bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of road noise on the calling behavior of Pacific chorus frogs
Authors: Nelson Danielle V. , Klinck Holger , Garcia Tiffany S.
Published: October 2014

Fitness consequences of anthropogenic noise on organisms that have chorus-dependent breeding requirements, such as frogs, are not well understood. While frogs were thought to have innate and fixed call structure, species-specific vocal plasticity has been observed in populations experiencing high noise conditions. Adjustment to call structure, however, can have negative fitness implications in terms of energy expenditure and female choice. The Pacific chorus frog (Pseudacris regilla), a common vocal species broadly distributed throughout the Pacific Northwest, often breeds in waters impacted by road noise. We compared Pacific chorus frog call structure from breeding populations at 11 high- and low-traffic sites in the Willamette Valley, Oregon. We used passive acoustic monitoring and directional recordings to determine mean dominant frequency, amplitude, and call rate of breeding populations, individual frogs, and to quantify ambient road noise levels. Preliminary results indicate that while individuals do not differ in call rate or structure across noisy and quiet sites, high road noise levels decrease the effective communication distance of both the chorus and the individual. This research enhances our understanding of acoustic habitat in the Willamette Valley and the impacts of anthropogenic noise on a native amphibian species.
Inter-individual difference of one type of pulsed sounds produced by beluga whales (Delphinapterus leucas)
Authors: Mishima Yuka , Morisaka Tadamichi , Itoh Miho , Suzuki Ryota , Okutsu Kenji , Sakaguchi Aiko , Miyamoto Yoshinori
Published: October 2014

Belugas often exchange one type of broadband pulsed sounds (termed PS1 calls) which possibly functions as a contact calls (Morisaka et al., 2013). Here we investigate how belugas embed their signature information into the PS1 calls. PS1 calls were recorded from each of five belugas including both sexes and various ages at the Port of Nagoya Public Aquarium using a broadband recording system when in isolation. Temporal and spectral acoustic parameters of PS1 calls were measured and compared among individuals. Kruskal-Wallis test revealed that inter-pulse intervals (IPIs), the number of pulses, and pulse rates of PS1 calls had significant differences among individuals, but duration did not (χ2 = 76.7, p<0.0001; χ2 = 26.2, p<0.0001; χ2 = 45.3, p<0.0001; and χ2 = 4.7, p = 0.316 respectively). The contours depicted by the IPIs as a function of pulse order were also individually different and only the contours of a calf fluctuated over time. Four belugas except a juvenile had individually distinctive power spectra. These results suggest that several acoustic parameters of PS1 calls may hold individual information. We found PS1-like calls from the other captive belugas (Yokohama Hakkeijima Sea Paradise) suggested that the PS1 call is not the specific call for one captive population but the basic call type for belugas.
Numerical study of biosonar beam forming in finless porpoise (Neophocaena asiaeorientalis)
Authors: Wei Chong , Wang Zhitao , Song Zhongchang , Au Whitlow , Wang Ding , Zhang Yu
Published: October 2014

Finless porpoise (Neophocaena asiaeorientalis) is known to use the narrow band signals for echolocation living in the Yangtze River and in the adjoining Poyang and Dongting Lakes in China. In this study, the sound velocity and density of different tissues (including melon, muscle, bony structure, connective tissues, blubber, and mandibular fat) in the porpoise’s head were obtained by measurement. The sound velocity and density were found out to have a linear relationship with Hounsfield unit (HU) obtained from the CT scan. The acoustic property of the head of the porpoise was reconstructed from the HU distribution. Numerical simulations of the acoustic propagation through finless porpoise’s head were performed by a finite element approach. The beam formation was compared with those of the baiji, Indo-pacific humpback dolphin, and bottlenose dolphin. The role of the different structures in the head such as air sacs, melon, muscle, bony structure, connective tissues, blubber, and mandibular fat on biosonar beam was investigated. The results might provide useful information for better understanding of the sound propagation in finless porpoise’s head.
Evidence for a possible functional significance of horseshoe bat biosonar dynamics
Authors: Müller Rolf , Gupta Anupam K. , Gillani Uzair , Fu Yanqing , Zhu Hongxiao
Published: October 2014

The periphery of the biosonar system of horseshoe bats is characterized by a conspicuous dynamics where the shapes of the noseleaves (structures that surround the nostrils) and the outer ears (pinnae) undergo fast changes that can coincide with pulse emission and echo reception. These changes in the geometries of the sound-reflecting surfaces affect the device characteristics, e.g., as represented by beampatterns. Hence, this dynamics could give horseshoe bats an opportunity to view their environments through a set of different device characteristics. It is not clear at present whether horseshoe bats make use of this opportunity, but there is evidence from various sources, namely, anatomy, behavior, evolution, and information theory. Anatomical studies have shown the existence of specialized muscular actuation systems that are clearly directed toward geometrical changes. Behavioral observations indicate that these changes are linked to contexts where the bat is confronted with a novel or otherwise demanding situation. Evolutionary evidence comes from the occurrence of qualitatively similar ear deformation patterns in mustached bats (Pteronotus) that have independently evolved a biosonar for Doppler-shift detection. Finally, an information-theoretic analysis demonstrates that the capacity of the biosonar system for encoding sensory information is enhanced by these dynamic processes.
Analysis of some special buzz clicks
Authors: Gerard Odile , Carthel Craig , Coraluppi Stefano
Published: October 2014

