bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling and design of lightweight, hyperdamping metamaterials for large, broadband vibroacoustic energy attenuation
Authors: Harne Ryan L. , Song Yu , Dai Quanqi
Published: May 2016

The absorption and dissipation of spectrally broadband vibration and wave energy are long-standing pursuits for researchers and engineers. In vehicular applications, light-weighting demands have led to the common use of flexible structural components that exacerbate concerns of low frequency energy transmission and radiation while joints and geometrical features result in higher frequency vibrations that produce adverse noise fields for occupants. To address the needs for broadband vibroacoustic energy attenuation via a lightweight material solution, this research integrates concepts from recent studies on elastic and poroelastic composite materials and investigates a new idea to cultivate hyperdamping effects in an engineered metamaterial. A finite element (FE) model is developed to identify ways in which to effect hyperdamping properties by virtue of controlled instability mechanisms embedded within the metamaterial. Throughout the design space, the simulations predict numerous design parameter selections that generate hyperdamping properties for large, broadband energy trapping and dissipation. Experimental studies verify the trends of FE model predictions and exemplify the potentials for hyperdamping phenomena once leveraged in practice.
Numerical prediction and analysis of electromagnetic vibration and noise of claw pole alternator
Authors: Wu Shuanglong , Zuo Shuguang , Wu Xudong
Published: May 2016

With the improvement of internal combustion engine noise, the noise of claw pole alternator which is universally used on modern automobiles is becoming more distinct. Extensive experimental results show that the noise of claw pole alternator is annoying at low to middle speed and mainly originates from the electromagnetic noise. In this paper, a complete methodology for electromagnetic vibration and noise prediction of claw pole alternator is presented. It is a three-step multiphysics simulation. The first step is to calculate the magnetic force exerted on the inner surface of the stator using 3D FEM. The second step is the structural analysis, which is to investigate the natural resonant frequencies and modal shapes of the alternator system taking into account the real mechanical boundary conditions. The third is the electromagnetic vibration and noise calculation by using modal superposition method and boundary-element method, respectively. Simulation results agree well with those measured by experiments. Furthermore, the mechanisms of electromagnetic vibration and noise are analyzed by using the electromagnetic theory. The method can be used in the initial design stage of claw pole alternator and is also suitable for other types of motor.
Analytical prediction of radiation from a multi-element variable-directivity spherical loudspeaker array and construction and measurement of a prototype
Authors: Laub Taylor R. , Bliss Donald B.
Published: May 2016

An analysis of radiation from a spherical surface with twelve radiating spherical caps oriented in a dodecahedral arrangement is performed. The approach generalizes the classical single cap solution by utilizing spherical trigonometry transformations to create many spherical caps in different orientations. The calculations include far-field directivity, surface impedances, and net radiated power for a variety of cap motions within the spherical array. Simulations show how well the discrete caps can produce monopole, dipole, and higher mode directivity patterns. Relative motions of the caps are calculated that best simulate these individual radiation modes. The frequency ranges for accurate reproduction of these radiation modes using discrete caps are quantified, and the role of large cap sizes to extend the range is shown. At higher frequencies, the phase interference between discrete cap radiators cause the intended radiation patterns to break down in complicated ways. A prototype 12-element spherical speaker enclosure has been constructed, with the help of a 3-D printer, and tested in an anechoic chamber. The configuration of typical cone loudspeakers creates constraints on the practical design of spherical speakers, limiting the radiating area fraction. Driver design changes to allow more compact spherical speakers with extended frequency range are suggested.
Gender differences and speech accommodation in occupational settings
Authors: Hunter Eric J. , Hargus Ferguson Sarah , Leishman Tim , Maxfield Lynn , Graetzer Simone , Bottalico Pasquale
Published: May 2016

Nearly one quarter of the U.S. workforce depends on a healthy, versatile voice as a tool for their profession. These are individuals who, lose voice quality and/or vocal endurance, would not be able to perform their job effectively. These occupational voice users include professionals such as teachers, counselors, emergency dispatchers, air traffic controllers, performers, and telephone workers. Women tend to have a disproportionate incidence of reported voice problems compared to men. They also make up the majority of several of these high voice-use occupations (e.g., public school teachers, call center workers). This presentation will provide an overview of our current understanding of gender discrepancy in vocal health issues as well as a discussion of recent results identifying underlying causes, which may contribute to their heightened risk. Such results include compensatory adjustments women use in different communication environments, speech accommodation to stress, and the relationship between vocal fatigue and pulmonary function.
The effect of compromised pulmonary function on speech production among female school teachers
Authors: Maxfield Lynn M. , Hunter Eric , Greatzer Simone
Published: May 2016

