bluuebunny/crossref_metadata_2025 huggingface dataset:
Classroom acoustics and children's speech perception
Authors: Leibold Lori , McCreery Ryan W. , Buss Emily
Published: June 2017

Children must learn in classrooms that contain multiple sources of competing sounds. While there are national standards aimed at creating classroom environments that optimize speech intelligibility (e.g., ANSI/ASA 2010), these standards are voluntary and many unoccupied classrooms fail to meet the acceptable levels specified. Moreover, little attention has been given to measuring and understanding effects of competing speech on children’s performance in the classroom. Data will be presented that describe typical noise levels in the classroom. Results from experiments investigating the consequences of competing noise and speech on speech perception at different time points during childhood will be presented. Findings from experiments investigating potential benefits associated with manipulating acoustic cues thought to aid in separating target from background speech will also be discussed.
Frequency-domain passive cavitation imaging
Authors: Haworth Kevin J. , Bader Kenneth B. , Rich Kyle T. , Holland Christy K. , Mast T. Douglas
Published: June 2017

Apfel’s three golden rules (know thy sound field, know thy liquid, and know when something happens) should be considered when monitoring acoustic cavitation-based ultrasound therapies. The third rule is often followed using passive cavitation detection with a single-element transducer. However, therapy guidance demands monitoring cavitation activity in the entire tissue volume of interest. Using array-based passive cavitation detection with appropriate beamforming, maps of cavitation activity can be superimposed on pulse-echo, grayscale images of tissue anatomy. In this talk, we will discuss one approach for generating cavitation activity maps, frequency-domain passive cavitation imaging (FD-PCI). FD-PCI implements a delay, sum, and integrate algorithm, which will be described conceptually and mathematically. The advantages and limitations of the algorithm will be discussed in the context of examples. Advantages of FD-PCI include the innate frequency selectivity of the algorithm, the ability to use parallel computing for increased processing speed, the independence of the image resolution from the therapy insonation pulse shape, and the ability to quantify the acoustic power of emissions detected by the array. Challenges of the algorithm will also be discussed, including poor axial resolution and limitations of estimating the emitted acoustic power.
Passive acoustic mapping in aberrating media with the angular spectrum approach
Authors: Schoen Scott J. , Arvanitis Costas
Published: June 2017

The ability to localize and characterize ultrasound-induced microbubble oscillations through the intact skull with high spatial and temporal resolution holds significant promise for the diagnosis and treatment of brain diseases and disorders. In this study, we investigated the ability of angular spectrum (AS) method, a fast planar projection method, to perform passive acoustic mapping of microbubbles through an intact skull. Finite-difference time-domain numerical simulations were used to model microbubble emissions’ propagation through homogeneous, stratified, and 2D inhomogeneous (skull) environments approximately 80 mm by 160 mm. Reconstructions with the AS approach were performed with constant and effective sound speeds, as well as with multi-step propagation, to evaluate their ability to correct for induced aberrations and localize the microbubbles. We also investigated the impact of the receiver position on the localization accuracy. Results for skull simulations indicated that the multi-step AS method reduced the error in axial localization of the microbubbles by on the order of 50% compared with the effective sound speed method, while incurring approximately a 25% increase in computation time for each doubling of the number of propagation steps. Both AS methods were several orders of magnitude faster than time-domain reconstruction. Further investigation of the potential of this approach to correct skull aberrations is warranted.
Nonlinear propagation of two dimensional sound waves observed at lipid interfaces
Authors: Shrivastava Shamit , Schneider Matthias F.
Published: June 2017

Experimental results are presented on the acoustic propagation of mechanical perturbations in a lipid monolayer along the air-water interface. The interface was excited by a piezo-cantilever, and propagating impulses were measured optically using Forster Resonance Energy Transfer (FRET). The velocity of propagation varied from 0.1 to 1 m/s depending on the compressibility of the interface. Near a nonlinearity in the state diagram of the interface, for example, near a phase transition of the lipids, impulses propagated only when the initial mechanical impulse was greater than a certain threshold. In fact, the impulse then propagated as a solitary shock wave causing local adiabatic phase transition of the lipid molecules along the way. Although the phenomenon has been observed here in pure lipid monolayers, which represent a well-documented model for biological membranes, the origin of the observed phenomenon lies in the conservation of the entropy of the interface, determined by the change in state of the interface during the impulse. Given that the state diagrams of biological membranes have nonlinearities near physiological conditions, nonlinear sound waves are expected to be fundamentally involved in inter and intra cellular communication. Indeed, the observed acoustic phenomenon is characteristically similar to nerve impulses.
Summary and progress made in modeling of sonic boom propagation during AIAA sonic boom prediction workshops
Authors: Rallabhandi Sriram , Loubeau Alexandra
Published: June 2017

