bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of speaking styles on the relevance of the Speech Transmission Index in the presence of reverberation
Authors: van Wijngaarden Sander J. , Houtgast Tammo
Published: October 2013

The Speech Transmission Index (STI) predicts speech intelligibility under various speech degrading conditions, including noise and reverberation. Measurements of sentence intelligibility in noise and reverberation, for three different talkers adopting different speaking styles, indicate that the STI is sometimes inaccurate in the presence of reverberation. For a trained talker speaking clearly, the STI predictions are accurate, but for conversational speech by untrained talkers, the effect of reverberation is underestimated. By using a wider range of modulation frequencies than prescribed for the standardized STI calculation (up to 31.5 Hz instead of 12.5 Hz), more accurate predictions are obtained for conversational speech. This can be understood by comparing the envelope spectrum between talkers and speaking styles: conversational speech tends to spread more of the energy in its envelope spectrum to higher modulation frequencies. Since higher modulation frequencies are more susceptible to reverberation, conversational speech tends to be affected more by reverberation than clear speech. To investigate the range of between-talker variations, envelope spectra were calculated for a population of 134 talkers. Upper boundaries of the STI modulation frequency range of 12.5 and 31.5 Hz seem approximately appropriate for the 5th and 95th percentile of this population.
Multiple speech signal enhancement using a microphone array
Authors: Ewalt Heather E. , Johnson Michael T.
Published: October 2013

The ability to extract and enhance a primary speech signal from an environment with multiple speakers is an important issue. While methods exist for a variety of beamforming techniques [M. Brandstein and D. Ward, Microphone Arrays: Signal Processing Techniques and Applications (Springer, New York, 2001)] as well as for multi-source filtering in stationary noise [H. Saruwatari et al., ‘‘Speech Enhancement Using Nonlinear Microphone Array With Noise Adaptive Complementary Beamforming,’’ Proc. of IEEE ICASSP, pp. 1049–1052 (2000)], the theory has yet to be developed for integrating spatial filtering with additional enhancement methods to deal with non-stationary interference from interfering talkers. This paper presents a novel method for incorporating multiple parallel beamformers with traditional speech enhancement algorithms, particularly the Wiener filter and spectral subtraction. By iteratively improving the spectral magnitude estimates of each speech source, substantial improvement in overall signal separation can be obtained. The performance of the algorithm is illustrated using a simulated multiple speaker environment with resulting SNR and sSNR plots. [Work supported by the GAANN Fellowship.]
The evolution of rippled seafloor topography with acoustic implications
Authors: Richardson Michael D. , Traykovski Peter
Published: October 2013

Rippled seafloors are often responsible for anisotropic patterns of acoustic backscattering and allow penetration of high-frequency energy into the seafloor below the critical angle. Both natural and manipulative experiments conducted during the Sediment Acoustic Experiment (SAX99) demonstrate the importance of understanding the temporal evolution and characterizing the spatial statistics of naturally occurring ripple fields for prediction of sonar performance and the detection of buried targets. Current and wave-induced sand ripples evolve in a more or less predictable pattern. Numerous empirical and semi-empirical predictive models, based on well-established principles of sediment transport, allow prediction of ripple wavelength, height, and shape. Degradation of sand ripple fields, especially by biological processes such as feeding, burrowing, and emergence is less known and has not been modeled. The temporal evolution of rippled topography measured with sector scanning sonar in high-energy environments is presented. These high-fidelity and nearly continuous observations coupled with measurements of bottom currents and near-bottom wave-induced orbital motion provide improved insights and new models of the evolution of rippled seafloor topography. In low-energy environments (SAX99 and the proposed SAX04) the longer times between storms allow characterization of rates of biological processes which destroy ripple structure and create isotropic roughness. [Work supported by ONR.]
Model/data comparisons of subcritical grazing angle detection of targets buried under a rippled sand interface
Authors: Williams Kevin , Thorsos Eric , Tang Dajun , Lim Raymond , Lopes Joe
Published: October 2013

Subcritical grazing angle target detection results for a sphere buried in Coastal System Station’s Facility 383 pond are compared to predictions from two different models. Both models use perturbation theory to calculate the transmission across the rough interface due to ripple scattering. One is a simple sonar equation model that uses a first-order expression [Eq. (16), Jackson et al., IEEE J. Ocean. Eng. 27, 346–361 (2002)] to calculate the penetration, taking into account the measured ripple profile and the target strength estimate for the buried sphere. The other model uses the penetrating field to calculate target backscattering via a T-matrix formalism adapted to account for the specified sinusoidal roughness. These models have been combined with a reverberation model to predict detection SNR. The reverberation model uses a power law fit to the sand/water interface roughness spectrum determined from measured roughness profiles. [Work supported by ONR.]
Using acoustic measurement and analysis computer programs to teach architectural acoustics to architectural students
Authors: Coffeen Robert C.
Published: October 2013

