bluuebunny/crossref_metadata_2025 huggingface dataset:
Design and Implementation of a Leg–Wheel Robot: Transleg
Authors: Wei Zhong , Song Guangming , Qiao Guifang , Zhang Ying , Sun Huiyu
Published: June 2017

In this paper, the design and implementation of a novel leg–wheel robot called Transleg are presented. Transleg adopts the wire as the transmission mechanism to simplify the structure and reduce the weight. To the best knowledge of the authors, the wire-driven method has never been used in the leg–wheel robots, so it makes Transleg distinguished from the existing leg–wheel robots. Transleg possesses four transformable leg–wheel mechanisms, each of which has two active degrees-of-freedom (DOFs) in the legged mode and one in the wheeled mode. Two actuators driving each leg–wheel mechanism are mounted on the body, so the weight of the leg–wheel mechanism is reduced as far as possible, which contributes to improving the stability of the legged locomotion. Inspired by the quadruped mammals, a compliant spine mechanism is designed for Transleg. The spine mechanism is also actuated by two actuators to bend in the yaw and pitch directions. It will be beneficial to the turning motion in the legged and wheeled modes and the bounding gait in the legged mode. The design and kinematic analyses of the leg–wheel and spine mechanisms are presented in detail. To verify the feasibility of Transleg, a prototype is implemented. The experiments on the motions in the legged and wheeled modes, the switch between the two modes, and the spine motions are conducted. The experimental results demonstrate the validity of Transleg.
Proper Orthogonal Decomposition–Radial Basis Function Surrogate Model-Based Inverse Analysis for Identifying Nonlinear Burgers Model Parameters From Nanoindentation Data
Authors: Hamim Salah U. , Singh Raman P.
Published: June 2017

This study explores the application of a proper orthogonal decomposition (POD) and radial basis function (RBF)-based surrogate model to identify the parameters of a nonlinear viscoelastic material model using nanoindentation data. The inverse problem is solved by reducing the difference between finite element simulation-trained surrogate model approximation and experimental data through genetic algorithm (GA)-based optimization. The surrogate model, created using POD–RBF, is trained using finite element (FE) data obtained by varying model parameters within a parametric space. Sensitivity of the model parameters toward the load–displacement output is utilized to reduce the number of training points required for surrogate model training. The effect of friction on simulated load–displacement data is also analyzed. For the obtained model parameter set, the simulated output matches well with experimental data for various experimental conditions.
Vocal repertoire of long-finned pilot whales (Globicephala melas) in northern Norway
Authors: Vester Heike , Hallerberg Sarah , Timme Marc , Hammerschmidt Kurt
Published: June 2017

The knowledge of the vocal repertoire of pilot whales is very limited. In this paper, the vocal repertoire of long-finned pilot whales recorded during different encounters in the Vestfjord in northern Norway between November 2006 and August 2010 are described. Sounds were analysed using two different methods: (1) an observer-based audio-visual inspection of FFT-derived spectrograms, with which, besides a general variety of clicks, buzzes, nonharmonic sounds, and whistles, 129 different distinct call types and 25 subtypes were distinguished. These call types included pulsed calls and discrete structured whistles varying from simple to highly complex structures composed of several segments and elements. In addition, ultrasonic whistles previously not described for pilot whales were found. In addition to the diversity of single calls, call sequences consisting of repetitions and combinations of specific call types were recorded and (2) a parametric approach that permitted the confirmation of the high variability in pilot whale call structures was developed. It is concluded that the pilot whale vocal repertoire is among the most complex for the mammalian species and the high structural variability, along with call repetitions and combinations, require a closer investigation to judge their importance for vocal communication.
Three-dimensional-printed membrane-type acoustic metamaterial for low frequency sound attenuation
Authors: Leblanc Alexandre , Lavie Antoine
Published: June 2017

Membrane-type acoustic metamaterials have received much attention for low-frequency sound manipulation, especially in the form of decorated membrane resonators. In this paper, such resonators are obtained using fused deposition modeling. Beyond the practical aspects provided by this manufacturing method, the low density of the flexible filament used increases their effectiveness. Indeed, the mass usually added to the membrane center can easily be divided into several disjoint elements. Using rotary inertia of the added structures, new peaks of efficiency in both absorption and normal transmission loss appear when compared to usual decorated membrane resonators.
Experience with a virtual reality auralization of Notre-Dame Cathedral
Authors: Katz Brian F. , Postma Barteld N. , Poirier-Quinot David , Meyer Julie
Published: June 2017

