bluuebunny/crossref_metadata_2025 huggingface dataset:
Impedance tube experiments as a tool to teach acoustics of porous media
Authors: Turo Diego , Glean Aldo A. , Good Chelsea E. , Vignola Joseph F. , Ryan Teresa , Judge John A.
Published: May 2015

As a practical matter, sound propagation in many everyday situations includes interactions with porous materials. Such materials include textiles, foams, gravel, grass-covered ground, asphalt, and trees. Modeling sound propagation in complex environments, such as passenger cabins or urban spaces, with porous materials like these is essential to understanding realistic acoustics problems. The theory behind the sound absorption in porous material is not typically included in introductory acoustics courses. This is, at least in part, attributable to the mathematical complexity of the topic. Despite this barrier, acoustic properties of porous material can be easily introduced to typical undergraduate students using simple experiments to demonstrate the acoustic effects of different materials. This presentation describes acoustic property measurements of rigid-frame porous material with straight cylindrical pores as well as foam and soil included in an “Introduction to Acoustics” class at the Catholic University of America. The apparatus is composed of a LabVIEW measurement interface, a pair of microphones, and a simple aluminum impedance tube. The modular design allows students to adapt the software or hardware for other experiments. These hands-on experiences are intended to impart a conceptual understanding of the theory of sound absorption and the acoustic performance of sound absorbing (porous) media.
Accurate mobile noise measurements: Challenges for the app developer
Authors: Faber Benjamin
Published: May 2015

The ubiquity of mobile computing devices, their connection to the cloud, and their media-centric nature makes them attractive for wide scale acquisition of acoustical information, including human noise exposure in various environments and at various times. One concern in harnessing the potential of such a network of devices is ensuring that each device is able to acquire the desired acoustical information with sufficient accuracy. It is possible to make accurate acoustical measurements, as long as care is taken to ensure that the hardware, software, and users all work together to ensure success. System software, signal acquisition hardware, microphones, the mobile devices and the people who use them each present certain issues and challenges to the process of making accurate and reliable acoustical measurements. Various of these issues and challenges will be presented and discussed from an app developer’s perspective.
Characterization of the smart-phone radiated noise using nearfield acoustic holography
Authors: Kim Donghyun , Park Taeyoung , Ohm Won-Suk
Published: May 2015

Smart phones have dramatically evolved on the functional and aesthetic fronts in recent years. However, as smart phones get slimmer, problems arise where the noise radiated from the smart phone, albeit small in SPL, interferes with the conversation and degrades the call quality. The noise radiation is primarily due to the vibration of the internal electronics components and its transmission through the circuit board and the casing. In this paper the nearfield acoustic holography (NAH) is used to characterize the 3-D sound field of the smart-phone radiated noise, which is tailored specifically to deal with the small size and the low SPL of the sound radiator. Quantities such as acoustic pressure, particle velocity, and intensity at the smart phone surface are obtained and utilized to identify parts that are responsible for noise generation. In this respect, the NAH proves to be an effective tool for the characterization and control of the smart phone acoustics.
Acoustic emissions of ice fracture
Authors: Yashinski Melisa , Hayashi Rintaro , Heei-Wai Tyler , Allen John S.
Published: May 2015

Acoustic signals of ice movement and breaking has been recorded in previous field studies, but the specific role of salinity on ice fracture noise remains an open research topic. In lab studies, salinity has been shown to alter the mechanical properties but the associated emissions are not well understood. In this study, high-speed optical visualization is done in conjunction of acoustic measurements of ice fracture for three salinity values in air and underwater. Fracture strength is determined through three point bending and the role of columnar structure representative of Arctic ice is explored. The elastic–plastic behavior is characterized through time-frequency analysis.
Evaluation of the spatial impulse response of planar ultrasonic radiators
Authors: Kalkan-Savoy Ayse , Misiunas Nicholas , Miniter J. Cory , Chandra Kavitha , Thompson Charles
Published: May 2015

A method for evaluating the spatial impulse response for a planar source having arbitrary velocity and delay distribution is presented. The time-domain approach is based on the Rayleigh integral formulation for the velocity potential. To obtain the velocity potential one must evaluate and superpose the contribution from each elemental element of the radiator. This step entails the accumulation of the amplitude contribution from each elemental source arriving at the observation point at a prescribed time. The problem of sorting of these arrivals is examined in this work and procedures for mapping the algorithm for implementation on general-purpose graphics processing units are presented.
Lessons learned from multichannel cochlear implants that are relevant to a visual prosthesis
Authors: Patrick Jim
Published: May 2015