This paper summarizes the atmospheric propagation modeling portion of the Second American Institute of Aeronautics and Astronautics (AIAA) Sonic Boom Prediction Workshop held in 2017 as well as an informal propagation comparison and benchmarking effort conducted prior to the First AIAA Sonic Boom Prediction Workshop in 2014. The motivation behind these workshops is the industry's increased interest in low boom supersonic aircraft designs and the need to have an open, unbiased forum to promote best practices. The propagation test cases from both exercises are described and discussed. Discussion is also included on the selection of test case conditions with multiple atmospheric profiles, representing geographical and seasonal variations of the relevant meteorological data. Propagated sonic boom ground signatures, loudness metrics, extent of the boom carpets and other propagation-related details were gathered from a group of international participants. Comparisons are made between submissions, and the differences are analyzed in detail to understand the state-of-the-art in sonic boom atmospheric propagation modeling. The progress made between the workshops and the lessons learned will be discussed.
Beyond acoustophoresis: Attractive and repulsive forces on particles
Authors: Hilgenfeldt Sascha , Rallabandi Bhargav , Agarwal Siddhansh , Raju David
Published: June 2017

Inertial effects in microfluidics afford an interesting set of tools for the control of particle positions. The gradients of steady channel flows, as well as the gradients of acoustic field amplitudes, have been used prominently to this purpose, the latter in acoustofluidics. Here, we investigate directly the effect of an oscillating interface on the fluid surrounding it and particles suspended in the fluid. The fast oscillatory motion gives rise to strong inertial effects, while the method allows for versatile force actuation because of the variety of flow fields, frequencies, and length scales under the experimentalist's control. We show in experiment and theory that the forces on particles can be evaluated analytically, on both the oscillatory and the steady, time-averaged time scales. The latter formalism generalizes streaming flow computations to particle motion, and reveals new potential strategies for manipulating particles with tunable attractive or repulsive forces, depending not only on characteristics of the particles and physical properties of the fluid, but also the dynamical parameters of the driving.
Evaluation of object-based audio—What is the reference?
Authors: Sporer Thomas , Liebetrau Judith , Clauss Tobias
Published: June 2017

During the development of audio coding schemes, a number of methods for evaluation of the perceived audio quality have been developed. To enable comparisons across test sites, several methods have been standardized. In standardized methods like ITU-R Recommendations BS.1116 and BS.1534 (MUSHRA), the output of a codec (signal under test) is compared to an open reference. This reference is the unimpaired input of the codec. Assuming that the codec is “transparent,” the signal under test should sound exactly like this reference. For object-based audio, the input of a codec is a combination of raw audio channels and metadata describing position and other properties of the audio objects. It does not make sense to listen directly to the raw data. For listening, it is necessary to calculate the driving signal for each loudspeaker available in the listening room (rendering). Therefore, the comparison of different renderers is difficult: the renderer used to generate the reference signal has an advantage. Using a dedicated loudspeaker as the reference does not solve the problem either: loudspeakers always sound different than virtual sound objects. The presentation will discuss problems and solutions in more detail. Some promising setups based on multi attribute testing are presented.
Investigation of perceptual attributes associated with projected sound sources
Authors: Wühle Tom , Altinsoy M. Ercan
Published: June 2017

One solution to reproduce sound from various directions is the projection of sound sources on reflective boundaries. In this case, the perceived direction of the auditory event changes from the direction of the real source to the direction of the projected source. Therefore, highly focused sound sources are necessary. However, the focusing capabilities of such sources are physically limited. Thus, the total amount of sound at the listening position is formed by the projected sound and by sound which is directly radiated from the real source. Both of these sound proportions influence the perception of the listener. In a scenario with projected sound sources, a complex mixture of perceptual attributes change besides the direction of the auditory event. The present study investigates some of those attributes.
Individual attributes describing the perception of synthesized sound fields in listening rooms
Authors: Erbes Vera , Spors Sascha
Published: June 2017

Sound field synthesis techniques such as Wave Field Synthesis (WFS) are in theory defined in an anechoic environment but real-world installations have to be placed inside listening rooms with reflective walls. The arising reflections influence the desired synthesized sound field both from a physical and a perceptual point of view. This study investigates the perceptual aspects that are relevant for WFS in reflective environments by means of the Repertory Grid Technique (RGT). By comparing a representative range of auditory scenes with real and virtual sources in free field and in different listening rooms, subjects generate individual constructs to describe perceived differences and similarities as contrastive pairs. In a second step, subjects rate the scenes on scales constructed by their own contrastive pairs. The ratings are used to reveal relations between the constructs and the scenes on an individual basis. Clusters of constructs can be found that in terms of content can be associated with a common perceptual aspect.
Using binaural and spherical microphone arrays to assess the quality of synthetic spatial sound fields
Authors: Braasch Jonas , Deshpande Nikhil , Mathews Jonathan , Chabot Samuel
Published: June 2017

