bluuebunny/crossref_metadata_2025 huggingface dataset:
Dah-You Maa, friend and scholar
Authors: Beranek Leo L. , Xiang Ning
Published: May 2013

Maa, Dah-You’s life as a scholar and a close friend of many both in China and North America is the theme. A number of his scholarly achievements from his UCLA and Harvard time, to the post-Cultural Revolution period, up to recent years, is reviewed. His two years as a research fellow at UCLA and Harvard which ended with his receiving his Ph.D. at Harvard University in 1940 is detailed. Then began his life in Kunming during World War II where he was a professor in the E.E. Department of the National S.-W. Associated University. He returned to Beijing and became the first Dean of Engineering in the National Peking University (now Beijing University). During the Cultural Revolution, 1966–1976, he was under house arrest. His sponsorship of the first All-China Acoustics Conference after the Cultural Revolution in 1979 heralded his position as China’s leading acoustician. Excerpts from his many letters through the years complete the presentation.
Three directions in research on auditory scene analysis
Authors: Bregman Albert S.
Published: May 2013

Research on auditory scene analysis (ASA) began with some simple laboratory phenomena such as streaming and illusory continuity. Subsequently, research has gone in three directions, downwards toward underlying mechanisms (by neurophysiologists), upwards toward system organization (by computer scientists), and sideways toward other species (by neurobiologists). Each direction has its problems. The downward approach sometimes takes a phenomenon-oriented view of ASA, leading to simple explanations of a single ASA demonstration, such as streaming, with no obvious connection to any larger system. Research done by the upward approach usually takes the form of a computer program to achieve ASA in a working system, often ignoring known facts about human ASA, in favor of mathematically understood principles. The sideways approach often finds that non-human animals can respond to an important sound despite the presence of other interfering sounds. However, there is no reason to believe that a frog, a fish, and a human accomplish this by means of the same mechanisms. So finding out how some animal does this, while interesting in its own right, may shed little light on how humans do it. I will describe some properties of the human ASA system that should be borne in mind when manufacturing explanations.
Mechanisms of perceiving communication sounds in scenes
Authors: Woolley Sarah M.
Published: May 2013

Vocal communicators must perceive the vocal signals of social partners in complex auditory scenes that include distracting background sounds. The auditory system must therefore parse auditory scenes into multiple information streams and/or accurately encode individual vocalizations despite the presence of competing sounds. Explaining mechanisms whereby neural representations of vocalizations are extracted from neural representations of scenes is an important part of understanding how auditory processing leads to perception of communication signals in complex scenes. We study how songbirds recognize individual vocalizations (songs) in scenes of conspecific choruses. We combine behavioral studies with neurophysiological studies of song and scene coding in midbrain and cortex. We find dramatic transformations in the neural coding of songs and scenes between different regions of auditory cortex. Neural representations of individual songs are dense and non-selective in the midbrain and primary cortex, but are sparse and highly selective in higher cortex. Sparse coding neurons produce background-invariant responses to individual songs in scenes, providing a potential neural mechanism for the perception of individual communication vocalizations in complex auditory scenes. Acoustic manipulations of song and pharmacological manipulations of neural coding suggest that sparse and background-invariant representations of songs in higher cortex are due to context-dependent inhibition.
Auditory processing for contrast enhancement of salient communication vocalizations
Authors: Dunlap Alex G. , Lin Frank G. , Liu Robert C.
Published: May 2013

In a natural acoustic environment, coherent representations of auditory objects and sources are streamed from the myriad sounds that enter our ears. Features of those sounds that are familiar and behaviorally salient to us are detected and discriminated into invariant precepts that inform us about our external world. Research into how this occurs is increasingly converging on the idea that there is a transformation from the auditory periphery wherein an initial acoustically faithful representation by neurons becomes progressively altered to enhance the population neural representation of perceptually relevant aspects of the sound. How this occurs may vary for sounds whose meanings are acquired in different ways, perhaps depending on what actions and decisions must be executed upon recognition. We have investigated this process in a natural social context in which mouse mothers “learn” about the meaning of pup ultrasound vocalizations through their maternal care. Here we discuss our recent studies in awake mice using electrophysiological, behavioral, immunohistochemical, and computational methods. Our results suggest that experience with natural vocalizations may alter core auditory cortical neural responses so that the contrast in activity across the neural population enhances the detection and discrimination of salient calls.
A neuroethological analysis of the information in propagated communication calls
Authors: Theunissen Frederic E. , Mouterde Solveig , Mathevon Nicolas
Published: May 2013

