficient data, thus providing equivalent lumped parameters.
Integration of auditory and vibrotactile stimuli: Effects of phase and stimulus-onset asynchrony
Authors: Wilson E. Courtenay , Reed Charlotte M. , Braida Louis D.
Published: October 2009

The perceptual integration of 250 Hz, 500 ms vibrotactile and auditory tones was studied in detection experiments as a function of (1) relative phase and (2) temporal asynchrony of the tone pulses. Vibrotactile stimuli were delivered through a single-channel vibrator to the left middle fingertip and auditory stimuli were presented diotically through headphones in a background of 50 dB sound pressure level broadband noise. The vibrotactile and auditory stimulus levels used each yielded 63%–77%-correct unimodal detection performance in a 2-I, 2-AFC task. Results for combined vibrotactile and auditory detection indicated that (1) performance improved for synchronous presentation, (2) performance was not affected by the relative phase of the auditory and tactile sinusoidal stimuli, and (3) performance for non-overlapping stimuli improved only if the tactile stimulus preceded the auditory. The results are generally more consistent with a “Pythagorean Sum” model than with either an “Algebraic Sum” or an “Optimal Single-Channel” Model of perceptual integration. Thus, certain combinations of auditory and tactile signals result in significant integrative effects. The lack of phase effect suggests an envelope rather than fine-structure operation for integration. The effects of asynchronous presentation of the auditory and tactile stimuli are consistent with time constants deduced from single-modality masking experiments.
Riverbed sediment classification using multi-beam echo-sounder backscatter data
Authors: Amiri-Simkooei AliReza , Snellen Mirjam , Simons Dick G.
Published: October 2009

A method has recently been developed that employs multi-beam echo-sounder backscatter data to both obtain the number of sediment classes and discriminate between them by applying the Bayes decision rule to multiple hypotheses [Simons and Snellen, Appl. Acoust. 70, 1258–1268 (2009)]. In deep water, the number of scatter pixels within the beam footprint is large enough to ensure Gaussian distributions for the backscatter strengths and to increase the discriminative power between acoustic classes. In very shallow water (<10m), however, this number is too small. This paper presents an extension of this high-frequency methodology for these environments, together with a demonstration of its performance using backscatter data from the river Waal, The Netherlands. The objective of this work is threefold. (i) Increasing the discriminating power of the classification method: high-resolution bathymetry data allow precise bottom slope corrections for obtaining the true incident angle, and the high-resolution backscatter data reduce the statistical fluctuations via an averaging procedure. (ii) Performing a correlation analysis: the dependence of acoustic backscatter classification on sediment physical properties is verified by observing a significant correlation of 0.75 (and a disattenuated correlation of 0.90) between the classification results and sediment mean grain size. (iii) Enhancing the statistical description of the backscatter intensities: angular evolution of the K-distribution shape parameter indicates that the riverbed is a rough surface, in agreement with the results of the core analysis.
A comparative analysis of acoustic energy models for churches
Authors: Berardi Umberto , Cirillo Ettore , Martellotta Francesco
Published: October 2009

Different models to improve prediction of energy-based acoustic parameters in churches have been proposed by different researchers [E. Cirillo and F. Martellotta, J. Acoust. Soc. Am. 118, 232–248 (2005); T. Zamarreño et al., J. Acoust. Soc. Am. 121, 234–250 (2006)]. They all suggested variations to the “revised” theory proposed by Barron and Lee [J. Acoust. Soc. Am. 84, 618–628 (1988)], starting from experimental observations. The present paper compares these models and attempts to generalize their use taking advantage of the measurements carried out in 24 Italian churches differing in style, typology, and location. The whole sample of churches was divided into two groups. The first was used to fine-tune existing models, with particular reference to the “μ model,” which was originally tested only on Mudejar-Gothic churches. Correlations between model parameters and major typological and architectural factors were found, leading to a classification that greatly simplifies parameter choice. Finally, the reliability of each model was verified on the rest of the sample, showing that acoustic parameters can be predicted with reasonable accuracy provided that one of the specifically modified theories is used. The results show that the model requiring more input parameters performs slightly better than the other which, conversely, is simpler to apply.
Talker-to-listener distance effects on speech production and perception
Authors: Cheyne Harold A. , Kalgaonkar Kaustubh , Clements Mark , Zurek Patrick
Published: October 2009