Explaining the concepts of sound amplitude and frequency to architectural students is difficult unless suitable visual and audible presentations are used. Computer programs designed for professional sound measurement and evaluation, and computer programs designed for acoustic analysis and auralization provide tools that can be employed to bring to life the basic sound concepts that must be understood by those students who will later be responsible for designing building spaces where hearing conditions are important.
Teaching architectural acoustics to students of engineering versus students of architecture
Authors: Wang Lily M.
Published: October 2013

The author currently teaches architectural acoustics at the University of Nebraska to students in the College of Engineering and to students in the College of Architecture. These two groups have different backgrounds and focuses: for example, engineers are more mathematically prepared, while architects are more visually oriented. However, the instructor’s goals for the members of both groups are similar, namely that they (1) master the fundamentals of good architectural acoustic design and (2) learn to respect and communicate well with each other during the design process, leading to more successful projects. This presentation will demonstrate the similarities and differences in the methods that are used by the author to address these two groups.
Architectural acoustics to non acousticians: Prediction auralization in design and consulting
Authors: Ciao Quinsan
Published: October 2013

Acoustic theories and principals are not necessarily familiar to most of the parties closely related to architectural acoustic issues. For example, architects involved in building designs, occupant communicates involved in space improvements are often the clients of architectural acoustic consultants. On one hand they are responsible to make knowledgeable decisions, on the other hand they do not have time or interest to be systematically trained in acoustics principals and theories. Properly educating such clients is one of the challenges constantly faced by architectural acoustic consultants. Traditionally, consultants are tormented between two different approaches. One is to deeply educate clients in architectural acoustics. The other is to convince the clients to trust and leave the matter to experts. Neither has been satisfactory. The former is insufficient and inefficient to establish appreciation of practical results, while the lattter is resisted for lack of transparency. Thanks to the latest development of computing technologies, a new approach is available, which is to demonstrate the acoustic effects in audible media through auralization and prediction in conjunction with explanation of simple principles. This paper discusses this approach of client education in practices with case study examples.
Ocean noise and marine mammals: A summary report of the U.S. National Research Council Committee on Potential Impacts of Ambient Noise in the Ocean on Marine Mammals
Authors: Frisk George V.
Published: October 2013

In 2000, the U.S. National Ocean Partnership Program, with leadership by the Office of Naval Research, requested that the U.S. National Academies examine the potential effects of noise in the sea on marine mammals. A committee of 11 international experts was convened to study this controversial issue. The committee included marine mammals specialists, acousticians, bioacousticians, a geophysical exploration expert, and an expert in vessel engineering. Specifically, the committee was asked to evaluate the human and natural contributions to ocean noise and describe the long-term trends in noise levels, especially from human activities. In the report, the committee outlines the research needed to evaluate the impacts of marine noise from various sources (natural, commercial, naval, and acoustic-based ocean research) on marine mammal species, especially in biologically sensitive areas. The study reviews and identifies gaps in existing marine noise databases and recommends research needed to develop a model of ocean noise that incorporates temporal, spatial, and frequency-dependent variables. The findings and research recommendations of the committee will be presented.
Acoustic signal detection of manatee calls
Authors: Niezrecki Christopher , Phillips Richard , Meyer Michael , Beusse Diedrich O.
Published: October 2013

The West Indian manatee (trichechus manatus latirostris) has become endangered partly because of a growing number of collisions with boats. A system to warn boaters of the presence of manatees, that can signal to boaters that manatees are present in the immediate vicinity, could potentially reduce these boat collisions. In order to identify the presence of manatees, acoustic methods are employed. Within this paper, three different detection algorithms are used to detect the calls of the West Indian manatee. The detection systems are tested in the laboratory using simulated manatee vocalizations from an audio compact disc. The detection method that provides the best overall performance is able to correctly identify ≊96% of the manatee vocalizations. However the system also results in a false positive rate of ≊16%. The results of this work may ultimately lead to the development of a manatee warning system that can warn boaters of the presence of manatees.
Nonlinear pulse-echo imaging methods for HIFU-induced lesion visualization
Authors: Ebbini Emad
Published: October 2013

We have recently investigated the use of two different nonlinear imaging methods for visualization of HIFU-induced lesions. The hypothesis is that bubble activity at the location of the HIFU beam can be observed using diagnostic ultrasound with proper post-beamforming signal processing of the rf data. In particular, pulse inversion (PI) and quadratic imaging techniques have been investigated for this purpose. Results from over 100 ex vivo tissue experiments clearly demonstrate the superiority of the nonlinear imaging techiques over conventional B-scan imaging in terms of accurate mapping of lesion boundaries. We are currently examining imaging data to determine the use of nonlinear imaging methods for quantitative assessment of tissue damage. In this paper, we will describe a new experimental procedure for determining the existence of bubble activity associated with different levels of exposure to HIFU, from underexposure to overexposure conditions. Images from conventional B-scan will be compared and contrasted with quadratic and pulse inversion images for various levels of exposure. These results continue to support the hypothesis that bubble activity is extremely important in both lesion formation and lesion visualization using ultrasonic techniques.
Factors affecting radiation force method for monitoring therapeutic ultrasonic lesions
Authors: Lizzi Frederic L. , Muratore Robert , Mikaelian Samuel , Lee Paul , Alam S. Kaisar
Published: October 2013