The detection and recognition of communication signals in natural soundscapes is a difficult task that animals and birds in particular excel at. We have used a neuroethological approach to quantify the recognition performance for propagated communication signals in the zebra finch, specifically regarding the information about individual identity. The propagated signals were analyzed using a regularized discriminant function analyses on a complete spectrographic representation of the signals. We found (1) a reduction in the informative frequency range a long distances yielding a frequency band sweet-spot, (2) that call duration and pitch are important parameters at short distances, and (3) that frequency modulation gains are important parameters at longer distances. Operant conditioning experiments showed that female songbirds were able to discriminate male calls at up to 128 m but not at 256 m. Finally, neurophysiological recordings showed a similar pattern in that high neural discrimination for calls was observed at 16 m and that this information degraded as a function of distance. We are currently analyzing the tuning properties of neurons that showed the most invariant responses to propagated sounds and hypothesized that these will be tuned to the parameters that we found were the most informative in the discriminant function analysis.
Spatially and temporally resolved single bubble sonoluminescence and its entrainment in Rayleigh-Taylor jets
Authors: Sukovich Jonathan R. , Anderson Phillip A. , Sampathkumar Ashwinkumar , Holt R. Glynn
Published: May 2013

Previous investigations of the temporal and spatial evolution of single bubble sonoluminescence (SBSL) have shown events to last on the order of tens to hundreds of picoseconds with spatial extents of less than 1 μm. Here we present observations of the temporal and spatial evolution of laser-nucleated SBSL events in a high-pressure spherical resonator. Using high-speed imaging, we observe large, long-lived SBSL events reaching diameters of up to 50 μm and lasting on the order of 30 ns. Observations of events entrained in Rayleigh-Taylor jets resulting from instabilities in the final stages of the bubbles collapses will also be presented. We observe the light emitting region entrained in these jets to reach velocities well in excess of Mach 1 and to travel up to 100 μm before being extinguished. The size and duration of events, and the velocity of those entrained in Rayleigh-Taylor jets, will be compared to the maximum radius and collapse velocity of the bubbles responsible for generating them to develop a better understanding of the dynamics leading to, and the mechanisms responsible for light emissions during highly energetic collapse events. [Work supported by Impulse Devices, Inc.]
Modeling of microbubbles pushed through clots via acoustic radiation force
Authors: Guarini Ascanio , Everbach E. C.
Published: May 2013

Previous studies have shown that thrombi, which may completely block the blood flow in a vessel, can be dissolved by ultrasound acting on echo-contrast agent microbubbles. The presumed mechanism is acoustic cavitation, the radial oscillations of the bubbles, which can exert locally large forces on the fibrin ropes that make up the clot matrix. However, the movement of the bubbles through the clot in the absence of flow suggests that acoustic radiation force also plays an important role. Because detailed mechanistic modeling of this process is not available, we present here a heuristic study in which microbubble transit times in gels of various porosities were measured and described by a simplified percolation theory. Results suggest considerations for optimizing the penetration of active microbubbles in sonothrombolysis.
Measurement of surface acoustic wave in soft material using swept-source optical coherence tomography
Authors: Kato Yukako , Wada Yuji , Mizuno Yosuke , Kentaro Nakamura
Published: May 2013

In endoscopic elastography, it is needed to observe small area with high spatial resolution. Optical coherence tomography (OCT) is one of the candidate imaging methods, which has the depth resolution of several 10 μm. In this study, we try to find the propagation velocity of surface acoustic wave (SAW) using a swept-source OCT (SS-OCT). The depth scanning rate in the SS-OCT is rather fast, which is determined by the wavelength sweep of the light source as fast as 20–100 kHz. However, on the other hand, the lateral scanning is limited up to 100 times per second, since it is performed using a mechanical moving mirror. We develop a theory to estimate SAW velocity of tissues ranging from 1 to 20 m/s from data taken by the slow lateral scanning of less than 1 m/s using the OCT. The present method is tested for agar samples with different concentrations and also for several tissue samples. Vibrations are excited on the sample surface using a small stick connected to a loudspeaker. The measurements are carried out at many frequencies from 500 to 1000 Hz. The dependence of the SAW velocity on the concentration successfully agreed the previous results.
Subjective and objective evaluation of sound quality of radio programs transmitted via Digital Audio Broadcast (DAB+) System
Authors: Dobrucki Andrzej B. , Kin Maurycy J.
Published: May 2013