Toothed whales are known to click regularly to find prey. Once a prey has been detected, the repetition rate of the clicks increases; these sequences are called buzzes. Previous work shows that the buzz clicks spectrum slowly varies from click to click for various species. This spectrum similarity allows buzz clicks association as a sequence using multi-hypothesis tracking (MHT) algorithms. Thus buzz classification follows automatic click tracking. The use of MHT reveals that in some rare cases a variant of this property has been found, whereby sub-sequences of clicks exhibit slowly varying characteristics. In 2010 and 2011, NATO Undersea Research Centre (NURC, now CMRE Centre for Maritime Research and Experimentation) conducted sea-trials with the CPAM (compact Passive Acoustic Monitoring), a volumetric towed array comprised of four or six hydrophones. This configuration allows for a rough estimate of clicking animal localization. Some buzzes with sub-sequences of slowly varying characteristics were recorded with the CPAM. Localization may help to understand this new finding from a physiological point of view. The results of this analysis will be presented.
Acoustic metamaterial absorbers based on multi-scale sonic crystals
Authors: Guild Matthew D. , García-Chocano Victor M. , Kan Weiwei , Sanchez-Dehesa Jose
Published: October 2014

In this work, thermoviscous losses in single- and multi-scale sonic crystal arrangements are examined, enabling the fabrication and characterization of acoustic metamaterial absorbers. It will be shown that higher filling fraction arrangements can be used to provide a large enhancement in the complex mass density and loss factor, and can be combined with other sonic crystals of different sizes to create multi-scale structures that further enhance these effects. To realize these enhanced properties, different sonic crystal lattices are examined and arranged as a layered structure or a slab with large embedded inclusions. The inclusions are made from either a single solid cylinder or symmetrically arranged clusters of cylinders, known as magic clusters, which behave as an effective fluid. Theoretical results are obtained using a two-step homogenization process, by first homogenizing each sonic crystal to obtain the complex effective properties of each length scale, and then homogenizing the effective fluid structures to determine the properties of the ensemble structure. Experimental data from acoustic impedance tube measurements will be presented and shown to be in excellent agreement with the expected results. [Work supported by the US ONR and Spanish MINECO.]
Quasi-flat acoustic absorber enhanced by metamaterials
Authors: Azbaid El Ouahabi Abdelhalim , Krylov Victor V. , O'Boy Daniel J.
Published: October 2014

In this paper, the design of a new quasi-flat acoustic absorber (QFAA) enhanced by the presence of a graded metamaterial layer is described, and the results of the experimental investigation into the reflection of sound from such an absorber are reported. The matching metamaterial layer is formed by a quasi-periodic array of brass cylindrical tubes with the diameters gradually increasing from the external row of tubes facing the open air towards the internal row facing the absorbing layer made of a porous material. The QFAA is placed in a wooden box with the dimensions of 569 × 250 × 305 mm. All brass tubes are of the same length (305 mm) and fixed between the opposite sides of the wooden box. Measurements of the sound reflection coefficients from the empty wooden box, from the box with an inserted porous absorbing layer, and from the full QFAA containing both the porous absorbing layer and the array of brass tubes have been carried out in an anechoic chamber at the frequency range of 500–3000 Hz. The results show that the presence of the metamaterial layer brings a noticeable reduction in the sound reflection coefficients in comparison with the reflection from the porous layer alone.
Design of sound absorbing metamaterials by periodically embedding three-dimensional resonant or non-resonant inclusions in rigidly backed porous plate
Authors: Groby Jean-Philippe , Nennig Benoit , Lagarrigue Clément , Brouard Brunuo , Olivier Dazel , Umnova Olga , Tournat Vincent
Published: October 2014

Air saturated porous materials, namely, foams and wools, are often used as sound absorbing materials. Nevertheless, they suffer from a lack of absorption efficiency at low frequencies, which is inherent to their absorption mechanisms (viscous and thermal losses), even when used as optimized multilayer or graded porous materials. These last decades, several solutions have been proposed to avoid this problem. Among them, metaporous materials consist in exciting modes trapping the energy between the periodic rigid inclusions embedded in the porous plate and the rigid backing or in the inclusions themselves. The absorption coefficient of different foams is enhanced both in the viscous and inertial regimes by periodically embedding 3D inclusions, possibly resonant, i.e., air filled Helmholtz resonators. This enhancement is due to different mode excitation: a Helmholtz resonance in the viscous regime and a trap mode in the inertial regime. In particular, a large absorption coefficient is reached for wavelengths in the air 27 times larger than the sample thickness. The absorption amplitude and bandwidth is then enlarged by removing porous material in front of the neck, enabling a lower impedance radiation, and by adjusting the resonance frequencies of the Helmholtz resonator.
Seismic metamaterials: Shielding and focusing surface elastic waves in structured soils
Authors: Guenneau Sebastien R. , Enoch Stefan , Brule Stephane
Published: October 2014