Simulating talker-to-listener distance (TLD) in virtual audio environments requires mimicking natural changes in vocal effort. Studies have identified several acoustic parameters manipulated by talkers when varying vocal effort. However, no systematic study has investigated vocal effort variations due to TLD, under natural conditions, and their perceptual consequences. This work examined the feasibility of varying the vocal effort cues for TLD in synthesized speech and real speech by (a) recording and analyzing single word tokens spoken at 1 m≤TLD≤32 m, (b) creating synthetic and modified speech tokens that vary in one or more acoustic parameters associated with vocal effort, and (c) conducting perceptual tests on the reference, synthetic, and modified tokens to identify salient cues for TLD perception. Measured changes in fundamental frequency, intensity, and formant frequencies of the reference tokens across TLD were similar to other reports in the literature. Perceptual experiments that asked listeners to estimate TLD showed that TLD estimation is most accurate with real speech; however, large standard deviations in the responses suggest that reliable judgments can only be made for gross changes in TLD.
Informational masking in young and elderly listeners for speech masked by simultaneous speech and noise
Authors: Agus Trevor R. , Akeroyd Michael A. , Gatehouse Stuart , Warden David
Published: October 2009

Three experiments measured the effects of age on informational masking of speech by competing speech. The experiments were designed to minimize the energetic contributions of the competing speech so that informational masking could be measured with no large corrections for energetic masking. Experiment 1 used a “speech-in-speech-in-noise” design, in which the competing speech was presented in noise at a signal-to-noise ratio (SNR) of −4dB. This ensured that the noise primarily contributed the energetic masking but the competing speech contributed the informational masking. Equal amounts of informational masking (3dB) were observed for young and elderly listeners, although less was found for hearing-impaired listeners. Experiment 2 tested a range of SNRs in this design and showed that informational masking increased with SNR up to about an SNR of −4dB, but decreased thereafter. Experiment 3 further reduced the energetic contribution of the competing speech by filtering it into different frequency bands from the target speech. The elderly listeners again showed approximately the same amount of informational masking (4–5dB), although some elderly listeners had particular difficulty understanding these stimuli in any condition. On the whole, these results suggest that young and elderly listeners were equally susceptible to informational masking.
Steady state and time-dependent energy equilibration in two-dimensional random elastic slabs
Authors: Wan Yanyi , Wu Ying , Zhang Zhao-Qing
Published: October 2009

The static and dynamic transport properties of elastic wave propagation through two-dimensional random slabs without internal reflection were studied at two different scattering parameters: one for Rayleigh scattering and the other for Rayleigh–Gans scattering. The spatial distribution and temporal evolution of shear (s−) and compressional (p−) wave energy densities inside the slabs were calculated by solving the radiative transfer equation and the generalized diffusion equation (GDE). The comparison of their results can determine the region of validity of the GDE. The process of energy equilibration between the two wave modes was demonstrated explicitly as well as the process of diffusion. The depth inside a slab that is needed to reach energy equilibration or diffusive behavior is found to be dependent on source polarization. The results also show that the bulk equilibration ratio can be found inside a sample only when the sample is sufficiently thick. Deviations of the equilibration ratio from its bulk value are found near the output surface due to the absence of in-flow energy flux. The behavior of the deviations is sensitive to the scattering parameter but independent of source polarization.
Mixing studios complications.
Authors: Hoover K. Anthony
Published: October 2009

A new suite of mixing and teaching studios had been discussed for many years at Berklee College of Music in Boston. The authorization to proceed with design and construction of the studios finally came with a new Dean of the Music Technologies Department, who, without benefit of much of the background and previous discussions, contacted an old colleague for the final studio design and contracted with a reputable full-service contractor for construction services. Problems developed during construction, which apparently sensitized the client to subsequent situations, in turn requiring acoustical consulting services. This paper will review some of the project history, outline the problems, and discuss solutions and recommendations, and will address some of the concerns with the specialized construction and unusual complications.
Key planning steps for performance based designs.
Authors: Cushner Joshua
Published: October 2009

In architecture and engineering, leading firms will often value the opportunity to collaborate with unconventional clients to create bespoke building designs. However, such projects also require greater early planning and create new risks for the project team to manage. When generating “customized” designs with a specific tenant in mind rather than simply relying on industry standards for similar facilities, the rigors of a performance-based design must be understood. This case study reviews a project where key planning steps for this type of design approach were overlooked, which created conflicting project goals that were never fully resolved. While efforts were made by team members over time to improve collaboration, the process-related problems which manifested early in the project persisted, and the design team was never able to establish cohesion amongst themselves or with the owner. This case study details the main elements which predicated the project failures and suggests alternate approaches which could have better served the goals of the project. As a more successful framework, a broadened use of the performance-based design model is reviewed.
Biggest mistakes encountered on projects without acoustical consultants.
Authors: Markham Benjamin , Wagner Alicia , Fullerton Jeffrey , Hinckley Jennifer
Published: October 2009