The work presents results of research on the sound quality of different radio programs transmitted via Digital Audio Broadcasting (DAB+). This assessment has been provided with a use of psychoacoustic model as well as standard listening tests, using an Absolute Category Rating (ACR) method of scaling, and Comparison Category Rating (CCR) method. Results have shown that sound quality gets worse when bit-stream is of the lowest values (48 kbit/s or 24 kbit/s). Application of the Spectral Band Replication processor significantly improves the perceived quality, which is satisfying for bit streams higher than 64 kbit/s, particularly for jazz and popular music. The assessment with ACR method (recommended for broadcast by International Telecommunication Union) showed better notes than CCR one. It means that recommended method is less critical. Also results obtained with psychoacoustic model are more similar to obtained with CCR method. The attributes of spatial impression change in different ways. The greatest distortion has been observed for the perspective and spaciousness of sound image, while the sound color as well as localization stability and accuracy of phantom sources remained almost the same.
Reduction of sound leakage in handheld devices using open loop control
Authors: Lee GunWoo , Cha Aran , Kim SeoungHun , Kim YoungTae , Choi JungWoo
Published: May 2013

Recently, handheld devices with sound functionality are popular. A problem encountered by using such devices is sound leakage due to inappropriate volume setting, which should be reduced not to disturb people around the user. In previous study, we presented an active control (ANC) technique to control such sound leakage in handheld devices. The least squares (LS) optimum control under various positions of error sensors was investigated. Based on the results, desirable and feasible microphone-loudspeaker setups were suggested. In this paper, we present a novel open loop leakage reduction scheme, and it is compared with adaptive noise control method. To achieve this, control available frequency bands and spatial ranges are studied. And the influence of leakage reduction performance by the receiver and control speaker's radiation pattern are analyzed. Also the effects of the physical environment including the user's hand for the leakage control performance are studied. Finally, the proposed method is implemented on the mobile phone mock-up, and the performance of actual measured leakage reduction is investigated.
Active control applied to simplified wind musical instrument
Authors: Meurisse Thibaut , Mamou-Mani Adrien , Caussé René , Sharp David
Published: May 2013

Musicians have always been interested in the evolution of their instruments. This evolution might be done either to adapt an instrument’s quality to musicians’ and composers’ needs, or to enable it to produce new sounds. In this study, we want to control the sound quality and playability of wind instruments, using active control. The active control makes it possible to modify the input impedance (frequency, gain, and damping) of these instruments and to modify the instrument’s quality. Simulations and first experiments on a simplified reed instrument are presented. We simulate a control of the modes (frequency, damping) of a cylinder using two different approaches: classic feedback and modal active control. Then, we apply these control methods on a simplified reed instrument with embedded microphone and speaker. Finally, the effects on sound and playability of the instrument is studied.
Predicting speech transmissibility using ray tracing and statistical energy analysis
Authors: Merz Sascha , Cotoni Vincent , Shorter Phil
Published: May 2013

Statistical Energy Analysis (SEA) is widely used for predicting interior noise across many different industries. SEA typically describes steady-state reverberant responses, for example the response at interior passenger locations in transportation applications due to steady-state exterior sources. However, many applications exist where the direct field is also important. This includes prediction of Speech Transmissibility for audio systems in automotive applications or public address systems in train and aircraft applications. For predicting Speech Transmissiblity, the transient response at a given receiving location due to transient excitation applied at a particular source location must be known. Geometrical methods such as ray tracing are often used for describing the first few reflections of the direct field; however, they are not well suited for describing the reverberant field and typically include approximate statistical assumptions about late time reflections. These assumptions often do not consider the detailed distribution of sound package in interior spaces. An alternative approach is to use ray tracing for predicting the direct field and low order reflections and to use SEA to predict late time reflections and background noise. This approach is computationally efficient and can use information contained in existing SEA models. The method is discussed and validation examples are presented.
Black box measurements – Using a family of electrical circuits as a tool for self-guided learning in acoustical engineering
Authors: Murta Bernardo H. , Aguirre Sergio , Lins Jessica , Paul Stephan , Brandao Eric , Dietrich Pascal
Published: May 2013

A partnership between Brazil’s first undergraduate program in Acoustical Engineering and the Institute of Technical Acoustics of RWTH Aachen University yielded in a didactic project that uses the engineering software MATLAB with the ITA-Toolbox to teach acoustic measurements. Simple electrical circuits are used to mimic typical behavior of acoustical systems. This low-cost solution has proven to be didactically very effective since it helps students to identify themselves with the measurement tasks. Two hardware solutions were developed-a simple oscillator circuit integrated into connectors of audio cables and a desktop box containing seven different transfer characteristics ranging from ideal linear and time-invariant to nonlinear and time-varying behavior. Undergraduate students of Acoustical Engineering used both devices in classroom experiments for self-guided learning by comparing their results to published results. Students were able to learn the fundamental concepts of acoustical measurements and to handle measurement tasks. Besides the practical experiences and the learning effect, the students were also encouraged to step into the open source routines of the software, understand the signal processing steps, adapt routines, and even write their own ones, e.g., a GUI that provides effective control of the measurement via touch-screens.
A for play!
Authors: Butko Daniel
Published: May 2013