Phononic crystals and metamaterials are man-made structures (with periodic heterogeneities typically a few micrometers to centimeters) that can control sound in ways not found in nature. Whereas the properties of phononic crystals derive from the periodicity of their structure, those of metamaterials arise from the collective effect of a large array of small resonators. These effects can be used to manipulate acoustic waves in unconventional ways, realizing functions such as invisibility cloaking, subwavelength focusing, and unconventional refraction phenomena (such as negative refractive index and phase velocity). Recent work has started to explore another intriguing domain of application: using similar concepts to control the propagation of seismic waves within the surface of the Earth. Our research group at the Aix-Marseille University and French National Center for Scientific Research (CNRS) has teamed up with civil engineers at an industrial company, Ménard, in Nozay, also in France, and carried out the largest-scale tests to date of phononic crystals. Arrays of boreholes in soil which are a few centimeters to a few meters in diameter are encouraging, thereafter called seismic metamaterials, can be used to deflect incoming acoustic waves at a frequency relevant to earthquake protection, or bring them to a focus. These preliminary successes could one day translate into a way of mitigating the destructive effects of earthquakes.
Measurement of acoustic emissions from F-35B vertical landing operations
Authors: Downing Micah , James Michael , Gee Kent , Reichman Brent , McKinley Richard , Aubert Allan
Published: October 2014

A multi-organizational effort led by the Air Force Research Laboratory conducted acoustic emissions measurements from vertical landing operations of the F-35B aircraft at Marine Corps Air Station Yuma, Arizona, in September 2013. These measurements followed American National Standards Institute/Acoustical Society of American S12.75-2012 to collect noise data from vertical landing operations for community noise models and noise exposures to aircraft personnel. Three circular arcs and two vertical microphone arrays were deployed for these measurements. The circular microphone arrays ranged from distances from 250 ft to 1000 ft from touch down point. A description of the vertical landing acoustic measurements, data processing, preliminary data analysis, the resultant dataset, and a summary of results will be provided.
Acoustic interaction of turbofan exhaust with deflected control surface for blended wing body airplane
Authors: Papamoschou Dimitri , Mayoral Salvador
Published: October 2014

Small-scale experiments simulated the elevon-induced jet scrubbing noise of the Blended-Wing-Body platform with a bypass ratio ten turbofan nozzle installed above the wing. The elevon chord length at the interaction zone was similar to the exit fan diameter of the nozzle. The study encompassed variable nozzle position, variable elevon deflection, removable inboard fins, and two types of nozzles—plain and chevron. Far-field microphone surveys were conducted underneath the wing. The interaction between the jet and the elevon produces excess noise that intensifies with increasing elevon deflection. When the elevon trailing edge is near the edge of the jet, excess noise is manifested as a low-frequency bump on the sound pressure level spectrum. An empirical model for this excess noise is presented. The interaction noise becomes severe, and elevates the entire spectrum, when the elevon intrudes significantly into the jet flow. The increase in effective perceived noise level (EPNL) falls on well-defined trends when correlated versus the penetration of the elevon trailing edge into the flow field of the isolated jet. The cumulative takeoff EPNL can increase by as much as 19 dB, underscoring the potentially detrimental effects of jet-elevon interaction on noise compliance.
A new method of estimating acoustic intensity applied to the sound field near a military jet aircraft
Authors: Stout Trevor A. , Gee Kent L. , Neilsen Tracianne B. , Thomas Derek C. , Christensen Benjamin Y. , James Michael M.
Published: October 2014

Intensity probes are traditionally made up of closely spaced microphones, with the finite-difference method used to approximate acoustic intensity. This approximation is not reliable approaching the Nyquist frequency limit determined by microphone spacing. However, the new phase and amplitude estimation (PAGE) method allows for accurate intensity approximation far above this limit. The PAGE method is applied to measurements from a three-dimensional intensity probe, which took data to the sideline and aft of a tethered F-22A Raptor. It is shown that the PAGE method produces physically meaningful intensity approximations for frequencies up to about 6 kHz, while the finite-difference method is only reliable up to about 2 kHz. [Work supported by ONR.]
Locus equations estimated form a corpus of running speech
Authors: Kiefte Michael , Nearey Terrance M.
Published: October 2014

