bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis and mitigation design of acoustics for performance hall at the Catholic University
Authors: Coyle Jonathan P. , Kramer Christopher J. , Bull Nicole A. , Maclin Jacob , Vignola Joseph
Published: May 2016

This presentation will discuss a student level assessment designed with the goal to analyze a Music Hall located on the campus of The Catholic University of America. Ward Recital Hall is 97,712 ft3, seating 108 and was built as a hall intended for liturgical musical performance, but since the early 1900’s the purpose of the room has changed, since then minor improvements have been implemented. We have found that the three significant problems within the room are the HVAC noise contamination, stage projection homogeneity, and sound transmission through barriers (doors and windows). We will present the findings on each of the problems above in how the stage projection is not currently homogeneous, the issue with exterior noise contamination, and how the HVAC can directly affect the listening of viewers. We also will present remedies for each issue as well as the associated cost for the remedies. We will have a list for these problems with several different solutions, with the intent of having a good, better, and best solution with costs with respect to predictions of performance.
Estimating source levels and depth distributions of calling bowhead whales using geoacoustic inversion
Authors: Thode Aaron , Blackwell Susanna , Kim Katherine , Macrander A. Michael
Published: May 2016

Every year during open-water season in 2008–2014, up to 40 passive acoustic recorders (DASARs) were deployed in the Beaufort Sea. Over the eight-year period, more than 3.1 million bowhead calls were localized. A vertical array was also deployed near DASARs in some years, enabling the matched-field geoacoustic inversion of bowhead whale calls to estimate the local acoustic propagation environment. In turn, these environments were used to estimate the source level and calling depth distributions of nearly 50,000 calls between 2008 and 2014. The resulting source level distributions exhibited a stable mode near 160 dB re 1 uPa @ 1 m (rms), which proved robust to the year investigated, the whale call analysis method (manual or automated), and the type of acoustic propagation model (a simple empirically-derived “power-law” transmission loss model or a detailed waveguide propagation model). Depth distributions of calling whales were more sensitive to the environmental model used but always showed a mode at ~25 m depth. The evolution of the frequency distribution of calls over the years will also be discussed. This research highlights the importance of incorporating geoacoustic inversion and propagation modeling into marine mammal behavioral or density estimation studies. [Sponsored by Shell Exploration and Production Company.]
Humpback whale-generated ambient noise levels provide insight into singers’ spatial densities
Authors: Seger Kerri D. , Thode Aaron M. , Urbán R. Jorge , Martínez-Loustalot Pamela , Jiménez-López M. E. , López-Arzate Diana
Published: May 2016

Previous research has investigated whether diffuse ambient noise levels can be used to estimate relative baleen whale abundance in environments where their vocal activity dominates ambient noise levels. Presented here is an analytical model of ambient noise levels as generated by randomly distributed singing humpback whales. The model exploits earlier ones that derive ambient noise levels by assuming randomly distributed wind-driven breaking surface waves. Using a parametrized acoustic propagation environment and various assumptions about humpback whale singing behavior, the current model predicts ambient noise levels as a function of frequency and population size. It also predicts that the “sensitivity” of ambient noise levels to changes in population size should be relatively independent of an individual’s singing behavior, but does depend strongly on the population’s spatial density. Using visual survey and bottom-mounted recorder data from the 2013 and 2014 humpback whale breeding seasons off Los Cabos, Mexico, a generalized linear model estimated the sensitivity of song-generated ambient noise levels across several frequency bands, while compensating for diel cycles. The results indicate that whales generally space themselves evenly over a constantly expanding region, but may tolerate a slightly higher density as the number of participating singers increases.
High-frequency broadband acoustic backscatter from phytoplankton
Authors: DeGrâce Dylan L. , Ross Tetjana
Published: May 2016

Current methods in phytoplankton detection and monitoring are often limited by low temporal and spatial resolution. In principle, the use of a high-frequency broadband acoustic system would be advantageous when used in conjunction with current methods; providing improvements both temporally and spatially. With this motivation, a high-frequency broadband active acoustic system has been developed and used in four separate trials to measure the backscatter from four morphologically-distinct species of phytoplankton. The morphologies studied include (1) a siliceous shelled cylinder, (2) a chain-forming siliceous shell cylinder, (3) a fluid-like spheroid, and (4) a soft-shelled spheroid; and whose sizes range from 10 to 60 µm. Organism cultures were insonified at frequencies between 0.75 MHz and 6.9 MHz giving a ka study range of 0.03–1.73. Volume scattering strength as it varies with ka is presented for each species and compared to potential scattering models drawn from the zooplankton scattering literature. Modifications to the models or model parameters are discussed. Additionally, volume scattering strengths at multiple phytoplankton concentrations are presented and compared to both chlorophyll-a estimates obtained from fluorometers and densities found via flow cytometry. The potential for a phytoplankton species-detection and monitoring system is discussed and evaluated.
Measurements of the acoustic properties of the seagrass Posidonia oceanica
Authors: Johnson Jay R. , Venegas Gabriel R. , Wilson Preston S. , Hermand Jean-Pierre
Published: May 2016

