bluuebunny/crossref_metadata_2025 huggingface dataset:
Smartphones as research platform for hearing improvement studies
Authors: Kehtarnavaz Nasser , Panahi Issa M.
Published: June 2017

This poster presents the development of software tools at the University of Texas at Dallas to turn smartphones into a research platform for hearing improvement studies as part of the newly funded R01 NIH project entitled “Smartphone-Based Open Research Platform for Hearing Improvement Studies.” The challenge in deploying smartphones as a research platform for hearing improvement studies lies in the use of programming languages that researchers are most familiar with. These languages are MATLAB and C. In other words, the challenge to deploy smartphones as a research platform is by not demanding researchers to know the programming languages associated with smartphones (Java for Android smartphones and Objective C for iOS smartphones) in order to turn smartphones into implementation research platforms. This challenge is met in this work by developing software shells that allow signal processing codes that are written in either C or MATLAB to be run on the ARM processors of smartphones/tablets. As part of this poster presentation, demos of the apps that have been generated so far based on these developed software shells will be presented.
Resonant gas oscillation in a tube of square cross section
Authors: Yano Takeru
Published: June 2017

Nonlinear resonant gas oscillations in a tube of square cross section are studied by solving the full system of Navier-Stokes equations for three-dimensional compressible gas flows with a finite-difference method. The nonlinear gas oscillations with and without shock waves and resulting time-averaged transport phenomena of mass, momentum and energy are investigated in the tube of square cross section. In particular, we find that there exist streamlines of acoustic streaming visiting both the inside and outside of boundary layer, which means that the mass, momentum and energy transports are confined neither in the inside nor in the outside of boundary layer on the tube wall, contrary to two-dimensional flows.
Influence of the exact source and receiver positions on the uncertainty of acoustical measurements in concert halls
Authors: Witew Ingo B. , Vorlaender Michael
Published: June 2017

Acoustical measurements are crucial to backing up theories or supporting conclusions in research and practical applications. In concert halls, however, it is well known that small changes to the receiver position yield a measurable change to the impulse response and the calculated single number parameter. This gives raise to the questions whether these spatial fluctuations limit the validity of measurements and whether there are implications for measurement applications? The presented study discusses how a measurement uncertainty approach may provide a new perspective to these problems. Based on array measurements a relationship has been established that quantifies how a change in measurement position leads to an average change to a room acoustic quantity. Strategies as outlined by the “Guide to the Expression of Uncertainty in Measurement” (GUM) are used to determine the bounds in which valid measurement results can be collected. It is discussed how these findings can be considered in applied measurement studies.
Applying subjective perception to acoustical planning
Authors: Engel Gunter
Published: June 2017

Traditional room acoustical planning suffers from a considerable gap between the available measurement techniques and quality criteria at the one side and the subjective perception on the other side. Since the subjective perception is to a certain extent a matter of taste and moreover considerably overlaid by expectations and impressions which have nothing to do with acoustics, it is no wonder that it is so hard to find a suitable approach for creating the all over demanded perfect and world class acoustics. Applying new insights into the influence of early reflections on the perceived sound characteristics helps considerably to tailor the acoustics of a hall to your wishful thinking. The approach is illustrated by two concert halls with innovative design measures.
Comparison of listener preference in concert halls from the stage and the audience
Authors: Clapp Samuel W. , Guthrie Anne , Braasch Jonas
Published: June 2017

The perception of concert hall acoustics has been studied extensively from the perspective of the audience, but less extensively from the perspective of the musicians performing on stage. In this study, impulse response measurements were conducted in a group of eight concert and recital halls in the northeastern United States. A multi-channel microphone array was used to measure listening positions both on the stage and in the audience. The impulse responses recorded with the microphone array were used to generate auralizations for playback over multi-channel loudspeaker arrays, to investigate listeners’ and musicians’ preferences via listening tests. The audience positions were presented to the test subjects via static, pre-convolved auralizations. For the stage positions, all test subjects were musicians who, during the course of the test, performed on their instruments and heard the resulting auralizations from the stages of the different concert halls, generated in real-time. The results allowed for a comparison of listener preferences from the stage and audience positions in the same set of halls. The microphone array recordings also allowed for spatial energy analysis and the development of new spatial room impulse response parameters that could be correlated with listeners’ preference judgments.
Contemporary multi-use concert hall design: Experience and analysis
Authors: Guthrie Anne , Brooks Todd , Patel Raj , Solway Joe
Published: June 2017

The acoustic design practice at Arup in New York has designed multiple performing arts spaces with a wide range of acoustic characteristics and functions, several of which have opened within the past few years. Many of these spaces make use of adjustable acoustics to accommodate a wide range of program within a single space, including acoustics control chambers, adjustable-height canopies, adjustable sound absorbing curtains and banners, and flexible configurations of various stage elements. Traditional objective parameters have been examined for both audience and stage acoustics, and additional spatial analysis is explored through visualization of 3D impulse responses. The relationships between these parameters and each venue’s program goals will be addressed. Our experiences and findings obtained through the process of design, construction, and post-opening will be shared.
Methods to measure stage acoustic parameters: Overview and future research
Authors: Wenmaekers Remy , Hak Constant , Hornikx Maarten , Kohlrausch Armin
Published: June 2017