Females face a significantly higher risk than males of developing long-term voice problems with lifetime instances occurring in 46% of females compared to 37% of males. The higher incidence of prolonged problems among women has been associated with a number of gender differences, including physiological differences in the laryngeal system, differences in the endocrine system, and differences in pulmonary usage. Additionally, inefficient pulmonary utilization and reduced lung volume have been linked with vocal health concerns. Our study sought to use established spirometry measures and a relatively new questionnaire, the Vocal Fatigue Index (VFI), to determine if there is a relationship between pulmonary function and vocal fatigue among teachers. Additionally, if there is a relationship, to determine if that relationship is stronger in females than in males. 122 (96 females, 26 males) elementary and middle school teachers from the Jordan School District in northern Utah participated in this research. For females, VFI was a predictor of several spirometry measures; however, the same correlation was not found among male participants. These results indicate that reduced pulmonary function in combination with other gender differences in speech production may lead to increased incidences of vocal fatigue among female teachers than their male counterparts.
Phonetic convergence and talker sex: It’s complicated
Authors: Pardo Jennifer , Urmanche Adelya , Wilman Sherilyn , Wiener Jaclyn
Published: May 2016

Investigations of phonetic convergence report conflicting results with respect to talker sex. Some studies report that females converge to a greater degree than males, while others find no difference or the opposite pattern. These discrepancies frustrate attempts to characterize the impact of talker sex on phonetic variation and convergence in a straightforward manor. The current investigation reveals that talker sex interacts with other variables, both lexical and phonological. A set of 92 talkers (47 females) shadowed monosyllabic words that manipulated word frequency within eight vowels. Phonetic convergence was assessed in an AXB perceptual similarity task and in F1 x F2 vowel space. Convergence in F1 x F2 vowel space did not differ between males and females on average, but female talkers converged to front vowels (/i/, /ɛi/, /ɛ/, /æ/) more than to back vowels (/ɑ/, /ou/, /ʊ/, /u/), and male talkers showed the opposite pattern. Furthermore, higher vowels (/i/, /ɛi/, /ʊ/, and /u/) showed the largest differences in convergence between men and women. These patterns were largely driven by convergence on F2 alone. These findings relate to broader sociolinguistic concerns about the impact of gender on phonetic variation and sound change.
Same versus opposite-sex accommodation in digital media speech
Authors: Flores Tanya
Published: May 2016

This presentation focuses on the linguistic and social factors that motivate phonetic variation of the /tɾ/ cluster in Chilean Spanish, specifically producing the cluster as an alveo-palatal affricate [tʃ] (or with rhotic [tʃɾ]). The data consist of 1,596 tokens produced by 72 Santiago speakers in a corpus of digital radio recordings. Results from a mixed-effects logistic regression analysis confirm that several linguistic and social factors, including speakers’ sex and age, affect /tɾ/ cluster variation in this dataset. Using a speech accommodation analysis, the study allows for an examination of the effect that social traits of the direct addressee (co-host or in-studio guest) have on speakers’ variant choice and usage rates. Results from the two-population binomial tests on speaker-listener pairings reveal that the affricated variant [tʃ] is significantly affected by the age of the addressee. Moreover, opposite-sex pairs had a significantly higher [tʃ] production rate than same-sex pairs or solo hosts of either sex. Specific patterns by sex will be elaborated in this presentation.
Quantity of mothers' and fathers' speech to sons and daughters
Authors: VanDam Mark , Tully Tracy
Published: May 2016

The literature on child-directed speech has shown that mothers, on average, talk to their children with higher token frequency than fathers, but fathers may use more complex language or more variable word types. Other recent research has shown that mothers may use greater fundamental frequency variability and range when talking to their children, as compared with fathers who showed no fundamental frequency differences between child- and adult-directed speech. There is also some evidence that mothers may talk more often with their daughters than sons. Whether fathers are sensitive to the sex of their children is unknown. This work looks at the quantity of fathers' and mothers' speech to their sons and daughters from a large database of daylong recordings collected from a body-worn recorder on preschool boys and girls in their natural daily environments. The recordings were analyzed offline with automatic speech processing software which tallied the quantity of syllables produced for all individual talkers and the conversational exchanges among mothers and fathers with their sons and daughters. Contrary to previous findings, results indicate that fathers may engage more often with their sons than daughters, but mothers are not sensitive to child sex.
Talker gender effects in the Ferguson Clear Speech Database
Authors: Ferguson Sarah H.
Published: May 2016

The Ferguson Clear Speech Database (FCSD; Ferguson, 2004) was designed to support a talker-differences approach to the investigation of the acoustic characteristics that underlie the superior intelligibility of clear speech. However, its size (41 talkers) and balanced gender composition (21 females and 20 males) have made it useful for exploring talker gender effects on a wide array of acoustic and perceptual measures. In this talk, I will present comparisons of male and female talkers from previous studies as well as more recent ones, along with new analyses of old data. I will also consider how the magnitude of any talker gender differences compares to the variability observed within each gender.
Are women more unstable than men? Shaky topics
Authors: Barkmeier-Kraemer Julie M.
Published: May 2016