Investigations are being conducted to develop a method using motion induced by radiation force to monitor HIFU lesions, by virtue of their increased stiffness. A therapeutic transducer, periodically excited at subthreshold levels, generates the radiation force: a collinear diagnostic transducer monitors the degree and time-course of induced motion. Lesions are detected by changes in pre- and post-treatment motion patterns. In vitro experiments and computer simulations have been performed to clarify the roles of several phenomena so that optimized systems can be designed for practical on-line applications. Lesion attenuation has been found to be a key factor since it directly affects radiation force. Lesions with near-normal attenuation exhibit less motion than normal, because of increased stiffness. Lesions with significantly higher attenuation can exhibit increased motion, due to increased force, but they demonstrate spatial patterns differing from normal. The profile of the push beam was found to affect the magnitude, spatial pattern, and time course of induced motion. The diagnostic transducer’s bandwidth and beam profile were shown to affect the precision and sensitivity of motion characterization. Quantitative findings from these studies are being combined with thermal studies to design monitoring systems for specific applications.
Acoustic field of a spherically curved wedge transducer
Authors: Ketterling Jeffrey A.
Published: October 2013

High-intensity focused ultrasound (HIFU) applications typically utilize spherically curved transducers, often with modifications to the surface electrode. These modifications, such as rectangular cut-outs, can normally be modeled as a collection of annular rings and wedges. The acoustic field of an annular ring has been well characterized, but a wedge shape has not. We present a model of the acoustic field of a wedge transducer based on the spatial impulse response (SIR) method. A wedge transducer is created by making a cut normal to a spherical cap and keeping the section with the smaller surface area. Analytic expressions for the SIR are derived for an arbitrary point P in space. To find the time domain pressure at P, the SIR is convolved with the time derivative of the wedge surface velocity. Numerical examples of SIRs and the acoustic pressure field are given for a wedge formed from a spherical cap with a geometric focus of 9 cm and an outer diameter of 8 cm. For a single frequency drive of 4.7 MHz, calculations of pressure are compared to hydrophone measurements of a HIFU transducer with equivalent geometry. The results show an excellent agreement between theory and experiment.
Nonlinear acoustic spectroscopy applied to damage detection of elastic structures
Authors: Vanderborck Gerard , Lagier Michel
Published: October 2013

The strong linkage between damage and nonlinear elasticity of materials leads to much research in the field of nonlinear response of mechanical structures. The aim of this work is to demonstrate the relevance of nonlinear acoustic spectroscopy for damage detection in elastic structures. The proposed method consists of the observation of linear and nonlinear responses to harmonic excitations of the structure: the damage detection and localization are obtained from an array of sensors. The nonlinear response amplitude is proportional to the local nonlinearity (failure nonlinear elastic response). A dual frequency method has been demonstrated for cracked beam excited by two force sources located at different points; the theoretical analysis comes from the Green function method applied to each overtone displacement field, the crack elastic response is handled by a nonlinear force/displacement behavior. Small scale experiments are presented for aluminum and concrete beams and the experimental results confirm the capability of nonlinear acoustic spectroscopy for detection and monitoring of damaged structures. [Work supported by European Community.]
Acoustical investigations of borate glasses containing oxides of some transition elements and ferric oxide dopants
Authors: Bhatti Surjit Singh , Singh Kanwar Jit
Published: October 2013

Glass samples of manganese oxide borate and zinc oxide borate (with and without ferric oxide doping) have been prepared to study their acoustical, mechanical, and thermal behavior as function of composition. Sound velocities and attenuation measurements in these glass systems at 1,2, and 5 MHz give elastic moduli, Poissons ratio, micro-hardness, acoustic impedance, internal friction, thermal expansion coefficient and Debye and softening temperatures. Structural changes involve boron anomaly, field strengths of cations, difference in ionic radii, and charge state of iron. Makishima–Mackenzie (theoretical model) and IR and NGR techniques confirm the conclusions arrived at. The network modifier (NWM) is varied from 25 to 45 mol% for manganese oxide borate and from 15 to 40 mol% with 10 mol% doping of ferric oxide. For zinc oxide borate glasses, it varies from 26 to 34 mol% and with 10 mol% of ferric oxide, its variation is from 15 to 35 mol%. Impact of doping by ferric oxide on the properties of these glass systems have been investigated.
Predicting sound propagation in the atmosphere using an artificial neural network
Authors: Mungiole Michael , Wilson D. Keith
Published: October 2013