Recently, we completed the Collaborative-Research Augmented Immersive Virtual Environment Laboratory (CRAIVE-Lab) with a usable floor area of 12 × 10 m2 at Rensselaer. The CRAIVE-Lab project addresses the need for a specialized virtual-reality (VR) system for the study and enabling of communication-driven tasks with groups of users immersed in a high-fidelity multi-modal environment located in the same physical space. For the acoustic domain, a 134-loudspeaker-channel system has been installed for Wave Field Synthesis (WFS) with the support of Higher-Order-Ambisonic (HoA) sound projection to render inhomogeneous acoustic fields. An integrated 16-channel spherical microphone array makes the CRAIVE-Lab an ideal test bed to study different spatial rendering techniques such as Wave-Field Synthesis, Higher-Order Ambisonics and Virtual Microphone Control (ViMiC). In this talk, sound-field measurements taken with a traditional binaural manikin will be compared to spherical microphone recordings to assess the quality of the different rendering techniques for large-scale labs. A focus will hereby be set on assessing the sweet spot area for different rendering techniques. [Work supported by NSF 1229391, NSF 1631674, and the Cognitive and Immersive Systems Laboratory (CISL).]
Active listening in 3D auditory scenes
Authors: Moss Cynthia F.
Published: June 2017

As an animal moves in its natural environment, to seek food, track targets, and steer around obstacles, its distance and direction to objects continuously change, invoking dynamic feedback between 3D scene representation, attention, and action-selection. Animals that rely on active sensing provide powerful systems to investigate neural underpinnings of sensory-guided behaviors, as they produce the very signals that inform motor actions. Echolocating bats, for example, transmit sonar signals and process auditory information carried by echoes to guide behavioral decisions for spatial orientation. Further, the bat adapts its echolocation signal design in response to 3D spatial information computed from echo returns, and therefore, the directional aim and temporal patterning of its calls provide a window into the animal’s attention to objects in its surroundings. In addition, the bat actively controls pinna position and head movements to enhance auditory cues about 3D target position. These adaptive behaviors require an interface between auditory processing and motor commands, and our research findings implicate the midbrain superior colliculus in sensory-guided spatial orienting behaviors. This talk will review behavioral and neurobiological studies of 3D sonar scene analysis in the echolocating bat, an animal whose active control over acoustic signals provides a window into its perceptual world.
Draft standard on “Methods for the Prediction of Ground Vibration from Rail Transportation Systems.”
Authors: Phillips James E.
Published: June 2017

A draft American National Standards Institute (ANSI) standard on “Methods for the Prediction of Ground Vibration from Rail Transportation Systems” is nearing completion for review. The intent of this document is to standardize methods that were initially developed thirty years ago and adopted by the Federal Transit Administration in the guidance manual “Transit Noise and Vibration Assessment” for determining environmental vibration impacts at sensitive land uses adjacent to transit projects. This paper will outline the topics in the draft standard.
Ground vibration propagation measurements in extreme conditions
Authors: Edwards Scott
Published: June 2017

Ground vibration propagation measurements are often required during the environmental impact assessment process for transit projects per Federal Transit Administration (FTA) guidance. Cross-Spectrum Acoustics (CSA) conducted these measurements in extremely hot (100 + degrees Fahrenheit) and extremely cold (sub-zero degrees Fahrenheit) environments in 2016. This presentation will provide an overview of conducting such procedures in extreme climates and lessons learned from CSA staff. Topics to be discussed will include the effects of extreme temperatures on equipment, staff, and the collected data.
Ground-borne vibration issues from rail transit near university research buildings
Authors: Johnson Timothy , Glickman Gary
Published: June 2017

A new light rail transit project being designed and constructed through a university campus presents many potential ground-borne vibration issues. The rail alignment passes near numerous buildings on campus that contain various types of vibration sensitive research equipment. Appropriate vibration criteria for the project are critical to ensure that future operation of the light rail vehicles (LRVs) will not adversely affect activities on campus. Ground-borne vibration criteria are based on equipment sensitivity and the existing vibration environment. Projections of future vibration levels from LRV operations were developed based on field measurement programs. Site specific vibration measurements on campus were conducted to document the soil vibration propagation characteristics and building response characteristics. Additionally, input vibration force characteristics, or vehicle force density levels, of a comparable vehicle were measured and incorporated into the projections. Finally, site specific track design and vibration mitigation measures were modeled and incorporated into the project design.
Prediction of ground-borne vibrations on historical structures due to tram traffic in Antalya, Turkey
Authors: Alan Salih , Caliskan Mehmet
Published: June 2017

