bluuebunny/crossref_metadata_2025 huggingface dataset:
Jet pump oscillating-flow behavior at different Womersley numbers
Authors: Nassif Abdelrahman , Abd El-Rahman Ahmed I. , Abdel-Rahman Ehab
Published: May 2016

Few numerical works simulate the laminar-flow behavior within the diverging passages of typical thermoacoustic jet pumps. The associated boundary-layer separation is mostly delayed by maintaining a slowly increasing flow passage and thereby the corresponding pressure drop and consumed acoustic energy are noticeably reduced. Of equal importance is the effect of the transition to turbulence on the boundary-layer separation and the resulting flow-pattern. To our knowledge, no simulation has been developed that numerically predict and capture the conditionally turbulent flow regime within typical jet pumps. Here, a new finite-volume model is reported that employs the non-linear CFD solver of ANSYS FLUENT. The k-kl-ω transition model is considered and its parameters are particularly adjusted for present application. A sinusoidal pressure oscillation is enforced at one end, while the far-field approximation is considered at the other end to model the non-reflecting boundary condition. An axisymmetric model along with careful meshing are applied. The transient simulation run proceeds till stationary flow behavior is obtained. Both the flow streamlines and vorticity field are plotted for three different acoustic frequencies, Womersley numbers of which correspond to 5, 15, and 30. The numerical results capture the onset of flow transition into turbulence and characterize the flow patterns at different frequencies. The results also illustrate the influence of the developed turbulent flow-patterns on the boundary-layer separation.
Loudspeaker design and analysis
Authors: Mascolo Joseph , Bartolomeo Nico , Laprade Alexander , Gorczynski Ethan , Wolff Gabrielle , Pisani Gordon , Turo Diego
Published: May 2016

This presentation will demonstrate the planning, construction, testing, and final performance of a student designed loudspeaker system. The purpose of this project was to create a 2.1 channel, high quality sound system that produces a bandwidth just short of the full range of human hearing, which is then cut off and sent to the appropriate speakers. This system consists of 2 two-way speakers utilizing a woofer and tweeter, arranged in unison with one sole subwoofer. The function of this particular sound system is to reproduce sound faithfully in a 350–400 square foot room, yet still be lightweight and maneuverable. The performance characteristics of this system will be presented through frequency response and linearity testing results. These tests were used to help warrant modifications made to the cabinet size and shape while adhering to a strict budget of $1,200. The analysis of every performance will also reveal data for different electrical component values in designing the Linkwitz-Riley crossovers. The aim of this presentation is to highlight the various key factors that are important in loudspeaker design.
High frequency sound speed measurements in liquids and solids using a smartphone
Authors: Sturtevant Blake T. , Sinha Dipen N.
Published: May 2016

Much has been written in recent years on the use of smartphones and other personal electronic devices (PED) in the high school and college teaching laboratories. Due to the bandwidth limitations (< 20 kHz) of these devices, experiments proposed to date have focused almost exclusively on measurements of phenomena in air and in the audible range. This talk will focus on a simple way to extend the use of these devices to measure sound speed in liquid and solids which have significantly higher sound speeds than air. High frequency acoustic standing waves in these media can be generated using standard teaching laboratory instrumentation (e.g., signal generators providing white noise, chirp signals, CW signals with manually adjusted frequency, etc.) and two opposing piezoelectric disks. By down-converting the high frequencies with an inexpensive diode mixer and measuring the difference frequency spectrum with a PED, it is possible to determine multiple successive standing wave frequencies in the medium. The measured frequencies, along with the distance between the disks, can then be used to determine sound speed accurately. Simple and inexpensive, the proposed system provides a learning experience traditionally inaccessible without research grade RF measurement instrumentation.
Noise illustrated
Authors: Ermann Michael
Published: May 2016

Principles and research findings on the subject of noise control are presented in the graphic language of architecture in the hope that not only architects, but others will benefit from the translation. (1) Mass, airtightness, and structural discontinuity are illustrated with baseline/better comparisons; (2) transmission loss data are culled and translated from tables to graphs for easy contrasts, (3) families of assemblies are illustrated and ranked by STC and IIC values, (4) the frequency domain of impact noise is explored graphically, (5) barrier design principles are demonstrated, (6) AHU fan noise and turbulence attenuation strategies are presented visually, and (7) common in-the-field construction mistakes are drawn to illustrate flanking paths, vibration isolation short-circuiting, and barrier construction acoustic bridging. Rules-of-thumb and nomographs are offered for early-design best-practices in building site selection, duct distances, ducted air velocities, window selection, and space planning. The illustrations presented come from over 250 drawings in the book, Architectural Acoustics Illustrated (Wiley, 2015), half of which is dedicated to noise control.
Characterization of phased array-steered acoustic vortex beams
Authors: Pazos-Ospina Jhon F. , Franco Ediguer E. , Ealo Joao L.
Published: May 2016