The spectral content of acoustic signals is dramatically altered as sound propagates through the atmosphere due to refraction from vertical gradients in wind and temperature, ground interactions, and other effects. Parabolic equation (PE) techniques have been successfully used to calculate numerical solutions for many of these effects. The PE models generally produce accurate attenuation values, but execution time is excessive for many applications where near real-time results are required. To obtain sound level attenuation predictions more quickly, we developed an artificial neural network for a range of heights and source/receiver horizontal separations. The PE and boundary conditions were modified to obtain a nondimensional representation, which resulted in seven parameters required to specify all input combinations. This model version was then used to train the neural network, using a range of values for each parameter. The standard deviation of the errors (propagation model minus neural network simulations) was generally within 2 dB for the training data set containing approximately 15000 cases. The smaller test data sets resulted in errors having standard deviations of approximately 1 dB. The neural network was a good predictor of the sound propagation model results except for small values of the nondimensional ground impedance parameter.
On a connection between amplitude fluctuations, phase fluctuations, and processing gain
Authors: Wagstaff Ronald A.
Published: October 2013

Weston et al. [Philos. Trans. R. Soc. London, Ser. A 265, 595 (1969)] show the remarkable agreement between the spectra for the coefficients of variation of amplitude and phase, i.e., amplitude and phase fluctuations, for a hydrophone in shallow water. Wagstaff [J. Acoust. Soc. Am. 112, 2422 (2002)] showed the functional similarity between phase angles and pseudo-phase angles for an outdoor microphone. Pseudo-phase angles are amplitude fluctuations that have been scaled appropriately to have a similar functionality in temporally coherent signal processing as phase angles. The concepts of the two previously mentioned references are merged to exploit the similarity of phase fluctuations and amplitude fluctuations to achieve multiplicative pseudo-coherent gain. Gains in excess of 20 log(N) have been achieved (N is the number of samples averaged). 10 log(N) is considered ideal for vector averaging. It is seldom achieved, because of coherent attenuation and cancellation associated with the use of real phase angles. Results are included for wind noise in outdoor measurements. [Work supported by U.S. Army Armament Research Development and Engineering Center.]
On the use of modal expansions to model broadband propagation in the nighttime boundary layer and other downward refracting atmospheres over lossy ground planes
Authors: Waxler Roger
Published: October 2013

A modal expansion for long-range, low-frequency propagation in downward refracting atmospheres over complex impedance planes has been developed. This modal expansion decomposes the sound field in the frequency domain into a ducted part (the modal sum) and an upwardly propagating part (expressed as an integral over a continuum). One may simulate the propagation of a pulse released from a point source by multiplying the Fourier transform of the pulse shape by the frequency domain Greens function and inverting the Fourier transform. At long distances from the source one expects that the sound field is adequately described by the modal sum alone. For sound speeds which are asymptotically (with height) constant this is indeed the case. However, the nighttime boundary layer is characterized by a sound speed which is downward refracting near the ground, increasing up to an inversion point, above which it decreases slowly becoming slightly upward refracting. In this case there are certain exceptional frequencies for which the continuum integral contains a resonant component which propagates to large horizontal distances and must be added to the modal sum.
SEA applications to wind instruments
Authors: Hoekje Peter L.
Published: October 2013

The behavior of wind instruments, including brass instruments, is primarily determined by the shapes of their air columns, and their interaction with the sound generation mechanism. However, the influence of the surrounding body of the instrument has been a matter of some debate, and papers exploring this question have been published since the early years of the J. Acoust Soc. Am. An apparent correlation between instrument material and playing behavior is disputed by arguments that the structure is stiff and massive compared to the air inside, and that many of the apparent effects are linked to machining differences among materials. The complexity of the instrument body makes this problem well suited for Statistical Energy Analysis (SEA), which treats the air column and the external structure as coupled statistical subsystems that share energy. For trumpets and trombones, the power radiated from the structural vibrations is about 40 dB lower than the energy radiated directly from the air column, with an enhancement at high frequencies due in part to the increasing modal density of the three dimensional structure. The coupling to the structural vibrations themselves from the player’s lips and from the air vibrations are similar to each other in magnitude.
Structural dynamics of concert harps with wooden and composite material soundboards
Authors: Carney Melinda , Royston Thomas J.
Published: October 2013

The replacement of a Sitka spruce grand concert harp soundboard with a carbon fiber-reinforced plastic soundboard could provide improved durability and long-term stability. Experimental vibratory studies on concert harps with wooden soundboards are reviewed. A computational finite-element model is used to identify critical material properties by matching its predictions to the experimental data. With the material properties identified in the finite-element model, the lay-up of the composite soundboard is created using matching criteria based on research of wood replacements for violin top plates. The composite lay-up is then incorporated into the finite-element model, verifying that the dynamic response closely approximates that of the wooden soundboard. The identification technique and composite replacement design process may be applicable to other musical instruments, as well as other nonmusical, wooden plate structures.
NSF funding opportunities in the behavioral and cognitive sciences
Authors: Rubin Philip
Published: October 2013