A one-dimensional resonator technique was used to test the acoustic response of fresh leaves of Posidonia oceanica collected from both Crete, Greece and Sicily, Italy. The sound speed was inferred from resonance frequencies measured between 1 and 8 kHz. This sound speed is also compared with ultrasonic time-of-flight measurements between 1 and 4 MHz. Measurements of intact leaves as well as a homogenous tissue “soup” were made to investigate tissue properties and the role of leaf structure in sound propagation. This work expands on similar measurements, published previously by the authors, made on three other seagrass species Thalassia testudinum, Halodule wrightii, and Syringodium filiforme.
Time-difference-of-arrival localization of bowhead whales using asynchronous recorders
Authors: Warner Graham A. , Dosso Stan E. , Hannay David E.
Published: May 2016

This paper estimates bowhead whale locations and uncertainties using linearized Bayesian inversion of the time-difference-of-arrival (TDOA) of whale calls recorded on omni-directional asynchronous recorders in the Chukchi Sea, Alaska. A Y-shaped cluster of seven autonomous ocean-bottom hydrophones, separated by 0.5–9.2 km, was deployed for several months over which time their clocks drifted out of synchronization. Hundreds of recorded whale calls are manually annotated with time-frequency bounds and associated between recorders. The TDOA between all hydrophone pairs are calculated from filtered waveform cross-correlations and depend on the whale locations, hydrophone locations, relative recorder clock drifts, and an effective waveguide sound speed. The inversion estimates all of these parameters and their uncertainties as well as data error statistics using prior information to constrain the otherwise underdetermined problem. Whale location uncertainties are estimated to be approximately 100 m which allows tracking whales that vocalize repeatedly over several minutes. Estimates of clock drift rates are obtained from inversions of TDOA data over several weeks. The inversion is computationally efficient and suitable for application to large datasets of manually- or automatically detected whale calls.
High-frequency ultrasonic measurements of ischemia and revascularization in mice
Authors: Cadet Michaelle A. , Quiroz Andrea N. , Chappell Andrew , Doyle Timothy E.
Published: May 2016

The ability to rapidly determine the degree of vascularization in small animals in vivo would provide a useful characterization tool for regenerative medicine. This study’s objective was to determine if ultrasonic material property measurements in the 10–100 MHz range could be used as a vascularization assay for small animals. The study was performed at the Ludwig Boltzmann Institute for Experimental and Clinical Traumatology (Vienna, Austria), where the femoral artery in one hind limb of each of sixteen mice was ligated and tested over a time period of eight days. Eight of the ligated limbs were treated with vascular endothelial growth factor (VEGF). The remaining eight ligated limbs were allowed to grow ischemic. The unligated limbs were controls. Wave speed, attenuation, waveform coda amplitude, and spectral measurements were acquired using a high-frequency ultrasound system. Ischemic limbs displayed a steady decrease in wave velocity over the test period as compared to VEGF-treated limbs. Coda amplitude increased for ischemic limbs, but decreased and then returned to normal in VEGF-treated limbs. No trends were observed for either attenuation or spectral peak density. The results indicate that high-frequency ultrasonic measurements may provide an added dimension to small animal imaging methods for detecting revascularization.
Effect of mammographic breast density on high-frequency ultrasonic parameters used to evaluate surgical margins
Authors: Coffman Zachary A. , Cowan Nicole , Omer Robyn K. , Doyle Timothy E.
Published: May 2016

Breast density, the proportion of connective tissue versus fat tissue in the breast, is typically determined using mammography. Women with higher breast density are four to five times more likely to develop breast cancer than women with lower densities. A surgical study performed by Utah Valley University with the Huntsman Cancer Institute showed that high-frequency ultrasound (20–80 MHz), and the parameters peak density (number of spectral peaks and valleys from 20 to 80 MHz) and attenuation, are sensitive to breast tissue pathology. This study also showed that breast density had no effect on peak density across the entire breast density range while attenuation increased 2X from entirely fat to extremely dense. The present study’s objective was to determine the effect of breast density on these parameters using histology mimicking phantoms. Phantoms were created from distilled water, agarose powder, 10X TBE stock solution, and polyethylene microspheres and fibers to simulate breast tissue histology. Phantoms were produced with microspheres only, fibers only, and a combination of microspheres and fibers. Pitch-catch measurements were acquired using a high-frequency ultrasound system and glycerol as the coupling agent. The phantom results validate the surgical study, showing attenuation increasing with inclusion concentration but no significant change in peak density.
Interpreting attenuation at different excitation amplitudes to estimate strain-dependent interfacial rheological properties of monodisperse contrast microbubbles
Authors: Sarkar Kausik , Xia Lang , Porter Tyrone
Published: May 2016