As part of the 850-year anniversary of Notre-Dame cathedral, Paris, there was a special performance of “La Vierge.” A close-mic recording of the concert was made by the Conservatoire de Paris. In an attempt to provide a new type of experience, a virtual recreation of the performance using these roughly 45 audio channels was made via auralization. A computational acoustic model was created and calibrated based on in-situ measurements for reverberation and clarity parameters. A perceptual study with omnidirectional source and binaural receiver validated the calibrated simulation for the tested subjective attributes of reverberation, clarity, source distance, tonal balance, coloration, plausibility, ASW, and LEV when compared to measured responses. Instrument directivity was included for each track's representative orchestral section based on published data. Higher-Order Ambisonic (3rd order) RIRs were generated for all source and receiver combinations using the CATT-Acoustic TUCT software. Virtual navigation throughout a visual 3D rendering of the cathedral during the concert was made possible using an immersive rendering architecture with BlenderVR, MaxMSP, and Oculus Rift HMD. We present major elements of this project: calibration, perceptual study, system architecture, lessons learned, and technological limits encountered with regards to such an ambitious undertaking. [Previously presented in part at EuroRegio2016 & FISM2016.]
Active learning in modern schools
Authors: Lang Markku
Published: June 2017

We know that world is changing and in near future workforce is going to be more independent, contingent and temporary. Therefore future learning environments and learning activities are essential to prepare all students for the challenges of work and life. Finland started this school year with a new core curriculum for basic education, which is focusing on developing future skills (developing the key competences as it is described in curriculum). To train and to develop future skills in schools new methods, learning landscapes and activities are needed. Future Classroom Network (European Schoolnet) is using activities as a guideline for creating Learning Zones. These activities and Learning zones are supporting key future skills: Critical Thinking—Investigate Creativity—Create Collaboration—Exchange Learning to learn—Develop Digital competences—Interact Communication—Present But how do these future learning activities look and sound like? What are teachers and students doing, when they are training Future skills? How school design should respect it?
Attenuation estimation using passive acoustic mapping
Authors: Gray Michael , Coussios Constantin
Published: June 2017

Passive acoustic mapping (PAM) techniques have been developed in order to reduce risk and improve treatment efficacy by localizing and quantifying cavitation emissions during therapeutic ultrasound procedures. The performance of these techniques may be significantly degraded by attenuation between the internal therapeutic target and the external monitoring system. Attenuation itself is an essential parameter in the determination of therapeutic outcomes and safety of treatments such as HIFU ablation or volumetric hyperthermia. However, the spatial and temporal distributions of this parameter are not typically known in clinical scenarios. To address these challenges, we present a method for estimating attenuation using broadband cavitation emissions, potentially allowing for restoration of PAM performance, improved treatment monitoring and guidance, and mapping of tissue attenuation over the course of a treatment. Results from simulations and flow phantom experiments illustrate: (1) the impact of soft tissue-like attenuation on PAM images, (2) the ability to estimate attenuation from cavitation data, and (3) the enhancement of cavitation source imaging and energy estimation following PAM input data attenuation compensation. In the future, the technique could be expanded as a general broadband method of attenuation correction for conventional diagnostic ultrasound images and improved therapeutic ultrasound treatment planning.
Development of high fidelity tools and robust design approaches for low boom aircraft
Authors: Ozoroski Lori , Bangert Linda
Published: June 2017

The NASA Commercial Supersonic Technology Project recently completed a project Technical Challenge, “Low Sonic Boom Design Tools” which ran from 2011 to 2015. As part of this research effort, tools were developed, refined, and validated to support full-vehicle low-boom analysis, including inlet and nozzle effects. In addition, new and updated tools and processes were developed and demonstrated for application to robust low boom shape optimization. The work included both fundamental research efforts, computational analysis of full vehicle configurations, and application of robust low boom design methods to low boom aircraft concepts. This presentation will primarily focus on the technical achievements during the last 2 years leading to the recent successful completion of this technical challenge.
Advances in numerical simulation of sonic boom in realistic atmospheres
Authors: Coulouvrat François , Luquet David , Marchiano Régis , Dagrau Franck
Published: June 2017

Efficient and accurate numerical simulation of sonic boom is a key issue for both the design of low boom aircraft and the definition of a standard on supersonic overland flights. Atmospheric turbulence is known since the 1960s to significantly alter the ideal N-wave boom waveform. Such random fluctuations cannot be reproduced by the standard ray tracing method. Neither can it simulate the lateral boom beyond the geometrical carpet edge. There occur many non-geometrical features such as creeping waves, wave guiding or scattering. To progress in the direction of boom simulation beyond the geometrical approximation, we developed the so-called FLHOWARD3D software. For accuracy, it can handle 3D temperature, density or wind heterogeneities, atmospheric absorption, and nonlinear propagation effects. For efficiency, a one-way approximation is performed, neglecting the backscattered field. Nevertheless, the forward field satisfies an accurate dispersion relation, even in moving atmospheres. Involved physical effects are handled separately by optimized algorithms, combined by a second-order split-step approach. The resulting software is parallelized using the MPI paradigm. The performances of the software will be illustrated by two cases: boom scattering by turbulence, and lateral boom propagation in case of temperature inversion. This last case will be compared with flight test data.
Progress made during the first two American Institute for Aeronautics and Astronautics Sonic Boom Prediction Workshops for calculating near field signatures of supersonic aircraft
Authors: Park Michael A.
Published: June 2017