The clinical success of the multichannel cochlear implant was built on the successful outcomes of the multidisciplinary research program led by Professor Graeme Clark at the University of Melbourne and many of the outcomes from these studies can also be applied to other sensory prostheses, including the visual prosthesis. A primary requirement of any neural prosthesis is that it is safe, and this presentation will include studies that define stimulus parameters that allow stable long term responses, with no evidence of metabolic overload or neural degeneration. Any device that is chronically implanted for the life of a patient must be reliable, with a low likelihood of need for replacement because of device failure or infection, and the presentation will include both the results from Clark's infection studies and long term cochlear implant reliability observations. The presentation will describe the design of an experimental retinal prosthesis that uses an electrode array that is based on an array that was used to stimulate the cochlear nucleus of profoundly deaf patients. It will include preliminary results for volunteer patients, and approaches that may improve these pilot study outcomes.
Lessons learned from cochlear implants that are relevant to a vestibular prosthesis
Authors: Rubinstein Jay T. , Phillips Chris , Nie Kaibao , Ling Leo , Phillips James O.
Published: May 2015

In October, 2010, we began human studies of a vestibular prosthesis. Our goal is to develop a device for the management of several vestibular disorders that defy existing treatment modalities. We have long-term data on four human subjects and ten non-human primates and are awaiting regulatory approval of our second-generation device, modified based on that data. We have been guided by a wealth of information based on lessons learned from cochlear implants. These lessons include first and foremost the otherwise hubristic idea that an effective vestibular prosthesis is technically feasible. Indeed the extraordinary compensation mechanisms of the central vestibular system convince us that such a prosthesis could be even more effective than for hearing. Second, the ability to leverage CI engineering expertise and industry relationships has been critical to our success so far. Third, the regulatory comfort with the success and favorable risk profile of cochlear implants has greatly speeded up human translation. Fourth, surgical familiarity with these devices has greatly enabled our research and facilitates future multicenter studies. Lastly, experience with “soft-surgery”, hearing preservation, and single-sided deafness cochlear implantation holds forth alluring possibilities for the range of vestibular disorders that may eventually succumb to this closely related technology.
Anatomical considerations for the design and applications of cochlear implants
Authors: Rask-Andersen Helge E. , Liu Wei , Schrott-Fischer Annelies , Glueckert Rudolf
Published: May 2015

This presentation aims to display some important anatomical characteristics and variations of the human cochlea that may influence outcomes with cochlear implants. I will describe the complexity of the “hook” region and how it may challenge atraumatic insertion of an electrode array. In addition, I will discuss advantages and disadvantages of various cochleostomy approaches and of various trajectories for insertions. These anatomical considerations are informed by micro dissections of human temporal bones and plastic casts of different parts of the bones. In addition, the studied microanatomy of the basilar membrane may inform insertions and insertion depths needed to preserve cochlear structures. In particular, the studies suggest that the vulnerability of the membrane may be greatest at the apex and this possibility has implications for electrode designs and insertions. Also, the apical region may be most susceptible to inflammation and fibrosis due to its anatomy. The anatomical considerations for safe insertions of electrodes, including preservation of the remaining neural tissue, will be discussed. This work was supported by grants from Uppsala University Hospital and Uppsala University; the Tysta Skolan Foundation; the Swedish Deafness Foundation; the European Community 7th Framework Programme; and kind private donations from Börje Runögård.
Tissue engineering and pharmaceutical interventions
Authors: Miller Josef M. , Raphael Yehoash , Duncan Keith R. , Altschuler Richard A. , Corfas Gabriel
Published: May 2015

Hearing performance with modern cochlear implants is dependent on remaining sensory and neural elements. CNS plasticity and individual capacity for outstanding performance with meager peripheral neural survival provide some exceptions; however, both human and animal studies support a direct relationship of performance with structural integrity/function of remaining sensory and neural elements in the implanted ear. This dependency will increase with next generation implants. This has driven interventions based on increased understanding of molecular mechanisms underlying cell death and survival to enhance sensory and neural survival. It has driven tissue engineering of remaining elements with neurotrophic and other factors to induce regeneration, neurite outgrowth, and stem cell replacements of lost elements. Delivery to the cochlea is being accomplished via middle ear or transtympanic application, direct delivery in bolus or continuous administration via osmotic pumps, as coatings or channels in implants, gene transfer via viral vectors, factors incorporated in nano- and micro-particles, and via systemic administration. Current results provide a base for optimism for a future integrated system of cochlear implant-drug/gene delivery system. Each agent and delivery has risks and benefits. Challenges to select the best strategy for translation and application in humans will be discussed. [This work was s supported by NIH/NIDCD grants R01 DC010412, DC 004820, DC011294, P30 DC005188, and DOD W81XWH-12-10492.]
Inverse problems in transient structural acoustics
Authors: Walsh Timothy F. , Aquino Wilkins
Published: May 2015