This study investigates the ground-borne vibrations on historically landmarked structures in the city of Antalya due to tram traffic. Assessments are conducted over predicted vibrations with respect to international standards. The study serves as a guidance for the tenders in the upcoming tender process for projects of upgrading existing tram lines as well as construction of new lines. In the prediction procedure, an existing Fourier transform based theoretical model for the track and layered ground is implemented coupling vehicle dynamics. Groundborne vibrations calculated at the base level of structures are considered. Vibration assessment criteria taken from ISO 2631 standard are employed in the evaluations of predicted vibrations at the respective locations in three mutually perpendicular directions.
Predicting structure-borne sound from railway traffic
Authors: Negreira Juan , Persson Peter , Bard Delphine
Published: June 2017

Since noise exposure can disturb the well-being, acoustical comfort in the built environment is of great importance when constructing new dwellings. Population growth causes densification of cities, which together with space limitation issues, lead to buildings being constructed closer to existing vibration sources such as motorways and railways, and vice versa. Likewise, architectural trends, environmental benefits and cost result in increased use of lighter materials such as wood and hollow-core concrete slabs. Lightweight structures make the achievement of acoustical comfort in dwellings an increasing challenge. A major issue when designing buildings regarded as acoustically pleasant, especially in the low-frequency range, is the lack of reliable prediction models to be used during the design stage of the building. Predictions of structure-borne noise are nowadays mostly made based on measurements performed on existing buildings and engineers’ experience. Hence, it is of interest to develop tools that could adequately predict noise and vibrations. The computer models developed for that purpose could combine different numerical methods, and they may use measurement data as input. The aim here is to investigate and develop numerical models that could be used in the early design stage of structures, specially aimed at predicting structure-borne noise in railway tunnels.
Selecting frames for automatic speech recognition based on acoustic landmarks
Authors: He Di , Lim Boon Pang P. , Yang Xuesong , Hasegawa-Johnson Mark , Chen Deming
Published: June 2017

Most mainstream Mel-frequency cepstral coefficient (MFCC) based Automatic Speech Recognition (ASR) systems consider all feature frames equally important. However, the acoustic landmark theory disagrees with this idea. Acoustic landmark theory exploits the quantal non-linear articulatory-acoustic relationships from human speech perception experiments and provides a theoretical basis of extracting acoustic features in the vicinity of landmark regions where an abrupt change occurs in the spectrum of speech signals. In this work, we conducted experiments, using the TIMIT corpus, on both GMM and DNN based ASR systems and found that frames containing landmarks are more informative than others during the recognition process. We proved that altering the level of emphasis on landmark and non-landmark frames, through re-weighting or removing frame acoustic likelihoods accordingly, can change the phone error rate (PER) of the ASR system in a way dramatically different from making similar changes to random frames. Furthermore, by leveraging the landmark as a heuristic, one of our hybrid DNN frame dropping strategies achieved a PER increment of 0.44% when only scoring less than half, 41.2% to be precise, of the frames. This hybrid strategy out-performs other non-heuristic-based methods and demonstrated the potential of landmarks for computational reduction for ASR.
A flexible discriminative approach to automatic phone and broad phonetic group classification
Authors: Kaewtip Kantapon , Alwan Abeer
Published: June 2017

In this work, we present a novel framework to phone and broad phonetic group (BPG) classification. The overall system adds discriminative power to the traditional HMM framework. All phones share one HMM. However, instead of using generative models (e.g., GMMs), our framework uses a discriminative classifier to predict the state probability (i.e., the probability of an HMM state given a feature vector input). Then, the optimal state sequence is decoded resulting in a time-alignment function between the acoustic feature vector sequence and the state sequence. For each state s, the corresponding feature vectors are averaged resulting in a single feature vector that represents the s-th vector of the block. Each phone class is represented by a block of feature vectors whose size is equal to the number of states. All feature vectors of the block are then concatenated to a single feature vector to represent a phone unit, which is used for a discriminative phone classifier. We validate our framework using the TIMIT database. The proposed framework with MFCCs has comparable performance to the-state-of-the-art phone classification algorithms, but with increased flexibility to account for duration and other features such as articulatory features. Improved performance for BPG classification is also observed.
Robust speaker identification via fusion of subglottal resonances and cepstral features
Authors: Guo Jinxi , Yang Ruochen , Alwan Abeer , Arsikere Harish
Published: June 2017

This paper investigates the use of subglottal resonances (SGRs) for noise-robust speaker identification (SID). It is motivated by the speaker specificity and stationarity of subglottal acoustics, and the development of noise-robust SGR estimation algorithms which are reliable at low SNRs for large datasets. A two-stage framework is proposed which combines the SGRs with different cepstral features. The cepstral features are used in the first stage to reduce the number of target speakers for a test utterance, and then SGRs are used as complementary second-stage features to conduct identification. Experiments with the TIMIT and NIST 2008 databases show that SGRs, when used in conjunction with PNCCs and LPCCs, can improve the performance significantly (2-6% absolute accuracy improvement) across all noise conditions in mismatched situations.
Learning acoustic features for English stops with graph-based dimensionality reduction
Authors: Reidy Patrick , Beckman Mary E. , Edwards Jan , Munson Benjamin , Johnson Allison
Published: June 2017