As consultants, the authors have been called into dozens of projects built without the benefit of guidance from an acoustician, and the results are often disastrous (and in many cases, litigious). This presentation, replete with photographic evidence, outlines some of the biggest mistakes encountered recently by design teams that lack a critical team player: the qualified acoustical consultant. Consider a natatorium with all hard surfaces and a 6-s reverberation time to match, a fieldhouse gymnasium with a 70-dB background noise level, and a distressingly common problem in New England: residential condominiums converted from an old mill building with nothing between stacked residences except exposed, unimproved hardwood decking. Other examples relate to inadequate (or altogether absent) vibration isolation of elevator machinery and other mechanical equipment, cacophonous restaurant acoustics, blatant disregard for a nearby railway, and poor music practice facilities.
Center for the studies of nonlinear dynamics, 1982–1985.
Authors: Henyey Frank S.
Published: October 2009

Stan Flatte was the third director of the Center for the Studies of Nonlinear Dynamics (CSND), from 1982 to 1985 (and for another year after he returned to Santa Cruz). Upon joining CSND, he assembled a group to work on the path integral method for predicting internal wave effects on acoustic propagation in the ocean. This talk discusses the work done by that group. Topics of this work include travel time bias, relation to moment equation methods, fourth moment calculations, and pulse spread.
Scaling turbulent dissipation and finestructure: The wave-propagation method.
Authors: Duda Timothy F.
Published: October 2009

In the 1980s the team of Flatté et al. developed a theory relating the turbulent kinetic energy dissipation rate in the open ocean to finestructure feature observations (1–100 m scale), building on work of Henyey and Pomphrey. Formulas derived from this work are now prevalently used for indirectly estimating cross-isopycnal ocean mixing, a process of critical interest, using platforms and sensors unable to directly measure viscous-scale dissipation and associated turbulent transport processes. The method originally involved the internal-wave energy level. Revisions of the method introduced by follow-on investigators involve internal-wave shear and strain. The physics behind the method is that short-wavelength shear-rich internal waves propagate in a background of larger-scale internal waves, with action conserved, and can have their energy concentrated spatially. The concentrated waves are inferred to break, and in doing so provide the energy to support diapycnal mixing. The approach is one of “wave propagation in random media,” a specialty of Flatté.
Ray methods in long-range deep ocean sound propagation.
Authors: Brown Michael G. , Udovydchenkov Ilya A. , Rypina Irina I.
Published: October 2009

Although ray methods have limitations, they remain extremely important because they provide insight into the underlying wave propagation physics that is difficult, if not impossible, to obtain by any other means. In this talk the utility of ray methods in long-range deep ocean sound propagation will be discussed and illustrated. Topics to be discussed include ray-mode duality and action quantization; adiabatic invariance for rays and modes; beamforming and Radon transforms; caustics and catastrophes; travel time sensitivity kernels, Fresnel zones and other measures of ray widths; nonlinear resonances, KAM theory, and mode coupling; the waveguide invariant and its ray equivalent; and beam dynamics—from weakly divergent to explosive. [Work supported by ONR.]
Acoustic signal horizontal coherence variability: Relationship to internal tide and storm events.
Authors: Orr Marshall H. , Mignerey Peter C. , Walsh David
Published: October 2009

Acoustic signal horizontal coherence has been extracted from a 31-day data set taken during the late fall/early winter time period. The coherence variability for both 300- and 500-Hz acoustic signals appears coupled to shelf/slope frontal motion, internal tides, and associate internal waves as well as changes in the surface gravity field. Acoustic signal and environmental data illustrating the coupling will be presented. The data were taken on the New Jersey Shelf with a 460-m-long bottomed array placed in ∼89 m of water. The cross shelf propagation range was ∼20 km. The acoustic sources were in ∼60 m of water.
Cross-mode coherences and decoupling of equations for mode intensities in two-dimensional and three-dimensional fluctuating ocean.
Authors: Voronovich Alexander G. , Ostashev Vladimir E. , Colosi John A. , Morozov Andrey K.
Published: October 2009