Essential vocal tremor was reported by Sulica and Louis (2010) to predominantly occur in females (90%) compared to males (10%) even though the overall diagnosis of essential tremor demonstrates equal representation of both groups. Interestingly, vocal tremor manifests in 30% of individuals diagnosed with essential tremor as well as spasmodic dysphonia. However, information regarding the proportion of females and males exhibiting vocal tremor in those diagnosed with spasmodic dysphonia remains unclear. A predominance of females represented with isolated vocal tremor and in those diagnosed with spasmodic dysphonia could suggest either a genetic or endocrine system link to the onset of vocal tremor. The purpose of this study was to compare and contrast the representation and characteristics of males and females diagnosed with isolated vocal tremor to spasmodic dysphonia with vocal tremor. Comparisons will be made between speech structures exhibiting tremor on endoscopic examination and vocal tremor acoustic patterns. A preponderance of females with vocal tremor in both groups supports a genetic link to the onset of vocal tremor. Differences in acoustic patterns and structural involvement profiles between males and females would support the possible influence of the endocrine system in the development of vocal tremor.
Maximum likelihood estimation to denoising channels in beamforming circular array
Authors: Bozzi Fabricio A. , de Seixas José Manoel , Xavier Thiago C. , Barreira Leonardo M.
Published: May 2016

The delay and sum beamforming is the most simple technique in direction of arrival (DOA) Estimation. Although its performance on spatial discrimination is poor, compared to other beamforming, delay and sum still is used in large operating sound navigation and ranging (SONAR) because of its low computational cost. A circular hydrophone array (CHA), commonly used in SONAR system, is an attractive alternative to provide a more uniform directive response over all azimuth angle. This array is analyzed here, working with experimental data, acquired in a acoustic tank and in the sea. Maximum likelihood estimation (MLE) is applied to denoising noisy channels, summing up them after in delay-and-sum. First of all, a noise in an acoustic tank is considered to represent the hydrophones, cables, and acquisition system noises. Then, an environmental noise is collected in the sea. The MLE use both of them to calculate the weights in the beamforming. A boat is used to running around the array, and the DOA of the uniformly weight and MLE in delay-and-sum shows the performance improvement.
Experimental research on acoustic array sonde in borehole azimuthal reflection logging tool
Authors: Hao Xiaolong , Ju Xiaodong , Wu Xiling , Lu Junqiang , Men Baiyong , Yu Zhijun
Published: May 2016

Phased combined arc array technology was adopted when designing acoustic sonde to enhance 3D detection capability and resolution in borehole azimuthal reflection logging tool. After constructing experimental measurement system, horizontal and vertical radiation characteristics of the transmitter with different phased excitation delays were tested in a 5 m*5 m*4 m water tank as well as consistency and phased combined effects for 80 array elements in 10 stations of the receiver. Also, this tool was placed in an open waters to explore the response of reflector including size, placed radial distance, and azimuth with optional phased excitation delay. Experimental results show that when the phased excitation delay is 30 us, the main lobe direction of vertical radiation energy of the transmitter could be up-deflected by 150 and less side lobe energy. The −3 dB width of main lobe is obviously narrowed using 3 array elements combination in receiver. This tool possesses the ability of recognizing a 2 m*1 m*0.05 m aluminum plate at 10 m radial distance which means about 40 m in real formation, the reflected wave energy intensity distributes symmetrically in eight directions. This work is helpful for acquiring performance of the tool and data processing.
Dynamic time warping: Compensating for temperature variations
Authors: Douglass Alexander C. , Harley Joel B.
Published: May 2016

Guided wave structural health monitoring has the potential to monitor large structural areas. Yet, temperature variations are known to misalign measurement data and cause false alarms. Current popular temperature compensation methods include the optimal signal stretch method and interpolation method. While these methods perform well for small temperature changes, they fail in large temperature variations. In this paper, dynamic time warping is used to realign signal responses that have been distorted by temperature. Baseline subtraction between the realigned signal and the baseline can then be used to detect and identify damage responses. We demonstrate dynamic time warping with guided wave measurements taken from an aluminum plate that is heated in cycles from roughly 75°F to 125°F. Dynamic time warping achieves a correlation between the chosen baseline and the pre-damage measurements greater than 90%. Applying no temperature compensation or more traditional methods, such as optimal signal stretch, demonstrate correlations of 0% and 30%, respectively. This shows that dynamic time warping removes temperature effects more accurately than other current approaches.
Modifying nearfield acoustic holography for use in building leak detection
Authors: Muehleisen Ralph T. , Chelliah Kasanthamy , Patel Hirenkumar , Raman Ganesh
Published: May 2016

The use of nearfield acoustic holography (NAH) for locating and sizing leaks in building envelops has been previously presented [J. Acoust. Soc. Am. 137, 2233 (2015); J. Acoust. Soc. Am. 137, 2325 (2015), and J. Acoust. Soc. Am. 136, 2172 (2014)]. Standard NAH algorithms are fairly limited in the distance from the sources at which reconstruction can be made. In this paper, the authors present new research that shows that with judicious choices of matrix regularization, the distance from source to NAH measurement can be greatly increased making use of NAH for estimating building leakage much more practical. The application several different NAH matrix regularization methods are compared.
Spatial power spectral estimation using coprime sensor array with the min processor
Authors: Liu Yang , Buck John R. , Bautista Radienxe
Published: May 2016