The acoustics on stage has been recognized as an important design consideration for concert halls and other performance or rehearsal spaces. Stage acoustic parameters such as STearly and STlate are used to judge the early and late reflected sound levels on the stage. However, correlation of these parameters to perceptual attributes have not always been found. An explanation could be that the parameters used are not appropriate and/or that musicians find it hard to judge acoustic conditions. Another possible explanation is that the measurement methods used are not accurate enough. The goal of previous research by the authors was to investigate the uncertainties in the physical measurement. In this paper, an overview will be presented of the main findings that can serve as a starting point for future research. The following topics are covered: time windows for early and late sound, the reference level at 1 m distance, directivity of the omnidirectional sound source, impulse response quality, occupied stage measurements and directional transducers. Finally, a fast and musician friendly measurement method is presented that can be used to accurately measure acoustic parameters on a stage occupied by a full orchestra. The paper concludes with recommendations for future research.
The loudness of an amplitude-modulated sinusoid as a function of interaural modulator phase, modulation rate, and level
Authors: Moore Brian C. , Jervis Matthew , Harries Luke , Schlittenlacher Josef
Published: June 2017

The aim was to test a model of loudness for binaurally presented time-varying sounds (Moore et al., Trends in Hearing, in press). A 1000-Hz sinusoidal carrier was 100% sinusoidally amplitude modulated. The effect on its loudness of varying the interaural modulation phase difference (the IMPD) was assessed. The IMPD of the test sound was 90° or 180° and that of the comparison sound was 0°. A two-interval, two-alternative forced-choice method with a one-up/one-down rule was used to estimate the level difference between the test and the comparison sounds at the point of equal loudness (the LDEL) for baseline levels of 30 and 70 dB SPL and modulation rates of 1, 2, 4, 8, 16, and 32 Hz. The LDELs were negative (mean = -1.2 and -1.6 dB for IMPDs of 90° and 180°), indicating that non-zero IMPDs led to increased loudness. The model predicted that the LDELs should be most negative for modulation rates up to 4 Hz, and should be close to zero for the rate of 32 Hz. The data showed a pattern similar to the predicted pattern, but the LDELs for the modulation rate of 32 Hz were about 0.6 dB more negative than predicted.
Kenneth J. Plotkin—A most unforgettable character
Authors: Sharp Ben H.
Published: June 2017

In a career lasting over 45 years, Ken Plotkin established himself as a world leader in aeroacoustics, best known for his research studies of sonic boom. He developed the first practical method of predicting focused sonic booms and has been a key participant in recent studies to mitigate sonic booms, for which he has been awarded several NASA awards for excellence. But Ken’s contributions to the field of acoustics have been much more diverse than many realize. They have included topics such as highway, vehicle and tire noise, psychoacoustics, aircraft noise simulation modeling, soundscape analysis and monitoring, and community noise. Ken was one of the most intelligent people the author has ever met, and one of the most inventive. He had the ability to break down complex problems into simple components that could be understood and solved, often using limited available data and simple theoretical models. Refreshingly modest with a self-deprecating and cynical sense of humor, Ken was one of those rare people who, once met, would never be forgotten. As a long-term colleague and friend, the author will discuss some of his major contributions and share some of his experiences working with him.
Memorable interactions with Dr. Ken Plotkin during NASA sonic boom research
Authors: Coen Peter
Published: June 2017

Dr. Ken Plotkin was an active and vital contributor to numerous NASA research activities over the course of his career. His involvement clearly advanced NASA’s objective and improved the state of knowledge of the prediction and reduction of sonic boom noise, but it also created many fond and amusing memories for those fortunate to work with him. This remembrance of Ken will recall some of his intellectual and comical contributions.
Kenneth J. Plotkin's contributions to acoustics and sonic boom research at NASA
Authors: Loubeau Alexandra
Published: June 2017

Dr. Kenneth J. Plotkin played a significant role in furthering knowledge related to outdoor sound propagation and, in particular, propagation of sonic booms from supersonic aircraft. This presentation focuses on Dr. Plotkin's support of NASA's research in these areas. In recent years, he worked with NASA on expanding the capabilities of the modeling software PCBOOM for prediction of sonic boom propagation for a variety of aircraft flight conditions in complex atmospheric environments. Dr. Plotkin was also instrumental in the planning, execution, and analysis of several NASA supersonic flight test campaigns aimed at gathering data for development and validation of prediction models like PCBOOM. NASA's sonic boom research has benefited greatly from these collaborations, and it is our hope to honor his legacy by continuing work in this area.
Overview of acoustic and sonic boom advancements during development of NASA launch vehicles
Authors: Houston Janice , Jones Jess , Kenny R. Jeremy , Nesman Tomas , Reed Darren , Vu Bruce
Published: June 2017