Acoustic vortex (AV) beams generation is a subject of current interest. Even though different applications have been proposed using AV, their potential of use is still to be explored. Recent research works on particle manipulation use phased array systems for AV generation because it allows a flexible beam configuration, i.e., the beam can be easily focalized and modified in its shape. However, little attention has been paid to the fact that the AV can also be electronically steered. In view of this, this work presents an study of the steering capability of an AV. In particular, we analyze the effect of the applied delay law on the structure of AV beams steered at different angles using an array transducer of 32 equidistant elements, deployed on a triangular lattice, operating at 40 kHz. Special attention is paid to the appearance of grating vortices and their characteristics. The effect of the individual element directivity on the resultant beam is also studied. Experimental measurements were carried out in order to validate numerical estimations. Obtained results paves the way for the use of electronically steered vortices in different applications. Also, the potential of use of acoustic grating vortices is discussed.
Taming tornadoes: Controlling orbits inside acoustic vortex traps
Authors: Marzo Asier , Caleap Mihai , Drinkwater Bruce W.
Published: May 2016

Bessel-shaped acoustic vortices have been theorized to be ideal candidates for tractor beams—that is, acoustic beams that exert forces opposite to the direction of propagation. Recently, it has been shown experimentally that these pulling forces exist and that particles can be trapped inside a focused vortex beam, both in water and air. However, our experiments and simulations reveal that the behavior of particles trapped inside a focused vortex is strongly dependent on the particle size. We trapped expanded polystyrene spheres (ranging from 0.6 mm to 4 mm diameter) 4 cm above a phased array made of 52 transducers (40 kHz and 1 cm diameter each) that generated an airborne acoustic vortex. Depending on its size, a particle remained trapped, oscillated between being trapped and orbiting, orbited or was ejected; only small particles (< 1 mm) were stably trapped. We then devised a new procedure for making vortex traps stable for a wider range of particle sizes; the strategy relies on switching the direction of the vortex at 4 kHz. In addition, by regulating the amount of time that each direction is emitted, it is possible to controllably rotate symmetric particles. This enables new applications in particle manipulation such as centrifugation of cells or actuation of micromachines.
Evaluating how fine-grained changes in the spatial and temporal properties of audiovisual speech influence the perception of linguistic meter
Authors: Fuhrman Robert A. , Nowak Stanislaw , Vatikiotis-Bateson Eric
Published: May 2016

The visual information that contributes to speech perception has been known for over a half century (Sumby and Pollack, JASA, 1954). More recent work has demonstrated two important constraints on the benefit of visual information to speech perception. First, the benefit patterns with temporal constraints on general audiovisual sensory processing, and degrades when auditory and visual signals are misaligned by an offset on the order of the duration of a syllable. Second, studies have demonstrated that low spatiotemporal frequency visual information is sufficient for boosting speech intelligibility. Collectively, these findings suggest that visual information facilitates processing of linguistic information organized in the speech stream primarily at the level of the syllable. Our experiments address how manipulation of the phasing and amplitude of visual components of the audiovisual stream associated with reiterant speech affects the perception of linguistic stress. Our analyses focus on determining the sensitivity of speech perception to changes in the fine-grained structure of visible motion (kinematics) and its alignment with the speech acoustics.
Improving ray-based blind deconvolution of random shipping sources with short arrays in an ocean waveguide using adaptive beamforming
Authors: Yang Juan , Byun Sung-Hoon , Sabra Karim G.
Published: May 2016

This paper introduces an improved ray-based blind deconvolution(RBD) algorithm for sources of opportunity, such as shipping noise, recorded on a short vertical line array (VLA) by using adaptive beamforming. The original RBD algorithm [Sabra et al., JASA, 2010, EL42-7] relies on first estimating the unknown phase of the random source using broadband beamforming along a well-resolved ray path to estimate the full channel impulse responses (CIR) between the unknown source and the VLA elements (up to an arbitrary time-shift) as well as recovering the radiated signal by the random source. Hence, RBD performance is limited by the VLA ability to separate adjacent ray path, especially for the case of small aperture. To address this limitation, broadband MVDR is used as a high resolution estimator to improve the RBD performance when using single snapshot recordings and short VLAs. To do so, smoothing techniques are used to increase the rank of cross-spectral data matrix since the ray arrivals emanating from the same random source are naturally correlated in an ocean waveguide when using single snapshot recordings. The improvement of this proposed RBD algorithm will be demonstrated using both numerical simulation and at-sea shipping noise data recorded in shallow water.
Effects of vertical obliquity on sonar images and elastic mechanisms for cylinders near a flat interface
Authors: Plotnick Daniel , Marston Philip
Published: May 2016