Broadband attenuation of ultrasound measured at different excitation pressures being different raises a serious theoretical concern, because the underlying assumption of linear and independent propagation of different frequency components nominally requires attenuation to be independent of excitation. This issue is investigated by examining ultrasound attenuation through a monodisperse lipid coated microbubble suspension measured at four different acoustic excitation amplitudes. We use the attenuation data to determine interfacial rheological properties (surface tension, surface dilatational elasticity and surface dilatational viscosity) of the encapsulation according to three different models. Although different models result in similar rheological properties, attenuation measured at different excitation levels (4–110 kPa) leads to different values for them; the dilatation elasticity (0.56 N/m to 0.18 N/m) and viscosity (2.4×10−8 Ns/m to 1.52×10−8 Ns/m) both decrease with increasing pressure. Numerically simulating the scattered response, nonlinear energy transfer between frequencies are shown to be negligible, thereby demonstrating the linearity in propagation and validating the attenuation analysis. There is a second concern to the characterization arising from shell properties being dependent on excitation amplitude which is not a proper constitutive variable. It is resolved by arriving at a strain-dependent rheology for the encapsulation.
Quantitative microultrasound characterization of gastrointestinal tissue for ultrasound capsule endoscopy
Authors: Lay Holly , Cox Benjamin F. , Demore Christine E. , Spalding Gabriel C. , Cochran Sandy
Published: May 2016

Gastrointestinal (GI) disease progression is often characterized by cellular and architectural changes within the mucosal and sub-mucosal layers. One relevant disorder, Barrett’s esophagus, is of particular interest as a recognized predictor of esophageal cancer. To enhance the clinical ability to detect cellular changes deeper in tissue and earlier, we are exploring quantitative microultrasound) techniques in healthy ex vivo porcine GI tissue for implementation in ultrasound capsule endoscopy. A single-element, piezocomposite mUS transducer operating at fc = 47.7 MHz was used to obtain pulse-echo images of ex vivo porcine gastroesophageal samples, which were bisected and mechanically scanned along the long GI axis. Selected samples were mechanically separated to isolate the upper mucosal layers from the underlying muscle layers and placed on a known agar substrate to calculate the attenuation coefficient of the tissue. All other sample data were digitally segmented. Reflectivity data from the top 50, 100, and 250 μm of tissue were analysed to assess the effect of variable surface density on the calculated acoustic impedance. The entire thickness of the segmented tissue was then used to calculate position-dependent backscatter coefficient (BSC) along with intra- and inter-sample variability for use as a baseline from which to make further quantitative advances.
Evaluating lymph node status with high-frequency ultrasound during breast conservation surgery
Authors: LaFond Amy A. , Carter Caitlin , Sanjinez Dolly A. , Omer Robyn K. , Neumayer Leigh A. , Factor Rachel E. , Doyle Timothy E.
Published: May 2016

High-frequency (20–80 MHz) ultrasound was used to evaluate 78 lymph nodes from 39 patients to identify metastatic breast cancer during breast conservation surgery. Point measurements were collected from resected lymph nodes in both through-transmission and pulse-echo modes using 50-MHz, 6.35-mm diameter, single-element transducers. Attenuation and peak density (the number of peaks and valleys in a specified frequency band) were calculated from the ultrasonic waveforms and power spectra, respectively. The two parameters were additionally combined to perform a multivariate analysis. Fisher’s exact test was used to determine the accuracy, sensitivity, and specificity of each parameter and the multivariate analysis for detecting malignant lymph nodes. The multivariate analysis showed the greatest statistical measures, with an 83.3% accuracy, 87.5% sensitivity, 82.9% specificity, and a p-value of 0.000078 (high statistical significance). The results demonstrate that high-frequency ultrasound provides very good sensitivity and specificity for malignant lymph nodes in the breast, and that high-frequency ultrasound is a viable, prospective method to be used as a rapid, intraoperative, and potentially in vivo diagnostic tool by surgeons for a wide range of soft tissue cancers.
Acoustical factors affecting the playability of brass wind instruments with side holes
Authors: Campbell D. Murray
Published: May 2016

Almost all modern instruments of the brass wind family radiate sound through a single terminating bell. From the Middle Ages until the second half of the nineteenth century, lip-excited wind instruments with side holes were also in frequent use in both secular and sacred musical ensembles. The acoustical properties of labrasones with side holes, such as the cornetto, the serpent, the keyed bugle, and the ophicleide, resemble in may ways those of conventional brass instruments such as the trombone, but also have features which recall woodwind instruments like the oboe and saxophone. This paper presents some recent studies on the playability of labrasones with side holes, acknowledging the outstanding contributions of William J. Strong and his collaborators to the experimental study and modelling of both woodwind and brass instruments.
Acoustics research at Brigham Young University during the late 1960s
Authors: Plitnik George
Published: May 2016

As Dr. Strong's first Ph.D. student in musical acoustics (I actually arrived one semester before he did), he took on the task of reorganizing the musical acoustics program as well as adding a research division in speech. The fact that these programs were, and continue to be, successful is a tribute to Dr. Strong's dedication and hard work.
Conical reed instruments: A hierarchy of parameters
Authors: Kergomard Jean , Guillemain Philippe , Silva Fabrice , Vergez Christophe
Published: May 2016