This study applies a semi-supervised graph-based dimensionality reduction algorithm (Laplacian Eigenmaps [Belkin & Nyogi, 2002]) to analyze burst spectra from adult productions of English /k/ and /t/. Multitaper spectra calculated over 25-ms windows were passed through a gammatone filter bank, which models the auditory periphery’s frequency selectivity and frequency-scale compression. From these psychoacoustic spectra, a graph was constructed: node pairs (two spectra) were connected if they shared a common talker or target word, and connecting edges were weighted by the symmetric Kullback-Leibler divergence between the spectra. This graph’s eigenvectors map the spectra into a low-dimensional feature space. Our preliminary experiments with 512 tokens produced by 16 talkers suggest that this algorithm is able to learn a two-dimensional representation of the bursts which reflects well-established articulatory constriction features. The first dimension linearly separated /k/ from /t/ in the back vowel environment, reflecting posterior versus anterior constriction place; the second dimension linearly separated /k/ from /t/ before front vowels, reflecting apical versus dorsal lingual articulator. Experiments are underway to test how well the algorithm generalizes from the training set to handle unseen productions both from the same talkers and from 5 novel talkers.
Vowel synthesis related to equal-amplitude harmonic series in frequency ranges > 1 kHz combined with single harmonics < 1 kHz, and including variation of fundamental frequency
Authors: Maurer Dieter , Suter Heidy
Published: June 2017

Front vowels can be synthesized on the basis of series of harmonics equal in amplitude, with frequencies only above 1 kHz. In these cases, spectral energy usually attributed to the first formant frequency is lacking. The present paper reports results of an experiment in which sound synthesis was performed on the basis of harmonic series covering higher frequency ranges above 1 kHz, combined with a single lower harmonic < 1 kHz, all harmonics equal in amplitude. Thereby, two or three sounds were synthesized for which the higher frequency range and the frequency of the lower harmonic is identical, but the frequency distance of the higher harmonics differs resulting in different perceived pitches of the sounds. Vowel recognition of all sounds was investigated by means of a listening test in which five phonetic expert listeners were asked to assign the synthesized sounds to Standard German vowel qualities. The results of the experiment reveal that the perceived vowel quality of such types of sound pairs or sound triples differs, confirming earlier indications of the spectral envelope being ambiguous with regard to vowel quality. Implications for the acoustics and perception of vowels are discussed.
Influence of noise on the speaker verification in the air traffic control voice communication
Authors: Rusko Milan , Marian Trnka , Darjaa Sakhia , Ritomský Marian , Guoth Igor
Published: June 2017

The voice communication between pilots and the air traffic controllers is vulnerable to various types of attacks. Speaker verification could be used as an add-on security feature; however, there are several factors that make the use of voice biometry in this scenario difficult to apply. These are among others: open set of speakers, very short utterances, speaker noises, signal clipping, foreign accent of non-native speakers, and high content of background and channel noises in the signal. This paper identifies sources of noise in the entire communication channel and analyzes the influence of these noise components of different types and levels on the reliability of the speaker verification. An i-vector based speaker recognizer with PLDA scoring is used for the experiments. Cockpit noises of several aircrafts and limited-band channel noises are simulated by a software noise-generator. The sensitivity of the speaker verification to the noises of different frequency bands is studied in comparison to the long-term speech spectrum and its variability. Possible measures for increasing the noise robustness of the system are discussed.
Formant pattern ambiguity of vowel sounds revisited in synthesis: Changing perceptual vowel quality by only changing fundamental frequency
Authors: Maurer Dieter , Dellwo Volker , Suter Heidy , Kathiresan Thayabaran
Published: June 2017

The influence of varying fundamental frequency on the perception of vowel quality in synthesized vowels was tested in two experiments. In experiment 1, based on investigations of natural Standard German vowel sounds, various model formant patterns F1’ to F3’ were created and, for each single pattern, sounds were synthesised on two or three fundamental frequencies (range 200-600 Hz). In experiment 2, corresponding to open-tube resonance characteristics for men, women and children respectively, sounds were synthesised with formant patterns F1’ to F5’, formant frequencies being odd multiples of 500, 600, or 700 Hz and fundamental frequencies being 1/3, 1/2 or 1/1 of the first formant frequency. Five phonetic expert listeners identified all synthesised sounds in a multiple-choice identification tasks. The results of both experiments revealed that the perceived vowel quality can be changed systematically by varying fundamental frequency only and that the changes can exceed the perceptual boundaries of two neighboring vowels. Further, sounds related to open-tube resonance patterns are not consistently perceived as neutral schwa vowels when fundamental frequency substantially varies. Thus, the result of both experiments strongly confirm previous claims of formant pattern ambiguity as well as of spectral envelope ambiguity of vowel sounds.
Model selection for profile structure in Bayesian geoacoustic inversion
Authors: Dosso Stan E. , Dong Hefeng , Duffaut Kenneth
Published: June 2017