A coprime sensor array (CSA) commonly estimates the spatial power spectral density (PSD) of the observed signal by multiplying one conventionally beamformed subarray scanned response with the complex conjugate of the other [Vaidyanathan and Pal, 2011]. This product processor removes the CSA subarray spatial aliasing ambiguities, but has a peak sidelobe higher than the peak sidelobe of a fully populated uniform linear array (ULA) [Adhikari et al., 2014]. Moreover, the resulting spatial PSD estimate is not guaranteed positive semi-definite, and as a result, weak sources can be masked by the negative side lobes of strong interferers. This paper proposes choosing the minimum between the two CSA subarray periodograms at each bearing to resolve the spatial aliasing ambiguities. This min processor achieves lower peak sidelobe height and total sidelobe area than the product processor and preserves the PSD positive semi-definite characteristic. Closed-form expressions for the first two moments of the CSA min PSD estimator are available. Simulations and real data show that the min processor achieves a lower PSD estimate variance than the product processor while keeping the PSD estimate approximately unbiased. [Work supported by ONR BRC Program.]
An overview of the Sediment Characterization Experiment 2015 survey cruise
Authors: Wilson Preston S. , Kmobles David P.
Published: May 2016

The acoustics of fine grained marine sediments, how they impact shallow water acoustic propagation, and the use of inverse and statistical inference techniques for sediment characterization are being studied in this multi-year, multi-institutional project, which is focused on an area of the Southern New England continental shelf known as the New England Mud Patch. An overview of the first survey cruise associated with this project, which took place in July and August of 2015, will be presented. Measurements during that cruise included sub-bottom profiling and multi-beam bathymetry surveys of the experimental area, as well as CTD and gravity core, box core, and multicore sampling. A limited number of acoustic propagation measurements were made along with ship-board laboratory measurements of recovered sediment sound speed and attenuation measurements. A preliminary assessment of the presence and effect of ocean bottom biology was conducted. In this talk, an overview of the survey cruise will be presented. Later in the session, a number of other more detailed presentations on the individual measurements conducted during the survey will appear, along with talks on various other aspects of the acoustics of fine-grained marine sediments, and their impact on underwater acoustics. [Work supported by ONR.]
Recent oceanographic variability and warming of the continental shelf south of New England and implications for acoustic propagation and sub-bottom characterization
Authors: Gawarkiewicz Glen
Published: May 2016

The continental shelf south of New England is a complex oceanographic environment for underwater acoustics. The combination of large seasonal changes in stratification, complicated frontal phenomena associated with the shelfbreak front, and small spatial scales of variability for soundspeed results in important effects on acoustic propagation and sub-bottom characterization. Two recent trends have also become important. Longer-term warming, on the decadal scale, is affecting shelf water temperatures and soundspeed profiles. In addition, from April 2014 to December 2015, there was a substantial influence on shelf water mass properties from Gulf Stream warm core rings impinging on the continental shelf. The rings also diverted the shelfbreak front onshore at times as well. Some implications for propagation and sub-bottom characterization will be discussed.
Shipboard low frequency sound speed measurements in the New England Mud Patch
Authors: Venegas Gabriel R. , Wilson Preston S. , Lee Kevin M. , Ballard Megan S. , Reed Allen H. , Roosen Ellen , Ecker Daniel , Fringer Kyle , Smith Joseph P.
Published: May 2016

Muddy ocean bottoms have been shown to be acoustically softer than the water column, presenting challenges in resolving inverse problems such as in remote parameter sensing and target detection. In addition, the acoustic properties of mud are less adequately understood compared to sandy sediments. As part of the Sediment Characterization Experiment, a survey cruise was conducted in August 2015 in the New England Mud Patch, in order to further study the acoustic properties of mud. In addition to gravity coring operations to determine the properties of the mud layer, box cores and multicores were collected to examine the surficial sediment properties. Samples were extracted from within the multicores and transferred to a resonator tube, where shipboard low frequency laboratory measurements of sound speed were performed. Before discarding the sample, it was perturbed and allowed to settle in the resonator over a period of two days, during which low frequency sound speed measurements were taken. Experimental challenges and preliminary results from the acoustic measurements and settling experiment will be presented. [Work supported by ONR.]
Estimation of sound speed and attenuation in mud sediments using combustive sound source signals measured on the New England continental shelf
Authors: Wan Lin , Badiey Mohsen , Knobles David , Wilson Preston , Goff John
Published: May 2016