The American Institute for Aeronautics and Astronautics (AIAA) Sonic Boom Workshops examine the international state of the art in sonic boom prediction of supersonic aircraft. A summary is provided for the first and second workshops held in 2014 and 2017. The nearfield CFD (Computational Fluid Dynamics) cases from both workshops are described. They include a range of simple to complex configurations. The first workshop used models with N-wave, flat-top, and shaped ground signatures. The second workshop used models with quieter shaped ground signatures. To assess state of the art in nearfield CFD prediction, signatures are gathered from the international participants. These nearfield signatures are propagated to the ground with an augmented Burgers equation method and noise metrics are calculated. Statistics of the noise metrics are utilized to identify outliers for further examination. Comparisons are also made to wind tunnel measurements through validation metrics where available. The convergence of these metrics with grid refinement is also documented. This allows the determination of state of the art for nearfield sonic boom prediction and documents progress made between the two workshops.
A user-centered taxonomy of factors contributing to the listener experience of reproduced audio
Authors: Woodcock James , Davies William J. , Cox Trevor J.
Published: June 2017

The traditional paradigm for the assessment of audio quality is that of a listener positioned in the geometric center of a standardized loudspeaker setup, fully attending to the reproduced sound scene. However, this is not how listeners generally interact with audio technology. Audio is consumed in a variety of environments and situations, over devices with varying quality, and by listeners with different expectations and needs. Drawing on research from soundscapes, human computer interaction, and multimedia quality of experience, this paper proposes a user-centered taxonomy of factors that influence the listener experience of reproduced audio. The taxonomy is supported by data from recent research into the perception of complex reproduced sound scenes, and by new data from a web-based survey investigating the structure of experiences with audio technology. In this survey, participants were asked to consider previous experiences with audio technology, and data were collected on the experience itself (psychological need fulfillment and affect), perceptual attributes related to the reproduced audio, and the importance of audio quality to the experience. Results point toward a model of listener experience that can be used to profile listener experiences in different contexts and can be used as a measurement tool in future controlled experiments.
Landmark-based consonant voicing detection on multilingual corpora
Authors: Kong Xiang , Yang Xuesong , Hasegawa-Johnson Mark , Choi Jeung-Yoon , Shattuck-Hufnagel Stefanie
Published: June 2017

This study tests the hypothesis that distinctive feature classifiers anchored at phonetic landmarks can be transferred cross-lingually without loss of accuracy. Three consonant voicing classifiers were developed: (1) manually selected acoustic features anchored at a phonetic landmark, (2) MFCCs (either averaged across the segment or anchored at the landmark), and (3) acoustic features computed using a convolutional neural network (CNN). All detectors are trained on English data (TIMIT) and tested on English, Turkish, and Spanish (performance measured using F1 and accuracy). Experiments demonstrate that manual features outperform all MFCC classifiers, while CNN features outperform both. MFCC-based classifiers suffer an overall error rate increase of up to 96.1% when generalized from English to other languages. Manual features suffer only an up to 35.2% relative error rate increase, and CNN features actually perform the best on Turkish and Spanish, demonstrating that features capable of representing long-term spectral dynamics (CNN and landmark-based features) are able to generalize cross-lingually with little or no loss of accuracy.
Toward real-time physically-based voice synthesis
Authors: Zhang Zhaoyan
Published: June 2017

While physically based voice production models have potential applications in clinical intervention of voice disorders and personalized natural speech synthesis, their current use is limited due to the high computational cost associated with simulating the voice production process. In our previous studies [Zhang 2015, J. Acoust. Soc. Am. 137, 898], we have developed a reduced-order voice synthesis program with significantly improved computational efficiency toward real-time applications. One of the simplifications is the use of vocal fold eigenmodes as building blocks to reconstruct more complex vocal fold vibration patterns, which has significantly reduced the computational time, particularly if only a few eigenmodes are used in the simulations. The goal of this study is to identify the minimum number of eigenmodes that need to be included in order to achieve a balance between computational speed and fidelity in voice acoustics and voice quality. The results show that for most voice conditions as few as 30 eigenmodes are sufficient to accurately predict the fundamental frequency, vocal intensity, and selected spectral measures. It is expected that for applications in which absolute values are not as essential, even smaller number of eigenmodes would be acceptable, allowing near real time capability. [Work supported by NIH.]
Room acoustic modal analysis via model-based Bayesian inference
Authors: Beaton Douglas , Xiang Ning
Published: June 2017