This presentation will provide a brief overview of existing and emerging funding opportunities at the National Science Foundation (NSF). The Division of Behavioral and Cognitive Sciences (BCS) at the NSF supports research to develop and advance scientific knowledge focusing on human cognition, language, social behavior and culture, as well as research on the interactions between human societies and the physical environment. BCS programs consider proposals that fall squarely within disciplines, but they also encourage and support interdisciplinary projects, which are evaluated through joint review among Programs in BCS, as well as a joint review with programs in other Divisions, and NSF-wide multi-disciplinary panels, as appropriate. All programs in BCS consider proposals for research projects, conferences, and workshops. Some programs also consider proposals for doctoral dissertation improvement assistance, the acquisition of specialized research and computing equipment, group international travel, and large-scale data collection. BCS participates in special initiatives and competitions on a number of topics, including cognitive neuroscience, children’s research, human origins, and the development of infrastructure to improve data resources, data archives, collaboratories, and centers.
Air Force program in hearing research
Authors: Larkin Willard D.
Published: October 2013

The Air Force Office of Scientific Research (AFOSR) manages all the basic science activity for the U.S. Air Force. Research is supported in the Air Force Laboratory, and grants are provided to universities and research institutions. This presentation will outline the scope of AFOSR’s support for basic research in areas germane to human hearing. Topics of current interest include the complex of problems associated with spatial hearing, the psychophysical and perceptual foundations for the design of auditory displays, problems of auditory information overload, and neurologically informed computational models of auditory perceptual processing. To develop better methods of hearing protection, AFOSR also supports efforts to understand the biophysical basis of cochlear excitation via bone conduction. Opportunities to contribute to these and related topics will be described.
Acoustic imaging of small water-lain sand deposits
Authors: Deffenbaugh Max , Adair Neal L. , Hoyal David C. J. D. , Giffin David E.
Published: October 2013

Reduced-scale physical modeling of depositional systems, like submarine fans, river deltas, and point bars, provides insight into the formation and internal structure of the full-scale systems which may become economic hydrocarbon reservoirs. Turbid water with controlled sediment concentration and flow velocity is discharged into a 3 m×5 m tank of still water to create deposits up to typically 10 cm thick. These deposits are imaged by a pencil-beam high-frequency (7 MHz) acoustic system to capture the evolution of deposit topography and by a broad-beam lower-frequency system (150 kHz) to image an internal structure. An x–y positioning system moves the transducer to create detailed 3D images. At 7 MHz, the deposit surface is ‘‘rough,’’ so significant backscattered energy is detected even for non-normal incidence. This, together with the narrow beamwidth, allows the deposit elevation directly below the sensor to be measured independent of the local slope. The deposit surface is ‘‘smooth’’ to the 150 kHz system, so reflections come only from points of normal incidence. This makes imaging more complicated, but the lower frequencies penetrate the deposit and reveal some internal structure. Images from both systems will be shown and compared.
High frequency bottom scattering: Theory and experiment
Authors: Yamamoto Tokuo , Ohkawa Keiichi , Yamaoka Haruhiko
Published: October 2013

The exact solution of the Biot theory for the transmission of an acoustic wave at the fluid–porous seabed interface is obtained in closed form. For grazing angles larger than 5 degrees, the transmission effect on volume scattering is ca. 20 dB larger than that of a fluid–fluid bottom model. If grain size and porosity is known, the Biot model calculates the attenuation. A Biot scattering model is constructed by replacing the transmission coefficients and attenuation of the fluid–fluid bottom model by Yamamoto (1996). During the Shallow Water Acoustic Technology (SWAT) 2000 experiments, the 5.5 kHz 3D backscattering data from the sandy bottom at the SS site were obtained using a self-contained UM 32 channel bi-linear hydrophone array rigidly mounted on a 5 m high rigid metal tower. The Biot model extracted, sound velocity, aspect ratio, and backscatter model parameters. The Biot model is also applied to the 15 kHz 3D backscattering data from a clay bottom. For this case, the difference between the Biot model and the fluid–fluid bottom was small. It is concluded that the Exact Biot model should be used when dealing with the high frequency bottom backscattering or forward scattering from the sandy bottom. [Work supported by ONR Code 321OA.]
Long-term noise statistics from the Gulf of Mexico
Authors: Eller Anthony I. , Ioup George E. , Ioup Juliette W. , Larue James P.
Published: October 2013