Sound waves propagating in the ocean are scattered by internal waves (IWs) and spice. A modal approach for studies of low-frequency, long-range sound propagation in a fluctuating ocean seems to be the most adequate. This approach has been employed in a number of works, including recently published papers [A. G. Voronovich and V. E. Ostashev, J. Acoust. Soc. Am. 125, 99–110 (2009)] and [J. A. Colosi and A. K. Morozov, J. Acoust. Soc. Am. 124, 2598 (2008)]. Based on these two papers, in this presentation important aspects of sound scattering in a fluctuating ocean are considered for both two-dimensional (2-D) and three-dimensional (3-D) geometries. First, we compare equations for the coherence function of a sound field in 2-D and 3-D fluctuating ocean. Then, decoupling of equations for the mode intensities from equations for the cross-mode coherences is studied for the two geometries. Numerical examples of evolution of the mode intensities and cross-mode coherences with range are presented and discussed. Finally, insonification of an acoustic shadow zone by sound waves scattered by IWs is studied. [Work supported by ONR.]
Antipodal acoustic propagation and a half-century of ocean warming.
Authors: Dushaw Brian D.
Published: October 2009

In 1960, sound signals traveling from Perth, Australia were recorded at Bermuda. Previous work focused on the path traveled by the sound [Munk et al., JPO, 1876–1898 (1988)]. Calculation of the horizontal refraction of sound, across the Southern Ocean in particular, gave the perplexing result that Bermuda was in the shadow of Africa. Heaney et al. [J. Acoust. Soc. Am., 2586–2594 (1991)] used low-resolution atlases for global sound speed and bathymetry to obtain two viable acoustic paths between Perth and Bermuda, both influenced by bathymetry. From a modern perspective, however, the explanation of Heaney et al. is unconvincing [Dushaw, GRL (2008)]. High-resolution ocean models put the Perth-to-Bermuda acoustic problem into a new light. These models suggest that intense, small-scale features, e.g., Agulhas rings near the Cape of Good Hope, would greatly influence the acoustic paths. The antipodal travel time, 13 382 s, is a measure of the ocean temperature in 1960. If the acoustic propagation issues can be fully understood, data-assimilating ocean general circulation models might be used to calculate a present-day travel time. The travel-time change over the past half-century, expected to be about 10 s based on nominal estimates of ocean warming, is a measure of ocean climate change.
Seismo-acoustic modal scattering by volume heterogeneities in shallow water sediments.
Authors: Soukup Darin J. , Odom Robert I.
Published: October 2009

Elastic anisotropy is a nearly ubiquitous feature of marine sediments. The simplest type of sediment anisotropy is transverse isotropy, characterized by five elastic constants, and results from layered deposition. A modal scattering theory for volume perturbations of the sediment elastic moduli is presented. The scattering theory is based on the coupled mode formulation for propagation in range dependent fluid-elastic media. The Born approximation is employed to derive a modal scattering matrix. Although the perturbations of the elastic moduli are random, they may not be arbitrary in the sense that certain symmetry and energy constraints among the moduli must be respected. Mode-mode coupling matrices are computed for quasi-P-SV-SH seismo-acoustic modes, which show mode mixing and the importance of non-nearest neighbor interactions. The effects of volume scattering can be combined with rough surface scattering and also incorporated into mode coupling caused by deterministic range dependence of the material properties. This work has implications for acoustic loss estimates for low-frequency shallow water acoustic propagation. [Work supported by ONR.]
Deep seafloor arrivals: Scattering or multi-path from ocean thermal structure?
Authors: Stephen Ralph A. , Dzieciuch Matthew A. , Worcester Peter F. , Andrew Rex K. , Mercer James A. , Colosi John A. , Howe Bruce M.
Published: October 2009

An unexplained set of arrivals has been observed on ocean bottom seismometers (OBSs) during the NPAL04 long-range ocean acoustic propagation experiment in the North Pacific. The observed intensity pattern of the OBS arrivals is significantly more complex than the waterborne arrivals seen on the deep vertical line array (DVLA). These “deep seafloor” arrivals occur later than the first PE predicted arrival; their arrival time is not predicted by acoustic PE propagation models, they do not correspond to decay from shallower turning points (as is the case for deep shadow zone arrivals), and they are not readily observed on the DVLA hydrophone just 750 m above the seafloor. The arrival structure in the observed data, in time and amplitude, varies substantially between three OBSs that are separated by less than 4 km. Could these unexplained arrivals be scattering or horizontal multi-path from persistent ocean thermal structure?
Sound propagation in a refractive, turbulent atmosphere above a statistically rough, impedance ground surface.
Authors: Ostashev Vladimir E. , Wilson D. Keith , Vecherin Sergey N.
Published: October 2009