The task was straightforward; design and build a playhouse to be raffled for a charitable organization. A team consisting of students, volunteers, and faculty banded together to not only meet the requirements but to exceed the typical preconceived ideas of a totally enclosed miniature home. Based upon the needs of juvenile clients, the design team focused more on “play” than on “house” when working out conceptual ideas. The playful design was based upon the enclosure being partially open to allow air flow, sunlight, and the ability for the inhabitants to have an aural connection to the outside. The idea of having partially open space on the lower level, a mere 5’-0” x 5’-0” footprint, flanked by stepped bands of cedar and cypress yielded a particular acoustical presence. The space is not only visually unique, but the selection of materials, how they were cut and assembled, and the scale in relation to a seated child enhance the fun factor by creating an enveloping and somewhat amplified acoustic. This project provided pedagogical opportunities within an atypical learning environment. The final inhabitable playhouse exceeded our visual and acoustical expectations of a small space and prove acoustics “plays” an intrinsic role despite occupant age.
Modeling of the subjective quality of saxophone reeds
Authors: Petiot Jean-François , Kersaudy Pierric , Scavone Gary , McAdams Stephen , Gazengel Bruno
Published: May 2013

The subjective quality of cane reeds used on saxophones or clarinets may be very different from one reed to another even though the reeds have the same shape and strength. The aim of this work is to understand the differences in the subjective quality of reeds and to explain them with objective measurements. A subjective study, involving a panel of 10 musicians, was first conducted on a set of 20 reeds of the same strength. Second, signal recordings during saxophone playing (in vivo measurements) were made of the pressures in the player’s mouth, in the mouthpiece and at the bell of the instrument. These measurements enable us to deduce specific parameters, such as the threshold pressure or the spectral centroid of the notes. After an analysis of the subjective and objective data (assessment of the agreement between the assessors and the main consensual differences between the reeds), correlations between the subjective and objective data were performed. To propose a model of the subjective quality, a machine learning approach was proposed using partial least-squares (PLS) regression and PLS discriminant analysis. Results show interesting performance of the model in cross validation and open the potential for an objectification of the perceived quality.
Perceptual evaluation of violins: A comparison of intra-individual agreement in playing vs. listening tasks for the case of richness
Authors: Saitis Charalampos , Scavone Gary P. , Fritz Claudia , Giordano Bruno L.
Published: May 2013

In previous studies by the authors, it was shown that there is a significant lack of agreement between violinists when evaluating different instruments in terms of perceived richness in free-playing tasks. A new experiment was designed to further investigate the perceptual evaluation of richness using both a constrained-playing task, which was recorded, and a subsequent listening task (using the previously recorded sounds). The goal was to compare the evaluation of richness from playing vs. listening tasks in order to better understand whether they are based more on auditory feedback or tactile and proprioceptive cues in the wider context of correlating audio features extracted from the recordings with richness judgments. Skilled violinists were asked to rank five different instruments by playing only certain notes on the G-string. Subsequently, the players were asked to listen to their recordings and rank the violins. Results appeared to show a higher inter-individual agreement relative to previous studies. Furthermore, the rankings in the playing task were generally different from those in the listening task, indicating that the evaluation of richness is based on different criteria in the two cases. Results from matching the tristimulus and spectral centroid of recorded tones to richness judgments will be presented at the conference.
Music of the body: An investigation of skull resonance and its influence on musical preferences
Authors: Suwangbutra Jitwipar , Tobias Rachelle , Gordon Michael S.
Published: May 2013

Musical preferences can be attributed to environmental and biological factors. This research analyzes the specific influence of body resonance, and in particular, how the resonant properties of the skull might contribute to auditory perception of music and musical preferences. To examine this issue resonances were sampled from a set of participants and analyzed using FFTs. The fundamental frequencies of each participant’s head was correlated against their preference amongst a set of novel melodies presented in each of the 12 major keys. Using this method the spectral properties of the melody could be directly related to the resonant properties of a listener’s skull to evaluate their influence. While results were subtle, participants were found to be influenced in their judgments of loudness and musical preference for the melodies. Conclusions from this research support speculation on an embodied model of cognition for musical interactions.
Development of a new series of tests to assess the effectiveness of hearing aids for the perception of music
Authors: Kirchberger Martin , Russo Frank A. , Derleth Peter , Hofbauer Markus
Published: May 2013