During the study and development of NASA space vehicles, acoustic environments have been a critical design input. This paper surveys some of the key challenges and focuses on the contributions and collaborations of Kenneth J. Plotkin/Wyle Laboratories with various NASA centers and personnel. In the mid-1960’s and early 1970’s, a method for predicting in-flight fluctuating environments for vehicle systems was developed for the Saturn Development Programs at NASA Marshall Space Flight Center (MSFC). With the Space Shuttle Vehicle development in the 1970’s, sonic boom became a concern and sonic boom focusing was studied. Attention was turned to the Space Shuttle Orbiter entry maneuvers during the approach to the KSC landing site. In 1993, a PC version for sonic boom prediction was developed for the National Launch System study. Near-field pressure data from computational fluid dynamics analyses were used to develop the shape factors used in the X-33 sonic boom analyses. For the X-34 sonic boom analyses, the influence of plumes on the shape factor was included. In the 2000s, rocket noise prediction software at the KSC launch platform was developed for the Constellation Program. All this acoustic work is being leveraged on NASA’s latest vehicle, the Space Launch System.
Remembering Ken Plotkin: Colleague, mentor, and friend
Authors: Page Juliet
Published: June 2017

Dr. Kenneth J. Plotkin's contributions to the field of acoustics are numerous and cover a variety of areas such as sonic boom, jet noise, community noise, and atmospheric propagation. I will review many of Ken's contributions to the field of acoustics, including shared experiences during unique and challenging projects and field measurement programs. I will also highlight Ken's leading role in the development of acoustic visualization techniques.
Macro-scale cell manipulation using bulk ultrasonic standing waves for biopharmacy and cellular therapy applications
Authors: Lipkens Bart , Chitale Kedar C. , Ross-Johnsrud Benjamin P. , Presz Walter
Published: June 2017

Acoustic standing wave fields are widely used in MEMS applications to manipulate micron sized particles in fluids with typical fluid channel dimensions of half a wavelength. This report presents three novel acoustofluidic platforms for particle separation and/or manipulation at macroscale, i.e., tens to hundreds of wavelengths. The first platform uses multidimensional standing waves which generate lateral radiation forces that trap and tightly cluster suspended fluid or particulate, enhancing the gravitational settling effect that results in continuous, macroscale separation. The second platform employs acoustic radiation forces generated near the edge of an acoustic standing wave to hold back particles and generate a wall type separation effect. The third platform uses the acoustic radiation forces generated by a macroscale, angled standing wave to deflect particles in a controlled fashion for particle manipulation and/or differentiation. Applications are focused in biopharmacy and cellular and gene therapy: mammalian cell clarification, continuous perfusion of bioreactors, cell concentration and washing, cell sorting and differentiation, fractionation, microcarrier-cell separation, and affinity acoustic separation. A commercial cell clarification device has been introduced. The key physics principles related to acoustic radiation force and low Reynolds number multi-phase flows are discussed. Experimental results of cell clarification, perfusion, and manipulation are shown.
Acoustofluidic manipulation of biological bodies: Applications in medical and environmental diagnosis
Authors: Carugo Dario , Hammarström Bjorn , Jonnalagadda Umesh , Lei Junjun , Plazonic Filip , Messaoudi Walid , Shaglwf Zaid Ibrahim , Glynne-Jones Peter , Hill Martyn
Published: June 2017

Ultrasound-based external forcing of biological bodies in microfluidics has emerged as a contactless way of manipulating cells and particles for a range of applications, including sample enrichment, filtration, and sorting. Recently, acoustic radiation forces have shown potential for manipulating pathogenic organisms in biological assays. In this presentation, we demonstrate the development of acoustofluidic systems designed for high-throughput manipulation and capturing of biological bodies in applications ranging from medical to environmental diagnosis. Specifically, we apply our acoustofluidic systems to the detection of (i) cancer and immune cells in the early-stage diagnosis of blood malignancies and allergies, and (ii) bacterial microorganisms, spores, and planktonic cells for screening of environmental and industrial samples.
Macroscale angled ultrasonic standing waves: A novel approach for particle manipulation
Authors: Chitale Kedar C. , Presz Walter , Lipkens Bart , Ross-Johnsrud Benjamin P. , Hyman Miles , Lamontagne Marc
Published: June 2017