Inverse problems are frequently encountered in transient structural acoustics. Given measured accelerometer or microphone time histories, one may need to estimate material properties in a structure, impedance conditions on the boundaries, shape or topology of an object, or characterize acoustic and structural sources that produced the measured data. Applications include model calibration, acoustic testing of aerospace structures, military surveillance, and underwater acoustics. Typically, accelerometer or microphone pressures are measured experimentally, and it is desired to characterize the material parameters, boundary conditions, topology, or acoustic sources that produced these accelerations or microphone pressures. In this talk, we will present a set of example inverse problems in structural acoustics, and a framework for their solution using an operator-based partial differential equation (PDE) constrained optimization approach. This abstract framework enables one to reduce any inverse problem to a set of fundamental operations and enables re-use of several software constructs. Formulations will be presented in both the time and frequency domain, and the merits and drawbacks of both approaches will be discussed. [Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL850000.]
Time windowed comparisons between models and measurements
Authors: McDaniel James G.
Published: May 2015

The present work proposes and demonstrates a method for improving the accuracy of large finite element models using measurements. Finite element analysis routinely allows for the construction of dynamic models with millions of degrees of freedom. The models often involve a large number of parameters, such as material properties and dimensions, that are not precisely known. For example, one may measure the material properties of a homogeneous sample but those properties will vary from sample to sample. Moreover, material properties may change considerably during construction as the material is prestressed, bonded, or welded. Therefore, it is often the case that the finite element model does not agree with measurements and one is faced with the task of modifying model parameters to yield agreement. This is made difficult by the large number of parameters as well as the computational cost of evaluating the model for each set of parameter choices. The present work proposes a time windowing method that localizes the spatial volume of response in the model and experiment and therefore isolates a small number of model parameters that may be varied to bring agreement. Numerical examples are presented to illustrate the method.
Non-distorting method of vowel normalization by transposition in the semitonal scale
Authors: Gomulkin Danila
Published: May 2015

Converting formant values from Hertz into semitones provides a remarkable “area agreement” between vowel systems in the F1/F2 plane without distorting intervals between the formants. Further simple transposition of a Sample system in relation to a Reference system by the difference between the mean of all converted F1s and F2s for the Sample speaker/group and the mean of those for the Reference speaker/group efficiently eliminates physiological mismatch between the speakers/groups and allows for convenient comparison of the vowel systems in a meaningful scale of pitch intervals. To convert formant n of vowel V from Hertz to semitones (expressed in MIDI keyboard numbers) use formula: [1] Fn[V]midi = midi(Fn[V]Hz), where [2] midi(x) = 12*log2(x/440) + 69. To normalize converted formants of a Sample speaker/group against those of a Reference speaker/group, deduct from the converted Sample formants (Fn[V]midi (Sample)) the difference between the mean of all converted F1s and F2s for the Sample speaker/group and the mean of those for the Reference speaker/group (Δ MEANmidi(Sample-Ref)): [3] F*n[V]midi (Sample) = Fn[V]midi (Sample) - Δ MEANmidi(Sample-Ref)
Realtime voice activity and pitch modulation for laryngectomy transducers using head and facial gestures
Authors: Mohan Gautam , Hamilton Katherine , Grasberger Andrew , Lammert Adam C. , Waterman Jason
Published: May 2015

Individuals who have undergone laryngectomy often rely on handheld transducers (i.e., the electrolarynx) to excite the vocal tract and produce speech. Widely used electrolarynx designs are limited, in that they require manual control of voice activity and pitch modulation. It would be advantageous to have an interface that requires less training, perhaps using the remaining, intact speech production system as a scaffold. Strong evidence exists that aspects of head motion and facial gestures are highly correlated with gestures of voicing and pitch. Therefore, the goal of project MANATEE is to develop an electrolarynx control interface which takes advantage of those correlations. The focus of the current study is to determine the feasibility of using head and facial features to accurately and efficiently modulate the pitch of speaker's electrolarynx in real time on a mobile platform using the built-in video camera. A prototype interface, capable of running on desktop machines and compatible Android devices, is implemented using OpenCV for video feature extraction and statistical prediction of the electrolarynx control signal. Initial performance evaluation is promising, showing pitch prediction accuracies at double the chance-level baseline, and prediction delays well below the perceptually-relevant, ~50 ms threshold.
Documenting sound change with smartphone apps
Authors: Leemann Adrian , Kolly Marie-José , Britain David , Purves Ross , Glaser Elvira
Published: May 2015