Long-term, omnidirectional acoustic noise measurements were conducted in the northeastern Gulf of Mexico during the summer of 2001. These efforts were a part of the Littoral Acoustic Demonstration Center project, Phase I. Initial looks at the noise time series, processed in standard one-third-octave bands from 10 to 5000 Hz, show noise levels that differ substantially from customary deep-water noise spectra. Contributing factors to this highly dynamic noise environment are an abundance of marine mammal emissions and various industrial noises. Results presented here address long-term temporal variability, temporal coherence times, the fluctuation spectrum, and coherence of fluctuations across the frequency spectrum. [Research supported by ONR.]
Underwater sound from the whale’s point of view
Authors: Arveson Paul T.
Published: October 2013

There have been numerous reports in the recent literature of apparently stressful effects on marine mammals due to sonar experiments. But another man-made source—the radiated noise from ships—contributes significantly to the ocean ambient, nearly everywhere and all the time. The technical basis for this talk is a set of accurate and detailed measurements of the radiated noise of a typical cargoship [P. Arveson and D. Vendittis, ‘‘Radiated noise characteristics of a large cargo ship,’’ J. Acoust. Soc. Am. (2000)]. However, the talk will be a popular-level demonstration and a (necessarily) fictitious narrative of acoustical experiences from a humpback whale’s point of view. Room acoustics permitting, the audience should be able to gain an experiential insight into the environmental impact of shipping noise on the life and habits of these creatures.
Base-building architectural and engineering acoustic concerns unique to museums and exhibit environments
Authors: Reber Mark
Published: October 2013

Museums, especially those with intensive multimedia programs, require special attention by the base building design team to ensure that the final aural experience throughout the exhibit galleries is optimized. Often, exhibit galleries and public spaces are designed with minimal attention placed on the acoustic environment. There are countless new and old museums that suffer from excessive liveness, extremely noisy mechanical/electrical systems, and significant bleed between multiple sound sources. The author will describe the importance of addressing the above issues, how the base building design team interfaces with the exhibit design team, and present some case study examples of how improperly designed museum buildings could have a detrimental impact on the acoustic function of the exhibit experience.
Acoustic and electo-acoustic design of the Country Music Hall of Fame and Museum in Nashville
Authors: Haas Steve
Published: October 2013

The Country Music Hall of Fame and Museum in Nashville is the newest major music museum to open in the United States. It represents the latest in acoustic and audio delivery technology to provide excellent sound quality and sound control for museum public, performance and exhibit spaces. The author will present some of the unique approaches and technologies that were first implemented into this facility and explain how the acoustic/electroacoustic interface allowed the Hall of Fame to maximize their use of sound in the exhibits as well as hold simultaneous special functions in many of the public spaces.
A new seamless, smooth, interior, absorptive finishing system
Authors: D’Antonio Peter
Published: October 2013

Architects and acousticians have sought a field-applied, absorptive finishing system that resembles a smooth plaster or painted drywall surface, since the dawn of architectural acoustics. Some success has been achieved using sprayed cellulose or cementitious materials, but surface smoothness has been a challenge. A new approach utilizing a thin microporous layer of mineral particles applied over a mineral wool panel will be described. This material can be applied to almost any shape surface, internally pigmented to match almost any color and renovated. It is currently finding application in many architectural applications, including museums. A recent installation in the New Pinakothek Museum in Munich will be illustrated.
Parametric mechanism of subharmonic generation by the microbubble contrast agents
Authors: Genis Vladimir , Oboznenko Igor , Tran Dat
Published: October 2013

Contrast agents, consisting of gas-filled microbubbles, are widely used in biomedical ultrasound for enhancing the capabilities of ultrasound imaging. The behavior of contrast agents has been shown to lead to the generation of harmonic and subharmonic components in the backscattered signal. The mechanism of subharmonic generation is not quite understood. It is known that the oscillation of gas-filled bubbles is described by nonlinear equations. In this work, the parametric approach to solving this problem is introduced, where the nonlinear equation is substituted by the linear equation with time-varying parameters, such as flexibility of the bubble. The equation describing the oscillation of the bubble is reduced to the Mathieu equation, and conditions for unstable solutions are presented. It has been demonstrated that the regions of instability occur in the vicinity of the frequencies w=1/2 wo, w=3/2 wo, etc., which correspond to generation of the first and higher subharmonics. Criteria for determining the relationship between the acoustic pressure, required for subharmonic generation, and the radius of the air-filled bubble are also determined.
An assessment tool for auditory realism
Authors: Lakatos Stephen , Cook Perry R. , Harbke Colin R.
Published: October 2013

An item-based survey was developed to evaluate how effectively physically-based models can yield sounds that appear realistic to the ear. Based on past research and current insights, realism as a construct was hypothesized to comprise eight orthogonal factors: detail, physical plausibility (biological and nonbiological), temporal consistency, vividness, presence, and whether a sound evokes sensory images and associated memories. Sets of 8–9 declarative statements were selected by committee for each factor from large initial lists of such statements. Another committee selected weak, moderate and strong sound exemplars for each factor from digital libraries that were felt to vary uniquely along that factor. In an exploratory phase, 82 participants rated how representative each sound exemplar was of each statement. Based on factor analyses, the three highest loading statements for each factor were compared across sound exemplars; statistically significant differences were found between exemplars for all factors. A subsequent confirmatory phase used new sounds, coupled with synthetic versions from physically-based simulations, to validate the proposed realism factors. Data from an additional 200 participants ratings for these stimuli supported the surveys construct validity. The survey should benefit sound engineers wishing to evaluate the degree to which their synthesis algorithms generate realistic output.
Sex, acceleration, brain imaging, and rhesus monkeys: Converging evidence for an evolutionary bias for looming auditory motion
Authors: Neuhoff John G.
Published: October 2013