Locus equations, or the linear relationship between onset and vowel second-formant frequency F2 in terms of slope and y-intercept, have been presented as possible invariant correlates to consonant place of articulation [e.g., Sussman et al. (1998). Behav. Brain Sci. 21, 241–299]. In the current study, formant measurements were extracted from both stressed and unstressed vowels taken from a database of spontaneous and read speech. Locus equations were estimated for several places of articulation of the preceding consonant. In addition, optimal time frames for estimating locus equations are determined with reference to automatic classification of consonant place of articulation as well as vowel identification. Formant frequencies are first measured at multiple time frames—both before and after voicing onset in the case of voiceless plosives—to find the pair of time frames that best estimates place of articulation via discriminant analysis and other classification methods. In addition, locus-equation slopes are compared between stressed and unstressed vowels as well as between spontaneous and read speech samples. In addition, the role of total vowel duration across these contexts is described. The evaluation of several strategies for optimizing the automatic extraction of formant frequencies from running speech are also reported. [Work supported by SSHRC.]
Formant trajectory analysis using dynamic time warping: Preliminary results
Authors: Regier Kirsten T.
Published: October 2014

In English, there are at least two mechanisms that affect vowel duration—vowel identity and postvocalic consonant voicing. Previous studies have shown that these two mechanisms have independent effects on vowel duration (Port 1981, Todt 2010). This study presents preliminary results on the use of dynamic time warping to distinguish between the effects of vowel identity and postvocalic consonant voicing on the formant trajectories of English front vowels. Using PraatR (Albin 2014), formant trajectories are extracted from sound files in Praat and imported into R, where the dynamic time warping analysis is conducted using the dtw package (Giorgino 2009). Albin, A. L. (2014). PraatR: An architecture for controlling the phonetics software “Praat” with the R programming language. JASA 135, 2198. Giorgino T. (2009). “Computing and Visualizing Dynamic Time Warping Alignments in R: The dtw Package,”J. Stat. Software, 31(7), pp. 1–24. Port, R. F. (1981). Linguistic timing factors in combination. JASA 69(1), 262–274. R Core Team (2014). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Todt, K. R. (2010). The production of English front vowels by Spanish speakers: A study of vowel duration based on vowel tenseness and consonant voicing, JASA 128, 2489.
A “pivot” model for extracting formant measurements based on vowel trajectory dynamics
Authors: Albin Aaron L. , Rankinen Wil A.
Published: October 2014

Formant measurements are commonly extracted at fixed fractions across a vowel's duration (e.g., the 1/2 point for a monophthong and the 1/3 and 2/3 points for a diphthong). This approach tacitly relies on the convenience assumption that a speaker always maximally approximates the intended acoustic target at roughly the same point across a vowel's duration. The present paper proposes an alternate method whereby every formant point sampled within a vowel is considered as a possible "pivot" (i.e., turning point), with monophthongs modeled as having one pivot and diphthongs modeled as having two pivots. The optimal pivot for the vowel is then determined by fitting regression lines to the formant trajectory and comparing the goodness-of-fit of these lines to the raw formant data. When applied to a corpus of an American English dialect, the resulting measurements were found to be significantly correlated with previous methods. This suggests that the aforementioned convenience assumption is unnecessary and that the proposed model, which is more faithful to our understanding of articulatory dynamics, is a viable alternative. Moreover, rather than being assumed a priori, the location of the measurement can be treated as an empirical question in its own right.
Exploiting second-order statistics improves statistical learning of vowels
Authors: Llanos Fernando , Jiang Yue , Kluender Keith R.
Published: October 2014

Unsupervised clustering algorithms were used to evaluate three models of statistical learning of minimal contrasts between English vowel pairs. The first two models employed only first-order statistics with assumptions of uniform [M1] or Gaussian [M2] distributions of vowels in an F1-F2 space. The third model [M3] employed second-order statistics by encoding covariance between F1 and F2. Acoustic measures of F1/F2 frequencies for 12 vowels spoken by 139 men, women, and children (Hillendrand et al. 1995) were used as input to the models. Effectiveness of each model was tested for each minimal-pair contrast across 100 simulations. Each simulation consisted of two centroids that adjusted on a trial-by-trial basis as 1000 F1/F2 pairs were input to the models. With addition of each pair, centroids were reallocated by a k-means algorithm, an unsupervised clustering algorithm that provides an optimal partition of the space into uniformly-sized convex cells. The first-order Gaussian model [M2] performed better than a uniform distribution [M2] for six of seven minimal pairs. The second-order model [M3] was significantly superior to both first-order models for every pair. Results have implications for optimal perceptual learning of phonetic differences in ways that respect lawful covariance across vocal tract lengths that vary across talkers.
Analysis of acoustic to articulatory speech inversion for natural speech
Authors: Sivaraman Ganesh , Espy-Wilson Carol , Mitra Vikramjit , Nam Hosung , Saltzman Elliot
Published: October 2014