Macro scale acoustophoretic devices use radiation forces to trap particles inside a standing wave to separate them from a mixture in a continuous fashion. However, these devices are limited by factors such as flow rates, residence times, and temperature rise which could be detrimental for certain applications. A novel method of separating, sorting and differentiating various particles using bulk angled ultrasonic standing waves is presented. This technique offers very sensitive separation capability with respect to size and acoustic contrast of particles. Universal curves are developed for particle deflection from the bulk flow direction at all wave angles as a function of a non-dimensional parameter defined by the ratio of acoustic radiation force to viscous drag force. Both CFD (Computational Fluid Dynamics) and model test data verify the analytical predictions. New macro-scale, ultrasonic separator concepts are presented that use the angle wave technology to effectively deflect and/or separate microcarrier beads from a flowing mixture at high speeds when compared to conventional ultrasonic separators. Model test data verify the ability to move, differentiate, separate, or fractionate particles in suspension by size and acoustic contrast.
Boundary interactions with vortical disturbance in an acoustofluidic channel
Authors: Chandra Kavitha , Thompson Charles , Mehta Vineet
Published: June 2017

In this work, mechanisms governing the generation of unstable vortical disturbances and their spatiotemporal characteristics are examined. Time-harmonic boundary and pressure driven flows are of particular interest. In the inner region near the solid-fluid interface, the vortical components of the particle velocity are taken to behave incompressibly. To accommodate time-dependent channel wall geometries a curvilinear coordinate based pseudo-spectral method is developed. The method allows for the direct numerical solution of the three-dimensional time-dependent Navier-Stokes equation for high streaming Reynolds conditions. The conditions for centrifugal destabilization and transition are examined.
Ultrasonic robotics in microfluidic cavities
Authors: Dual Jürg , Gerlt Michael , Hahn Philipp , Lakaemper Stefan , Leibacher Ivo , Lamprecht Andreas , Reichert Peter , Vertti Quintero Nadia S. , Casadevall i Solvas Xavier , Gunawan Rudiyanto , deMello Andrew
Published: June 2017

Ultrasonic standing waves are often used in biomedical applications. It has become quite common to move beads, cells, droplets, and other particles for sorting or biomedical analysis in microfluidic cavities by bulk acoustic waves or by vibrations excited by piezoelectric transducers. The motion of particles is determined by streaming and radiation forces. For the calculation of the radiation forces acting on single particles Gorkov’s potential is considered to be the modeling tool of choice, once the acoustic field and the properties of constituents (fluid and particle density and compressibility, respectively) are known. For the acoustic streaming, predictions can be made numerically. For both aspects large uncertainties exist, due to the complexity of the system and fluid structure interaction at multiple levels. In this paper, first various characterization tools for the acoustic field in the cavity are described. They consist of the interplay between numerical modeling of the device, impedance analysis of the piezoelectric transducer used, interferometric analysis of surface displacements and an optical trap to measure the forces on the particles directly. Secondly, a number of recent applications are shown, including the sorting and immobilization of C. elegans. Furthermore, fascinating behavior of multiple interacting particles is reported.
Acoustic nonlinearity and the generation of large tensile pressures to explain atomization in drop-chain acoustic fountains
Authors: Sapozhnikov Oleg , Annenkova Elena , Kreider Wayne , Simon Julianna C.
Published: June 2017

An ultrasound beam propagating upward in a liquid creates an acoustic fountain at a gas interface in the form of a drop chain. High-speed photography shows that one or several drops in such a fountain explode in less than a millisecond, resulting in liquid atomization [Simon et al. J. Fluid Mech., 2015, 766, pp. 129-146]. To explain this phenomenon, a nonlinear theory involving an isolated spherical drop is developed. The model considers an initial excitation in the form of a spherical standing acoustic wave at the lowest resonance frequency, i.e., when the drop diameter coincides with a wavelength. If higher harmonics are generated inside the drop due to acoustic nonlinearity, these harmonics will also have the form of standing spherical waves. At higher frequencies, more of the energy of each harmonic is localized near the drop center. Calculations demonstrate that harmonic generation can lead to large increases in both peak positive and peak negative acoustic pressure at the drop center. Such large tensile pressures may exceed the intrinsic cavitation threshold, leading to the nucleation of a bubble at the center and explosion of the drop as the bubble grows rapidly. [Work supported by RFBR 17-02-00261 and NIH R01EB007643.]
Acoustic characterization of microbubble clouds by attenuation and celerity spectroscopy
Authors: D'Hondt Lilian , Payan Cedric , Mensah Serge , Cavaro Matthieu
Published: June 2017

In 4th generation nuclear reactors cooled with liquid sodium, argon microbubbles are present in the primary sodium. Due to the opacity of liquid sodium, acoustic control methods are chosen for operating inspections but this bubble presence greatly affects the acoustical properties of the medium. It is therefore required to characterize the microbubble cloud, i.e., to provide the bubble’s volume fraction and the size distribution. Safety demands the proposed method to be robust and applicable with few assumptions (about the bubble populations) as possible. The objective of this study is to evaluate the performance of spectroscopic methods (based on celerity and attenuation) in the presence of bubbles whose sizes and surface (or volume) contributions are very different. Two methods of evaluating the histogram and the void fraction are compared. The first is based on the inversion of the integral equation of the complex wave number derived by Commander and Prosperetti. The second, which assumes the populations to have log-normal or sums of Gaussians distributions, performs an adjustment of the distribution’s parameters to fit attenuation and celerity curves measurements. These methods are compared with experimental data obtained using ACWABUL facilities at CEA Cadarache.
T-matrix method implementation for acoustic Bessel beam scattering from elastic solids and shells
Authors: Gong Zhixiong , Marston Philip L. , Chai Yingbin , Li Wei
Published: June 2017