The backscattered signal from targets located near a flat interface is highly dependent on the relative positions and orientations of the acoustic source/receiver, the interface, and the target. The acoustic backscattering spectrum versus aspect angle, also called the “acoustic color'' or “acoustic template,'' of solid cylinders was previously studied for the case where the cylinder axis was vertically oblique relative to a nearby water-air interface [D. Plotnick et al., J. Acoust. Soc. Am. 137, 470–480 (2015)]. The presence of the interface allows for multiple orientation-dependent paths by which sound is backscattered; this work examines the effects of vertical obliquity on these paths. Experimental data were on a solid cylinder at various obliquities near an air-water interface collected using a circular synthetic aperture sonar system. Emphasis will be placed on the effects of vertical obliquity on features in reconstructed sonar images. Several robust orientation dependent features are considered and the physical mechanisms identified through geometric arguments. Information about a target's 3-D orientation and size may be gleaned from these images, aiding the interpretation of features within the target's acoustic template. The coupling conditions for surface elastic waves are also considered. [Work supported by ONR.]
Heating, ventilation, and air conditioning noise calculations after the slide rule and calculator
Authors: Thorburn Steven
Published: May 2016

Computer programs that predict HVAC system noise are now common. But, what was the basis of the design of the programs, what are the noise control assumptions? This paper will present how the 1984 ASHRAE Chapter 37 Sound and Vibration from the Systems Handbook was converted into a computer program and the limitations that were found in the chapter and how they were modified to more accurately predict the HVAC system noise and it control. This program has been updated 4 times over the years and is now an EXCEL bolt on.
There must be mucus: Using a lumped-parameter model to simulate the “thump” and “ring” of a bottlenose dolphin echolocation click
Authors: Thode Lester , Thode Aaron , Au Whitlow
Published: May 2016

Bottlenose dolphin echolocation clicks display a great diversity in temporal and spectral structure, with both unimodal and bimodal spectra observed (Houser et al., JASA, 1999). Wavelet scalograms applied to data collected by the Navy Marine Mammal Program and the Bioacoustic Measuring Tool (BMT) (Martin et al., JASA, 2005) show that echolocation clicks can display two distinct phases: an initial “thump,” followed by an extended “ring” that is adequately modeled by a damped harmonic oscillator. The thump and ring can display either similar or different spectral characteristics, giving rise to a unimodal or bimodal spectrum. A three-mass lumped parameter model, adapted from the speech processing and terrestrial bioacoustics literature, has been used to simulate the oscillation and collision of the dorsal bursae in a dolphin’s nasal passage. The three-mass model reproduces many of the time and frequency domain features of entire click trains as well as individual clicks, including unimodal and bimodal spectra. A key insight of the models is that some slight adhesion between the faces of the colliding bursue seems necessary in order to reproduce the high-frequency click structure. A viscoelastic mucus coating could provide one possible mechanism for this required adhesion force. [Data provided by Steve Martin, NMMF.]
The spatial unmasking of pure tones by laboratory mice
Authors: Screven Laurel A.
Published: May 2016

The ability of animals to identify signals in their acoustical environment when confronted with sounds from multiple sources relies on them extracting the important information and filtering out background noise. Previous reports have shown that many animals are able to attend to a single sound more easily when that signal is spatially separated from the background noise. This spatial unmasking of a sound has previously not been behaviorally measured in mice, despite their use as a model for human hearing and communication. The present experiment examined if laboratory mice are able to show spatial release from masking, as seen in other animals, by testing the detection of 2, 4, 8, 12, 16, and 24 kHz pure tones in the presence of a white noise masker. The masker was spatially coincident with the signal or separated by 90°. We hypothesized that the mice would experience more spatial unmasking for the higher frequency tones since they rely heavily on these frequency ranges for their communication signals. Preliminarily, we have found that mice are able experience spatial unmasking at some, but not at all frequencies.
Adaptive imaging processing for reducing ultrasonic ringdown interference pattern
Authors: Zhang Zhijuan , Patterson Douglas , Steinsiek Roger , Han Wei
Published: May 2016

In the oil and gas industry, ultrasonic imaging tools are actively used in stress identification and fracture detection. Pulse-echo transducers measure the properties of the echoes reflected from the formation, and the signal peak amplitude and travel time are typically displayed as a circumferential image of the borehole wall. A well-known problem is that the pulse-echo transducers have internal ringdown which constantly modulates formation echoes. As a result, the acquired image is often dominated by a “wood-grain” interference pattern which degrades image quality. Traditional ringdown reduction methods try to remove the ringdown effect by estimating the ringdown waveform. However, the ringdown signal varies versus borehole conditions, which make it inadequate for traditional methods to efficiently reduce the image interference pattern. In this paper, we proposed an image processing method which significantly reduces the interference pattern. This new image processing method does not require any ringdown waveforms. It adaptively estimates the ringdown modulation template and after that constructs the interference amplitude pattern. Examples shows promising results and have proven the propose method is more efficient than traditional ringdown reduction methods on the ringdown interference pattern reduction.
In-situ ultrasonic measurements of creep specimens
Authors: Guers Manton J. , Tittmann Bernhard R.
Published: May 2016

Performing in-situ measurements of specimens in research reactors is challenging because of the environmental conditions. In this work, ultrasonic guided waves were investigated for performing in-situ measurements of the change in length of creep specimens. Both theoretical calculations and experimental measurements were used to determine the proposed method’s sensitivity to changes in temperature and elongation. The experimental tests demonstrated that careful consideration must be given to the signal processing of the data. Successful measurements of the creep elongation of a 3 in. gauge length specimen were demonstrated.
Active compensation of nonlinear distortion in balanced armature receivers
Authors: Xu Buye , Zhang Tao
Published: May 2016