Speech inversion is a technique to estimate vocal tract configurations from speech acoustics. We constructed two such systems using feedforward neural networks. One was trained using natural speech data from the XRMB database and the second using synthetic data generated by the Haskins Laboratories TADA model that approximated the XRMB data. XRMB pellet trajectories were first converted into vocal tract constriction variables (TVs), providing a relative measure of constriction kinematics (location and degree) and synthetic TV data was obtained directly using TADA. The natural and synthetic speech inversion systems were trained as TV estimators using these respective sets of acoustic and TV data. TV-estimators were first tested using previously collected acoustic data on the utterance “perfect memory” spoken at slow, normal, and fast rates. The TV estimator trained on XRMB data (but not on TADA data) was able to recover the tongue tip gesture for /t/ in the fast utterance despite the gesture occurring partly during the acoustic silence of the closure. Further, the XRMB system (but not the TADA system) could distinguish between bunched and retroflexed /r/. Finally, we compared the performance of the XRMB system with a set of independently trained speaker-dependent systems (using the XRMB database) to understand the role of speaker-specific differences in the partitioning of variability across acoustic and articulatory spaces.
Surveying the nasal peak: A1 and P0 in nasal and nasalized vowels
Authors: Styler Will , Scarborough Rebecca
Published: October 2014

Nasality can be measured in the acoustical signal using A1-P0, where A1 is the amplitude of the harmonic under F1, and P0 is the amplitude of a low-frequency nasal peak (~250 Hz) (Chen 1997). In principle, as nasality increases, P0 goes up and A1 is damped, yielding lower A1-P0. However, the details of the relationship between A1 and P0 in natural speech have not been well described. We examined 4778 vowels in French and English elicited words, measuring A1, P0, and the surrounding harmonic amplitudes, and comparing oral and nasal tokens (phonemic nasal vowels in French, and coarticulatorily nasalized vowels in English). Linear mixed-effects regressions confirmed that A1-P0 is predictive of nasality: 4.16 dB lower in English nasal contexts relative to oral and 5.73 dB lower in French (both p<0.001). In English, as expected, P0 increased 1.42 dB and A1 decreased 3.93 dB (p<0.001). In French, however, both A1 and P0 lowered with nasality (5.73 and 0.93 dB, respectively, p<0.001). Even so, in both languages, P0 became more prominent relative to adjacent harmonics in nasal vowels. These data reveal cross-linguistic differences in the acoustic realization of nasal vowels and suggest P0 prominence as a potential perceptual cue to be investigated.
Statistical sampling and Bayesian illumination waveform design for multiple-hypothesis target classification in cognitive signal processing
Authors: Clark Grace A.
Published: October 2014

Statistical sampling algorithms are widely used in Bayesian signal processing for drawing real-valued independent, identically distributed (i.i.d.) samples from a desired distribution. This paper focuses on the more difficult problem of how to draw complex correlated samples from a distribution specified by both an arbitrary desired probability density function and a desired power spectral density. This problem arises in cognitive signal processing. A cognitive signal processing system (for example, in radar or sonar) is one that observes and learns from the environment; then uses a dynamic closed-loop feedback mechanism to adapt the illumination waveform so as to provide system performance improvements over traditional systems. Current cognitive radar algorithms focus only on target impulse responses that are Gaussian distributed to achieve mathematical tractability. This research generalizes the cognitive radar target classifier to deal effectively with arbitrary non-Gaussian distributed target responses. The key contribution lies in the use of a kernel density estimator and an extension of a new algorithm by Nichols et al. for drawing complex correlated samples from target distributions specified by both an arbitrary desired probability density function and a desired power spectral density. Simulations using non-Gaussian target impulse response waveforms demonstrate very effective classification performance.
Bayesian inversion and sequential Monte Carlo sampling techniques applied to nearfield acoustic sensor arrays
Authors: Bai Mingsian R. , Agarwal Amal , Chen Ching-Cheng , Wang Yen-Chih
Published: October 2014

This paper demonstrates that inverse source reconstruction can be performed using a methodology of particle filters that relies primarily on the Bayesian approach of parameter estimation. The proposed approach is applied in the context of nearfield acoustic holography based on the equivalent source method (ESM). A state-space model is formulated in light of the ESM. The parameters to estimate are amplitudes and locations of the equivalent sources. The parameters constitute the state vector which follows a first-order Markov process with the transition matrix being the identity for every frequency-domain data frame. The implementation of recursive Bayesian filters involves a sequential Monte Carlo sampling procedure that treats the estimates as point masses with a discrete probability mass function (PMF) which evolves with iteration. It is evident from the results that the inclusion of the appropriate prior distribution is crucial in the parameter estimation.
Particle filtering for robust modal identification and sediment sound speed estimation
Authors: Aunsri Nattapol , Michalopoulou Zoi-Heleni
Published: October 2014