Increasing acoustic intensity is a primary cue to looming auditory motion. Perceptual overestimation of increasing intensity could provide an evolutionary selective advantage by specifying that an approaching sound source is closer than actual, thus affording advanced warning and more time than expected to prepare for the arrival of the source. Here, multiple lines of converging evidence for this evolutionary hypothesis are presented. First, it is shown that intensity change specifying accelerating source approach changes in loudness more than equivalent intensity change specifying decelerating source approach. Second, consistent with evolutionary hunter-gatherer theories of sex-specific spatial abilities, it is shown that females have a significantly larger bias for rising intensity than males. Third, using functional magnetic resonance imaging in conjunction with approaching and receding auditory motion, it is shown that approaching sources preferentially activate a specific neural network responsible for attention allocation, motor planning, and translating perception into action. Finally, it is shown that rhesus monkeys also exhibit a rising intensity bias by orienting longer to looming tones than to receding tones. Together these results illustrate an adaptive perceptual bias that has evolved because it provides a selective advantage in processing looming acoustic sources. [Work supported by NSF and CDC.]
From sound to size: A research in ecological acoustics
Authors: Grassi Massimo
Published: October 2013

Two experiments investigated the perception of the size of a solid ball from the sound it produces when dropped upon a plate (i.e., object’s vibration contributing only slightly to the resulting pressure wave). Experiment one: listeners estimated metrically the size of seven balls when dropped upon a 215-mm-diam plate. Experiment two: a new group of listeners performed the same scaling, however, balls could be dropped either upon the 215-mm-diam plate or upon a 185-mm-diam plate. In both experiments listeners had no foregoing information about the sound-producing event. Overall, listeners’ estimations matched veridically the actual size of the balls. However, in the second experiment, listeners’ estimations were dependent on the dimension of the plate: balls were judged slightly larger when dropped on the largest plate. Results were analyzed in order to understand whether physical or acoustical features of the sound-producing event could predict the performance: the actual size of the ball resulted in the best predictor for all estimations in both experiments. Nonetheless, the difference in spectral centroid of the sound produced by the two plates could explain the different estimations obtained in the second experiment. [Work supported by European Commission, Contract No. IST-2000-25287.]
VOT of American English stops with prosodic correlates
Authors: Van Dam Mark
Published: October 2013

It is known that in a word-medial bisyllabic sequence, a stop beginning a stressed syllable (e.g., /p/ in póodle) has a much longer voice-onset time (VOT) than following an unstressed syllable (e.g., /p/ in strípper). The current study investigates VOT of stops in unstressed syllables not immediately following the primary stressed syllable in the word, e.g., before the primary word stress (the /p/ in Winnepegósis, the /k/ in baccaláureate), and after the primary word stress (the /p/ in Óedipus, the /k/ in américan). A set of 42 test words were recorded in carrier phrases spoken by 4 native speakers of American English. In bisyllabic words, word initial or stressed-syllable initial stops (e.g., póodle, appéal) averaged 63 ms while following unstressed stops (e.g., strípper) averaged 25 ms. Stops in unstressed syllables preceding the primary stressed syllable (e.g., Winnepegósis) averaged 32 ms while those stops in following unstressed syllables (e.g., Óedipus) averaged 41 ms. To account for these results, we need at least four VOT levels. Also interesting is the interaction between stop place /p/ vs /k/ and position: Óedipus has the same VOT as américan while Winnepegósis and baccaláureate differ significantly.
The influence of phonetic context and formant measurement location on acoustic vowel space
Authors: Turner Greg S. , Hutchings David T. , Sylvester Betsy , Weismer Gary
Published: October 2013

One way of depicting vowel production is by describing vowels within an F1/F2 acoustic vowel space. This acoustic measure illustrates the dispersion of F1 and F2 values at a specific moment in time (e.g., the temporal midpoint of a vowel) for the vowels of a given language. This measure has recently been used to portray vowel production in individuals with communication disorders such as dysarthria and is moderately related to the severity of the speech disorder. Studies aimed at identifying influential factors effecting measurement stability of vowel space have yet to be completed. The focus of the present study is to evaluate the influence of phonetic context and spectral measurement location on vowel space in a group of neurologically normal American English speakers. For this study, vowel space was defined in terms of the dispersion of the four corner vowels produced within a CVC syllable frame, where C includes six stop consonants in all possible combinations with each vowel. Spectral measures were made at the midpoint and formant extremes of the vowels. A discussion will focus on individual and group variation in vowel space as a function of phonetic context and temporal measurement location.
On the relation of apparent naturalness to phonetic perceptual identification
Authors: Remez Robert E. , Yang Cynthia Y. , Piorkowski Rebecca L. , Wissig Stephanie , Batchelder Abigail , Nam Hedy , Timberlake Anne E.
Published: October 2013