Crowdsourcing linguistic phenomena with smartphone applications is relatively new. Apps have been used to train acoustic models for automatic speech recognition (de Vries et al. 2014) and to archive endangered languages (Iwaidja Inyaman Team 2012). Leemann and Kolly (2013) developed a free app for iOS—Dialäkt Äpp (DÄ) (>78k downloads)—to document language change in Swiss German. Here, we present results of sound change based on DÄ data. DÄ predicts the users’ dialects: for 16 variables, users select their dialectal variant. DÄ then tells users which dialect they speak. Underlying this prediction are maps from the Linguistic Atlas of German-speaking Switzerland (SDS, 1962-2003), which documents the linguistic situation around 1950. If predicted wrongly, users indicate their actual dialect. With this information, the 16 variables can be assessed for language change. Results revealed robustness of phonetic variables; lexical and morphological variables were more prone to change. Phonetic variables like to lift (variants: /lupfə, lʏpfə, lipfə/) revealed SDS agreement scores of nearly 85%, i.e., little sound change. Not all phonetic variables are equally robust: ladle (variants: /xælə, xællə, xæuə, xæɫə, xæɫɫə/) exhibited significant sound change. We will illustrate the results using maps that show details of the sound changes at hand.
The recorder's paradox: Balancing high-quality recordings with spontaneous speech in noisy recording environments
Authors: De Decker Paul
Published: May 2015

While sociophonetic analysis requires high-quality sound recordings, sociolinguistic interviews (Labov 1984) are often conducted in uncontrolled, natural environments to elicit casual speech (Tagliamonte 2006). The effects of room acoustics and background noise on formant measurements, however, have never been systematically examined. To empirically investigate how ambient noise affects recording quality and measurements, a male speaker of English was simultaneously recorded to multiple devices reading 260 carrier phrases. Three naturally occurring background noise conditions ( + 20dB, + 10dB, and + 0dB SNR) were created in Praat 5.4 (Boersma and Weenink 2014) and mixed with the original audio recordings. 10,028 measurements of F1 and F2 were taken at the temporal midpoint of each vowel in each of the four recordings using LPC analysis in Praat. Pearson's r tests in R (R Core Team, 2014) assessed the correlation between measurements from each recording. Main results reveal positive correlations between “noiseless” and + 20dB, and + 10dB SNR conditions for each device, all vowels and both formants. When the signal was not appreciably louder than the background noise (i.e. + 0 dB SNR) correlations significantly weakened. These findings are discussed as they relate to sociolinguistic investigations that need to balance high-fidelity recordings with noisier speaking environments.
Vowel nasalization might affect the envelop of the vowel signal by reducing the magnitude of the rising and falling slope amplitude
Authors: Eshghi Marziye , Alemi Mohammad Mehdi , Eshghi Mohammad
Published: May 2015

Electrical analog study of the vocal tract has long time ago shown that nasalization can cause a drop of 5–10 dB in the overall vowel amplitude (House and Stevens, 1956). In this preliminary study, the magnitude of rising and falling slope amplitudes from the vowel signal was introduced as a new index to discriminate oral vowels from nasalized vowels. Two speech samples of /iti/ and /iki/ were produced by two normal children and two age-matched children with cleft lip and palate and hypernasal speech. Speech samples were digitally recorded using a microphone and CSL software. The PRAAT software was used to extract the text file of the vowel segment (i.e., from the initiation of the vowel periodicity to the initiation of the constriction interval of the following plosive). Then, the text files were analyzed by MATLAB to measure amplitude rising and falling slopes of the vowel signal. Results indicated that mean falling and rising slopes of the amplitude in the nasalized vowel are smaller than those of the oral vowel. This technique might be considered as an objective index to measure vowel quality in disordered speech studies as well as speech synthesis.
Acoustic modeling of the perception of place information in incomplete stops
Authors: Willi Megan , Story Brad
Published: May 2015

Previous research on stop consonant production found that less than 60% of the stops sampled from a connected speech corpus contained a clearly defined hold duration followed by a plosive release [Crystal & House, JASA 1988]. How listeners perceive the remaining portion of incomplete stop consonants is not well understood. The purpose of the current study was to investigate whether relative formant deflection patterns, a potential model of acoustic invariance proposed by Story and Bunton (2010), is capable of predicting listeners’ perceptions of acoustically continuous, voiced stop consonants lacking a canonical hold duration. Listeners were randomly presented a total of 60 voiced stop-consonant VCV stimuli, each 100 ms in duration, synthesized using a computational model of speech production. Stimuli were created using a continuum of 20 equal step constrictions along the length of the vocal tract in three vowel-to-vowel contexts [see Story & Bunton, JSLHR 2010]. Participants listened to the stimuli and performed a forced choice test (i.e., /b-d-g/). The phonetic boundaries predicted by the relative formant deflection patterns and phonetic boundaries obtained by the forced choice test were compared to determine the ability of the acoustic model to predict participants’ perceptions. The acoustic and perceptual results are reported. [Work supported by NIH R01-DC011275.]
Measures of tone difficulty
Authors: Shih Chilin
Published: May 2015