This work illustrates the application of Bayesian Inference in analyzing modal behavior in an experimentally measured room impulse response at a single location. The Prony Model is employed to model the impulse response as a sum of exponentially decaying sinusoids in the time domain. Bayesian model selection is applied to estimate the appropriate number of modes in the model. Bayesian parameter estimation determines the amplitude, decay time, and modal frequency of each mode. The Bayesian analysis is performed using a nested sampling approach to approximate the evidence for each candidate model. Results from the analysis are verified by a Fourier analysis of the experimentally measured data, and also with classical modal theory. Additional experimental measurements are performed to validate individual modal parameter estimates. The likelihood landscape for the selected model is further explored by uniformly sampling near the point of convergence at the end of nested sampling. Animations are used to observe transient behavior of the sample population throughout the analysis.
Fluctuations in the cross-correlation for fields lacking full diffusivity: The statistics of spurious features
Authors: weaver richard , Yoritomo John Y.
Published: June 2017

Inasmuch as ambient noise fields are often not fully diffuse the question arises as to how, or whether, noise cross-correlations converge to Green’s function in practice. Well-known theoretical estimates suggest that the quality of convergence scales with the square root of the product of integration time and bandwidth. However, correlations from natural environments often show random features too large to be consistent with fluctuations from insufficient integration time. Here, it is argued that empirical seismic correlations suffer in practice from spurious arrivals due to scatterers, and not from insufficient integration time. Estimates are sought for differences by considering a related problem consisting of waves from a finite density of point sources. The resulting cross-correlations are analyzed for their mean and variance. The mean is, as expected, Green’s function with amplitude dependent on noise strength. The variance is found to have support for all times up to its maximum at the main arrival. The signal-to-noise ratio there scales with the square root of source density. Numerical simulations support the theoretical estimates. The result permits estimates of spurious arrivals’ impact on identification of cross-correlations with Green’s function and indicates that spurious arrivals may affect estimates of amplitudes, complicating efforts to infer attenuation.
Passive acoustic remote sensing of the coastal ocean using interferometry of diffuse noise fields
Authors: Godin Oleg A. , Brown Michael G.
Published: June 2017

A two-point correlation function of a perfectly diffuse noise field is known to contain all the information about the environment that can be obtained using transceivers placed at the two points, provided that environmental parameters are time-independent. This theoretical prediction underlies the approach to passive remote sensing that is known as noise (or wave) interferometry. However, acoustic noise in the ocean is never perfectly diffuse, except at very high frequencies, where noise of thermal origin dominates. Moreover, the averaging times necessary for deterministic features to emerge from noise cross-correlations far exceed the time scales of temporal variations of the ocean surface, e.g., due to surface gravity waves and in the water column, e.g., due to internal gravity waves and tides. This paper reviews current theoretical understanding of limitations of noise interferometry, which result from time-dependence of environmental parameters and noise anisotropy in the horizontal and vertical planes. It is demonstrated that, within these limitations, phase-coherent data processing techniques, including back-propagation, waveform matching, and time-warping, can be successfully applied to measured noise cross-correlations to characterize seafloor properties and evaluate current velocity in a coastal ocean. [Work supported by NSF and ONR.]
Evaluation of mock up testing as a method to predict impact ratings of new hard surface floors in existing buildings
Authors: Levins Jennifer , Dong David W. , LoVerde John
Published: June 2017

Renovations in multifamily residential buildings often involve the installation of new hard surface flooring. The new flooring must comply with building code minimum ratings. Homeowners Associations may also impose more stringent acoustic criteria. In many cases, the structure of the building is unknown or there are no published tests available for the desired floor-ceiling assembly. One method to evaluate performance of floor-ceiling assemblies is to conduct impact testing on a small sample of the floor assembly in situ. Although this is less costly than testing a fully installed floor, performance variations have been observed between mock up test assemblies and the final installation. This paper will evaluate the accuracy of mock up tests in predicting the impact rating of final floor installations.
Assessment of auralizations of monosyllabic words for hearing impaired students
Authors: Saher Konca
Published: June 2017

This paper discusses results of a research project, which seeks to develop Turkish speech recognition tests by auralizations for hearing impaired students based on monosyllabically structured words. In the context of this study, two sets of 25-items phonetically balanced monosyllabic Turkish words were recorded in the anechoic chamber of TUBITAK National Metrology Institute in Gebze, Turkey. Each monosyllabic word was recorded through a carrier sentence. After the vocal quality, accent and pronunciation in the recordings were approved by qualified audiologists, auralizations of the recorded sentences were developed in an acoustic simulation software (ODEON v12). Listening tests developed from auralizations in three classroom models with varying reverberation times and signal to noise ratios were presented to ten hearing impaired students. The preliminary results of these listening tests are presented and discussed in this study. This paper also aims to compare the results of listening tests with hearing impaired students with the listening tests made previously with normal hearing students.
Design of a dynamic sonar emitter inspired by hipposiderid bats
Authors: Yang Luhui , Yu Allison , Müller Rolf
Published: June 2017