Some aspects of sound production by wind musical instruments are rather well understood. A minimum model for reed cylindrical instruments was proposed in 1983 by Mc Intyre et al. When the reed dynamics and resonator losses are ignored, the mouthpiece pressure is a square signal. Three primary parameters are necessary: (i) the mouth pressure; (ii) the “valve” parameter (based on the reed opening and its stiffness); (iii) the length of the cylinder. The model gives a simplified shape of the waveform; the playing frequency and the amplitude are rather well predicted. For further spectrum details, it is necessary to add losses, therefore a secondary parameter, the radius. Furthermore other parameters influence the spectrum: reed dynamics, toneholes, vocal tract.... What happens for conical reed instruments? Considering the waveform of the mouthpiece pressure, a fourth primary parameter is the length of the missing part of the truncated cone. Similarly to cylindrical instruments, a secondary parameter is related to the losses depending either on the input or the output one, or on the apex angle: one of these three parameters allows the determination of the two others. A discussion is proposed concerning the different kinds of conical instruments.
High-resolution directivities of musical instruments and the human voice: Recent research collaborations of Bill Strong
Authors: Leishman Timothy W. , Bodon K. J. , Whiting Jennifer K.
Published: May 2016

Over the past few years, Bill Strong has worked with other researchers at Brigham Young University to develop a feasible method to assess high-resolution directivities of played musical instruments and the human voice. The approach has produced numerous directivity balloons with 5-degree angular resolution and variable bandwidths, meeting the requirements of the AES56-2008 standard for loudspeaker measurements. This presentation will give an overview of the method, its validation, and some interesting results for several musical instruments and talkers. Data from the measurements are intended to enhance theoretical and practical efforts of professionals seeking to better understand and work with these live sources of sound.
Guidelines for developing regulations for acoustic impact, based on the stage of operation of wind farms in Chile
Authors: Montoya Elias N. , Gomez Ismael P.
Published: May 2016

Wind farms manifest different sonic characteristics than other sources, since the noise emitted depends on the wind which turns the blades and varies constantly, being able to tonal components, amplitude modulated, and low frequency noise. For these reasons, the international community has developed specific regulations to assess the acoustic impact associated. Nevertheless, the present Chilean noise regulations are not adjusted properly to the situation described above. Considering the exponential increase experienced by this energy source in recent years in Chile, the development of regulations for such features in the stage operation is suggested so that the noise impact can be properly addressed and quantified. Guidelines for the development of an eventual specific Chilean regulation will be proposed by analyzing and comparing international standards. From this work, we will determine the maximum noise levels, methodologies and other suggestions for the proposed target issues.
Holographic metamaterial using an acoustic leaky wave antenna
Authors: Naify Christina J. , Guild Matthew D. , Martin Theodore P. , Rohde Charles A. , Calvo David C. , Orris Gregory J.
Published: May 2016

Acoustic antennas in the form of active phased arrays have long been utilized to steer acoustic waves in both air and water. Although acceptable, these antennas form electrically complex, bulky structures. Acoustic leaky wave antennas have recently emerged as a method to achieve directional steering using a minimal number of active transducers coupled to an analog metamaterial aperture. In this study, a two-dimensional air-acoustic leaky wave antenna, coupled to only four sources, is shown to steer acoustic energy within a full three-dimensional space while also providing significant savings in terms of size, weight, and cost. By careful selection of the analog geometry, the aperture has the capability to produce a wide range of holographic acoustic images.
Experimental determination of pressure-dependent stiffness of a nonlinear acoustic metamaterial
Authors: Konarski Stephanie G. , Haberman Michael R. , Wilson Preston S. , Bertoldi Katia , Babaee Sahab , Shim Jongmin
Published: May 2016

The field of acoustic metamaterials (AMM) involves the design of subwavelength structures to create material properties exceeding those of traditional composite materials. One such structure developed recently, known as a “Buckliball,” displays strong pressure-dependent stiffness [Proc. Natl. Acad. Sci. USA 109, 5978 (2012)]. The unique response of these structures results from element geometry: spherical elastomeric shells with thin, patterned circular membranes whose skeleton buckles when subjected to a differential pressure. We present measurements of the properties of a nonlinear effective medium consisting of Buckliballs immersed in water. The experimental apparatus consists of four elements: (1) a pressure vessel, which contains (2) a resonance tube filled with Buckliballs suspended in water, (3) an air-coupled ultrasonic system to monitor water height in the resonance tube, and (4) acoustic excitation and measurement instrumentation to obtain the frequency dependent acoustic response of the Buckliball and water-filled resonator. Estimates of the effective stiffness and density are obtained by measuring the fundamental resonance frequency and water column height as a function of overpressure. Experimental results are compared with model estimates and discussed in the context of nonlinear acoustic wave propagation. [Work partially supported by ONR.]
Mie scattering obviates echoes in concert halls
Authors: Lee James B.
Published: May 2016