Balanced armature receivers have been widely used in hearing aids due to their higher efficiency and more discrete size comparing to moving coil loudspeakers. For the application of hearing aids, it may require a very high output sound pressure level (up to 110 dB in an opened ear canal) and, yet, minimum nonlinear distortions. This requirement often results in a larger receiver in size, which is less comfortable for wearing. It is highly desired if the linear range of a smaller receiver can be broaden without increasing its physical size. Active compensation of nonlinearity for moving coil loudspeakers through signal processing means have been well studied. However, similar research for balanced armature receivers is rarely seen in the literature. Although the two types of transducers differ in many aspects, they share commonalities in the nonlinearity mechanism. The current study surveys the active compensation techniques developed for moving coil loudspeakers and explores the possibility of adopting them to reduce the nonlinearity of balanced armature receivers.
Recording anechoic gunshot waveforms of several firearms at 500 kilohertz sampling rate
Authors: Routh Tushar K. , MAHER Robert C.
Published: May 2016

Acoustic gunshot signals consist of a high amplitude and short duration impulsive sound known as the muzzle blast. This experiment involved documenting gunshot muzzle blast sounds produced by eight commonly used firearms. An elevated bracket (3 m above the ground) was built to achieve a quasi-anechoic environment for the duration of the muzzle blast. Twelve microphones (GRAS 46DP) were mounted on the bracket in a semi-circular arc to observe the azimuthal variation of the muzzle blast. Signals were recorded using LabVIEW. Similarities and differences among waveforms are presented.
Vorticity-involved acoustic damping performance of an in-duct orifice with a bias flow
Authors: Zhao Dan , Han Nuomin , Jin Xiao
Published: May 2016

Acoustic damping performance of an in-duct perforated orifice with a bias flow in terms of power absorption and reflection coefficients are evaluated in this work. For this, experimental measurements of a cold-flow pipe system with a diameter of 2b with an in-duct perforated plate implemented are conducted first. It is shown that the maximum power absorption Δmax and reflection coefficients χmax are approximately 80% and 90%, respectively. In addition, Δ and χ are periodically changed with the forcing frequency. To simulate the experiments and gain insights on the damping performance of the orifice with a diameter of 2a, a 1D theoretical model embodying vorticity-involved damping mechanism is developed. It is based on the modified form of the Cummings equation describing unsteady flow through an orifice and the Cargill equation describing acoustically open boundary condition at the end of the downstream duct. It is shown that Δ and χ are strongly related to (1) the mean flow Mach number, (2) forcing frequency ω, and (3) porosity η = a/b, and (4) the downstream pipe length Ld. Theoretical predictions are found to agree well with experimental measurements. This confirms that the model has the potential to predict the acoustic damping performance of in-duct orifices.
Maximizing the acoustic benefits of vocal vibration and resonance in choral singing
Authors: Fagnan Laurier A.
Published: May 2016

As an artistic discipline, choral singing often shies away from fully exploiting the vocal and acoustic benefits of vibration and resonance. It is sometimes thought that those two properties are more germane to the solo voice than to ensemble singing where “sameness” is often lauded above all else and blend can easily turn to bland. As Berton Coffin aptly states, “there is no reason to have a Stradivarius sound like a cigar-box violin so that both will sound the same.” This session will show how the Stradivarius, complete-timbre-energy approach espoused by the old masters of the bel canto manner of singing is appropriate and beneficial to the art of choral singing. It will highlight the many acoustic advantages a choir can enjoy by applying the principles of regular, focused vibration and balanced, chiaroscuro (bright-dark) resonance throughout the voice’s range and dynamic extent. Analyses such as high-speed videostroboscopy and real-time spectrography will help to better define and bridge the scientific and artistic aspects of energized choral sound. It will be shown that the proper application of bel canto principles has a positive effect on spectral balance, notably the presence of Singers’ Formant energy, as well as on intonation and text intelligibility.
The effect of chiaroscuro and coup de glotte training on reducing the effects of intrinsic pitch in sung vowel transitions
Authors: Crosby Grace H. , Tucker Benjamin V. , Fagnan Laurier
Published: May 2016

Intrinsic pitch is an acoustic value that differs depending on vowel height. Sapir (1989) describes the various theories that provide an explanation for intrinsic pitch. Essentially, vowels which are produced higher in the filter (e.g., /i/ and /u/) tend to be pitched slightly higher than vowels produced at lower locations in the filter (e.g., /a/). The purpose of this study is to determine whether the chiaroscuro and coup de glotte vocal techniques used in the bel canto method of singing reduce the natural effects of intrinsic pitch of sung vowels by attempting to equalize both resonance and vibrational properties across the vowel spectrum. Six singers (2 sopranos, 2 tenors, and 2 basses) were recorded in this study. Participants sang a set of vowel transition exercises in a pre-training setting, then were trained in chiaroscuro and coup de glotte techniques, after which they did a post-training recording. Pitch, formant values, and amplitude (as mean values and at various times within each vowel) were extracted for a before versus after comparison. The results will be discussed in relation to how this technique might be helpful in reducing the effect of intrinsic pitch on sung vowels.
Removing effects of ear-canal acoustics from measurements of otoacoustic emissions
Authors: Charaziak Karolina , Shera Christopher
Published: May 2016