Acoustical measurements were made in coincidence with an environmental survey for future sediment characterization experiments in the mud patch region of the New England continental shelf from July 22 to August 3, 2015. One vertical line array (VLA) containing six hydrophones and 15 environmental sensors was deployed in 75-m water at the center of the survey (40.477o, −70.604o) in order to record noise data and the acoustic signals generated by the combustive sound source (CSS) [McNeese et al., J. Acoust. Soc. Am., 2014]. Fifteen CSS shots detonated at various ranges (2.5 km and 14.5 km) and depths (5 m, 10 m, and 20 m) were recorded by the VLA. The sub-bottom layering structure with a mud layer overlaying a sand bottom was obtained from the CHIRP sonar survey. This paper utilizes the modal dispersion characteristics to invert the sound speed in the bottom. Then, the sound attenuation in mud as a function of frequency is estimated using the transmission loss (TL) data. Measured modal dispersion curves are compared with modeled dispersion curves based on the inverted bottom acoustic parameters. [Work supported by ONR.]
Suggested methodology for direct and inverse characterization of marine sediments that contain mud
Authors: Pierce Allan D. , Siegmann William L. , Brown Elisabeth
Published: May 2016

Mud consists mostly of particles of clay minerals: kaolinite, illite, and smectite. Particles are hexagonally shaped platelets and have widths of the order of microns. In contrast, sandy/silty sediments are composed of silicate particles that are spheroidal is shape and have sizes of the order of millimeters. One distinction is that the platelets commonly carry electrical charges that repel each other. Relevant physics underlying their acoustic properties is considerably different than that for sandy/silty sediments. Naturally occurring mud also contains sandy/silty content, biological matter, and gaseous bubbles. The present paper discusses various techniques by which one can estimate quantitative information about mud sediments. Much can be learned from detailed geochemical analysis and microscopic observation of core samples, but enough is known about mud's general properties so that indirect methods can be used. These can estimate the density and sound speed as functions of depth into the sediment. The sound speed in mud is better approximated by the Mallock-Wood equations than for sandy/silty sediments. Density gradients in conjunction with statistical mechanics considerations yield information on how much of the mud is clay. Measurement of compressional wave attenuation can give information about the forces between platelets. [Work supported by ONR.]
Marine sediment core collection methods and analytical techniques for shallow water sub-seafloor acoustic characterization
Authors: Chaytor Jason D.
Published: May 2016

Collection of intact sub-seafloor sediment samples from aqueous environments requires a suite of coring and drilling tools that vary in complexity, size, and cost as a function of the location, thickness, and analysis requirements of the sediment to be recovered. In shallow water, continental shelf environments such as the Mud Patch offshore southern New England, piston-, gravity-, and vibra-coring techniques allow for the collection of continuous sediment cores that can exceed 10 m in length through a variety of fine- and coarse-grained sediments. Piston and gravity corers, which penetrate the seafloor through a combination of system weight and velocity, operate most effectively in clay and silt dominated materials, recovering relatively undisturbed cores suitable for a wide range of sedimentological, geotechnical, and acoustical analyses. Recovered cores proceed through a series of non-destructive and destructive testing stages to fully characterize the sediments, beginning with physical properties logging (e.g., wet bulk density, p-wave velocity, and magnetic susceptibility), visual stratigraphic description, shear-wave velocity, and photographic and x-ray/CT imaging. Laboratory testing of extracted sub-samples includes, but is not limited to, geotechnical index properties (e.g., water content, undrained shear strength, and density), grain size analysis, carbonate and organic material concentrations, and mineral content (via x-ray diffraction).
In situ measurements of sediment sound speed and attenuation in the frequency band of 0.5–10 kilohertz
Authors: Yang Jie
Published: May 2016

Knowledge of sediment sound speed and attenuation is crucial for predicting sound propagation. The sediment Acoustic-speed Measurement System (SAMS) was designed to measure frequency dependence of sound speed and attenuation within the surficial 3 m in the frequency band of 2–50 kHz. SAMS has two independent and interchangeable drill systems: one employs suction and the other a water jet. The suction system has minimal disturbance on the medium around the penetrating probe while the water jet system can help penetrate consolidated shell/sand layers. Depending on sediment types encountered, the two systems can be interchanged on site in less than 4 h. SAMS was successfully deployed during the Shallow Water 2006 experiment on the New Jersey continental shelf. It was also deployed during the Gulf Experiments 2011, 2012, and the Target and Reverberation Experiment 2013, all conducted off Panama City, FL, where sediment types range from mud to coarse sand. Sediment sound speed and attenuation results from the two experiments are presented. In preparation for the upcoming Seabed Characterization Experiment, the effort to extend measurements down to 500–1500 Hz, where dispersion is of particular importance, will be discussed as well. [Work supported by ONR.]
Design consideration of sound diffusers for wall surfaces in concert halls
Authors: Jeon Jin Y. , Jang Hyung S. , Lim Hansol
Published: May 2016

A wall diffuser has been designed for high scattering and diffusion coefficients using tenth-scale models. The diffuser profiles of the diffuser were designed based on using the Voronoi diagrams to create a randomized pattern with a plane surface with a particular structural height. The intaglio and embossed patterns of these profiles were compared by measuring the scattering and the diffusion coefficients. The intaglio diffusers showed higher scattering and diffusion coefficients than the embossed diffusers. Moreover, random arrays of the profiles presented resulted in higher scattering and diffusion coefficients than the sequential arrays ordered sequentially in terms of the profile in the structural height. The effects of diffusers on sound-field diffuseness were also investigated, and it was found that the diffusive surfaces tend to produce more diffused early reflections than the fine reflective surfaces.
Acoustical performance of a completely renovated music recital hall from subjective and objective points-of-view
Authors: Davis Abigail , Coffeen Robert C.
Published: May 2016