Measures of difficulty are needed in many real life as well as computer-simulated applications. Such measures for text, math and science have long received academic and industrial attention due to the demands for k-12 instruction and assessment. In recent years, the demands for comparable studies of speech are on the rise given the popularity of on-line second language teaching software and games. The goal of this project is to explore whether the acoustic attributes of Mandarin lexical tones obtained from individual sound files can explain their level of difficulty experienced by second language learners. The study uses monosyllabic tones, thus isolating the task from measurements of complexity in order to focus on acoustics. We recorded sound files that are rich in natural variation using different levels of talker-to-listener distance, used quadratic decomposition to obtain three coefficients that represent each tonal contour, and analyzed their relationship with learners' performance. We will report the difference between native and second-language tone perception. The results have potential applications in speech synthesis: to generate tone tokens with different levels of difficulty for language learners, and different levels of talker-to-listener distance.
Sources of variability in consonant perception and their auditory correlates
Authors: Zaar Johannes , Dau Torsten
Published: May 2015

Responses obtained in consonant perception experiments typically show a large variability across stimuli of the same phonetic identity. The present study investigated the influence of different potential sources of this response variability. It was distinguished between source-induced variability, referring to perceptual differences caused by acoustical differences in the speech tokens and/or the masking noise tokens, and receiver-related variability, referring to perceptual differences caused by within- and across-listener uncertainty. Two experiments were conducted with normal-hearing listeners using consonant-vowel combinations (CVs) in white noise. The responses were analyzed with respect to the different sources of variability based on a measure of perceptual distance. The speech-induced variability across and within talkers and the across-listener variability were substantial and of similar magnitude. The noise-induced variability was smaller than the above-mentioned contributions but significantly larger than the amount of within-listener variability, which represented the smallest effect. To determine how well the source-induced variability is reflected in different auditory-inspired internal representations (IRs), the corresponding perceptual distances were compared to the distances between the IRs of the stimuli. Several variants of an auditory-spectrogram based IR and a modulation-spectrogram based IR were considered and the importance of the different domains for consonant perception was evaluated.
Underwater acoustics at the Naval Air Development Center
Authors: Gabrielson Thomas B.
Published: May 2015

Much of the progress in underwater-acoustic research from World War II to the present has been funded by government agencies for development of sonar systems. Although sonar is often considered the domain of surface ships and submarines, the naval aviation community has made significant contributions to basic underwater-acoustic measurement and to acoustic-system development. In the 1940s, the U.S. Navy established the Naval Air Development Center (NADC) in Warminster, Pennsylvania, as the lead laboratory for naval aviation research and development and a substantial part of the work of that laboratory supported development of air-deployed sonar systems. Partnerships between NADC, other laboratories both domestic and foreign, and manufacturers produced a stream of innovative, inexpensive, and expendable devices to support the missions of marine patrol aircraft; these same devices were used extensively for ocean-acoustic measurements. Basic bottom-reflection loss, ambient-noise level and directivity, and reverberation measurements were made using air-deployed sonobuoys and acoustic sources. While lacking the precision of ship-based measurements, the cost of airborne surveys was low, deployment was rapid, and the coverage was ultimately global.
The pull of finite acoustic beams
Authors: Mitri Farid G.
Published: May 2015

The counterintuitive effect of pulling an object back towards a finite (bounded) circular source with the use of acoustic forces of progressive waves is demonstrated, which defines the acoustic “tractor beam” behavior [F. G. Mitri, “Near-field single tractor-beam acoustical tweezers,” Appl. Phys. Lett. 103(11), 114102, 2013; “Single Bessel tractor-beam tweezers,” Wave Motion 51(6), 986–993, 2014]. Experimental results and numerical predictions show the emergence of negative forces due to continuous (CW) and amplitude-modulated (AM) propagating waves. The circumstances under which a collimated beam emanating from a finite aperture can act as a tractor beam and related investigations are also discussed.
Acoustic radiation force on a particle in ultrasonic standing wave fields driven by a piezoelectric plate
Authors: Lipkens Bart , Ross-Johnsrud Ben , Liu Minghe , Ilinskii Yurii , Zabolotskaya Evgenia
Published: May 2015

Acoustic radiation forces on a particle or droplet in a liquid have been studied mostly for relative simple acoustic fields such as plane traveling waves, or planar standing waves. In this study, a more complicated acoustic field is considered, namely, the acoustic standing wave field generated by a rectangular piezoelectric plate with finite size. The piezo-electric plate is excited in its thickness mode. A three dimensional model of the vibration of the piezo-electric plate has been developed. The plate is loaded by an acoustic standing wave field in a fluid on one side, and is air backed on the other side. The three-dimensional acoustic standing wave field generated by the piezo-electric plate is calculated. The acoustic radiation force on a particle or droplet can then be calculated using a framework such as developed by Gor’kov or Ilinskii and Zabolotskaya. The theoretical calculations are compared with numerical predictions using a two-dimensional model of the piezo-electric plate and resonator. Finally, experimental results were obtained in a resonator with a one inch acoustic path length and driven by a 2 MHz PZT-8 one inch by one inch piezo-electric plate. Experimental results will be compared with theoretical and numerical predictions.
Enhancement of osteogenesis and stem cell differentiation by injectable nanocomposite and dynamic acoustic radiation force stimulation
Authors: Shrivastava Vaishnavi , Patel Sunny , Hu Minyi , Pongkitwitoon Suphannee , Sitharaman Balaji , Qin Yi-Xian
Published: May 2015