Bayesian methods provide a wealth of information on acoustic features of a propagation medium and the uncertainty surrounding their estimation. In previous work, we showed how sequential Bayesian (particle) filtering can be used to extract dispersion characteristics of a waveguide. Here, we utilize these characteristics for the estimation of geoacoustic properties of sediments. As expected, the method relies on accurate identification of modes. The effect of correct/erroneous mode identification on geoacoustic estimates is quantified and approaches are developed for robust modal recognition in conjunction with the particle filter. Additionally, the statistical behavior of the noise present in the data measurements is further investigated with more complex noise modeling leading to improved results. The approaches are validated with both synthetic and real data collected during the Gulf of Mexico Experiment. [Work supported by ONR.]
Efficient trans-dimensional Bayesian inversion for geoacoustic profile estimation
Authors: Dosso Stan E. , Dettmer Jan , Steininger Gavin , Holland Charles W.
Published: October 2014

This paper considers sampling efficiency of trans-dimensional (trans-D) Bayesian inversion based on the reversible-jump Markov-chain Monte Carlo (rjMCMC) algorithm, with application to seabed acoustic reflectivity inversion. Trans-D inversion is applied to sample the posterior probability density over geoacoustic parameters for an unknown number of seabed layers, providing profile estimates with uncertainties that include the uncertainty in the model parameterization. However, the approach is computationally intensive. The efficiency of rjMCMC sampling is largely determined by the proposal schemes applied to perturb existing parameters and to assign values for parameters added to the model. Several proposal schemes are examined, some of which appear new for trans-D geoacoustic inversion. Perturbations of existing parameters are considered in a principal-component space based on an eigen-decomposition of the unit-lag parameter covariance matrix (computed from successive models along the Markov chain, a diminishing adaptation). The relative efficiency of proposing new parameters from the prior versus a Gaussian distribution focused near existing values is considered. Parallel tempering, which employs a sequence of interacting Markov chains with successively relaxed likelihoods, is also considered to increase the acceptance rate of new layers. The relative efficiency of various proposal schemes is compared through repeated inversions with a pragmatic convergence criterion.
Bayesian tsunami-waveform inversion with trans-dimensional tsunami-source models
Authors: Dettmer Jan , Hossen Jakir , Cummins Phil R. , Dosso Stan E.
Published: October 2014

This paper develops a self-parametrized Bayesian inversion to infer the spatio-temporal evolution of tsunami sources (initial sea state) due to megathrust earthquakes. To date, tsunami-source uncertainties are poorly understood, and the effect of choices such as discretization have not been studied. The approach developed here is based on a trans-dimensional self-parametrization of the sea surface, avoids regularization constraints and provides rigorous uncertainty estimation that accounts for model-selection ambiguity associated with the source discretization. The sea surface is parametrized using self-adapting irregular grids, which match the local resolving power of the data and provide parsimonious solutions for complex source characteristics. Source causality is ensured by including rupture-velocity and obtaining delay times from the Eikonal equation. The data are recorded on ocean-bottom pressure and coastal wave gauges and predictions are based on Green-function libraries computed from ocean-basin scale tsunami models for cases that include/exclude dispersion effects. The inversion is applied to tsunami waveforms from the great 2011 Tohoku-Oki (Japan) earthquake. The tsunami source is strongest near the Japan trench with posterior mean amplitudes of ~5 m. In addition, the data appear sensitive to rupture velocity, which is part of our kinematic source model.
Very-high-speed 3-dimensional modeling of littoral target scattering
Authors: Burnett David
Published: October 2014

NSWC PCD has developed a high-fidelity 3-D finite-element (FE) modeling system that computes acoustic color templates (target strength vs. frequency and aspect angle) of single or multiple realistic objects (e.g., target + clutter) in littoral environments. High-fidelity means that 3-D physics is used in all solids and fluids, including even thin shells, so that solutions include not only all propagating waves but also all evanescent waves, the latter critically affecting the former. Although novel modeling techniques have accelerated the code by several orders of magnitude, it takes about one day to compute an acoustic color template. However, NSWC PCD wants to be able to compute thousands of templates quickly, varying target/environment features by small amounts, in order to develop statistically robust classification algorithms. To accomplish this, NSWC PCD is implementing a radically different FE technology that has already been developed and verified. It preserves all the 3-D physics but promises to accelerate the code another two to three orders of magnitude. Porting the code to an HPC center will accelerate it another one to two orders of magnitude, bringing performance to seconds per template. The talk will briefly review the existing system and then describe the new technology.
Modeling three-dimensional acoustic scattering from targets near an elastic bottom using an interior-transmission formulation
Authors: Dey Saikat , Szymczak William G. , Sarkissian Angie , Bucaro Joseph , Houston Brian
Published: October 2014

For targets near the sediment–fluid interface, the scattering response is fundamentally influenced by the characterization of the sediment in the model. We show that if the model consists of a three-dimensional elastic sediment with acoustic fluid on top, then the use of perfectly matched-layer (PML) approximation for the truncation of the infinite exterior domain for scattering applications has fundamental problems and gives erroneous results. We present a novel formulation using the an interior-transmission representation of the scattering problem where the exterior truncation with PML does not induce errors in the result. Numerical examples will be presented to verify the application of this formulation to scattering from elastic targets near a fluid–sediment interface.
A new T matrix for acoustic target scattering by elongated objects in free-field and in bounded environments
Authors: Lim Raymond
Published: October 2014