Swarthout Recital Hall located in Murphy Hall at the University of Kansas was initially constructed in the 1950s, with the original interior remaining largely intact until extensive renovations were completed in 2015. Two major complaints regarding the original hall were a lack of feedback from the hall to the performers onstage, and the acoustical coldness of the hall. With excellent cooperation between the School of Music Dean and the music faculty, the project architect, and the acoustic consultant and through the use of computer modeling, a new interior envelope was designed and interior materials selected which addressed these issues. In response, the renovated hall has received highly positive feedback from performers and patrons in both of these respects. This paper will address the measurable acoustic parameters of the renovated hall and how they correlate to both the digitally modeled versions of the hall and the hall acoustic perceptions by performers and audience.
A biomimetic perspective on the dynamics in horseshoe bat biosonar
Authors: Müller Rolf , Sutlive Joseph , Caspers Philip , Fu Yanqing
Published: May 2016

Research with behaving horseshoe bats has suggested that the animals' biosonar system is characterized by pervasive dynamics at the interfaces for ultrasound emission and reception. Baffle shapes that diffract the outgoing and incoming ultrasonic pulses change their geometries during emission and reception. However, it remains unclear if and how this dynamics could affect the function of bats' biosonar system. To investigate this question, biomimetic reproduction of this peripheral dynamics have been used to obtain system characterizations as well as echo recordings. The data obtained with these biomimetic sonar systems have yielded the following key results: If the static and dynamic geometries of the diffracting baffles as well as their coupling to the transducers is suitable, time-variant device characteristics can be produced—even for small and geometrically simple changes to the shapes. These characteristics depend on direction and frequency (like a static beampattern) as well as on time. Furthermore, the time-variant device characteristics were found to result in likewise time-variant signatures imposed on echoes from targets with simple geometries as well as natural targets such as foliages. It remains to be investigated whether and how horseshoe bats could make use of these time-variant echo signatures for the encoding of sensory information.
Quantifying the noseleaf and pulse dynamics in rhinolophid and hipposiderid bats
Authors: Yang Luhui , Zhang Liujun , Zhang Ru , Müller Rolf
Published: May 2016

Horseshoe bats (Rhinolophidae) and Old-World leaf-nosed bats (Hipposideridae) are two related bat families that emit their biosonar pulses nasally and diffract the outgoing wave-packets with elaborate baffle shapes (“noseleaves”). Since the noseleaf surfaces are frequently in motion during pulse emission, an experimental setup has been established to characterize the dynamics in their geometry in conjunction with the effects that this dynamics may have on the ultrasonic pulses. To achieve this goal, greater horseshoe bats (Rhinolophus ferrumequinum), great roundleaf bats (Hipposideros armiger), and Pratt's roundleaf bats (Hipposideros pratti) were trained to emit biosonar pulses while seated on a platform. At least 10 landmarks were placed on the noseleaves of the animals to track the dynamic geometry of these structures with an array of four high-speed video cameras (frame rate 400 Hz). Pairs of video frames were used to reconstruct the 3d trajectories of the noseleaf landmarks, and from these trajectories, shape changes were assessed based on point-distances and measures derived from them. The emitted ultrasonic pulses were measured as a function of direction with a cross-shaped array of ultrasonic microphones. The dynamics in pulse waveforms that were emitted concurrent with noseleaf motions was assessed using correlation and variability measures within and across channels.
Animal aeroacoustics: Fluttering feathers and humming hummingbird wings
Authors: Clark Christopher J. , Mistick Emily
Published: May 2016

Hummingbirds are so-named for the humming sounds their wings produce in flight. We review prior research on aerodynamic mechanisms that produce hummingbird wing sounds, such as aeroelastic flutter. We then present a new aeroacoustic model of the humming of hummingbird wings. This model was tested over a range of flight speeds on hummingbirds flying in an acoustic wind tunnel, and filming them with an Optinav acoustic camera. Possible implications of this model for the sounds produced by micro-air vehicles (“drones”) are discussed.
Phased array techniques for multiple focus synthesis in transcranial focused ultrasound
Authors: Hughes Alec , Hynynen Kullervo
Published: May 2016

Recent clinical successes of transcranial focused ultrasound have occurred in the treatments of essential tremor, neuropathic pain, and Parkinson's disease, among others. We will present results of an investigation into the synthesis of multiple foci using iterative steering through multiple points and phased array controls for multiple focus acoustic patterns. In this numerical study, exported computed tomography (CT) imaging data of the skull was segmented and positioned inside a hemispherical phased array. A combination of full-wave and ray acoustic models were used to simulate the calculation of phased array controls and the resultant acoustic field. Using techniques from previous work on simultaneous multiple focus synthesis and rapidly steered foci in homogeneous media, it is shown that it is possible to elevate the temperature in the brain to therapeutic hyperthermia levels. In addition, potential applications for microbubble-mediated therapies using these techniques are discussed. These results indicate that transcranial hyperthermia over large volumes using focused ultrasound is possible and may have applications to future thermal therapies.
Acoustics on YouTube: Using the internet to improve and inspire learning
Authors: Wilson Michael B.
Published: May 2016