T-matrix method (TMM) has been demonstrated to be an effective tool for the application of acoustic Bessel beam (ABB) scattering from rigid shapes, owing to the fact that the incident ABBs could be appropriate to expand on the basis of spherical harmonics [Gong et al., J. Sound Vibr. 383, 233-247 (2016)]. In this work, we try to extend the TMM to further calculate ABB scattering from complicated elastic shapes, spheroids/ spheroidal shells for instance. Some numerical techniques are successfully implemented to overcome the instability problem during matrix inversion procedures for nonspherical shapes. Resonance scattering theory and ray theory [Kargl and Marston, J. Acoust. Soc. Am. 88, 1103-1113 (1990)] are employed to explore and interpret several novel properties of scattering from elastic shapes illuminated by ABBs, thus revealing the corresponding mechanism of scattering by ABBs. Furthermore, the present work will perform as a foundation work to extend the applicability of TMM to study acoustic radiation force and torque in ABBs in future. [Work supported by NSFC.]
In “Lou” of the Lou you know
Authors: Trahiotis Constantine
Published: June 2017

Lou Braida has distinguished himself as a scientist, educator, and, to the dismay of many, critic-par excellence. Others will speak to his wide variety of fundamental contributions to knowledge concerning several areas of auditory perception. I will confine my remarks to Lou the person and friend. In my interactions with Lou I discovered and have cherished an individual for whom many of you has remained “e-Lou-sive.” I will introduce you to Lou the cheapskate, Lou the inventor, Lou the scammer, Lou the smuggler, Lou the travel agent, Lou the traveling chef, and Lou the practical engineer-observer. These other incarnations of Lou, taken together with the more widely known Lou, reveal the truly multidimensional ways in which he has led a very special life, one in which all of us have been fortunate to share.
Cochlear mechanisms underlying the sharp frequency selectivity of hearing
Authors: Freeman Dennis M. , Ghaffari Roozbeh , Farrahi Shirin , Sellon Jonathan B.
Published: June 2017

Sharp frequency selectivity, which is a hallmark of mammalian hearing, originates in the cochlea. However, the underlying mechanisms remain unclear. The pioneering work of von Bekesy showed that sounds launch waves of motion along the spiraling basilar membrane, and subsequent hydrodynamic analysis has shown how mechanical properties of the cochlear partition can interact with fluid forces to support sharp frequency tuning. These analyses have generally presumed (or even purported to prove) that longitudinal mechanical coupling through cochlear structures is negligible. Here, we demonstrate that the visco-elastic structure of the tectorial membrane (TM), a gelatinous structure that overlies the sensory receptor cells and plays a key role in stimulating them, also supports traveling waves. The distance over which TM waves propagate provides a measure of mechanical coupling and, through the cochlear map, determines a range of frequencies that correlates strikingly well with direct measurements of cochlear tuning in normal hearing mice, in mice with genetic disorders of hearing, and in humans. These results demonstrate significant longitudinal coupling through the TM and suggest that TM coupling plays an important role in determining the sharpness of cochlear frequency tuning.
All I really need to know I learned from Lou and Nat: Lou Braida
Authors: Picheny Michael
Published: June 2017

Lou Braida was one of my two primary mentors in graduate school at MIT. Lou taught me innumerable things. In this talk, I will only have time to focus on a few items. I will describe how I applied to Speech Recognition what I learned from him about the power of a psychophysical approach to research problems, the importance of good data collection, and the value of long-term spectral characteristics in perception. Speech recognition by now is a relatively mature field, but at the time the field was relatively unexplored territory. Lou’s training allowed me to see ways to make advances in speech recognition experimental design, speaker-independent speech recognition, and noise-immune features and processing. While many of these early ideas have been subsumed over the years by more sophisticated processing, many of them have their roots in techniques inspired by a combination of perceptual knowledge with principled engineering design. Lou was, and is a master of both and I am forever grateful for his inspiration, mentoring, and friendship in shaping my career.
Computational models of speech perception by cochlear implant users
Authors: Svirsky Mario , Sagi Elad
Published: June 2017