Mie-resonant-scattering from objects (of sizes similar to impinging waves) embedded in a plane surface has two aspects: it distributes sound into a pattern approximating a cosine law of diffuse reflection; it deconstructs phase relations among components comprising acoustic signals. The former is much better known than the latter. But in large rooms like concert halls, phase-preserving specular reflections constitute echoes, compromising musical information. Deconstructing phases of reflected musical signals by diffuse reflection confines temporal information to direct sound, presenting only the frequency spectrum in reflected sounds.
A novel image based approach to evaluate the room impulse response
Authors: Bhatta Ambika , Thompson Charles , Chandra Kavitha
Published: May 2016

In this work, a novel exact image based solution for a room impulse response is formulated. The resulting response of the rectangular room is an exact solution which is represented in terms of image-sources and branch integrals. It is shown to resolve some of the numerical and analytical constraints of the image based, geometric acoustics models and mode based solutions. The results are quantified in terms of the characteristic parameters, frequency and the dimensions of the room. The computation is also shown by using the features of parallel programming.
Anomalous diffusion of multiply scattered ultrasound in a two-component disordered medium
Authors: Kerhervé Sébastien O. , Page John H.
Published: May 2016

Measurements of multiply-scattered wave transport allow the characterization of heterogeneous media and may reveal anomalous wave properties. When a wave propagates through a sufficiently disordered medium, it will undergo many scattering events. This may lead to diffusive transport or even, in highly disordered media, to localized behavior in which transport comes to a halt. These two regimes can be distinguished by measuring the evolution of the transverse intensity profile when point-like ultrasonic pulse is incident on the opposite side of a slab-shaped sample. In the case of diffusive propagation, the profile width grows without limit as the square root of time, while for localized waves, the width reaches a saturation value at long times due to the trapping of the waves in the medium. In our experiment, the sample consists of aluminum beads randomly packed in silicone oil. Contrary to expectations, the width goes through a maximum as a function of time and varies slowly afterwards. This novel behavior may be due to the existence of two coupled modes of propagation: a fast component travelling through the liquid and a slower component traveling through the bead network. The resonances of the beads influence strongly the propagation inside the solid network.
Acoustic metafluids with multiple negative-index bands
Authors: Brunet Thomas , Poncelet Olivier , Aristegui Christophe , LENG Jacques , MONDAIN-MONVAL Olivier
Published: May 2016

The extraordinary properties of acoustic (random) metamaterials, such as negative refractive index, originate from low frequency resonances of sub-wavelength particles. While most of these functional materials are fabricated by mechanical engineering, we have recently shown that soft matter techniques coupled with microfluidics open a new synthesis route for acoustic metamaterials especially for ultrasonics [1]. As a demonstration, we have achieved 3D-bulk acoustic metafluids with an alternatively low, zero, and negative index by producing large amounts of calibrated soft porous micro-spheres, acting like strong Mie resonators [2]. The wide variety of physico-chemical processes offered by chemical engineering allows for the tuning of the resonant particle properties over a broad range of mechanical/acoustical parameters. In this talk we show that, according to a fine control of the Poisson coefficient of the macro-porous resonators, it is not only possible to achieve soft acoustic metamaterial with one negative band, but also with two separate and tunable ones [3]. As both their width and depth depend on particle properties, the “soft approach” should benefit the design and fabrication of building-block composites with specific extreme properties required in some targeted applications, such as spatial control of sound for beamforming or cloaking. [1] Brunet et al., Science 342, 323–324 (2013). [2] Brunet et al., Nat. Mater.14, 384–388 (2015). [3] Raffy et al., Adv. Mater. DOI: 10.1002/adma.201503524 (2016).
An investigation of free flooding, air-filled underwater resonators
Authors: McNeese Andrew R. , Lee Kevin M. , Wilson Preston S. , Wochner Mark S.
Published: May 2016

This paper investigates the acoustic behavior of free flooding resonators consisting of inverted cups that are lowered into a water column such that a volume of air is entrapped within the cavity upon submersion. Similar to a two-fluid Helmholtz resonator, the resonance frequency is determined by the compliance of the entrapped air and the radiation mass of water at the opening of the cavity. The entrapped air mass is compressed as the resonator is lowered to depth due to the increase in hydrostatic pressure, which affects the acoustic behavior. Collections of similar resonators with compliant walls were previously investigated for use in underwater noise abatement [Lee et al., Proc. Meeting Acoustics 22, 045004 (2015)]; however, recent work has shown an increase in quality factor and attenuation performance for stiffer walled resonators. Measurements were taken to determine the resonance frequencies and quality factors of both individual resonators and arrays of resonators comprised of various wall materials as a function of water depth, resonator geometry, and spacing between resonators. Low frequency sound attenuation through arrays of resonators was also measured. These measurements and associated model comparisons will be discussed. [Work supported by AdBm Technologies.]
The emergence of spurious arrivals in Green’s function extraction and passive imaging
Authors: Li Jie , Gerstoft Peter
Published: May 2016