More people have access to more information than ever before, and programs are organizing and providing educational content for free to millions of internet users worldwide. Popular video, blog, and social media websites have creators devoted to engaging an audience through education. This content ranges from interesting facts and demonstrations that introduce a topic to entire university courses. While styles and target audiences vary greatly, the focus is education, clarifying misconceptions, and sparking an interest in learning. Presented will be a survey of current online education, resources, and outreach, as well as ways the acoustics community can get involved in improving education in and out of the classroom.
Sound transmission measurements through porous screens
Authors: Young Sarah M. , Anderson Brian E. , Morrill Nicholas B. , Davis Robert C. , Vanfleet Richard R.
Published: May 2016

The two microphone transfer function technique is used to measure sound transmission properties of porous screens or membranes in a plane wave tube. This presentation will compare sound transmission of porous screens from several manufacturers. Measurements are made with two different plane wave tubes, one of diameter 10.2 cm to measure frequencies between 100 Hz and 2 kHz, and the other of diameter 1.3 cm to measure frequencies between 2 kHz and 16 kHz. Special considerations are made to account for the intrinsic losses in the smaller diameter tube.
A highly portable, lightweight windscreen for infrasound sensors
Authors: Frazier William G. , Harris David
Published: May 2016

It is often desired to deploy infrasound sensors in remote locations for short periods of time. Because of noise created by wind flow past the sensor in the atmosphere at infrasound frequencies, it is also desirable to employ a mechanical windscreen with the goal of reducing the effect of the wind so as to enhance the acoustic signal-to-noise ratio. One of the challenges in wind screen design for temporary applications is to achieve reasonable portability in addition to adequate wind noise filtering. In this presentation, we report the performance a new windscreen design that is highly portable and that achieves performance on par with a commonly used dome-shaped windscreen. Performance comparisons of this newly designed windscreen, a typical porous hose windscreen, and a commonly used dome windscreen are investigated. Specifically, wind noise reduction of these three windscreens compared with a un-screened sensor are presented as a function of frequency and wavenumber using the measured wind speed as a proxy for wave speed. Additionally, acoustic signal noise attenuation is also examined so as to compare signal-to-noise ratio gains. This investigation is similar to the one presented by Alberts, Ludwig, and Talmadge (J. Acoust. Soc. Am. 137, 2261 (2015)) for other small windscreens.
Using the Matérn covariance function to enhance detection and estimation of transient infrasound
Authors: Frazier William G.
Published: May 2016

Adaptive filtering techniques are well known to enhance detection of anomolous events in the presence of slowly changing (quasi-stationary), autocorrelated noise backgrounds such as those occurring in measurements of infrasound signals in the atmosphere. The noise in this case is dominated by the effect of the turbulent wind blowing over the sensing element. While mechanical windscreens can provide significant signal-to-noise ratio gains, additional benefits can be obtained by employing adaptive filters. In this presentation, a kernel-based adaptive filter based on the Matérn Covariance Function is demonstrated to improve the probability of detection of transient infrasound signals as well as improve signal estimation errors without increasing false alarm rates in the presence of wind noise. The choice of the Matérn Covaraiance Function to represent the wind noise process is motivated by its roots in fractional-order stochastic differential equations. Because the wind noise at infrasound frequencies can be influenced by shear-turbulence interaction and turbulence-turbulence interaction more than one kernel is required to obtain optimal performance for the filter. Results are presented under a range wind noise conditions.
An acoustic model of NIST’s long-wavelength acoustic flowmeter for gas flow in large-diameter pipes
Authors: Abbott JohnPaul R. , Gillis Keith A. , Gorny Lee J. , Moldover Michael R.
Published: May 2016

NIST is investigating long-wavelength acoustic flowmeter (LWAF) technology to accurately measure gas flow in large-diameter pipes, such as smokestacks used by coal-burning power plants. To aid in the data analysis and development of the method, we constructed a lumped-element acoustic model of the LWAF based on existing theory for sound propagation in circular ducts, modified to include flow. The model calculates the ratio of the acoustic pressure amplitudes and phase differences between two locations in a partial standing wave downstream of a continuous sound source up to the duct’s cut-on frequency. We used the numerical calculations of the reflection coefficient by Munt [J. Sound Vibration 142, 413–436 (1990)] to model the radiation impedance as a function of flow speed. In the absence of flow, the model was used to calibrate the positions of several microphones in the LWAF. In the presence of flow, the model predicts qualitatively the measured amplitude ratios and phase differences as a function of flow rate. Quantitative comparison is limited by the uncertainty of the radiation impedance and its flow dependence. This limitation prompts us to investigate ways to either measure the radiation impedance or eliminate it by using multiple coherent sound sources.
Feasibility of a long-wavelength acoustic flowmeter for measuring smokestack emissions
Authors: Abbott John Paul R. , Gillis Keith A. , Gorny Lee J. , Moldover Michael R.
Published: May 2016