The transition (T) matrix of Waterman has been very useful for computing fast, accurate acoustic scattering predictions for axisymmetric elastic objects but this technique is usually limited to fairly smooth objects that are not too aspherical unless complex basis functions or stabilization schemes are used. To remove this difficulty, a spherical-basis formulation adapted from approaches proposed recently by Waterman [J. Acoust. Soc. Am. 125, 42–51 (2009)] and Doicu, et al. [Acoustic & Electromagnetic Scattering Analysis Using Discrete Sources, Academic Press, London, 2000] is suggested. The new method is implemented by simply transforming the high-order outgoing spherical basis functions within standard T-matrix formulations to low-order functions distributed along the object’s symmetry axis. A free-field T-matrix is produced in a nonstandard form but computations with it become much more stable for aspherical shapes. Some advantages of this approach over Waterman’s and Doicu, et al.’s approaches are noted and, despite its nonstandard form, the feasibility of extension to objects in a plane-stratified environment is demonstrated. Sample calculations for an elongated spheroid demonstrate the enhanced stability.
Kirchhoff approximation for spheres and cylinders partially exposed at flat surfaces and application to the interpretation of backscattering
Authors: Gunderson Aaron M. , Smith Anthony R. , Marston Philip L.
Published: October 2014

For cylinders partially exposed at flat surfaces, the Kirchhoff approximation was previously evaluated analytically and compared with measured backscattering at a free surface as a function of exposure [K. Baik and P. L. Marston, IEEE J. Ocean. Eng. 33, 386–396 (2008)]. In the present research, this approach is extended to the cases of numerical integration for high frequency backscattering by partially exposed spheres and cylinders. The cylinder case was limited to broadside illumination at grazing incidence for which one-dimensional integration is sufficient and the limits of integration were previously discussed by Baik and Marston. In the corresponding sphere case, however, two-dimensional integration is required and the corresponding limits of integration become complicated functions of the amount of exposure and the grazing angle of the illumination. These approximations of the backscattering, while they omit Franz wave and elastic contributions, are useful for modeling the evolution of how the reflected scattering contributions depend on the target exposure. They are also useful for understanding the time evolution of specular scattering contributions. The sphere case was compared with the exact analysis of backscattering by a half exposed rigid sphere at a free surface that also displays partially reflected Franz wave contributions. [Work supported by ONR.]
Pressure gradient coupling to an asymmetric cylinder at an interface
Authors: Dudley Christopher
Published: October 2014

Invited Abstract Special session: “Investigation of target response near interfaces, where coupling between target and environmental properties are important.” Acoustic scattering results from solid and hollow notched aluminum cylinders are presented as a function of the incident angle. This flat machined into the circular cylinder resembles the topography(geometry) of an finned unexploded ordnance (UXO). Prior experiments have shown selective coupling to modes of a flat ended cylinder and the effect of pressure nodes to coupling to a similar notched cylinder [Espana et al., J. Acoust. Soc. Am. 126, 2187 (2009) and Marston & Marston, J. Acoust. Soc. Am. 127, 1750 (2010)]. The wavefront crossing the flat face of the notch in the paddle has a pressure gradient when not co-linear with the normal to the flat face of the notch. This pressure gradient applies a torque to the cylinder. Torsional modes can be setup in multiple scaled version of the pseudo-UXOs. Analysis of scattering experiments in the Gulf of Mexico and laboratory scale water tanks indicate robust returns form these fin like targets.
The impact of auralization on design decisions for the House of Commons of the Canadian Parliament
Authors: Eligator Ronald
Published: October 2014

The House of Commons of the Canadian Parliament will be temporary relocated to a 27,000 m3 glass-enclosed atrium with stone and glass walls while their home Chamber is being renovated and restored. Acoustic goals include excellent speech intelligibility for Members and guests in the room, and production of high-quality audio recordings of all proceedings for live and recorded streaming and broadcast. Room modeling and auralization using CATT Acoustic has been used to evaluate the acoustic environment of the temporary location during design. Modeling and testing of the current House Chamber has also been performed to validate the results and conclusions drawn from the model of the new space. The use of auralizations has helped the Owner and Architect understand the impact of design choices on the achievement of the acoustic performance goals, and smoothed the path for the integration of design features that might otherwise have been difficult for them to accept. Measured and calculated data as well as audio examples will be presented.
Cost effective auralizations to help architects and owners make informed decisions for sound isolating assemblies
Authors: Manley David , Bridgewater Ben
Published: October 2014