In recent years, considerable effort has been devoted to studies of sound propagation in a turbulent atmosphere. It was shown that temperature and wind velocity fluctuations can significantly diminish the coherence of a sound wave and, hence, degrade performance of modern acoustic sensor arrays for source detection. Outdoor sound waves are also affected by a rough, impedance surface of the ground. This paper is devoted to studies of the effects of a statistically rough, impedance ground surface on the coherence of a sound wave propagating in a refractive, turbulent atmosphere. Using the Beilis–Tappert transformation, the considered problem is reduced to sound propagation over a flat impedance surface in an atmosphere with an effective turbulence spectrum. Then, a closed equation for the coherence function of a sound field is derived using the Markov approximation similarly to that in the work of Wilson and Ostashev [J. Acoust. Soc. Am. 109, 1909–1922 (2001)]. The previously developed moment-screen method is used to numerically solve the closed equation for the coherence function. Possible approaches are discussed for comparing the relative roles of atmospheric turbulence and surface roughness in diminishing the coherence of a sound wave.
Nonuniformly spaced linear array.
Authors: Au Jenny Y. , Thompson Charles
Published: October 2009

In this presentation, we will examine the criterion for the design of nonuniformly spaced linear arrays. The transducer location selection based on the min-max optimization will be of particular interest. The purpose is to develop low-complex array structure. The influence of transduced interaction will also be considered.
Effects of heat exchanger size on gain of thermoacoustic prime mover.
Authors: Andersen Bonnie J. , Symko Orest G.
Published: October 2009

Thermoacoustic standing wave prime movers are discussed as self-sustained oscillators whose initial growth pattern of oscillation followed by amplitude limitation can be modeled by the Van der Pol equation. The best fit solutions offer quantitative comparisons of terms related to the energy supplied to the system and the losses. This study on engines near 2.6-kHz oscillations suggests that information on performance of the device is contained within the first second of oscillations. The Van der Pol equation is used to compare the performance of three hot heat exchangers. The hot heat exchangers used copper wire mesh with 40×40, 60×60, and 80×80 wires/in. The engine with the 40×40 mesh has a higher gain term and smaller loss term than either the 60×60 or the 80×80, as expected, since it has the largest wire diameter and the largest open area. The gain term for the three heat exchangers increases linearly with increasing surface area of the mesh in contact with the air in the resonator. This is evidenced in the build-up of the oscillations, in agreement with the Van der Pol equation.
Dialectal variations on the realization of high tonal targets for focused and non-focused syllables in Taiwan Mandarin.
Authors: Huang Yi-Hsuan , Fon Janice
Published: October 2009

This study investigated how focus and non-focus were realized across sentential positions for different dialects of Taiwan Mandarin. Ten male subjects from the northern and central regions of Taiwan participated in this study and were asked to read Mandarin high-falling tones in focus and non-focus positions placed sentence initially, medially, and finally. Results showed that F0 maxima for focused syllables were higher than non-focused syllables across sentential positions and dialects. Furthermore, the northern dialect had higher F0 maxima for both focused and non-focused syllables than the central dialect. A significant interaction among dialects, focus status, and sentential positions was found. For northern speakers, differences in F0 maxima for focused and non-focused syllables were greatest in sentence-final positions and smallest in sentence-initial positions. However, for central speakers, the magnitude of F0 maxima differences between focused and non-focused syllables were similar across sentential positions. Reasons for the tonal variations and different declination patterns of the two dialects were discussed.
Multilevel modeling of speaker variation in cross-dialectal articulation rate.
Authors: Jacewicz Ewa , Fox Robert Allen , Wei Lai
Published: October 2009