Cross-correlations of ambient noise at two receivers can extract the two-point Green’s function, given that the wave-field is spatially uniform. The presence of scatterers that act as uncorrelated secondary sources can destroy this condition. We retrieve the Green’s function in one-sided noise with a scatterer in an aeroacoustic experiment, using a pair of microphones (separation 1 m) parallel to the beach which generate one-sided surf noise. The scatterer is a 20-cm-radius polyvinyl chloride pipe 2.5 m to the landside of the microphone pair. We cross correlate 400–2000 Hz noise to retrieve the Green’s function. The results show that spurious scattered arrival emerges in the cross-correlation functions when the source distribution is limited. This causes the generalized optical theorem to break down, and thus, there is no guarantee that the spurious scattered arrival cancels. However, the spurious waves have a geometric interpretation, which are useful for inversion. By combining the travel times of the spurious and physical scattered waves, only a pair of receivers is sufficient to locate the scatterer passively.
An information-theoretic approach to understanding interrupted speech
Authors: Stilp Christian
Published: May 2016

Everyday listening conditions seldom present the listener with a completely intact speech signal. Research on understanding interrupted speech spans the last seven decades, yet few efforts have focused on what parts of the speech signal were being interrupted. Kewley-Port, Fogerty, and others explored the importance of consonants versus vowels for understanding speech when either was replaced by noise, but this approach is limited by their inherent differences such as segment duration. The present approach is inspired by Shannon information theory, where information is defined by unpredictability, uncertainty, or change. We developed a metric of biologically relevant spectral change in the speech signal, termed cochlea-scaled entropy (CSE). Sentences with high-CSE intervals (low predictability = high information) replaced by noise were understood more poorly than sentences with an equal number and duration of low-CSE intervals (high predictability = low information) replaced. CSE has been shown to better predict speech intelligibility than various temporal measures and consonant/vowel status. This approach has been validated across wide ranges of acoustic simulations of cochlear implant processing, suggesting that cochlear implant users might also utilize these information-bearing acoustic changes to understand speech. Extensions and future directions for this work will be discussed
The intelligibility of interrupted, time-compressed speech
Authors: Molis Michelle R. , Gallun Frederick J.
Published: May 2016

Speech is a highly redundant signal for young listeners with normal hearing, but access to that redundancy may be diminished for older listeners, with or without hearing loss. We compared the understanding of unprocessed speech with (1) time-compressed speech, (2) time-compressed speech expanded via interruptions, and (3) uncompressed speech interrupted with silence. Listeners were asked to identify the final four digits of spoken seven-digit strings presented in quiet and in a steady-state, speech-shaped background noise (SNR + 5). Three uniform compression ratios (2:1, 3:1, and 5:1) were used. Participants were younger normally-hearing listeners (YNH), somewhat older listeners (mid-50s to mid-60s) well-matched to the YNH group in thresholds up to 4 kHz (ONH), and older listeners with moderate hearing impairment well-matched in age to the ONH group (OHI). Employing this method, we have demonstrated the relative importance of the amount of information contained between the interruptions; and, the influence of age and hearing loss on the effective use of that information. [Work supported by VA RR&D I01RX001020.]
Sensorimotor development and speech production
Authors: Menard Lucie , Turgeon Christine , Trudeau-Fisette Pamela
Published: May 2016

According to Perkell’s view [J. Perkell, J. Neurol. 25, 382–407], phonemic goals correspond to multidimensional spaces in the auditory and somatosensory dimensions. The relationships between sensory goals and motor actions in speech are acquired during infancy through feedback-based control mechanisms. Although there have been numerous studies of speech development, little is known about the specific roles of auditory and somatosensory feedback. This paper reviews a few studies of how pre-school-aged children rely on sensory feedback to reach phonemic targets. The studies looked at children with normal-hearing and deaf children with cochlear implants. Vowels and consonants were recorded in various prosodic contexts (neutral and under contrastive emphasis) and perturbation conditions (with or without artificial perturbations of the articulators). Acoustic, articulatory, and perceptual analyses were conducted to assess the degree to which children reached the targets. The data showed that although children’s productions were more variable than adults, children generally adapted their articulatory gestures to produce the appropriate sensory speech goals. The effects of perceptual acuity and phonological knowledge in speech development are discussed.
Source symbol decisions in the presence of space and time varying shallow water acoustic response functions
Authors: Gendron Paul J. , Cannon Kari , Entwistle Graham
Published: May 2016