As an acoustical consultant, subjective descriptions of noise environments only get you so far. For example, it can be difficult for an Architect to qualify the difference between STC 35 and STC 40 windows on a given office space next to a highway. Often, justifying the increased cost for the increased sound isolation performance is at the forefront of the decision making process for the Owner and Architect. To help them understand the relative difference in performance, DLAA uses a simplified auralization process to create audio demonstrations of the difference between sound isolating assemblies. This presentation will discuss the process of creating the auralizations and review case studies where the auralizations helped the client make a more informed decision.
Using auralization to aid in decision making to meet customer requirements for room response and speech intelligibility
Authors: Tyson Thomas
Published: October 2014

To meet specific design goals such as a high degree of speech intelligibility along with targeted reverberation time; the presenter will show how the use of auralization can help determine the effectiveness of acoustic treatments and loudspeaker directivity types, beyond just the use of predicted numerical data.
Auralization as an aid in decision-making: Examples from professional practice
Authors: Markham Benjamin , Connick Robert , Sacks Jonah
Published: October 2014

The authors and our colleagues have presented dozens of auralizations in the service of our architectural acoustics consulting work, on projects ranging from large atriums to classrooms to sound isolation between nightclubs and surrounding facilities (and many others). The aim of most of these presentations is to communicate the relative efficacy of design alternatives or acoustical treatment options. In some cases, the effects are profound; in others, the acoustical impact may be rather subtle. Without perfect correlation, we have noted a general trend: when the observable change in acoustical attributes presented in the auralization is substantial, so too is the interest on the part of the owner to invest in significant or even aggressive acoustical design alternatives; by contrast, subtler changes in perceived acoustical character often leave owners and architects less inclined to dedicate design resources to pursue alternatives that differ from the architect or owner’s original vision. Examples of auralizations following (and contradicting) this trend will be presented, along with descriptions of the design direction taken following meetings and discussions that accompanied the auralizations.
Auralization and the real world
Authors: Kanter Shane J. , Bridgewater Ben , Coffeen Robert C.
Published: October 2014

Architects value their senses and strive to design spaces that are engaging all five of them. However, architects typically make design decisions based primarily on how spaces appear and feel, as opposed to acousticians who normally justify design intent with the use of numbers, graphs, and charts. Although the data are clear to acousticians, auralizations are a useful tool to engage architects, building owners, and other clients and their sense of hearing to help them make informed decisions. If auralizations are used to demonstrate the effect of design decisions based on acoustics, there must be confidence in the accuracy and realism of these audio simulations. In order to better understand the accuracy and realism of auralizations, a study was conducted comparing auralizations created from models of an existing facility to listening within the facility. Listeners were asked to compare the “real world” sound to the auralizations of this sound by completing a survey with questions focusing on such comparisons. By presenting the actual sound and the auralizations in the same space, a direct comparison can be made and the accuracy and realism of the auralizations can be determined. Results and observations from the study will be presented.
Directing room acoustic decisions for a college auditorium renovation by using auralization
Authors: Coffeen Robert C.
Published: October 2014

From an acoustical viewpoint, the renovation of a multipurpose college auditorium was predicted by music and theater faculty to be a compromise not suitable for either music or theater. It was obvious that either variable sound absorption or active acoustics would be required to satisfy the multipurpose uses of the auditorium. Active acoustics was rejected by the college due to cost and an experience by one faculty member. And the faculty committee was not familiar with variable sound absorption. Using a computer model of the auditorium it was determined that the volume of the venue could be established to produce the desired maximum reverberation time for music and that vertical rising drapery could produce the desired reverberation time for drama. Auralization was used to demonstrate to the faculty committee that with variable sound absorption the auditorium could properly accommodate music of various types and theatrical performances including drama.
“Illuminating” reflection orders in architectural acoustics using SketchUp and light rendering
Authors: Carter J. Parkman
Published: October 2014

The conventional architecture workflow tends to—quite literally—“overlook” matters of sound, given that the modeling tools of architectural design are almost exclusively visual in nature. The modeling tools used by architectural acousticians, however, produce visual representations, which are, frankly, less than inspirational for the design process. This project develops a simple scheme to visualize acoustic reflection orders using light rendering in the freely available and widely used Trimble SketchUp 3D modeling software. In addition to allowing architectural designers to visualize acoustic reflections in a familiar modeling environment, this scheme also works easily with complex geometry. The technique and examples will be presented.
The role of auralization utilizing the end user source signal in determining final material finishes for the Chapel at St. Dominics
Authors: Woolworth David S.
Published: October 2014

The Chapel at St. Dominics Hospital in Jackson, Mississippi, was created for religious services, prayer time, and serve other spiritual needs of the hospital's patients, employees, medical staff, hospital visitors, and the greater community. It is an intimate space seating up to 100 people and is used daily by the Dominican Sisters, who first started the Jackson Infirmary in 1946. This paper outlines the process used to record the voices of the sisters and then use them to generate auralizations, which helped drive decisions regarding acoustic finishes.