Otoacoustic emissions (OAEs) are the acoustic fingerprints of the inner ear—when carefully measured in healthy ears, their spectra, although highly individualized, remain stable over time. Thus, OAE changes usually indicate changes in cochlear function, e.g., due to efferent modulation, aging, noise trauma, and/or exposure to harmful agents. In humans, however, the reproducibility of OAE measurements is compromised by ear-canal standing waves at relevant frequencies. We show that even when stimulus levels are tightly controlled using methods designed to avoid standing-wave problems (forward-pressure-level calibration), distortion-product (DP)OAE levels vary by ~10–15 dB near half-wave resonant frequencies, depending on probe insertion depth (deep versus shallow). We propose a method, derived from a tube model of the ear canal, that separates the initial outgoing OAE pressure wave at the eardrum from reflected OAEs trapped in the residual ear-canal space. The emitted pressure level (EPL) represents the load-independent OAE level that would be recorded in an ideal, reflectionless canal. When DPOAE levels are converted to EPL, variability across insertion depths decreases by ~10 dB near half-wave resonant frequencies. EPL may provide a simple way to reduce confounding OAE variability across subjects and to improve the reliability of OAE measurements for detecting cochlear changes.
Hidden hearing loss in tinnitus with normal hearing thresholds
Authors: Paul Brandon T. , Bruce Ian , Roberts Larry
Published: May 2016

Tinnitus—the phantom ringing of the ears—is thought arise from neuroplastic changes in the central auditory system in response to peripheral hearing damage. However, a minority of tinnitus sufferers have clinically normal hearing thresholds. One explanation of these cases is that auditory nerve fibers with low firing thresholds (LT-ANFs) are intact, but ANFs with high thresholds (HT-ANFs) are not. HT-ANF damage would be “hidden” to the audiogram but evident in suprathreshold tests. To test this hypothesis, we measured the ability of tinnitus and control subjects with normal audiograms to detect amplitude modulation (AM) in a 5 kHz, suprathreshold tone in a narrowband noise. We also recorded by 32-channel EEG the “envelope following response” (EFR, generated subcortically) to the same AM tone in conditions of noise and no noise. Tinnitus subjects had worse AM detection thresholds and had smaller EFRs compared to controls. Simulations of ANF responses from the model of Zilany et al. (2014) found that in addition to ~100% loss of HT ANFs, a further ~30% loss of LT fibers was needed to account for the reduced EFRs of tinnitus subjects. ~30% of LT ANFs would not have been expected to affect hearing thresholds. [Work supported by NSERC of Canada.]
A study on a sound fire extinguisher using special sound lens
Authors: Ahn Iksoo , Park Hyungwoo , Bae Seonggeon , Bae Myungjin
Published: May 2016

Sound fire extinguisher is developed based on principle of quenching fire by blocking inflow of oxygen with contacting vibration energy from low frequency sound under 100 Hz to fire and then, lowering its temperature. The first sound fire extinguisher made by a Federal Defence researcher was very huge and based on theory of initial principles, making it hard to be commercialized. Although next sound fire extinguisher developed by students of George Mason University was smaller than before, it was also at the basic stage with early theory. What is more, disturbance from the too long cable and inconvenience of having to carry all the tools were not effective to be commercialized. By improving these drawbacks, Sori Sound Engineering Research Institute (SSERI) of Soongsil University has developed new concept sound fire distinguisher. It concentrates sound through special sound lens and increases energy 10 times more to put out the fire. This study researches about reducing weight of sound fire extinguisher based on new concept special sound lens created by Sori Sound Engineering Research Institute of Soongsil University.
Wavenumber analysis of vibrating dimpled beams
Authors: Myers Kyle R. , Naghshineh Koorosh
Published: May 2016

A structure’s noise and vibration characteristics can be changed by introducing dimples onto the surface. These structural modifications are an attractive form of noise control since they are simple to manufacture and do not add mass to the structure. In order to gain a better understanding of the effect of dimples, beams with different number of dimples are considered in this study. The natural frequencies and mode shapes of beams with any number of dimples are computed using a boundary value model derived from Hamilton’s Principle. The results of this model are compared to the finite element method and to previous literature. Then, the effect of the dimples on the radiation properties of beams is investigated by examination of their wavenumber spectra. By shifting the wavenumber content of the beam between supersonic and subsonic regions, dimples are able to change the amount of radiation emitted. For some boundary conditions, the wavenumber spectrum is time-dependent as the beam vibrates through a complete cycle. Several examples are presented that demonstrate how different numbers of dimples, as well as their locations and geometries, affect the wavenumber spectra of beams.
Achievable performance of a novel Bragg-scattered acoustic receiving array
Authors: Cray Benjamin , Kirsteins Ivars
Published: May 2016