Osteopenia affects mineral density, microstructure, and integrity of bone, leading to increased risk of fractures, as well as high rates of non-union, which affect patients’ quality of life. Current treatments are ineffective, requiring invasive surgeries and/or long-term drug therapy. The objective of this study was to develop a novel noninvasive biomimetic treatment for rapid regeneration to promote cell differentiation and osteogenesis. An injectable orthopedic implant was designed by developing a thermosensitive scaffold incorporating carbon nanotubes and chitosan-β glycerophosphate hydrogels. An innovative biophysical stimulation using dynamic ultrasound radiation force (ARF) was used to induce carbon nanotube resonance for regulating osteogenic differentiation of stem cells. An assay on activity of ALP, a biomarker of osteogenesis, and a fluorescence-based live/dead cell assay were conducted to determine the best treatment for inducing rapid cell formation. The single-walled carbon nanotube scaffold and 60 mW/cm2 ARF group was the best treatment, and enhanced ALP activity and stem cell differentiation by 430%. Cell viability was increased by 65% through the ARF treatment. This study developed a novel treatment for regulating cell proliferation using single-walled carbon nanotube nanocomposite implants and synergistic stimulation of stem cells with ultrasound. This rapid, noninvasive, cost-effective treatment may provide an innovative alternative for osteoporotic treatment and rapid fracture healing.
Understanding diffractive and reflective contributions to scattering and extinction of intersecting plane waves
Authors: Marston Philip L.
Published: May 2015

Scattering and extinction of intersecting plane waves is relevant to many processes of interest, including the interpretation of bistatic scattering and the understanding of acoustical radiation forces. A special case that exhibits diverse behavior is the illumination of a sphere by an acoustic Bessel beam. Consider high frequency scattering in which the sphere radius exceeds the wavelength. Recent progress in understanding diffractive scattering contributions uses Babinet’s principle and the Kirchhoff approximation [P. L. Marston, J. Acoust. Soc. Am. 135, 1668–1671 (2014)]. The optical theorem for invariant beams [L. Zhang and P. L. Marston, J. Acoust. Soc. Am. 131, EL329–EL335 (2012)] was used to evaluate the extinction. Comparison with the partial wave series for the extinction supports the utility of quasi-scaling involving the Bessel beam’s conic angle. The reflective scattering contribution is subtler; however, evaluating it quantitatively explains an abrupt transition in the spacing of fringes in bistatic scattering patterns for spheres centered in Bessel beams. The transition is visible where the scattering angle passes through the beam’s conic angle [P. L. Marston, J. Acoust. Soc. Am. 121, 753–758 (2007)]. Diffractive and reflective contributions for smooth objects illuminated by intersecting waves are relevant to many other situations. [Work supported by ONR.]
Spatially uniform harmonic acoustic radiation force excitation using one-dimensional linear array
Authors: Bayat Mahdi , Alizad Azra , Fatemi Mostafa
Published: May 2015

Low frequency harmonic force excitation can be used for both imaging and tissue characterization. This type of excitation can be achieved via intersecting two beams that slightly differ in frequency. One requirement of this technique is creating focused intersecting beams using available hardware. Previous studies have suggested different configurations for creating harmonic radiation force using linear arrays. However, these methods rely on identical frequency response assumption across all elements of the aperture. In practice, this assumption can be easily violated, especially if the transmit frequencies are not around the center frequency of the probe. When using electronic steering and focusing at different locations, this can result in a non-uniform radiation force pattern due to frequency changes in the sub-aperture. When used for vibro-acoustography, this manifests as vertical streaks in the final image that can severely degrade the quality of the image. We present a novel technique that minimizes element transmit frequency switching which in turn results in a more uniform excitation intensity. The results of applying this aperture configuration for vibro-acoustography imaging of breast phantoms with hard inclusions show significant improvements over previous methods. [This work was supported by NIH Grant R01 EB17213.]
Navigating the track to tenure: A liberal arts college perspective
Authors: Bradley David T.
Published: May 2015