A new series of tests has been designed to assess the effectiveness of hearing aids for the perception of music. Within each subtest, discrimination thresholds for low-level acoustic dimensions are determined adaptively using a 2AFC method within the context of a musical judgment regarding melody, harmony, timbre or meter. The presented test stimuli are synthesized and either unprocessed or processed by different hearing aid signal processing algorithms before being played back via loudspeaker. The battery will be used to evaluate different hearing aid algorithms with regard to their benefit for functional hearing in music. A group of six normal hearing control participants (6.7 dB HL) and five hearing impaired participants (34 dB HL) each performed the melody subtest and the harmony subtest twice. The hearing impaired subjects had higher discrimination thresholds than the control group. A comparison of the results from both administrations suggests that these two subtests have good test-retest reliability.
Modeling listener distraction resulting from audio-on-audio interference
Authors: Francombe Jon , Mason Russell , Dewhirst Martin , Bech So/ren
Published: May 2013

As devices that produce audio become more commonplace and increasingly portable, situations in which two competing audio programs are present occur more regularly. In order to support the design of systems intended to mitigate the effects of interfering audio (including sound field control, noise cancelation or source separation systems), it is desirable to model the perceived distraction in such situations. Distraction ratings were collected for a range of audio-on-audio interference situations including various target and interferer programs at three interferer levels, with and without road noise. Time-frequency target-to-interferer ratio (TIR) maps of the stimuli were created using a simple auditory model. A number of feature sets were extracted from the TIR maps, including combinations of mean, standard deviation, minimum and maximum TIR taken across the duration of the program item. In order to predict distraction ratings from the features, linear regression models were produced. The models were evaluated for goodness-of-fit (RMSE) and generalizability (using a K-fold cross-validation procedure). The best model performed well, with almost all predictions falling within the 95% confidence intervals of the perceptual data. A validation data set was used to test the model, suggesting areas for future improvement.
Evaluating the absolute volume of digital sound source measurement and standard measuring unit
Authors: Kyon Doo-Heon , Bae Myung-Jin
Published: May 2013

Listeners do not know the actual volume of sound before playing a sound source, so they have to adjust the volume through trials and errors. Moreover, they have to change the volume repetitively because each sound source has different volume. If we can identify the absolute volume of a sound source at the perspective of listener, the volume of all sound sources can be effectively standardized. This study evaluated a method to measure the absolute volume of a digital sound source and suggested the dB(N) as a measuring unit. The pink noise was used as a reference sound source, to be used for measuring the absolute volume. The pink noise was set as 60 dB(N), which is equal to sound output of 60 dB(A). The volume was adjusted until the pink noise and the target sound matches into a recognizable volume by reducing the pink noise or target sound source under the given environment. Subsequently, the difference is reflected to 60 dB(N) to determine the absolute volume. The accuracy of measured results was confirmed through a music listening test and suggested how to develop the volume system using the absolute volume.
Refining the stereo technique for augmented ambience gradient: Improvements in stereo image, spatial envelopment, and mixing flexibility
Authors: Tagg David J. , Fallis Kevin
Published: May 2013

While working on location, recording engineers are often challenged by insufficient monitoring. Poor (temporary control room) acoustics and/or mandatory headphone monitoring can make judgments regarding microphone choice and placement difficult. This compromised monitoring often leads to timbral, phase, and stereo image problems. We are often forced to choose between the improved spatial imaging of near-coincident techniques and the attractive acoustic envelopment from spaced omni-directional mics. This research reviews a new technique: Stereo Technique for Augmented Ambience Gradient (STAAG), which aims to improve stereo imaging, ambient envelopment, and flexibility in the mix. Building on a preliminary study, this research realizes ideal microphone angle/spacing combinations to promote spatial accuracy, investigates the quality of the ambient envelopment compared to omnidirectional-based techniques, and the ability of STAAG to allow an engineer to manipulate the direct to reverberant energy ratio during post-production without corrupting the stability of the stereo image.
Low amplitude sonic boom noise exposure and social survey design
Authors: Hodgdon Kathleen K. , Page Juliet
Published: May 2013

The Waveform and Sonicboom Perception and Response (WSPR) Program conducted a field study relating subjective response to noise from multiple low-amplitude sonic booms. The team was led by Wyle and included researchers from Penn State, Tetra Tech, and Gulfstream Aerospace Corp. The test exposed residents in the Edwards Air Force Base (EAFB) Housing area to two weeks of low-amplitude sonic booms while recording their responses via surveys. The noise exposure design balanced DNL across test days, the number of low, medium, and high booms, and the separation of booms between AM and PM flight sequences. Survey instruments consisted of a Baseline survey, a Single Event survey, and a Daily Summary survey. The WSPR low boom survey included a question on strength of annoyance, followed by questions on the strength of perception of five additional variables that contribute to the annoyance response. Three modes of administration were utilized for both the single event and daily summary surveys: paper/pen, web-based, and Mobile (Apple) device. The survey followed recommendations published by The International Commission on the Biological Effects of Noise (ICBEN). The data from the low boom field test provide a measure of the acceptance of low booms in an acclimated community.
Objective data collection and analysis for the waveform and sonic boom perception and response program
Authors: Cook Brian , Salamone Joe , Hobbs Chris , Page Juliet
Published: May 2013