The noseleaves of Old World leaf-nosed bats (family Hipposideridae) and the related horseshoe bats (Rhinolophidae) are notable for their elaborate static geometries and a conspicuous dynamics in which the noseleaves change their shapes during biosonar pulse emission as a result of muscular actuation. Whereas the noseleaves of horseshoe bats have already been used as an inspiration for dynamic sonar emitter prototypes, the possible functional role of the specific static and dynamic noseleaf features of Old World leaf-nosed bats have yet to be investigated in this manner. To accomplish this, a dynamic emitter based on the time-variant morphology of Pratt's roundleaf bats (Hipposideros pratti) has been designed. The baffle shape was simplified from a tomographic reconstruction of a biological sample. Five shape features (anterior leaf, sella, lancet, and the two nostrils) were preserved in the model. Motions of these parts were derived from three-dimensional reconstructions of landmark points that were placed on the noseleaf of echolocating bats and recorded with a stereo pair of high-speed video cameras. Actuation mechanisms driven by three stepper motors (one for lancet and sella, one for both nostrils, one for the anterior leaf) were implemented to reproduce the dynamic noseleaf motion pattern observed in the bats.
Study on parameter correlations in the modal dispersion based geoacoustic inversion
Authors: Wan Lin , Badiey Mohsen , Knobles David P.
Published: June 2017

The dispersion characteristics of acoustic normal modes are applied in the estimation of seabed parameters (e.g., sound speed, density, and layer depth). The modal arrival time difference is utilized to define the objective function, which calculates the difference between the modeled and measured modal arrival times. In this paper, a shallow water experimental dataset shows that the unknown sound speed, density, and layer depth of the sediment may not be successfully estimated by minimizing the modal dispersion-based objective function due to the correlations among them. For a given modal arrival time difference, an increase (decrease) in sound speed of the sediment can be compensated by increasing (decreasing) the density or layer depth of the sediment. Since there is more than one set of parameter values yielding the desired minimum of the objective function, an additional constraint from other objective functions or the knowledge from direct measurements is required. This paper utilizes a second objective function defined by mode shapes in conjunction with the dispersion-based objective function to partially remove the ambiguity of these unknown seabed parameters. [Work supported by ONR.]
Transcranial acoustic imaging for real-time control of ultrasound-mediated blood-brain barrier opening using a clinical-scale prototype system
Authors: Jones Ryan M. , O'Reilly Meaghan A. , Deng Lulu , Leung Kogee , Hynynen Kullervo
Published: June 2017

Multichannel beamforming of passively detected ultrasound (US)-stimulated acoustic emissions is a promising method for guiding cavitation-mediated therapies. In the context of brain applications, our group and others have previously demonstrated the use of conventional beamforming techniques to transcranially map cavitation activity during microbubble (MB)-mediated blood-brain barrier (BBB) opening. MB activity can be mapped at pressure levels below the BBB opening threshold, allowing target confirmation prior to therapy delivery. By including skull-specific phase and amplitude corrections in the reconstruction process, the aberrating effects of the cranial bone can be compensated for to improve image quality. Recently, we have designed, fabricated, and characterized multi-frequency, transmit/receive, sparse hemispherical phased arrays for MB-mediated brain therapy and simultaneous cavitation mapping [Deng et al., Phys. Med. Biol. 61, 8476-8501 (2016)]. This talk will review our progress to date in using these prototype systems to exploit the spatial information obtained from receive beamforming to actively modulate the therapeutic exposures during US-induced BBB opening, following our previously developed single-element internal calibration approach [O’Reilly & Hynynen, Radiology 263, 96-106 (2012)]. We anticipate that this technique will improve the safety and efficacy of MB-mediated BBB opening, as well as other future non-thermal US brain treatments such as cavitation-enhanced ablation, sonothrombolysis, and histotripsy.
Doppler passive acoustic mapping for monitoring microbubble velocities in ultrasound therapy
Authors: Pouliopoulos Antonios , Smith Cameron , El Ghamrawy Ahmed , Tang Mengxing , Choi James
Published: June 2017