The merits of a novel beamforming technique, based on generating Bragg-scattered acoustic wavelengths along the surface of an array, will be described. The technique, denoted acoustic trace wavelength enhancement, relies on embedding periodic structures within an array, chosen to precisely replicate and shift an incident acoustic wavenumber into higher wavenumber regions. Thus, shorter trace wavelengths are created over the aperture surface. The enhancement technique is documented in two recent publications: enhanced directivity with array grating [J. Acoust. Soc. Am. 136, 2014] and experimental verification of acoustic trace wavelength enhancement [J. Acoust. Soc. Am. 138, 2015). These references dealt, however, solely with high signal-to-noise ratios. Specifically, we will investigate the noise characteristics of this new array by calculating its array gain and Cramer-Rao lower bounds on bearing estimation error for plane wave signals embedded in an isotropic Gaussian noise field. Of particular interest is how the performance of the enhanced array compares to a conventional hydrophone-based array.
Wavenumber domain analysis of plates with embedded acoustic black holes
Authors: Feurtado Philip , Conlon Steve
Published: May 2016

Acoustic black holes (ABHs) have been developed and demonstrated as effective, passive, lightweight bending wave absorbers that reduce the structural vibration and radiated sound power of plates. By introducing a gradual change in the local plate thickness, the bending wave speed is reduced and the transverse vibration amplitude is increased. Energy can then be effectively dissipated through material losses or attached damping treatments. In this paper, wavenumber spectra were generated from the vibrational responses of a uniform plate, an undamped ABH plate, and a damped ABH plate. The results showed that wavenumber transform analysis is a useful method for investigating and characterizing ABH performance and behavior. The results also demonstrated that ABHs can distribute supersonic bending waves into subsonic wavenumbers. The results will be useful for the design, characterization, and optimization of ABH systems for real structures
Speech intelligibility for native and non-native talkers and listeners
Authors: Smiljanic Rajka
Published: May 2016

Much of daily communication occurs under a range of suboptimal conditions related to talker, listener, and signal characteristics. These “adverse” conditions (Mattys et al., 2012) increase intelligibility variation and impact perceptual processes, representations, attention, and memory functions. In this talk, I focus on two factors that condition intelligibility variation, namely, when interlocutors are non-native speakers of a target language and when communication occurs in noise. First, I will discuss a set of experiments examining how native and non-native talkers modify their speech with the goal of enhancing their intelligibility and the extent to which these modifications enhance word recognition in noise for native and non-native listeners. I also present results from studies examining how listeners adapt to more and less familiar foreign accents of varying intelligibility when presented in noise. These studies provide insights into the interplay between physical and mental factors in the production and perception of intelligible speech. They further reveal constraints on talker-listener adaptation processes during communication. A detailed understanding of speech intelligibility variation for native and non-native talkers and listeners will enhance our understanding of the compensatory and cognitive mechanisms that allow speech comprehension in naturalistic conditions.
Production and perception of clear speech
Authors: Bradlow Ann
Published: May 2016

When talkers are aware of listeners’ speech perception difficulties due to hearing loss, noise, or a language barrier, they typically adopt an intelligibility-enhancing speaking style known as “clear speech.” To the extent that clear speech is more intelligible than “conversational speech,” a cross-style acoustic-phonetic comparison provides information about factors that affect speech intelligibility. I will present data from a project that tested the hypothesis that clear speech is guided by both universal, auditory-perceptual factors and language-specific, structural factors. The former serve to enhance the overall acoustic salience of the speech signal such that it is more resistant to the adverse effects of noise or listener-related perceptual deficits; the latter serves to enhance the realization of phonological contrasts. This hypothesis predicts that clear speech production shows predictable and systematic cross-language similarities and differences, and that the clear speech intelligibility benefit is modulated by the listeners’ experience with the target language. To address these predictions, we present data from a cross-language comparison of clear speech production and a cross-population comparison of clear speech perception. These studies provide fundamental information about variability in speech intelligibility which may ultimately lead to effective, efficient, and listener-specific speech intelligibility enhancement strategies.
An overview of beamforming, matched-field processing, and time reversal techniques
Authors: Kuperman William A.
Published: May 2016

Beamforming (BF), matched-field processing (MFP), and time reversal (TR) are intimately related. On the simplest level, MFP is a generalization of BF in which the replicas are solutions to a wave equation descriptive of the environmental propagation physics as opposed to BF in which the replicas are typically plane waves. The TR process, on the other hand, is usually taken to be an active process, independent of computer modeling, in which the received signals at the elements of an array are time reversed and physically retransmitted. In the literature, one often finds examples for which the process of retransmission is implemented by a computer simulation. This is simply a linear version of BF or MFP. Further, passive TR does not refer to this latter case but is a special case. In all cases, there are adaptive processing augmentations. An interesting take on TR is that when TR works, it can be thought of as a kind of proof of existence that the medium supports the localization goal of BF and/or MFP. We review the connection between these various processors.
Insights from three profiling studies of auralized concert hall acoustics: Support for a three dimensional perceptual space?
Authors: Kuusinen Antti , Lokki Tapio , Pätynen Jukka , Tervo Sakari
Published: May 2016