The Waveform and Sonic boom Perception and Response (WSPR) program experiment was conducted in November 2011. Low-amplitude sonic booms were created by planned NASA F-18 supersonic flights executing a unique dive maneuver. The WSPR program was designed to simultaneously collect objective sonic boom acoustic data and subjective response data from residents in the Edwards Air Force Base residential community. Sonic Boom field kits were developed for the WSPR program consisting of a digital data acquisition system with networked nodes, deployable for extended periods of time. The Sonic Boom Unattended Data Acquisition System (SBUDAS) purposely developed for sonic boom community noise testing was deployed and details of the measurement system and all aspects of the objective data collection process are described. Data analysis during testing provided vital information to the flight planners for experimental execution. This paper also explains the post-experimental analysis of the objective data achieved by creation of a measurement data archive, predictions of sonic boom exposure at subject household locations, an automated algorithm to locate sonic booms within the recorded data and computation of a variety of indoor and outdoor metrics.
What will be the influence of e-mobility on soundscape?
Authors: Genuit Klaus
Published: May 2013

The increasing electrification of the powertrain after 125 years of continuous development of the internal combustion engine will not only lead to a sound pressure level reduction of vehicle exterior noises but to a complete change of sound quality. With this expected development road traffic noise affected persons hope for quiet cities and a better quality of life. The creation and successful preservation of quiet zones in cities and to avoid harmful effects of noise exposure are special focuses in European noise policy. However, different surveys have shown the increased risk of accidents for pedestrians and cyclists with respect to collisions with quiet vehicles, which caused a lively discussion about acoustical warning systems for the prevention of crashes. But it is obvious, that major conflicts between quietness and safety arise. Consequently, to address this issue, on the one hand, sustainable concepts must be developed for the successful avoidance of accidents and on the other hand the general traffic noise must be minimized. The sound of electric vehicles will influence in a significant way our soundscape at places and cities in the future. This is a special challenge for psychoacoustics to provide helpful contribution besides the A-weighted sound pressure level.
The practical SoundLab for architects: Sound parameters as a design tool
Authors: Bauer Juergen
Published: May 2013

The experience gained from exploring acoustics with architectural students in Waterford Institute of Technology (Ireland) suggests that a studio situation can be exploited and used as a case study for young designers to become familiar with basic sound phenomena. From phase 1 of previous research, the student “audiovisual design workshop” concluded that class rooms that perform poorly acoustically can help to strengthen the students' understanding of the sonic environment, in a way that the students were exposed day after day to high reverberation, low speech intelligibility, and the “Lombard” effect in their own studio. However, becoming aware of poor acoustics necessitates a creative follow-up: how to design and create good acoustics, or how to develop the environment as a “soundscape”? Consequently, phase 2 of our audiovisual design workshop introduced the practical sound lab: our students were required to design and to build acoustic panels for their own studio environment. These prototypes would be analyzed as part of an Acoustic Laboratory, with specialist advise from an Acoustic Consultant. The paper summarizes the findings from the audiovisual design laboratory. It also reflects on how to compile international case studies of buildings with good acoustics that can be used as references for designing architects.
Reduction of ultrasonic multiple scattering applied to flaw detection with array probes in polycrystalline materials
Authors: Shahjahan Sharfine , Aubry Alexandre , Rupin Fabienne , Chassignole Bertrand , Derode Arnaud
Published: May 2013

Flaw detection using ultrasonic evaluation of coarse-grain steels is perturbed by a high structural noise due to scattering. This leads to a decrease of the detection capabilities, particularly at high frequencies and large depths for which multiple scattering dominates. Recent academic studies have shown that the contribution of multiple scattering could be dramatically reduced. These results were obtained on a model random medium made of parallel steel rods immersed in water. The ability to detect a target could be significantly increased using a specific filtering method, based on the full matrix capture (F.M.C.) combined with a smart post-treatment based on random matrix theory, in supplement with the DORT method (i.e., decomposition of the time-reversal operator). Here, the same technique to separate simple and multiple scattering contributions is now applied to a real material. Experimental results were obtained on a nickel-based alloy (Inconel600®) with a thermically induced coarse grain structure and manufactured flaws (side drilled holes) at different depths. The experimental set-up used a multi-element ultrasonic array. Results are presented and compared to other detection techniques, at various depths and frequencies. Despite a dominant multiple scattering noise, a significant improvement of the detection performances is observed.
Impulse response of a medium in a three layered media
Authors: Bhatta Ambika , Thompson Charles , Chandra Kavitha , Mehta Vineet
Published: May 2013