Effective underwater acoustic communications requires source symbol decisions in the presence of an uncertain space and time varying acoustic response function. A hierarchical mixture Gaussian model is useful for modeling both the sparsity of arrivals as well as their spread in angle, Doppler and propagation delay [Canadian Acoust. 40]. In this framework, the delay spread, the degree of sparsity, and the Doppler spread all must be marginalized based on the observed data. We discuss the degree of sparsity as well as the correlation among multi-path arrival times and how these uncertain features in the response function can be efficiently treated in a computationally reasonable and statistically efficient manner via the hierarchy. The approach relies on iterative coherent symbol decisions with an empirical Bayes approach to estimating the hyper-parameters of the model permiting flexibility to adapt to environmental conditions. It is shown that coherent multi-path combining and Doppler compensation are possible at extremely low signal to noise ratios (i.e., < −18 dB), at ranges in excess of 1 km and with throughputs exceeding 100 bps with single element reception. Results are shown for large bandwidth M-ary orthogonal sequences tailored only to a maximum allowable multipath spread.
Reducing numerical dispersion and reflections in finite element and finite difference simulation of acoustic wave propagation and scattering
Authors: Guddati Murthy , Thirunavukkarasu Senganal
Published: May 2016

Discretization methods such as the finite element method (FEM) and the finite difference method (FDM) suffer from two types of accuracy problems: spurious wave dispersion for long-range propagation and artificial reflections from discretization of perfectly matched layers that are often used to represent the unbounded exterior. In this talk, we focus on lower-order FEM and compact FDM stencils, and show that these errors can be significantly reduced using simple measures: using modified integration rules for FEM, and modified compact stencils for FDM. It turns out that these needed corrections for reducing dispersion and reflections are in opposite directions, indicating that reducing one error results in increasing the other, which is not desirable. In this talk, we introduce a special technique that leads to reduction of both dispersion and reflection errors, and illustrate its effectiveness through theoretical analysis and numerical experiments.
ISO 717-1 introduction in Russia
Authors: Tsukernikov Ilya E. , Shubin Igor , Nevenchannaya Tatiana , Schurova Natalia
Published: May 2016

Two single-number quantities are used now in Russia: weighted sound reduction index for rating air noise insulation by internal protecting designs of buildings and the quantity, characterizing sound insulation of external transparent protecting designs from noise, created by municipal transportation streams. For other sound insulation characteristics determined by International Standards ISO 10140-2, ISO 140-4, and ISO 140-5, the corresponding single-number quantities are not established in the Russian standard documents. Besides methods for determination of single-number quantities to be used differ by their various physical senses too. It causes expediency of introduction of International Standard ISO 717-1 in which the corresponding single-number quantities are entered for all spectral characteristics, put into practice of air noise insulation by building protecting designs, and universal methods of their determination are stated. In this paper, features of introduction of International Standard ISO 717-1 in Russia are considered. Comparison of the A-weighted noise spectra for various categories of the railway transportation, to be maintained on the Russian railways, to the sound level spectra, applied in the International Standard to calculate the spectral adaptation terms. By the concrete examples, the divergences in values of spectral adaptation terms received are shown and the corresponding recommendations are offered.
Reverberation theory obscures real physics in concert halls
Authors: Lee James B.
Published: May 2016

Wallace Sabine posited sound in a room to be a uniform field, in equilibrium, varying but slowly with respect to time required to traverse the space: the “reverberant” field. It easy to demonstrate that such is not so, especially in rooms like occupied concert halls. But then, Sabine designed the Boston Symphony Hall, a paradigm of acoustic excellence. If that hall be regarded as a physics experiment, never has it been replicated by Sabine’s followers, even with extensive emendations to his concept of reverberation. The real physics of concert halls involves non-equilibrium manifestation of physical acoustics with respect to bounding surfaces, particularly proximity effects on stage and resonant scattering about the audience.
Death by alarm: An error model of hospital alarms
Authors: Busch-Vishniac Ilene
Published: May 2016

On any given day in the United States, there are about 480,000 patients in hospital for reasons other than psychiatric care or rehabilitation, each generating, on average, about 135 clinical alarms per day. Studies have shown that over 90% of these alarms result in no action being taken. Alarm errors, either alarms that sound and receive no response or alarms that fail to sound when they should, number roughly 8 million per day yet data on adverse alarm impacts indicate about 200 alarm-related deaths per year and a total of a little more than 500 adverse impacts per year. A compelling conclusion from this data is that clinical alarms in hospital are very inefficient and ineffective tools for monitoring medical emergencies. Much attention has been dedicated to alarms recently, with the general goal of improving response to alarms in order to ensure no medical emergency is missed. While this work is of immediate use and is vitally important to the operation of the modern hospital, it focuses on minor changes to the existing systems rather than on trying to design the optimum system for the future. It is future alarm systems that we consider here, with an aim of designing a more effective and efficient system for use in hospitals in roughly 20 years.
A novel method for perceptual assessment of small room acoustics using rapid sensory analysis
Authors: Kaplanis Neofytos , Bech Søren , Lokki Tapio , van Waterschoot Toon , Jensen Søren H.
Published: May 2016