Cochlear implant (CI) users have access to fewer acoustic cues than normal hearing listeners, resulting in less than perfect identification of phonemes (vowels and consonants), even in quiet. This makes it possible to develop models of phoneme identification based on CI users’ ability to discriminate along a small set of linguistically-relevant continua. Vowel and consonant confusions made by CI users provide a very rich platform to test such models. The preliminary implementation of these models used a single perceptual dimension and was closely related to the model of intensity resolution developed jointly by Nat Durlach and Lou Braida. Extensions of this model to multiple dimensions, incorporating aspects of Lou’s novel work on “crossmodal integration,” have successfully explained patterns of vowel and consonant confusions; perception of “conflicting-cue” vowels; changes in vowel identification as a function of different intensity mapping curves and frequency-to-electrode maps; adaptation (or lack thereof) to changes in frequency-place functions; and some aspects of speech perception in noise. Our latest studies predict that enhanced phoneme identification by cochlear implant users may result from deactivation of a subset of electrodes in a patient’s map. All these results build upon, and were made possible by concepts from Lou’s work.
Factors affecting accuracy and intelligibility of transliterators who use cued speech
Authors: Krause Jean C.
Published: June 2017

Some deaf individuals access spoken information via transliterators who use Cued Speech, a system of hand gestures that supplement information available through speechreading alone. In this presentation, the accuracy and intelligibility of 12 transliterators with varying degrees of experience are examined. Accuracy, or the percentage of cues correctly produced, was evaluated at three different speaking rates (slow, normal, and fast), and intelligibility, or the percentage of words correctly received, was measured by presenting the materials that the transliterators produced to nine expert receivers of Cued Speech. Results show that speaking rate had a large negative effect on accuracy, caused primarily by an increase in omitted cues, while increased experience level was generally associated with increased accuracy. Intelligibility was generally higher than accuracy, with accuracy accounting for roughly 25% of the variance in intelligibility scores. We conclude by discussing factors such as speechreadability that could explain additional portions of the variance.
Louis Braida’s influence on speech intelligibility research
Authors: Payton Karen
Published: June 2017

In the Sensory Communications Laboratory at MIT, several researchers have grappled with the question of how to predict listeners' perceptual performance using quantitative metrics. Most of the work has been motivated by the goal of understanding the effect of acoustic degradations on speech intelligibility for hearing impaired listeners and determining the best way to mitigate or counter those degradations. Louis Braida has been interested in this topic for many years. He worked with Ken Grant to investigate augmentation of the Articulation Index (AI) with visual information to obtain an audio-visual AI. He continued this work with other students modeling perceptual integration across modalities. Lou and I worked together to investigate the ability of the Speech Transmission Index (STI) to predict intelligibility for impaired listeners. Initially, we tried to use it as a way to try and capture acoustic differences between conversational and clearly-articulated speech. That evolved into the development of a speech-based STI. Ray Goldsworthy extended our work, comparing several speech-based STI techniques and developing a new one to predict speech intelligibility for cochlear implant users. This talk will review the work done in this area under Lou’s mentorship and recent advances.
Measuring speech intelligibility with speech and noise interferers in a loudspeaker-based virtual sound environment
Authors: Ahrens Axel , Marschall Márton , Dau Torsten
Published: June 2017

Loudspeaker-based virtual sound environments (VSEs) are emerging as a versatile tool for studying human auditory perception. In order to investigate the reproducibility of simple sound scenes, speech reception thresholds (SRTs) were measured with two interferers and in two spatial conditions (co-located and ±30° separated) using the Danish matrix sentence test Dantale II (Wagener et al., 2003). SRTs were measured in a typical listening room and in a VSE consisting of a spherical 64-channel loudspeaker array using simulated room acoustics with mixed-order-Ambisonics (MOA) playback. The speech maskers were taken from the same material as the target (different talker, same sex). The noise maskers had the same long-term spectrum and broadband envelope as the speech interferer but had random phase (Best et al., 2013). The co-located conditions were reproduced comparably in the real room and in the VSE, with both speech and noise interferers. However, spatial separation led to a 3 dB higher benefit in the VSE than in the real room in both interferer conditions. Previous studies using a larger number of sound sources and more reverberation did not show such systematic differences between virtual and reference conditions, suggesting that reproduction errors may be masked in more complex scenes.
The effect of reverberation and audio spatialization on egocentric distance estimation of objects in stereoscopic virtual reality
Authors: Bailey Will , Fazenda Bruno M.
Published: June 2017

It has been reported by numerous studies on distance perception in VR that a compression of visual space occurs in virtual environments presented using stereoscopic techniques. Other studies have shown that modified environmental auditory cues can affect egocentric spatial perception and that increased order of modality improved the experience of immersive media. Work was conducted to measure the effect of spatialized acoustic cues on egocentric distance estimation in head mounted display VR. Results suggest that the although early reflection content was not found to have significant effect on estimation of distance, presence of reverberation increases the perception of distance for objects further than 5m from the user and can compensate for the spatial compression observed in the use of stereoscopic VR.
Perceptual evaluation of multichannel synthesis of moving sounds as a function of rendering strategies and velocity
Authors: Camier Cédric , Guastavino Catherine
Published: June 2017