This paper considers model selection in Bayesian geoacoustic inversion, specifically, the role of seabed parameterization in resolving geoacoustic profile structure. Bayesian inversion is formulated in terms of the posterior probability density (PPD) over the model parameters which are sampled numerically: Metropolis-Hastings sampling in principal-component space enhanced by parallel tempering is employed here. A key aspect of quantitative geoacoustic inversion is that of parameterizing the seabed model. Trans-dimensional (trans-D) inversion methods model the seabed as a sequence of discontinuous uniform layers and sample probabilistically over the number of layers. However, in some cases it may be expected for seabed properties to vary as smooth, continuous gradients which are not well represented by uniform layers. Most gradient-based inversions assume a representative functional form, such as a power law. A recent alternative is based on a linear combination of Bernstein-polynomial basis functions. This approach is more general and allows the form of the profile to be determined by the data, rather than by a subjective model choice. This paper compares trans-D, power-law, and Bernstein-polynomial inversions for the problem of estimating seabed shear-wave speed profiles from the dispersion of interface waves. Simulations and data from Oslofjorden and/or the North Sea will be considered.
Tempered particle filters for non-linear model selection and uncertainty quantification of highly informative seabed data
Authors: Dettmer Jan , Dosso Stan E.
Published: June 2017

Knowledge about seabed properties is important for many geoscientific and navy applications, such as sediment transport, sonar performance prediction, and detection of unexploded ordnance. Bayesian model selection and uncertainty estimation have been shown to provide detailed, quantitative seabed knowledge that is valuable for these applications. However, the extreme computational cost limits the utility of Bayesian methods for increasingly common big data sets. Here, we consider geoacoustic reflectivity surveys based on towed source and receiver arrays. Such systems produce thousands of data sets with high information content that require non-linear inversion along tracks many kilometers in length and cannot be analyzed by standard Bayesian sampling. A particle filter that includes reversible jump Markov chain Monte Carlo updates is applied here for efficient posterior probability estimation. Efficiency is improved by likelihood tempering of various particle subsets and including information exchange within the particle cloud. The tempering applies to reversible jump updates and leads to significantly improved exploration of the trans-dimensional seabed model which accounts for changes in the number of sediment layers and their properties along the track. For challenging track sections, where data change abruptly, the particle cloud is resampled to increase the number of tempered particles. [Work supported by the U.S. Dept. of Defense, through SERDP, and by ONR Ocean Acoustics.]
Bayes, models, and data
Authors: Sullivan Edmund
Published: June 2017

The Kalman filter is often described as a Bayesian processor. However, it is more than that. It is also a natural framework for introducing a physical model into an estimation scheme. As, such, it is a processor that can improve an estimation scheme in two distinct ways—by using prior statistics and by introducing a model. It is shown how the prior statistics are implicitly included in the Kalman update equation, and how models can be introduced in two places—the prediction equation and the measurement equation. Assuming linearity and Gaussianity, it is outlined how the Kalman equations evolve from the particle filter upon the assumptions of linearity and Gaussianity. Since the update equation for the particle filter is Bayes’ rule, it is clear that the resulting Kalman update equation is also a form of Bayes’ rule, thus verifying that the Kalman filter is indeed a Bayesian processor. It is then shown how a model can be introduced, further improving the quality of the estimate. An example is given, based on real data, where the bearing estimate from a short towed array is found for the case of a significant bearing rate.
Bayesian modal identification with particle filtering for sediment property inversion
Authors: Michalopoulou Zoi-Heleni , Pole Andrew , Aunsri Nattapol
Published: June 2017

Sequential Bayesian filtering methods have been previously used in dispersion curve tracking for long range sound propagation in the ocean. Modal frequency probability density functions were extracted for sound speed inversion. Here, we calculate modal arrival time densities, instead, and employ them for inversion for sediment sound speed and thickness and water column depth. Bayesian mode identification is performed to this end. We investigate two methods for describing the statistical errors in power spectra, which we use in the arrival time density calculation using normal modes. We then link these densities to the parameters of interest. The approaches are tested with synthetic data as well as data collected in the Gulf of Mexico. [Work supported by ONR.]
A single-sided representation for passive and active Green's function retrieval, time-reversal acoustics, and holographic imaging
Authors: Wapenaar Kees
Published: June 2017