A set of synthetic test syllables was created varying in the attributes of apparent naturalness and phonetic place-of-articulation. These acoustic items were used in a new test of the relation of naturalness to phonetic perceptual resolution. An earlier study had found that variation in the form of the excitation of a formant pattern greatly affected impressions of naturalness while minimally affecting the resolution of the phonetic place. The present study assessed the relation of naturalness and intelligibility when the bandwidths of formant centers were varied. We conducted a naturalness tournament composed of items drawn from the test series; and, we assayed the sensitivity of perceivers to place contrasts by estimating the cumulative d’ across the series in identification tests. Unlike our prior observations, these new outcomes reveal both a narrower range of naturalness variation and a close relation in findings of the naturalness tournament and the measures of phonetic sensitivity. Together, this pair of studies shows that intelligibility and naturalness can be either orthogonal or contingent aspects of speech perception. These measures offer a tool to understand rule-based and exemplar-based components of phonetic perception. [Research supported by NIDCD.]
Talker and accent variability effects on spoken word recognition
Authors: Nyang Edna E. , Rogers Catherine L. , Nishi Kanae
Published: October 2013

A number of studies have shown that words in a list are recognized less accurately in noise and with longer response latencies when they are spoken by multiple talkers, rather than a single talker. These results have been interpreted as support for an exemplar-based model of speech perception, in which it is assumed that detailed information regarding the speaker’s voice is preserved in memory and used in recognition, rather than being eliminated via normalization. In the present study, the effects of varying both accent and talker are investigated using lists of words spoken by (a) a single native English speaker, (b) six native English speakers, (c) three native English speakers and three Japanese-accented English speakers. Twelve /hVd/ words were mixed with multi-speaker babble at three signal-to-noise ratios (+10, +5, and 0 dB) to create the word lists. Native English-speaking listeners’ percent-correct recognition for words produced by native English speakers across the three talker conditions (single talker native, multi-talker native, and multi-talker mixed native and non-native) and three signal-to-noise ratios will be compared to determine whether sources of speaker variability other than voice alone add to the processing demands imposed by simple (i.e., single accent) speaker variability in spoken word recognition.
An acoustic study of strident fricatives in Mandarin Chinese
Authors: Lee Chao-Yang
Published: October 2013

Mandarin has a distinction between flat and palatalized post-alveolar fricatives in addition to the alveolar–palatoalveolar contrast, which has been shown to have well-defined acoustic correlates. The goal of the study is to identify the acoustic cues to the place distinction in these strident fricatives and to evaluate how the acoustic properties map onto relevant phonetic features. Acoustic analyses were conducted of 216 fricative-vowel syllables produced by six speakers in three vowel and four tone contexts. Measures were taken of the properties of the frication noise and comparisons between fricative and vowel. The lower frequency limit of the frication noise, spectral peak location, spectral moments, spectral tilt, normalized amplitude, relative amplitude in specific frequency regions, and F2 onset frequency and movement in the adjacent vowel were examined. The results indicate the lower frequency limit of the frication noise is associated with distinct formant regions: F4 or F5 for the alveolar, F3 for the palatalized post-alveolar, and F4 for the flat post-alveolar fricative. Measures that successfully classified all three fricatives include spectral peak location, spectral mean, variance and skewness, amplitude difference between fricative and vowel in the F3 and F4 region, and F2 frequency at vowel onset. [Work supported by NIH.]
Effects of consonantal contexts on the perception of English vowels by experienced and inexperienced Japanese learners of English
Authors: Nozawa Takeshi , Wayland Ratree , Frieda Elaina M.
Published: October 2013

The perception of English vowels by experienced and inexperienced Japanese learners of English in different consonantal context were compared. Experienced Japanese learners of English were recruited in Gainesville, FL and inexperienced Japanese learners of English were recruited in Kobe, Japan and vicinity. In one experiment, subjects’ ability was tested to discriminate English vowels in different consonantal contexts. What was expected to affect the discriminability was (1) voicing of the preceding and the following stops, (2) places of articulation of the preceding and the following stops, and (3) nasality of the following consonant. In another experiment, the subjects identified English vowels in terms of Japanese vowel categories. Generally, English vowels identified with the same Japanese vowels were more difficult to discriminate than those identified with different vowels. In both experiments, the inexperienced learners were more susceptible to talker and consonantal context differences. [Work supported by Grant-in-Aid for Scientific Research (C)(1410635).]