Pursuing a career in the academy can be rewarding and challenging. Securing a tenure-track position at a liberal arts college can be particularly difficult since there are far fewer available positions, and because this type of institution is very different from the ones that grant the requisite Ph.D. degree for the job. A liberal arts college is an institution that is undergraduate focused, offering a breadth of courses in the humanities, social sciences, and natural sciences, while still providing the appropriate depth and rigor to prepare students for graduate school and industry. These colleges tend to have a stronger emphasis on teaching than larger universities, although professors are still expected to develop a thriving research program, typically only with the help of a few undergraduate research assistants. This presentation will discuss the unique aspects of being a professor at a liberal arts college while describing one successful path to the coveted tenured status.
An administrative perspective on preparing for careers in academia
Authors: Sommerfeldt Scott D.
Published: May 2015

As the dean of a college, one of my responsibilities is to interview each person that the departments in my college have some interest in hiring. As a result, I have interviewed dozens of candidates, some of whom were very strong and some of whom were far weaker. In this presentation, I will overview some aspects of career preparation that students can focus on that will help prepare them to be strong candidates if they are interested in pursuing a career in academia. I will also discuss some aspects of the interviewing process that students can prepare for in an effort to present themselves favorably during interviews.
Preparing University of Mississippi graduate students for careers in acoustics
Authors: Raspet Richard
Published: May 2015

The acoustics program at the University of Mississippi originated in the Physics Department and is still closely associated with physics. The physics department requires all students teach two semesters of laboratory under the supervision of a laboratory physicist. The required physics curriculum is extensive so that the acoustics students only receive two semesters of acoustics courses. This leads to careful course design so that our students are broadly literate in acoustics. The necessary compression of class work means that speaking and writing skills are taught to the student by their research advisor in preparing conference talks, written papers, and dissertations.
The harmonic vistaphone
Authors: Kvistad Garry M.
Published: May 2015

Percussion instruments offer a wide range of frequencies from the lowest gongs to the highest bells. The natural modes of vibrations of all percussion instruments produce overtones, which are inharmonic. Builders of keyboard percussion instruments must carve bars in specific ways to include a few harmonic overtones of their choosing. Garry Kvistad, founder/owner of Woodstock Percussion, Inc., has built a set of tubes/rods, which he calls the Vistaphone, carefully tuned to the first 32 partials of the harmonic overtone series. In this presentation, Mr. Kvistad will demonstrate how polyrhythmic patterns played slowly can be sped up by means of a proprietary software program to yield musical intervals that correspond to the ratios of just intonation. After this introduction illustrating the relationship of pulse and pitch, the Vistaphone will be played to reinforce the phenomena of pure harmonic relationships. The listener will be able to experience the pure harmonic overtone series in just intonation which yields a rich bouquet of sustained sound with a multitude of harmonically related difference/summation tones. The only way to obtain this effect acoustically is to build a unique instrument of this type.
Ancient Aztec drum, the Huehuetl
Authors: Beristain Sergio
Published: May 2015

The Aztecs and other cultures in Mesoamerica used to build and play during their festivities and warriors gatherings, simple drums made out from a hollow tree trunk, carved in the inside in order to make a fairly uniform thick surface to form the resonant chamber, topped by an ocelot skin, and open in the bottom, usually by three supports made from the same tree piece, called huehuetl, which means that these drums were of different shapes and sizes, some of these trunks were highly decorated by carving in the surface three dimensional images related to animals, faces, warriors, and other figures. These drums were excited on the top either by bare hand or wood sticks, varying the sound by the strength of the hit, and the area of the ocelot skin actually hit. Here are presented some pictures of ancient huehuetls together with the acoustic analysis of the sounds produced with a small replica of this percussion instrument.
An overview of issues in quantification of the tonalness of sounds
Authors: Davies Patricia
Published: May 2015

Audible pitches in noise increase annoyance, and tone corrections to noise level metrics have been used in noise impact quantification for over 50 years. These corrections are a function of the prominence of the tone relative to the nearby spectral components. Frequency masking, the width of the tonal feature, and the frequency may also be taken into account. All measures are derived from spectral estimates. When a single or well isolated tonal components are present in noise, sounds are stationary and sufficient data is available for good spectral estimation, many tonalness metrics (Prominence Ratio, Tone to Noise Ratio, Tone Audibility, and Aures Tonality) work well. More challenging is quantification of tonalness when: the frequency is varying with time, either slowly or quickly; there is a harmonic series that is predominantly heard holistically not as a series of individual pitches; or there is beating because of the presence of multiple tones within a critical band. In music, the characteristics of harmonic families help us identify different instruments and manipulation of harmonic series in machinery noise can make tonal sounds more or less pleasant. The challenges of quantifying tonal contributions and their impact in these more complicated cases will be described
Tonal noise characteristics from HVAC equipment and how to improve practically and technically
Authors: Wang Jyuhn-Jier J.
Published: May 2015