This paper investigates the point source response of a layered medium separating two semi-infinite impedance medium. A detailed numerical method to evaluate Laplace transform of the reflection coefficient for each boundary is presented. A description of the branch integral dominantly contributing to the reflection coefficient in Laplace domain for single and multiple reflections is given. The analysis utilizes the image theory to evaluate the order of the reflection and complex pressure amplitude at each image source location. The impulse response is also evaluated numerically from the Green’s function obtained from the reflection coefficient and complex pressure due to image sources. Fresnel’s plane wave reflection coefficient validates the solution when the height of layer containing the source and the observation position is relatively large. The obtained expression for reflection coefficient for large wave number and observation position is verified numerically.
Shaving foam: A complex system for acoustic wave propagation
Authors: Pierre Juliette , Leroy Valentin , Saint-Jalmes Arnaud , Dollet Benjamin , Ben Salem Imen , Crassous Jérôme , Guillermic Reine-Marie , Drenckhan Wiebke , Elias Florence
Published: May 2013

While liquid foams have applications in an increasing number of industrial areas (food, cosmetic, or petroleum industry), it remains difficult to non-invasively probe their structure and/or composition. Since the propagation of acoustic waves is very sensitive to parameters such that the liquid fraction, the bubble size distribution, or even the nature of the liquid phase, acoustic spectroscopy could be a very powerful tool to determine the structure and/or composition of liquid foams. In this context, we present an investigation of the acoustic properties of a useful and common foam, often considered as a model system: shaving foam. Phase velocity and attenuation of acoustic waves in a commercial shaving foam (Gillette) were measured over a broad frequency range (0.5 to 600 kHz), using four different experimental setups: an impedance tube (0.5–6 kHz), an acousto-optic setup based on diffusive wave spectroscopy (1–10 kHz), and two transmission setups with narrow-band (40 kHz) and broad-band (60–600 kHz) transducers. We present the results and discuss the advantages and shortcomings of each setup in terms of a potential spectroscopy technique.
Lamb modes and acoustic microscopy for the characterization of bonded structures
Authors: Naima Alaoui Ismaili , Camilla De Mello Da Silva , Mounsif Ech-Cherif El-Kettani , Gilles Despaux , Martine Rousseau , Jean-Louis Izbicki
Published: May 2013

This paper is a contribution to the evaluation of the bonding by means of guided waves, when the quality of the glue is degraded by addition of grease. Experimental dispersion curves are compared to the theoretical ones obtained either from a perfect welded tri-layer model or from a second model using delaminated conditions. It is shown that the second model is more convenient when the quality of the glue is highly degraded. On another hand, the parameters of Jones are extracted from experimental data by inverse problem. It is shown that the values of these parameters strongly diminish and the variation is of logarithmic type when the quality of the glue is progressively degraded. Acoustic microscopy is also performed, and it provides images of the inner structure giving a qualitative explanation of the values of the parameters of Jones.
Frequency-resolved measurements of the diffusion constant for ultrasonic waves in resonant multiple scattering media
Authors: Viard Nicolas , Derode Arnaud
Published: May 2013

Experimental measurements of the diffusion constant for ultrasonic waves (around 3 MHz) propagating in water through a random set of scatterers (parallel metallic rods arranged as a slab) are presented. The slab thickness is around 10 times the transport mean free path. Transmitted waves are recorded over hundreds of emitting/receiving positions in order to estimate the ensemble-averaged transmitted intensity 〈I(x,t)〉. Focused beamforming is performed on both faces of the sample in order to mimic a set of point-like sources and receivers. In theory, under the diffusion approximation, the ratio of the off-axis intensity 〈I(x,t)〉 to the on-axis intensity 〈I(0,t)〉 shows a simple gaussian dependence on the lateral dimension x, independently from absorption or boundary conditions. This yields a simple way to estimate the diffusion constant D and therefore characterize the scattering medium. Based on that method, broadband as well as frequency-resolved measurements of the diffusion constant are presented in controllable model media, such as these forests of steel rods. Experimental results and difficulties for measuring a reliable value for D on a real sample are discussed.
Wavetrain-long waves interaction in a non-homogeneous, non-stationary medium
Authors: Voronovich Alexander
Published: May 2013