The success of microbubble-mediated ultrasound treatments, such as blood-brain barrier disruption and sonothrombolysis, is determined by whether the correct cavitation dynamics are produced at the correct locations. Passive acoustic mapping (PAM) can track the location, magnitude, type, and duration of microbubble-seeded cavitation produced during sonication. Using a single element passive cavitation detector (PCD), we recently showed that microbubble velocities within the PCD listening volume can be determined by analysing the Doppler shifts in the microbubble acoustic emissions. Here, we developed a PAM-based algorithm to passively track microbubble velocities using a linear array. Microbubbles embedded within a vessel were sonicated using a 1 MHz focused ultrasound transducer (pulse length: 50 ms, peak-negative pressure: 200-600 kPa). Acoustic emissions were captured by a co-aligned L7-4 linear array. PAM using Capon beamforming was used to localize the acoustic emissions. We spectrally analyzed the time traces in order to derive position-dependent Doppler shifts and estimate axial velocities at each location. Doppler PAM imaged the axial microbubble velocities along the ultrasound propagation direction, at different time points during sonication. Microbubbles moved at peak velocities of 1-2 m/s due to acoustic radiation forces, producing a time dependent velocity profile. Doppler PAM allowed estimation of microbubble translation within an imaging plane, enabling enhanced monitoring of therapeutic ultrasound applications.
Electric power generation using acoustic helical wavefronts in air
Authors: Muelas H. Ruben D. , Pazos-Ospina Jhon F. , Ealo Joao L.
Published: June 2017

Acoustic Vortices (AV) are able to transfer angular momentum to matter and induce rotation to objects with different geometries. Several applications of this feature has already been reported. However, up to our knowledge, the possibility of generating electric power using this type of wavefronts has not been reported. In this work, we present experimental results on the electric power produced by a small generator coupled to a propeller of four blades that is insonified by an acoustic vortex beam of topological charge + 1. The AV is produced using a multitransducer of 123 commercially available emitters driven with a continuous signal of 20 Vpp at 40 kHz in air. The propeller was located 40 mm far from the multitransducer, perpendicular to the principal axis of the AV. A voltage of 6 mV was observed at the electric terminals. A discussion on the obtained efficiency of the conversion is presented. Also, the possibility of harvesting residual acoustic energy by means of wave-matter exchange of linear and/or angular momentum is discussed. Special attention is paid to non-dissipative processes.
Disentangling room acoustics though binaural measurements: The importance of individual ear-canal variations
Authors: Griesinger David H.
Published: June 2017

Evolution has endowed humans with extraordinary powers of hearing, powers that enable us to separate information-containing signals from noise and other signals with an acuity still unmatched by modern machines. We find that this ability depends critically on resonances in the ear canal. The ear canal and concha form a horn that boosts frequencies above 1000 Hz as much as 18 dB. These resonances are highly individual, headphones alter them, and just a 1 dB difference in the frequency balance at the eardrum can replace comprehension with confusion. We have developed a computer app that non-invasively equalizes headphones to accurately reproduce these resonances. Once headphones are individually equalized they reproduce binaural recordings with frontal localization and no head tracking. Using Lokki’s anechoic recordings we can manipulate a single binaural measurement to create a binaural rendition of a small ensemble nearly identical to a live recording in the same seat. We can then lower or boost specific reflections and hear how perceptions of proximity, clarity, and envelopment change. We find that successful separation of the direct sound from reflections and reverberation is essential for both proximity and envelopment. The earliest reflections, whether medial or lateral, are almost always either inaudible or detrimental.
The use and abuse of early energy in concert space design
Authors: Blair Christopher , Scarbrough Paul H.
Published: June 2017

Fifty-five years ago Leo Beranek introduced the notion of a short initial time delay gap as being essential for acoustic “intimacy.” However, in the authors’ consulting experience, it has become apparent that many problems in concert and recital halls, onstage and in the audience, can be laid at the feet of too much early energy muddying clarity. A layman’s description of the effect might be: “There’s not enough ‘air’ around the sound.” In support of this notion, recent research suggests that excessive early energy is actually the enemy of intimacy, masking the direct sound, modulating the phase of tonal components, inhibiting source localization. This paper presents the results of several listening experiments in halls of various sizes where adding absorption, venting or redirecting energy in specific critical locations dramatically enhanced the perception of both clarity and reverberation for musicians onstage and in the audience. Such methods often challenge traditional musician (and designer?) preconceptions, so whenever possible we employ quickly realized A/B comparisons to demonstrate treatment effectiveness.
Achieving the excellent listening experience—Notes from 30 years experience in the successful integration of physical and electronic architecture
Authors: Barbar Steve
Published: June 2017

This paper will discuss important considerations in the elements that comprise electronic systems that alter perceived acoustics. In addition, the paper will discuss aspects of optimizing physical architecture to enable electronic architecture to work efficiently.
Rich data trove gathered as a result of a unique opportunity with a capacity audience
Authors: Greenberg David , Ellison Steve , Parker Melody , Schwenke Roger W.
Published: June 2017