Articulation rate (excluding pause time) in spontaneous speech was examined for northern speakers of American English from Wisconsin and for southern speakers from western North Carolina. The corpus consisted of speech samples from 192 speakers, males and females, ranging from 8 to 90 years old. The focus of this study is to model statistically both the between-speaker and within-speaker variations. Within-speaker changes in tempo depend primarily on phrase length so that longer phrases, containing more syllables, tend to be spoken faster than shorter phrases. To capture this type of variation, mixed-effect models were used and the phrase length was included as a predictor. Fixed-effect covariates of interest included dialect, gender, age, and phrase length. The results indicate that phrase length has a highly significant fixed effect on articulation rate. When the differences in phrase length were controlled, the speech tempo of Wisconsin speakers was found to be significantly faster than of North Carolina speakers and male speech was significantly faster than female. The effects of age were also significant showing that articulation rate increases with age achieving the peak at 46 years and decreases with age thereafter. [Work supported by NIH.]
A linguistically-informative approach to dialect recognition using dialect-specific context-dependent phonetic models.
Authors: Chen Nancy F. , Shen Wade , Campbell Joseph P.
Published: October 2009

In this work, we explore automatic approaches to learn dialect discriminating pronunciation patterns and use these patterns to automatically recognize dialects. Since linguistic literature suggests that dialect differences often occur in certain phonetic contexts [2, 7, 8, 9], we extend adapted phonetic models [Shen et al. (2008)] to consider phonetic contexts. We evaluate our system on classifying American and Indian English. Despite many challenges (e.g., subdialect issues and suboptimal phone recognition accuracy due to lack of word transcriptions), we discover dialect discriminating biphones compatible with the linguistic literature, while outperforming a baseline system by 7.5% (relative). Our work is an encouraging first step toward a linguistically informative dialect recognition system, with potential applications such as forensic phonetics and accent training tools. [This work is sponsored by the Command, Control and Interoperability Division (CID), which is housed within the Department of Homeland Security’s Science and Technology Directorate under Air Force Contract No. FA8721-05-C-0002. N. C. F. is also supported by the NIH Ruth L. Kirschstein National Research Award and NIH/NIDCD Grant Nos. DC02978 and T32DC00038.]
The influence of linguistic complexity on the acoustic and perceptual correlates of gender typicality in boys’ speech.
Authors: Munson Benjamin , Kaiser Eden , Crocker Laura
Published: October 2009

Studies have shown that adults discern differences between the speech of boys and girls as young as 4 years old (e.g., Perry, Ohde, Ashmead, JASA, 2001). Crocker and Munson (2006, NWAV) examined variation in gendered speech within a group of boys. They examined acoustic measures of vowels and consonants in the single-word productions of 30 5–12 year old boys. Fifteen of these boys were given the label gender identity disorder (GID) by a trained psychometrist based on their nonspeech behaviors. The other 15 were age matched boys without GID. Crocker and Munson found acoustic differences between the groups. These were sufficient to lead naive adult listeners to rate the boys with GID as sounding less boy-like than boys with GID. We expanded on this by examining acoustic and perceptual measures of sentences produced by the same group of boys. The group differences in perceived gender typicality were larger than for single words. These were likely the consequence of the longer speech materials that were used, as acoustic differences were comparable to those found by Crocker and Munson. Together, these findings suggest a link between the early development and gender identity of the development of gender typicality in boys’ speech.
Acoustic changes associated with transgender speech therapy: A case study.
Authors: Dembowski James
Published: October 2009

This case study documents acoustic changes in speech and voice characteristics over the course of several months’ therapy to feminize the voice in a male-to-female (M-F) transgendered individual. Perceptual tests show that higher speaking fundamental frequency (F0) may be the only significant difference in voices perceived as female rather than male [Petit, J. M., MIT Encyclopedia of Communication Disorders, edited by R. D. Kent MIT, Cambridge, MA, 2003, pp. 223–226]. Paradoxically, however, changes in F0 alone are not sufficient to produce a feminine sounding voice. Voice quality, speech rate, and inflection also contribute to the perception of femininity. This presentation documents acoustic changes in a speaker who specifically did not wish to aggressively pursue alterations of F0, but wanted to achieve a more feminine voice by other means. Therapy goals focused on speech rate, voice quality, and prosodic patterns. Acoustic measures over the course of therapy included average F0, minimum F0, F0 variability, speech rate, rms intensity, and signal to noise ratios during selected vocalic segments. Preliminary data analyses suggest that changes in vocal quality and prosodic variability also produced F0 changes, even though these were not targeted therapeutically.
Acoustic correlates of gender and ethnicity in speaker perception.
Authors: Trent-Brown Sonja A. , Dreyer Joline C. , Woodworth Kyle P.
Published: October 2009