Sound-field synthesis for static sound sources has been extensively studied. Recently, dynamic sound sources synthesis has garnered increased attention. Classical sound-field rendering strategies discretize dynamic sound-fields as a sequence of stationary snapshots. The use of discrete multichannel arrays can generate further artifacts with moving sounds. Depending on the technique used, this results in an amplitude modulation due to successive loudspeaker contributions (VBAP) or in multiple comb-filtering (WFS) which could affect localization cues, especially at off-centered listening positions. We first present a detailed description of these artifacts. We then introduce a hybrid rendering strategy combining propagation simulation and VBAP at audio rate. We used this rendering strategy and WFS to synthesize white noise revolving around listeners on a circular 48-loudspeaker array. On each trial, participants had to identify the trajectory (circle, triangle, or square) for velocities ranging from 0.5 to 2 revolutions per second. Performance was well above chance level in all conditions. While WFS outperformed the hybrid rendering strategy at low velocities, no significant differences were observed at high velocities for which participants relied on temporal cues rather than spatial cues. The results highlight how artifacts of the rendering strategies interfere with dynamic sound localization at different velocities.
Auralization of acoustic spaces based on spherical microphone array recordings
Authors: Ahrens Jens , Hohnerlein Christoph , Andersson Carl
Published: June 2017

Microphone arrays can capture the physical structure of a sound field. They are therefore potentially suited to capture and preserve the sound of acoustic spaces within given physical limitations that are determined by the construction of the array. Especially spherical microphone arrays have received considerable attention in this context. Superposed onto the limitations of the microphone array are the limitations caused by the auralization system. We present results from user studies on the perceptual differences between spherical microphone array recordings that are auralized with headphones as well as with a circular 56-channel loudspeaker array and headphone auralization based on dummy head measurements of the same spaces. Head-tracking was applied in all cases in which headphones were used.
Vibration and sound of a flapping airfoil: The limit of small bending rigidity
Authors: Manela Avshalom , Weidenfeld Michael
Published: June 2017

We investigate the near and far fields of a thin elastic airfoil set at uniform low-Mach flow and subject to leading-edge heaving actuation. The airfoil is “hanged” in the vertical direction and is free at its downstream end, so that “hanging chain” gravity-induced tension forces apply. The structure bending rigidity is assumed small, and we focus on analyzing the differences between a highly elastic airfoil and a membrane (where the bending rigidity vanishes). The near field is studied based on potential thin airfoil theory, whereas the acoustic field is investigated using the Powell-Howe acoustic analogy. The results shed light on the specific effect of structure bending stiffness on the dynamics and acoustic disturbance of an airfoil.
Structural health monitoring under random flow loading
Authors: Roveri Nicola , Milana Silvia , Culla Antonio , Carcaterra Antonio
Published: June 2017

The aim of the work is the analysis of fluid-structure systems, when excited by a flow consisting of an incompressible potential fluid with embedded vortexes. In fact, in many problems of relevant application interests, the monitoring and the potentially detection of structural damages in structures undergoing loads in operative conditions is important. The present method tries to identify simultaneously the load characteristics together with the structural damage. The flow is characterized by the average velocity of the fluid conveying the vortexes and by the position and intensity of the conveyed vortexes. A method for the identification of these flow parameters, based on vibration signals measured at the elastic fluid-structure interface, is proposed. Vibration signals are numerically generated and then processed with time-frequency techniques, such as the ensemble empirical mode decomposition and the normalized Hilbert transform. The sensitivity of the algorithm to the measurement position and to single versus multi-points acquisitions are also investigated. A particular instantaneous frequency is firstly employed to estimate the load characteristics. The influence of the load is then removed from the instantaneous frequency, so that the damage position can be identified. The validity of the proposed method is analyzed varying the flow parameters, the damage locations and depths; effect of ambient noise is also taken into account.
Acoustic testing techniques for replicating in-flight dynamic loads
Authors: Cohen Kobi J. , Raveh Daniella
Published: June 2017

Modern weapon systems used on combat aircrafts have complex electronic assemblies that are required to operate in challenging dynamic environment throughout their life cycle. Among the various sources of excitation, aerodynamic noise is considered most significant. The paper presents vibroacoustic measurements from captive flight, and attempts to replicate them in acoustic laboratory testing. The question of interest is which testing method, in terms of configuration and control scheme, is the most adequate to accurately simulate the vibratory response of inner assemblies to flight loads. The paper examines acoustic test methods in a reverberant chamber. The tested article is a subsystem of a weapon system that includes electrical assemblies, integrated inside a structural envelope. Two test configurations are compared—“covered,” in which the subsystem is tested inside its structural envelope, and “uncovered,” in which the subsystem is directly exposed to acoustic excitation. Acceleration measurements show that when excited by in-flight acoustic levels, the acceleration responses of the uncovered subsystem, are significantly lower than those measured in flight. For the covered configuration, although the acoustic levels inside the envelope are attenuated by the structure, the resulting accelerations are significantly higher and closer to those of flight.
Acoustical analysis of English /r/ and /l/ by native Japanese adults and children
Authors: Aoyama Katsura , Flege James E. , Akahane-Yamada Reiko , Yamada Tsuneo
Published: June 2017