Since 2009, we have now completed three individual vocabulary profiling studies of auralized concert hall acoustics. In-line with the work of others, these studies have verified that the main perceptual aspects describing acoustic differences are, more or less, loudness, reverberance, width, envelopment, definition/clarity, brightness, bass, and proximity/intimacy. Our studies, however, do not indicate that these aspects would vary independently when moving from hall of to hall, but that the perceptual changes in many aspects generally co-occur. While independency can be understood in terms of attention, and the number of perceptual aspects by considering the different “tastes“ of listeners, it seems that the perceptual differences between halls are actually governed by three main factors. The interpretation of these factors depends on the viewpoint and here we discuss some possible interpretations based on these three profiling experiments and the literature as well as the implications concerning the objective parameters.
Overview of the behavioral effects of noise on animals
Authors: Mellinger David K.
Published: May 2016

Animal responses to noise vary with both the noise itself and with the condition, and especially the behavioral state, of the animal. Responses include movement away from or toward the noise source on time scales from seconds (immediate response) to minutes (changes in breathing rates of marine mammals) to months or years (abandonment or adoption of habitats); changing the frequency, duration, intensity, or rate of occurrence of vocalizations; non-response due to masking of sounds important for mate-finding, predator detection, prey detection, navigation, socialization, parent-offspring bonds, etc.; increases in stress responses; and so on. Responses are mediated by a host of condition of the receiving animal, including its behavioral state (feeding, resting/sleeping, traveling, advertising for mates, etc.), its age/sex class, its mating status, its location within its habitat, past exposure to noise, presence of conspecifics, presence of predators, and many more factors. An overview of these topics is presented. [Work supported by ONR and LMR.]
Relating the decreasing frequency of Sri Lankan pygmy blue whale calls to the local soundscape
Authors: Miksis-Olds Jennifer L. , Nieukirk Sharon
Published: May 2016

Sri Lankan pygmy blue whale calls consist of three components: (1) low frequency pulsive unit, (2) frequency modulated upsweep, and (3) long tonal downsweep. The (~100 Hz) tonal downsweep is the most distinct of the call units and lasts 20–30 s. Spectral characteristics of the tonal downsweep and long-term patterns of environmental sound levels were analyzed from the Comprehensive Nuclear-Test-Ban Treaty International Monitoring Station at Diego Garcia in the Indian Ocean from 2002 to 2012. Average weekly spectral frequency peaks and ambient sound levels were computed. The peak frequency of Sri Lankan pygmy blue whale calls decreased from approximately 107 Hz to 100 Hz over a decade corresponding to a 0.55 Hz/year rate of decrease. To date, this is the largest rate of decrease observed for any blue whale call. Analysis of the ambient sound levels in the vocalization and adjacent bands did not exhibit equivalent patterns in source level trends. Potential drivers of the observed trends will be discussed. [Work supported by the Office of Naval Research.]
Triggered drug release from liposome-microbubble pendant complexes: From model systems to tumor therapy in a murine adenocarcinoma model
Authors: Kilbanov Alexander , Du Zhongmin , Diakova Galina , Chin Chien Ting , Shi William , Raju Balasundar , Seip Ralf
Published: May 2016

Liposome-microbubble complexes allow delivery of drugs that cannot be otherwise associated with the bubble shell: water-soluble drugs and proteins. We prepared liposome-microbubble pendants by decorating biotinylated microbubbles with biotinylated liposomes via streptavidin. A model dye calcein was used as a model release marker. Using focused ultrasound (Philips TIPS, 1 MHz, 7 MPa) we were able to release ~30% of the entrapped dye. For an enzyme thrombin, ~11% of the entrapped material was released following pendant insonation. In vivo tumor therapy was performed with doxorubicin-liposome-microbubble pendants in a subcutaneous MC38 murine adenocarcinoma model. Doxorubicin was loaded in liposomes via an ammonium citrate gradient procedure. By using larger liposomes, >>80nm (as in Doxil/Lipodox), we prepared pendants carrying ~1 pg doxorubicin per particle. To avoid tumor blood flow stoppage caused by high-power insonation of microbubbles in tumor vasculature, we applied continuous sine wave ultrasound (Birtcher Megason, 1 MHz, 0.6 W/cm2, 3 s on/10 s off, for 10 min) immediately following iv administration of doxorubicin-liposome-microbubble pendants (6mg/kg mouse body mass) under isoflurane anesthesia. Treatments were performed for two weeks, 2–3 times a week. Suppression of tumor growth in the experimental group was observed. All of control animals demonstrated rapid tumor growth. Overall, pendant structures may become new tools for ultrasound-triggered drug delivery. [Study supported in part via NIH R21/33 CA102880, EB016752.]
Low-frequency ultrasound for the delivery of therapeutics to the gastrointestinal tract
Authors: Schoellhammer Carl M. , Schroeder Avi , Maa Ruby , Lauwers Gregory Y. , Swiston Albert , Zervas Michael , Barman Ross , DiCiccio Angela M. , Brugge William R. , Anderson Daniel G. , Blankschtein Daniel , Langer Robert , Traverso Giovanni
Published: May 2016