The homogeneous Green's function, defined as the superposition of the Green's function and its time-reversal, plays an important role in a variety of acoustic applications, such as passive and active acoustic Green's function retrieval, seismic interferometry, time-reversal acoustics, and holographic imaging. An exact representation of the homogeneous Green's function originates from the field of optical holographic imaging (Porter, 1970, JOSA). In this representation, the homogeneous Green's function between two points A and B is expressed as an integral along an arbitrary boundary enclosing A and B. This implies that the Green's function between A and B can be retrieved from measurements carried out at a closed boundary, or, via reciprocity, from passive observations at A and B of the responses to sources on a closed boundary. In practical situations, the closed-boundary integral usually needs to be approximated by an open-boundary integral. This can lead to significant artifacts in the retrieved Green's function. I will discuss a new, single-sided, representation of the homogeneous Green's function, which obviates the need for omnidirectional access. Like the classical closed-boundary representation, this new single-sided representation fully accounts for multiple scattering. I will indicate applications of this new representation in the aforementioned fields.
Global propagation of seismic body waves and correlation
Authors: Campillo Michel , Retailleau Lise , Boue Pierre , Li Lei , Poli Piero , de Hoop Maarten
Published: June 2017

We discuss the nature of retrieved body waves at teleseismic distances from correlation of records in two separate bands T<10 s and T>30 s. The short period correlations indicate the presence of deep phases that appear as correct reconstructions of actual phases. We present an example of application to the reflectivity of the core-mantle boundary region. Careful tests show the reliability of the images produced with ambient noise records. On the opposite, we analyze long period records and show that the correlations are dominated by strong coherent phases (with time close to actual ScS or P'P'df) that are the signatures of high quality factor normal modes. By using array analysis and spectral analysis, we identify the dominant constituents. We then make use of geometrical quantization to derive the ballistic reverberations of rays that contributes to the emergence of signals at times close to body wave arrivals. Our study indicates that the signals measured in the long period correlations have a physical significance, but their interpretation as station to station seismic ray is nontrivial.
Modeling the shipping noise in uncertain environment for marine space planning
Authors: Le Courtois Florent , Kinda G. Bazile , Stéphan Yann
Published: June 2017

The shipping noise is a major component of the underwater soundscape at low frequency. The increase of the fleet size at world scale for several decades have arisen the potential impacts of noise pollution on marine ecosystems. Modeling the shipping noise levels at large scale became an important task of marine environmental policies. However, because of fluctuating and unknown environmental parameters, the numerical model may present a bias in the estimated levels up to several tens of dB. To tackle this problem, this paper relies on a semi-empirical formulation of the noise level standard deviation, related to environmental mismatch. The model provides monthly noise atlas at world scale, using statistical distribution of shipping. Results are presented using worldwide ship traffic data for the years 2003, 2012, and 2016. It provides a relevant tool to monitor the ambient noise evolution and have been applied for the evaluation of the Marine Strategy Directive Framework.
Dynamically orthogonal equations for stochastic underwater sound propagation
Authors: Hajj Ali Wael , Vo Johnathan H. , Lermusiaux Pierre F.
Published: June 2017

Grand challenges in ocean acoustic propagation and inference are to accurately capture the dynamic environmental uncertainties and to predict the evolving probability density distribution of stochastic acoustic waves, all efficiently and rigorously, using the governing partial differential equations (PDEs). To start addressing these needs, the stochastic dynamically orthogonal (DO) PDEs for the parabolic wave equation are derived and numerical schemes for their integration are obtained. Within the parabolic approximation, these equations are the optimal reduced-order representation of stochastic acoustic waves within the uncertain sound speed environment. The DO equations govern the propagation of the mean field, the DO modes, and their stochastic coefficients. Examples are provided for a set of idealized test cases as well as for more realistic ocean environments, and predictions are contrasted with those of other uncertainty quantification schemes. The utilization of DO equations for end-to-end uncertainty prediction within oceanographic-seabed-acoustic-sonar dynamical systems is discussed.
Normal-mode statistics of sound scattering by a rough elastic boundary in underwater wave-guide in a full coupled mode approach, including back-scattering
Authors: Morozov Andrey K. , Colosi John A.
Published: June 2017

The underwater sound scattering by rough sea surface, ice, or rough elastic bottom is studied. The effects of scattering from a rough elastic boundary are included in a coupled mode propagation model by the analytical equation for solid-state layer impedance. A full two-way coupled mode solution was used to derive the stochastic differential equations for the second order statistics in a Markov approximation for a transport theory. The coupled mode matrix was approximated by a linear function of one random parameter such as ice-thickness or the surface perturbation. A one parameter Gaussian model has a form of a two-way differential stochastic equation for the correlation of normal mode coefficients. The derived equation relates the correlation matrix of mode coefficients (for both directions) with the correlation function of the rough boundary and the power spectrum of the its slopes. The theory gives a solution for sound attenuation and horizontal coherence over long-range propagation along random interfaces. The result can be used for the estimation of sound attenuation in long-range under-ice propagation or attenuation of seismic waves in an underwater wave-guide with random bathymetry.
Sonar inter-ping noise field characterization during cetacean behavioral response studies off Southern California
Authors: Guan Shane , Southall Brandon L. , Barlow Jay , Vignola Joseph F.
Published: June 2017