This study investigated the acoustic properties of American English /r/ and /l/ produced by native Japanese (NJ) and native English (NE) speakers. The purpose of this study was to examine the differences in production reported in Aoyama et al. (2004) acoustically. Aoyama et al. evaluated productions of /r/ and /l/ in 64 NE and NJ adults and children (16 participants each in 4 groups) using intelligibility ratings. The data were collected twice to study the acquisition of English by the NJ adults and children. In this study, four acoustic parameters (duration, F1, F2, and F3) were measured in 256 tokens each of /r/ and /l/. The results showed that all of the acoustic parameters differed significantly between NJ and NE speakers at both times of testing. Some aspects of acoustic parameters changed significantly over the course of one year in NJ children’s productions. Lastly, the formant values in NJ speakers’ productions indicated that their productions of both /r/ and /l/ resembled NE speakers’ productions of /r/ more than the NE speakers’ productions of /l/. This finding is consistent with Aoyama et al.’s claim that NJ speakers may have more difficulty in producing English /l/ than with English /r/.
Factors influencing intelligibility and fluency in non-native speech
Authors: Baese-Berk Melissa M. , Morrill Tuuli
Published: June 2017

Substantial research has examined the factors making non-native speech more difficult to understand than native speech. Prior work has suggested that speaking rate is one such factor, with slower speech being perceived as less comprehensible and more accented. Further, non-native speech is produced with shorter utterances and more frequent pauses than native speech. Recent work has suggested that in addition to non-native speech being produced more slowly than native speech, it is produced with a more variable speaking rate. In the present study, we examine the relationship between variability in speaking rate, pausing and utterance length, and intelligibility and fluency ratings of non-native speech. We asked listeners to transcribe sentences produced by non-native speakers and to rate the fluency of read speech. Preliminary results suggest that rate variability does correlate with intelligibility of non-native speech, but not of native speech, and rate variability does not correlate as strongly with fluency. In addition, pause duration may interact with sentence complexity, but appears independent of rate. These results suggest that while fluency and intelligibility are abstract constructs, examining variability in non-native speech and its relationship to a number of factors may help explain why non-native speech is difficult to understand.
Individual variation in the perception of different types of speech degradation
Authors: McLaughlin Drew J. , Baese-Berk Melissa M. , Bent Tessa , Borrie Stephanie A. , Van Engen Kristin
Published: June 2017

Both environmental noise and talker-related variation (e.g., accented speech) can create adverse listening conditions for speech communication. Individuals recruit additional cognitive, linguistic, or perceptual resources when faced with such challenges, and they vary in their ability to understand degraded speech. However, it is unclear whether listeners employ the same additional resources when encountering different types of challenging listening conditions. In the present study, we compare individuals’ ability on a variety of skills —including vocabulary, selective attention, rhythm perception, and working memory—with transcription accuracy (i.e., intelligibility scores) of speech degraded by the addition of speech-shaped noise or multi-talker babble and/or talker variation (i.e., a non-native speaker). Initial analyses show that intelligibility scores across degradations of the same class (i.e., either environmental or talker-related) significantly correlate, but correlations of intelligibility scores across degradation classes are weaker. The relationship between intelligibility scores and cognitive-linguistic skills is similar, showing that while vocabulary and working memory correlate with multiple degradation types, rhythm perception only correlates with environmental degradations. Taken together, these results indicate that listeners may recruit different resources when faced with different classes of listening challenges.
Effects of talker intelligibility and noise on judgments of accentedness
Authors: Gittleman Sarah , Van Engen Kristin
Published: June 2017

The damaging effect of background noise on the intelligibility of foreign-accented speech has been well documented, but little is known about the effect of noise on listeners’ subjective judgments of accents. Noise adds distortion to speech, which may cause it to sound more “foreign.” On the other hand, noise may reduce perceived foreignness by masking cues to the accent. In this study, 40 native English speakers listened to 14 English-speaking native Mandarin speakers in four levels of noise: -4 dB, 0 dB, + 4 dB, and quiet. Participants judged each speaker on a scale from 1 (native-like) to 9 (foreign). The results showed a significant decrease in perceived accentedness as noise level increased. They also showed a significant interaction between noise and intelligibility: intelligibility (which had been measured for the same talkers in a previous study) had the greatest effect on perceived accentedness in quiet, and a reduced effect with increasing noise levels. These findings indicate that listeners’ decreased access to acoustic-phonetic cues in the presence of background noise also reduces their sensitivity to phonetic variation arising from foreign accents. Furthermore, the link between intelligibility and accentedness is weakened by the presence of noise.