Rapid and effective drug delivery to the gastrointestinal (GI) tract can be a significant challenge. This is because of the harsh environment present in the GI tract and fast transit times in disease states. Physical enhancers, such as ultrasound (US), may enable the rapid delivery of therapeutics while circumventing the need for formulation development. Despite being investigated for other uses, low frequency US has not been studied for GI-based delivery previously. Our group has developed a hand-held device for the rapid delivery of therapeutics to the colonic mucosa. The device utilizes low-frequency US, which is able to painlessly and reversibly permeabilize the tissue. Short, 1-minute treatments in 80 kg Yorkshire pigs were found to enhance the delivery of mesalamine, a drug used for the treatment of inflammatory bowel disease, 22.4-fold over a conventional enema. The safety and efficacy of US were further validated in a rodent colitis model. The delivery of proteins was also possible. US-mediated GI delivery has many potential applications ranging from localized treatment with anti-inflammatories to the more broad delivery of macromolecules. This new technology could prove invaluable in both clinical and research settings, enabling improved therapies and expansion of research techniques applied to the GI tract.
In vitro and in vivo platforms for focused ultrasound-controlled drug delivery and release
Authors: Arvanitis Costas
Published: May 2016

Focused ultrasound (FUS) holds great promise for the development of effective and safe anticancer treatment protocols. FUS does not only allow to modulate the permeability of tumor vessels and enhance the extravasation of large molecules but to also locally trigger the release of their highly penetrating cargo. To utilize this potential in vitro and in vivo, platforms that allow for detailed assessment and optimization of the FUS-controlled drug delivery and release protocols are essential. We will present two such platforms for FUS-controlled drug delivery and release. First, we will introduce a novel acoustofluidic system with temperature and pressure sensor embedded that enables the accurate control of drug-release and the establishment of chemotherapeutic agent concentration gradients in a physiologically relevant 3D tumor model. Next, we will present an integrated US- and MR-guided FUS system for controlling the mechanical and thermal effects of FUS in vivo. Fast methods to visualize and control microbubble oscillations along with real time FUS-induced mild hyperthermia with this system will be shown in brain tumors of rodents. The FUS-induced release of the chemotherapeutic agent doxorubicin from a liposomal carrier is used to demonstrate the utility of the two systems for developing and optimizing new therapeutic protocols.
Nonlinear vibration experiment: Clamped circular elastic plate with granular material loading
Authors: Santos Emily V. , Korman Murray S.
Published: May 2016

Experiments using a soil-plate-oscillator (SPO) involve a vertical cylindrical column of granular medium (masonry sand, glass spheres, uncooked brown rice, un-popped popcorn kernels, or even “Toasty Oats” ™ cereal) that is supported by an air-backed thin circular elastic acrylic plate (20.3 cm diameter and 3.2 mm thick) that is rigidly clamped to the bottom of a thick-walled aluminum tube. The soil column is driven from below using an electrodynamic system. Here, an AC coil placed on axis and below the plate, drives a 1 cm diameter 1.5 cm long rare earth magnet that is fastened to the underside center of the plate. The coil is electrically driven by an amplified swept sinusoidal slowly varying chirp. A small accelerometer attached to the magnet is used to measure the vibration. In nonlinear tuning curve experiments the resonant frequency decreases significantly with increased amplitude—representing a softening in the nonlinear system. For fixed amplitude the resonant frequency vs. the granular medium mass loading (over the plate) reaches a minimum and then increases with increased loading due to the granular medium’s flexural stiffness—which overcomes the mass loading effects. For water loading, the frequency always decreases since there is no bending stiffness.
Vibration experiments using a clamped circular elastic plate with edible granular material loading
Authors: Lewis Blair E. , Smith Ebonie , Korman Murray S.
Published: May 2016

An apparatus called the soil-plate-oscillator (SPO), designed to study flexural vibration of a soil loaded plate, consists of a thin circular elastic (acrylic) plate (8 in. diam, 1/8 in. thick) clamped below a thick-wall cylindrical aluminum tube supporting a vertical soil (or sand) column or other granular material. A small accelerometer attached to a 1 cm diam rare earth magnet (which is fastened to the center of the plate from below) is used to detect the plate vibration response. The plate is driven from below by an AC coil (located coaxially below the plate and securely fastened) using an amplified swept sinusoidal current. The charge amplified accelerometer signal is measured versus frequency by a spectrum analyzer. With interest in studying light density granular media (with various grain sizes) experiments were performed with uncooked brown rice, quick oats, un-popped popcorn kernels pretzel gold fish crackers, and pretzel nuggets. The resonant frequency reaches a minimum and then increases with increased granular medium loading due to the material’s flexural stiffness which overcomes the mass loading effects. Results (normalized to the unloaded frequency and clamped plate mass) are compared with dry sifted masonry sand. A theoretical model is used to help describe the effects.