Identifying and perceptually characterizing the physical properties of rooms is a fundamental step in understanding the acoustical qualities of a space. Over the last century, numerous studies have investigated the perceptual qualities in performance spaces, such as opera houses and concert halls. In smaller spaces, such as domestic environments, the research focus has been primarily steered toward sound reproduction within a room, rather than the transmission medium, the room. In this study, a new methodology is used to perceptually assess and characterize a range of acoustical properties within small rooms and car cabins. In-situ measurements were performed to obtain a range of possible acoustical settings, by varying physically the spaces under investigation. The measured responses were spatially analyzed and synthesized to reproduce the observed fields in the laboratory. Expert listeners were presented with auralized sound over a loudspeaker array and followed a rapid sensory analysis protocol. The elicited attributes and ratings are analyzed and possible links to the acoustical properties of these spaces are discussed. [This study is a part of Marie Curie Network on Dereverberation and Reverberation of Audio, Music, and Speech. EU-FP7 under agreement ITN-GA-2012-316969.]
Empirical measure of absorption and scattering properties of living wall plants and systems and predictive modeling of room acoustic benefits
Authors: Connelly Maureen R. , Bolbolan Daver , Akbarnaejad Masha , Daneshpanah Sepideh
Published: May 2016

This series of research projects investigate the acoustical characteristics of interior living walls and predicts how they can be used to positively benefit room acoustics. Scaled and full scale evaluations were executed in a reverberation chamber to validate test methods for absorption and scattering coefficients of soil/substrate and plant species (characterized by height, stem diameter, mass, leaf geometries and dimensions, and leaf area index (LAI)). Wall systems were evaluated over a gradient of plant coverage with monoculture and community planting. Evaluation indicates that evenly distributed pumice can act as the baseline on the scattering turn-table in a method to evaluate scattering coefficients of plant-specific foliage. Findings indicate that percentage of plant coverage is related to absorption coefficients (0.16–1.1) as averaged across all evaluated species. Only at low plant coverage do specific plant characteristics affect the absorption coefficients. The percentage of plant coverage is related to scattering coefficients (0.05–0.51) at 500 Hz and higher. LAI x Mass predicts absorption and scattering coefficients at mid-frequency (200–2500 Hz). Comparison of prediction and field studies identify that use of scattering coefficients improves the prediction of the beneficial use of living walls in room acoustics.
Investigating the effect of body geometry on the acoustics of electric guitars
Authors: Rau Mark , Scavone Gary
Published: May 2016

Three electric guitars of different body geometries are investigated in an attempt to characterize their tonal differences. One guitar has a solid body, one is fully hollow, and one is semi-hollow which represents a midway point between the first two. The transfer functions of the electromagnetic pickups are determined by inducing a known signal through the pickup and measuring the output. Input admittance measurements are taken at the bridge and nut of each guitar to show the vibrational modes of the bodies. Wire break measurements are taken for different notes on each guitar, which are analyzed in conjunction with the admittance measurements. The results demonstrate significant admittance peaks in the hollow and semi-hollow guitars that are not present in solid body electric guitars. As well, “dead” notes with shorter decay times are found to be correlated with these admittance peaks, thus indicating that the bodies of hollow and semi-hollow electric guitars play a role in their tonal characteristics.
A study on minimizing the noise from a trailing edge by the use of optimized serrations
Authors: Brezina Matt , Rocha Joana
Published: May 2016

An optimization study is presented in which the noise produced by flow over the trailing edge of a flat plate is minimized via serrations. The theoretical optimum configuration is found by changing the geometry of the serrations with a non-linear gradient based algorithm. The theoretical noise produced by the trailing edge is determined using the semi-empirical model developed by Howe. As expected, the configuration of the trailing edge serrations that produced the least noise over all frequencies (from 20 Hz to 20 kHz) was found to be those with the smallest width (approaching zero) and largest root-to-tip distance (up to the assigned upper-bound). The optimum serration geometry for individual frequencies was found to be highly dependent on the upper bound given to the height. In addition to the optimization study, an analysis is presented of a method for modifying the noise model to capture the high-frequency noise increase (relative to a straight trailing edge) that is regularly observed in experiments. Results are presented for model validation by a comparison to the sound pressure level frequency spectrum produced experimentally.
Active control of a finite length line source by a novel secondary source
Authors: Hu Qi , Tang Shiu-keung
Published: May 2016

Active control of noise in free space tends to be challenging, especially for the overall attenuation. This paper focuses on the control of a finite line noise source using active approach. Previous study by the author reveals that the introduction of a directional source, an axially oscillating circular piston, as the secondary control source will improve the overall performance of the active noise control system. A novel directional source is theoretically studied in this work, which consists of a core piston and an outer concentric annulus. The two components are axially oscillating with different phases and amplitudes, and these parameters are optimized to maximize the source directivity. This structure can be further extended to add more outer annuluses, which also could be analytically analyzed of the optimal parameters according to the similarity of the construction components. This exquisitely novel control source is adjusted to radiate a sound field analogous to the primary line source with multi-lobe property, and its physical size is restricted within a practical dimension.