All HVAC equipment has rotating components, such as compressors and fans. These critical components often exhibit annoying tonal characteristics. Although there are many engineering methods to improve the tonal characteristics, there exists no commonly accepted tonal metrics in HVAC equipment specifications, which typically only include sound power or sound pressure levels at few operating conditions. However, the equipment sound level can vary greatly by the operating conditions—the range may be as much as 10 dB or more, depending on compressor/fan types, sizes, and speed range. Although HVAC manufacturers understand the impact of the equipment tonal characteristics to the acoustical comfort of built environment, lack of customer requirement in the annoyance of the tonal characteristics makes it very challenging to be assessed and improved upon with the other competing functional requirements. This presentation will show typical tonal noise characteristics of chillers, air handlers, and transport HVAC equipment, and then propose methods to improve practically and technically from equipment manufacturer’s point of view.
Transformers in the built environment
Authors: Doggett Felicia
Published: May 2015

Tonal noise in the built environment can be distracting, annoying, and at times make it practically impossible to live or work in a building. One of the worst offenders of tonal noise in buildings is electrical transformers. Whereas the airborne sound output of transformers is not particularly high, the vibration and subsequent structure-borne noise can be extreme. In large commercial buildings, transformers are typically installed directly on structural concrete floors. When these same transformers are located on upper floors of buildings, structure-borne sound transmission can be significant on the occupied floors below. For the most part, the transmission loss of the concrete floors is more than sufficient in attenuating airborne sound but structureborne sound can carry throughout the floors below for large distances from the transformer location. The best way to truly solve the problem is by isolating the transformer. So, how easy is it to elevate and isolate transformers that weigh as much as a truck? This presentation focuses on case studies of transformer noise in buildings that are incorrectly installed, what was subsequently done in an effort to remediate the problems, and whether or not it was successful.
Multidimensional characteristics of annoyance perception to tonal building mechanical noises
Authors: Lee Joonhee , Wang Lily M.
Published: May 2015

Tones in noises from building mechanical systems can be a leading cause of complaints in an indoor environment. One of the greatest challenges to quantifying annoyance perception from these noises is the lack of information on how assorted acoustic characteristics relate to perceptual annoyance. Recent evidence suggests that annoyance perception by noises should be treated as a multidimensional rather than a unidimensional problem. Thus, the aim of this study is to explore multidimensional aspects of annoyance perception specific for building mechanical noises with tonal components. Tone frequency, tonal strength, presence of harmonics, and time fluctuation characteristics are investigated using actual noise recordings as well as artificially synthesized signals. Two subjective tests were implemented with the noise signals. Part A of the experiment is designed to identify prevailing acoustic characteristics for annoyance perception. The dominant acoustic characteristics were determined by multidimensional scaling analysis technique. A multidimensional annoyance model is subsequently proposed based on the test results. Part B is conducted to specifically investigate perceptual weighting of individual tones to overall contributions towards annoyance perceptions when complex tones are present in signals. The results of this test help to increase the accuracy of the developed annoyance model.
Numerical hybrid TMM-modal FEM method prediction of the vibroacoustic of sandwich panels with add-on damping
Authors: Rzig Imen , Atalla Noureddine
Published: May 2015

This paper discusses the numerical modeling of the vibroacoustic response of sandwich-composite panels with add-on damping, under acoustic excitation, diffuse acoustic field (DAF). A modal synthesis approach is used for the calculation of the structural response and the Rayleigh’s integral is used for the acoustic response. Since the panel has a viscoelastic core, a methodology is presented to handle efficiently the modeling of the frequency depended properties of the viscoelastic layer. A hybrid TMM-modal FEM method is used to predict the acoustic response in high frequency, using the equivalents properties of panel, which are calculated from strain energies’ panel. Next, a parameters' study on the effect of the viscoelastic layer location is presented. In particular, three locations are compared: within the Honeycomb core, within the skins and added to the skin with a constraining layer. The effects of the excitation type on the vibration and acoustic response are also discussed using the hybrid: TMM-modal FEM method. Key words: Sandwich NIDA, Modal FEM method, TMM method, viscoelastic damping, acoustic response, equivalent properties.
Building leakage detection and quantification using statistically optimized nearfield acoustic holography technique
Authors: Chelliah Kanthasamy , Raman Ganesh G. , Muehleisen Ralph T. , Patel Hirenkumar , Tatara Eric
Published: May 2015

This paper presents a building infiltration detection and quantification technique using statistically optimized nearfield acoustic holography (SONAH) technique. A model building with known cracks on its wall was investigated in this study. The model building housed a synthetic acoustic source. A hologram measurement was performed outside the model building and the sound pressure levels on the walls were reconstructed. The correlation between the reconstructed pressure levels and the area of the crack was obtained. It was found that the acoustic technique can successfully detect and quantify the leakages from the building model. Two different frequencies of reconstructions are compared and it was found that the lower frequency reconstructions were more accurate. Effects of various regularization methods, phase matching, and quantization error are discussed. Various methods to suppress the wrap-around error in the reconstructions will be addressed.