Perceptual and acoustic explorations have determined that certain cues are evident in the auditory signal that provide information about speaker characteristics such as gender and ethnicity. Perceptual studies present stimuli to listeners who make decisions based on their perceptual interpretations. Results from such studies indicate that listeners are able to identify speaker ethnicity and gender [Lass et al., (1979); Boonstra et al., (2006)]. Acoustic studies analyze the speech to determine which cues, spectral or temporal, help listeners make their interpretations [Walton and Orlikoff, (1994); Xue and Fucci, (2001)]. The current study presents spectral and temporal analyses to provide a more comprehensive picture of various acoustic contributions to speaker voice types that listeners may utilize in their perceptual identifications. Speech samples (single word- and sentence-length utterances) were produced by 20 male and female, African American and European American speakers of General American English. Results suggest that various spectral and temporal measures contribute to differences across voice characteristics. Differences attributed to speaker gender include fundamental frequency, intensity, pitch and amplitude perturbations, and the harmonics-to-noise ratio. Measures of stimulus intensity and pitch perturbation differed across speaker ethnicity. Differences resulting from the interaction of speaker gender and ethnicity include fundamental frequency and intensity. [Hope College Psychology Department, The Carl Frost Center for Social Science Research.]
Listener voice identification in foreign and accented English.
Authors: Sims Michelle
Published: October 2009

This study investigates perceptual voice identification by analyzing the quantitative and qualitative acoustical characteristics listeners use to identify voices in non-native speech. Research on voice identification typically focuses on the direct quantitative comparison of voices to find unique identifiers [e.g., Morrison (2009) and Jessen (2008)]. However, in this study an experiment was run in order to analyze the acoustic cues people perceptually adhere to in identifying voices. Listeners of various native language backgrounds were asked to identify the voices of Mandarin Chinese speakers in both Mandarin and Mandarin-accented English speech. Listeners’ accuracy and speaker selections in fourteen voice line-ups (Sullivan and Schlichting 1998) were recorded. Speakers’ productions for all stimuli were analyzed using twelve acoustic features. The results find that though listeners were highly accurate at the voice recognition task, their errors do follow systematic trends. Quantitative and qualitative acoustic measures such as pitch, pitch variation, formant trajectories, intensity, and nasality prove to be reliable in patterning memorable and forgettable voices. That is, this study finds that certain acoustic characteristics are more salient in everyday voice identification.
The role of source and filter characteristics in human talker identification: Experiments with laryngeal and electrolarynx speech.
Authors: Perrachione Tyler K. , Stepp Cara E. , Hillman Robert E. , Wong Patrick C. M.
Published: October 2009

Differences in individuals’ vocal anatomy and physiology result in unique acoustic features of their vocalizations. Humans are exceptionally attuned to these variations and use them to identify familiar individuals. Although these abilities are often called “voice recognition,” talker identity cues actually arise through interactions between acoustic excitation produced at the source (typically, the larynx) and both static and dynamic properties of the filter (vocal tract, articulators, and their manipulations during speech). We investigated the differential contributions of source- and filter-related information to talker identification through four experiments using laryngeal (typical) and electrolarynx speech from five talkers. Using an electrolarynx energy source removed individual differences in vocal anatomy, leaving only unique filter properties for talker identification. Listeners learned talker identity best from typical, laryngeal speech, which contained both unique source and filter cues. Listeners were also able to learn talker identity from electrolarynx speech, which homogenized talker source characteristics. Curiously, listeners did not generalize talker identity across source mechanisms: Training on laryngeal or electrolarynx speech resulted in chance performance identifying the same talkers using the other source mechanism. We consider the implications of these results for models of talker identification and articulatory compensation during electrolarynx use. [Work supported by NIH.]
Variation and stability in judgments of talker similarity.
Authors: Munson Benjamin , Marnie Celina C.
Published: October 2009

Listeners judge some pairs of talkers sound more similar to one another than others. This study examined whether the parameters that listeners attend to when judging talker similarity depend on the type of experience they have listening the talkers’ voices. We hypothesized that judgments of talker similarity would change over the course of experiment depending on the type of exposure that listeners have to different talkers. Listeners who identify words that talkers produce should attend less to features not relevant for word recognition (i.e., f0 and voice quality), while listeners passively exposed to talkers should not change the parameters that they attended to. Two groups of listeners participated in a three-phase experiment. In the first phase, they judged the similarity of pairs of 16 talkers. In the second, one group conducted a recognition-memory task with the same talkers’ voices. The other listened passively while completing a visual-memory task. In the third, they listened to the same talkers and provided a new set of talker-similarity judgments. Multidimensional scaling was used to analyze the talker-similarity judgments. Preliminary analyses suggest that the dimensions that characterize talker similarity spaces are similar in the first and third phases for both groups of listeners.
Variations in intensity, fundamental frequency, and voicing for teachers in occupational versus non-occupational settings.
Authors: Hunter Eric J. , Titze Ingo R.
Published: October 2009