Concerns of effects from military mid-frequency active sonar (MFAS) on marine mammals have motivated considerable recent research and technology development. However, robust characterizations of the complex acoustic field during sonar operations have been limited. Additionally, potential effects to marine mammals beyond simple exposure levels are not well understood. Here, we investigate inter-ping reverberation during a behavioral response study with simulated MFAS off California in waters deeper than 300 m using drifting acoustic recording buoys. Acoustic data were collected before, during, and after playbacks of simulated MFAS. An incremental computational method was developed to quantify the inter-ping sound field during MFAS transmissions. Descriptive statistics are used to compare the characteristics of inter-ping sound field and the natural background. Results show significant elevated sound levels within the MFAS frequency band of the inter-ping sound field. In addition, the duration of elevated inter-ping sound field depends on the MFAS source distance. At a distance of 900-1300 m from the source, inter-ping sound field remained 5 dB above natural background levels for approximately 15 s. The elevated inter-ping sound levels at such large distances is most likely due to volume reverberation of the marine environment, although multipath propagation may also contribute to this phenomenon.
Soundscape versus noise—From the sound recording to the public space
Authors: Case Alexander U.
Published: June 2017

The enemy of desired sounds is unwanted sonic competition. The positive elements of an interior soundscape need to be rid of noisy rivals. Solutions in the built environment might be inspired by approaches taken in the creation of sound recordings. Of course, noise is minimized where possible, but remaining noise must be dealt with. Masking the noise, taking care that the noise does not mask the soundscape, embracing the noise, and creating an environment of heightened awareness can improve the listener’s comfort and sense of pleasure when immersed in a soundscape clouded by noise.
The soundscape of dining
Authors: Siebein Keely
Published: June 2017

This paper explores how applying soundscape theory can address the acoustic concerns for various classes of restaurants; from luxury/fine dining to moderate to fast food. A representative case study of each type of restaurant is examined. By analyzing the soundscape components of each dining space, such as the acoustic community, taxonomy, and itinerary, and the specific paths of communication that take place, one can begin to develop an “acoustic identity” for each room. Each “acoustic identity” is shaped by the users, the aesthetic intent and the soundscape analysis. Diagnostic measurements are made based on how people use the space and the various communication paths present. Impulse responses, alpha bars and other acoustic metrics are used that are based on these communication paths assist in determining basic design approaches and acoustic interventions for each space. By combining the soundscape analysis approach with taking diagnostic measurements rooted in actual communication paths that are present, one can define and shape the acoustical identity for the restaurant.
Auralization as a tool for acoustical design of restaurants and public spaces
Authors: Hochgraf Kelsey
Published: June 2017

Auralization is an invaluable decision-making tool for the acoustical design of restaurants and other public gathering spaces, and accurate modeling and calibration of sound sources is critical to achieving perceptually plausible soundscapes of such spaces. Unlike auralizations of performing arts venues, auralizations of restaurants and public gathering spaces afford owners, architects, and consultants the opportunity to directly experience how difficult (or easy) it is to communicate with others when immersed in the soundscape. Also unlike auralizations of performing arts venues, a realistic auralization of a restaurant or public gathering space must account for the Lombard Effect when calibrating source levels of occupant and activity noise. In this presentation, we will briefly review the history and recent improvements of Acentech’s 3DListening studio in Cambridge, MA, including Lombard Effect modeling. Three recent case studies will be used to illustrate the unique role of auralization in the architectural design process, including a restaurant, a college pub located underneath residences, and a multi-level collaborative, interdisciplinary work space at an independent school.
Experimental validation of Bayesian design for broadband multilayered microperforated panel absorbers
Authors: Hou Yiqiao , Fackler Cameron J. , Xiang Ning
Published: June 2017

Single-layer microperforated panel (MPP) absorbers often exhibit limited absorbing bandwidth. A Bayesian inference framework (encompassing both model selection and parameter estimation) has been utilized to design broadband MPP absorbers. In this work, the broadband multilayered MPP absorbers are experimentally validated. In demonstrating ability to meet practical requirements on both high absorption and wide bandwidth, the current investigation uses a sample design scheme in the frequency range from 300 Hz to 2.4 kHz. A minimum requirement for three MPP layers and the relevant three-layer MPP parameters are derived by the two levels of Bayesian inference to meet the design scheme. MPP samples, based on the predicted design scheme, are fabricated and used to conduct normal-incidence sound absorption measurements in an impedance tube. In order to quantify the fabrication tolerance, the measured acoustic data are used to estimate the MPP parameters of the constructed absorber, using an inverse Bayesian inference method. This paper will discuss the initial MPP design, experimental validations of the designed absorption performance, as well as fabrication tolerance estimations of the MPP parameters.