When an opportunity arises to perform an occupied room measurement, normally a short time is allotted to acquire data in order to minimize event disruption and audience discomfort. We therefore consider ourselves fortunate if one or two data sets are obtained under those conditions. An extremely rare—perhaps unique—opportunity arose from a confluence of factors: a 1600-seat concert hall at Liberty University, with a purposely over-sized area of movable curtains and banners to adjust the architectural reverberation; an installed active acoustics system, Constellation by Meyer Sound; a concert comprising distinct performances by orchestra, choir, and amplified worship band, with intermission to reset the architectural acoustics; and an interested client. The Constellation system provides 48 microphones distributed throughout the space, so a single set of sweeps through a system loudspeaker results in 48 measurements. The variables tested were (a) adjustable acoustic absorption in and out; (b) full audience in and out; and (c) a nominal Constellation setting on and off. Measurement analysis both confirmed design intentions and elucidated the behavior of the two adjustable acoustic systems in the occupied and unoccupied hall. The architectural and active acoustic system designs, performance, measurements, and usage recommendations will be discussed.
Frequency tones and elevated decibel level of tones that are indicators of ill health or a state of health with associated pain
Authors: Schnitta Bonnie , Sigmon Carter H.
Published: June 2017

A correlation was confirmed in a study between noise sensitivity and ill-health. This study included clients that had hired an acoustic engineer to solve a noise problem, or patients who had a scheduled doctor’s appointment. Male and female patients in diverse outpatient specialty clinics including: Sports Medicine, Pain Medicine, Hematology & Oncology and Breast Health were surveyed. The correlation shown of noise sensitivity to ill-health found was for a vast array of illnesses. A prior study was confirmed of a correlation of ill-health and noise sensitivity at lower frequencies that were typically only 1-2 dB(A) above ambient. Two additional findings were noted. First there was a heighted sensitivity to elevated noise levels of at least 15 dB(A) above ambient, such as construction noise, children screaming, sirens, etc. This noise sensitivity was found in people of various illnesses including but not limited to patients with cancer, atrial fibrillation, undescribed back pain, or untreated pain from a shoulder injury. The second finding was that some or all of the sensitivity dissipated upon treatment or remission of the illness or pain. This paper additionally discusses how to view this noise sensitivity as an indicator of ill-health, as well as influences on hospital design.
Assessing tones in refrigeration and air-conditioning equipment
Authors: Knight Derrick P.
Published: June 2017

AHRI 1140 is a procedure for assessing the quality of sound for air-conditioning and refrigeration equipment. The procedure is based on work by Wells and Blazier in 1963 and jury listening tests by Penn State in 2001. This standard describes the measurements and calculations needed to determine the Sound Quality Index (SQI). The AHRI Technical Committee on Sound (TCoS) conducted informal surveying of manufacturing, design and consulting engineers which failed to identify any active users of SQI. TCoS has begun editing this standard in order to make it meaningful in identifying sound quality problems in a way that is useful to consultants and design engineers while being practical for manufacturers to adopt. The current effort is intended define a metric which will quantify the tonal characteristics of refrigeration and air-conditioning equipment. This presentation will briefly cover SQI and why TCoS believes SQI failed to achieve adoption. Additional tonal metrics will be reviewed, and potential difficulties with the existing metrics will be discussed. Most importantly, half of the presentation time will be used to allow audience feedback and suggestions.
Uncertainty in tone quantification methods of background noise for enclosed spaces
Authors: Lee Joonhee , Wang Lily M.
Published: June 2017

The noticeable tones in background noises can annoy and disturb human listeners. The noise community has been developing methods to quantify perception of tones and lately trying to propose new tone guidelines to regulate the maximum level of tones in noise. Prior to proposing guidelines, the reliability of existing tone quantification methods should be examined. Thus, this paper investigates uncertainty of the tone quantifying methods from ANSI or ISO standards including Tonal Audibility, Prominence Ratio, and Tone-to-Noise Ratio. This study will discuss major causes of uncertainty in measuring the tones from using the methods. It will cover definitions of tones in each method, how these metrics separate tones and broadband noises, and how they analyze signals in time and frequency domains. Lastly, this paper will also investigate effects of room modes on the measured tonality in indoor environments. The variances of the measured tonality across measurement positions for the assorted metrics will be presented. Acceptability of the variances in tonality will also be discussed.
Acoustic edge effect: Novel acoustophoretic cell retention to enable continuous bioprocessing
Authors: Ross-Johnsrud Benjamin P. , Miller Erik , Hicks Hayley , Chitale Kedar C. , Presz Walter , Lipkens Bart
Published: June 2017