This study creates a more concise picture of the vocal demands placed on teachers by comparing occupational voice use with non-occupational voice use. The National Center for Voice and Speech voice dosimetry databank was used to calculate phonation time dose as well as average dB SPL and F0. Occupational voice use (9am–3pm) and non-occupational voice use (4pm–10pm, weekends) were compared from 57 subjects (2 weeks each, 8400+ h). Five key findings were uncovered: (1) previous findings of occupational (30%) and non-occupational (14%) voicing were substantiated; (2) teachers experienced a wide range of occupational voicing percentages (33%, SD ±11%); (3) the occupational voice was on average only about 1-dB SPL louder than the non-occupational voice and remained constant throughout the day; (4) the occupational voice exhibited an increased pitch, trending upward throughout the day; and (5) apparent gender differences in voicing percentages, as well as changes in dB SPL and F0, were shown. Data regarding voicing percentages, F0, and dB SPL provide critical insight into teachers’ vocal health. Further, because non-occupational voice use is added to an already vocally overloaded voice, it may add key insights into recovery patterns and should be the focus of future studies.
Categorization of animal sounds using algorithms from diverse applications.
Authors: Clark Grace A.
Published: October 2009

The proposed approaches to animal sound characterization are motivated by the philosophical theme of this special session; diverse problems, similar solutions. The literature primarily makes use of some fundamental algorithms. This paper proposes some powerful techniques that have the potential to effect significant advances in animal acoustics. Several classes of algorithms are discussed, along with examples of how they have been used to solve similar problems in diverse applications. The key algorithm areas discussed are (1) statistical feature extraction from two-dimensional or multi-dimensional hierarchical transforms, such as wavelet transforms, higher-order poly-spectral features, histogram features, texture features, etc.; (2) feature selection algorithms to choose a subset of most useful features and overcome the curse of dimensionality; (3) advanced classification algorithms; (4) performance measures that include estimates of statistical confidence for small sample sizes; and (5) sensor fusion algorithms for exploiting a variety of sensor modalities. Signal processing examples from diverse problem domains are presented. These include seismic oil exploration, ultrasonic nondestructive evaluation of materials, buried mine detection, target recognition, and others. It is demonstrated that these diverse problems have similar solutions, and it is proposed that some animal acoustics problems could be amenable to similar approaches.
Scattering by sinusoidal pressure-release surfaces.
Authors: Jackson Darrell
Published: October 2009

The problem of sound scattering by surfaces having sinusoidal shape has been intensively studied, yet fundamental questions remain. The present work employs this problem as a testing ground for our understanding of small-roughness perturbation theory. Extending previous work by the author, the convergence of the perturbation series is studied using numerical calculations. As has been noted previously, the Rayleigh hypothesis does not set the bounds for convergence to the correct radiated field, but is relevant to determination of the surface field. In the present work, both topics are examined in some detail, and conformal mapping is used to support some of the conclusions.
Scattering by unexploded ordnance with variable burial depth and seafloor roughness: A parametric study.
Authors: Calvo David C. , Houston Brian H. , Bucaro Joseph A. , Kraus Larry , Simpson Harry J. , Sarkissian Angie
Published: October 2009

Efficient search strategies for unexploded ordnance (UXO) by sonar greatly depend on the ocean environment, particularly bottom roughness, and the mean burial depth of the target. To gain insight into how detection ranges vary with statistical properties of the ocean bottom and factors associated with object burial, we apply full-wave numerical modeling using the time-domain elastodynamic finite-integration technique (EFIT). The numerical technique—which is not restricted to small interface slopes or amplitudes—allows us to obtain a uniform picture of enhancement of acoustic bottom penetration with frequency and roughness parameters, while providing roughness backscattering levels for variable incidence angles. For the target, attention is focussed mostly on scattering near beam incidence, and comparison with experiments is made for a 5-in. rocket UXO. Good agreement with measured target strength over the 4–30-kHz band is obtained using a two-dimensional EFIT model with simple finite-aperture corrections for three-dimensional (3-D) effects. We consider both forward and backscattering and discuss the potential advantages of both. For lower frequencies, we compare with a full 3D finite-element model which compares favorably with data. [Work supported by SERDP and ONR.]