Conventional gas flow measurements in large ducts, such as power plant smokestacks, have uncertainties of 5–20%. As part of its Greenhouse Gas and Climate Science Measurements Program, the National Institute of Standards and Technology (NIST) is testing long-wavelength acoustic flowmeters (LWAFs) as an alternative method to reduce this uncertainty. A LWAF uses the Doppler Effect to determine the speed of sound c and the average flow speed V. Theory predicts that, for plane waves in a duct, corrections due to flow irregularities, such as swirl and turbulence, are proportional to (V/c)2 £ 0.01. To investigate the feasibility of using an LWAF in a smokestack, we constructed a 1:100 scale model (10 cm diameter) test facility that generated flows up to 25 m/s using ambient air. The model LWAF simultaneously determined the speed of sound in air with a standard uncertainty of 0.01%, relative to NIST’s standard reference database, and measured the average flow velocity with a standard uncertainty of ±1% relative to a NIST-calibrated flow standard upstream from the LWAF. Similar results were obtained when the flows were highly distorted by elbows and obstructions, or when water was sprayed into the air, and for flows through larger diameter model LWAFs.
Differential effects of noise trauma and diminished endocochlear potential on neural temporal coding of complex sounds: Implications for speech perception
Authors: Henry Kenneth S. , Heinz Michael G.
Published: May 2016

Communication problems due to cochlear hearing loss are pervasive in today’s society, even with amplification from digital hearing aids. Threshold elevation may arise from noise-induced trauma to hair cells or, as an alternative mechanism, through age-related depletion of the endocochlear potential (EP; the power supply driving hair-cell function). While both noise trauma and diminished EP may frequently underlie hearing loss in older people, it is unclear whether these pathologies have different effects on neural coding of complex sounds, and ultimately, on speech perception. Here, we describe several recent neurophysiological studies of this question based on Wiener-kernel analyses of chinchilla auditory-nerve fiber responses to Gaussian noise. We find that noise trauma causes pronounced distortions in tonotopic coding of temporal fine structure and slower envelope cues, occurring with as little as 20 dB threshold elevation. Similar changes in neural coding occur with diminished EP, but only when thresholds exceed 60–70 dB SPL. More pronounced changes in temporal coding with noise trauma compared to diminished EP are likely to translate into greater deficits in speech perception (e.g., for noise-induced compared to age-related hearing loss). These results may help explain differences in speech perception abilities across individuals with the same degree of threshold elevation.
Investigating the role of supra-threshold auditory processing and cognitive abilities in presbyacusis
Authors: Fullgrabe Christian
Published: May 2016

Anecdotal evidence and experimental investigations indicate that older people experience increased speech-perception difficulties, especially in noisy environments. Since peripheral hearing sensitivity declines with age, lower speech intelligibility can often be explained by a reduction in audibility. However, aided speech-perception in hearing-impaired listeners frequently falls short of the performance level that would be expected based on the audibility of the speech signal. Given that many of these listeners are older, poor performance may be partly caused by age-related changes in supra-threshold auditory and/or cognitive processes that are not captured by an audiometric assessment. The presentation will discuss experimental evidence obtained from clinically normal-hearing adult listeners showing that auditory temporal processing, cognition, and speech-in-noise perception are indeed linked and, independently of hearing loss, decline across the adult lifespan. These findings highlight the need to take into account audibility-unrelated factors in the prediction and rehabilitation of speech intelligibility across adulthood.
Effects of low-pass filtering on dialect and gender perception
Authors: Fox Robert A. , Jacewicz Ewa , Smith Zane T.
Published: May 2016

In addition to linguistic (message-related) information, spoken language includes indexical information related to the speaker characteristics (e.g., gender, social status, and regional identity). This study is an extension of Jacewicz et al. (2015, JASA, 137, 2417–2418) which explored the nature of acoustic cues signaling indexical information. That study demonstrated that listeners were quite accurate in making decisions regarding the regional dialect and gender of a speaker when responding to short unprocessed phrases from 40 speakers (male and female) from two different dialects spoken in central Ohio and western North Carolina. However, when the signal was low-pass filtered at 400 Hz, sensitivity to both dropped significantly. The current study examined performance on the same phrases when the signal was low-pass filtered at progressively higher cutoff frequencies (500, 700, 900, and 1100 Hz). These stimuli were played to 20 listeners (10 males and 10 females) who identified the sex and dialect of the speaker. As expected, listener sensitivity improved with each wider low-pass filter condition. Performance in the 1100-Hz cutoff condition was very similar to that in the unprocessed condition. Discussion will focus on the nature of the acoustic cues utilized by listeners across the four low-pass filter conditions.