There is currently a shift in Bioprocessing towards continuous manufacturing of monoclonal antibodies or recombinant proteins in perfusion mammalian cell cultures (Konstantinov & Cooney, Journal of Pharmaceutical Sciences, 2015). A cell retention device is the key technology component that enables the shift to continuous production. A novel acoustic cell retention device operates by continuously drawing off a harvest flow, equal to the perfusion rate of the bioreactor, while recirculating the retained cells back to the bioreactor. The harvest flow path is tangent and significantly smaller than the recirculation rate. The device utilizes a novel acoustophoretic effect known as an “acoustic edge/interface” effect in conjunction with a recirculating flow beneath the acoustic harvest chamber which collects and returns cells to the bioreactor. This interface effect operates by creating a radiation pressure/force field at the interface between cell-free harvest and cell-laden circulating fluids. Numerical results show an insight into the mechanism of the acoustic edge effect. Experimental results confirm the existence of this novel acoustic edge effect. CHO cell perfusion cultures were operated continuously for >15 days. This technology delivers continuous cell retention and steady unhindered product transmission enabling continuous production of biopharmaceuticals unlike traditional hollow-fiber tangential flow filtration.
Evaluation of techniques for navigation of higher-order ambisonics
Authors: Tylka Joseph G. , Choueiri Edgar
Published: June 2017

Metrics are presented that assess spectral coloration and localization errors incurred by navigational techniques for higher-order ambisonics. Previous studies on the coloration induced by such navigational techniques have been largely qualitative, and the accuracy of previously-used localization models in this context is unclear. The presented metrics are applied in numerical simulations of navigation over a range of translation distances. Coloration is predicted using an auditory filter bank to compute the spectral energy differences between the test and reference signals in critical bands, and localization is predicted using a precedence-effect-based localization model. Coloration and localization errors are also measured through corresponding binaural-synthesis-based listening tests, wherein subjects are first asked to rate the induced coloration relative to reference and low-pass-filtered “anchor“ signals, and subsequently judge source position. Relationships are drawn between the metrics and the results of the listening tests in order to validate the predictive capabilities of the metrics.
Contributions of head-related transfer function choice and head tracking to virtual loudspeaker binaural rendering
Authors: Katz Brian F. , Stitt Peter , Simon Laurent , Hendrickx Etienne , Andreopoulou Areti
Published: June 2017

This presentation will provide an overview of recent and ongoing studies regarding evaluations of sound fields using virtual loudspeaker binaural synthesis. Of specific interest is an identification of perceptual attributes affected by Head-Related Transfer Function (HRTF) choice beyond basic localization error and the sensitivity of listeners to head tracking with regards to latency and externalization judgments. A list of perceptual attributes, created using a Consensus Vocabulary Protocol elicitation method, and validated through listening tests, resulted in eight valid perceptual attributes for describing the perceptual dimensions affected by HRTF set variations. Employing prescribed head movements, sensitivity to head tracker latency showed small but significant differences between single and multichannel audio source scenes. A similar protocol was employed to comparing the sense of externalization as a function of head rotation with and without head tracking. In contrast to several previous studies, results showed that head movements can substantially enhance externalization, especially for frontal and rear sources, and that externalization can persist even though the subject has stopped moving his/her head. These works were carried out during the course of the French funded BiLi (Binaural Listening) project (FUI-AAP14).
High-density data sonification of stock market information in an immersive virtual environment
Authors: Chabot Samuel , Braasch Jonas
Published: June 2017

Data sonification is an important tool to enhance a user's ability to capture and process complex information. In this system, stock market data for the top 128 publicly traded stock options are analyzed for the sonification. This information includes the daily trading price and volume of each stock. Audio streams for conveying the daily information of each stock are generated using sine tone click trains, pitch alterations, and noise bursts. Each audio stream is mapped to an individual loudspeaker in the 128 loudspeaker array of Rensselaer’s Collaborative-Research Augmented Immersive Virtual Environment Laboratory (CRAIVE-Lab) to create a high-density spatialized sonification within the immersive virtual environment. [Work supported by NSF #1229391 and the Cognitive and Immersive Systems Laboratory (CISL).]
Structural-acoustic optimization based on Fast Multipole Boundary Element Method sensitivity analysis of a coupled acoustic fluid-structure system
Authors: Yang Nian , Chen Leilei , Sepahvand Kheirollah , Yi Hong , Marburg Steffen
Published: June 2017

For the light structures immersed in water, a full fluid-structure interaction (FSI) has to be considered when structural acoustics is analyzed. However, the computation costs for the FSI prediction and optimization is always huge. The Fast Multipole Boundary Element Method (FMBEM) is one of the most widely used methods to accelerate the computations. Meanwhile, sensitivity analysis for FSI problems is the most time-consuming part of gradient-based optimization strategies. In this research, a FMBEM-based sensitivity analysis is applied to a practical underwater model’s structural-acoustic optimization. Object function that represents the overall radiated sound power are investigated, where the damping material thickness in some specific areas were chosen as design parameters. An improvement of the object functions are found within a limited number of function evaluations. The FEM/FMBEM based sensitivity analysis is used to calculate the sensitivity of the object function to the design parameters. The method of moving asymptotes (MMA) is chosen as the optimization algorithm. The efficiency of this optimization strategy applied on FSI practical model is investigated in detail.