A weakly nonlinear wavetrain of the acoustic waves apart from higher harmonics generates also a low-frequency, large-scale motion which in turn affects both the wavetrain itself and other wavetrains, thus leading to an effective wavetrains interaction. A closed set of equations describing interaction of a wavetrain with inhomogeneous medium including a recoil effect on the background motion is derived using Hamiltonian form of the equations of motion (viscosity is neglected). Corresponding energy and momentum conservation equations are derived which account for the energy and pseudo-momentum exchange between the wavetrain and a background, large-scale motion (the latter includes the nonlinearly generated component due to the wavetrains). A large-scale motion due to a single wavetrain propagating in an initially homogeneous medium is calculated. Far from the wavetrain nonlinearly generated large-scale current is confined by an expanding sphere with the velocity aligned with the wavetrain propagation direction; the velocity appears to be constant in the planes perpendicular to this direction. It is demonstrated that interaction between acoustic wavetrains lead to their effective repulsion which in a complex way depends on mutual location and velocities of the wavetrains. Generalization of the approach to the case of integral gravity waves will be also briefly mentioned.
Gaussian closure technique for Bouc's hysteretic model under white noise excitation
Authors: Waubke Holger
Published: May 2013

Bouc developed a hysteretic model for materials like rubber under dynamic excitation. The response of a hysteretic system under white noise excitation is normally estimated by means of the statistical linearization or a related method. Disadvantages of this method are the assumption of a Gaussian nature of the random distributions, the high computational efforts caused by the iterations needed, and the instability of the iteration in certain parameter regions. Using the assumption of Gaussian random distributions, the Gaussian closure technique can be applied. Analytic solutions of the integrals occurring in this approximation were found and are presented. These solution allow for an explicit time step procedure for the random moments in the transient case. For the stationary case, a fast and stable iteration about a set of non linear equations is needed. Both procedures allow to calculate the moments in a fast manner and allow to solve problems with more than one degree of freedom with limited computational efforts.
Numerical model of a causal and fractional all-frequency wave equation for lossy media
Authors: Wismer Margaret
Published: May 2013

A numerical algorithm, to simulate a lossy acoustic wave equation with fractional time derivative terms, is presented. The inclusion of fractional derivatives yields a causal acoustic wave equation which can model and predict power law attenuation for which the level of absorption is proportional to frequency raised to a non-integer power. The fractional Zener wave equation is derived from the fractional Zener stress-strain constitutive relation and contains two absorption terms. One term which includes the Laplacian, similar to the traditional wave equation in viscous fluids, has a coefficient, which is proportional to a relaxation time. The other term is a fractional time derivative, higher than second order, and is proportional to the creep or retardation time. Both relaxation and retardation parameters will affect the frequency behavior of the attenuation. The inclusion of two terms enables the modeling of power-law attenuation in all frequency ranges. It results in more stable numerical simulations as both the overall mass and stiffness matrices of the finite element algorithm are changed according to the level of absorption. Results show the animation of diffraction patterns of focused and planar acoustic waves by inclusions with different values for the two different parameters, retardation time and relaxation time.
Glenis Long's contribution to animal psychoacoustics
Authors: Fay Richard
Published: May 2013

Glenis and I were psychology graduate students together in 1970–1971. She was interested in auditory psychophysics, but soon developed an interest in comparative psychophysics which she pursued in a post-doc and a faculty position in Germany, where she obtained a behavioral audiogram for the horseshoe bat and later studied masking in the same species. This audiogram was one of the very first psychophysical investigations of hearing in any bat and the very first for the horseshoe bat. It confirmed a rather complex frequency response function with sensitivity peaks at about 20 kHz and 60 kHz, and a very sharp peak at about 80 kHz. The masked thresholds indicated rather normal critical masking ratios (CR) except in a narrow region at about 80 kHz where the CRs are up to 15 dB lower than expected, suggesting a critical band of about 300 Hz at 80 kHz that is presumably used in Doppler-shift compensation. In 1981–1983, Glenis went on to investigate frequency and rate modulation discrimination in the chinchilla, for the first time, and to study tone-on-tone masking in the chinchilla. Since these early works, Glenis has maintained her comparative interests with studies on birds, kangaroo rats, frogs, and fleas on cats.
The relevance of otoacoustic emission fine structure
Authors: Dhar Sumitrajit
Published: May 2013

The quasi-periodic fluctuations in otoacoustic emission (OAE) amplitude and phase, known as fine structure, provide critical insight into the mechanisms of OAE generation and propagation. Whether fine structure is relevant from the perspective of hearing health remains an open question. Starting with work done under the tutelage of Professor Long, our group has conducted a decade of work investigating the clinical relevance of fine structure in general, and distortion product (DP) OAE components in particular. These studies cover a significant portion of the human lifespan (0 to ~80 yr) and the collective results provide insights into the avenues of application that hold promise. Drawing from the results of several studies conducted in our laboratory and those of collaborators and colleagues we will make the case for focused clinical application of the DPOAE components that constitute fine structure. These constituent elements appear to be ideal for monitoring of cochlear status and expose physiological changes prior to their evidence in other measures of auditory function. However, harnessing the information encapsulated in fine structure directly is not without challenge and the examination of the constituent elements of fine structure may prove more profitable for clinical applications.