bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of a stress gradient enhanced piezoelectric actuator composite (GEPAC) with integrated ultrasonic NDE capablity
Authors: Bechet Antoine , Berthelot Yves , Lynch Christopher
Published: October 2013

Stress gradient enhanced piezoelectric composites (GEPACs) are unimorph based curved actuators that can be primarily used as low-frequency actuators embedded within an aircraft skin. The actuator is made of a thin PZT ceramic bonded between two composite layers with different coefficients of thermal expansion. Actuators have been manufactured with segmented upper electrodes so that they can also be used at ultrasonic frequencies to monitor continuously the integrity of the actuator itself (cracks), or of the actuator/skin assembly (debonding). This study will focus on the detection of debonding at the interface between the piezoelectric layer and the outer layers. The input signal is a one cycle burst at 1 MHz. The time domain signals recorded experimentally are compared with predictions from a finite element model (ABAQUS explicit). It is shown that the presence of a debonding defect can convert a symmetric pulse into a primarily antisymmetric wave. A simple correlation technique is used to estimate the size of the debonding defect. The ultrasonic NDE operation superposed to the low frequency actuation is demonstrated. [Work supported by the AFOSR.]
A rumbling index development for sound quality analysis of a vehicle
Authors: Lee Sang-Kwon , Kim Byung-Soo
Published: October 2013

Rumbling sound is one of the most important interior sounds of a passenger car, according to the conventional research. The evaluation of sound quality has been focused on the reduction of the A-weighted sound pressure level. However, an A-weighted sound pressure level cannot give the whole story about the sound quality based on human sensibility. The rumble index is required for the evaluation of the sound quality of a vehicle. In order to make a rumble index, the artificial neural network has been used. The sound metrics for the interior sounds of vehicles are used for the input of the neural network. The subjective ratio for the interior sounds of vehicles is used for the target of artificial neural network to train the weights of the neuron. For the train of the artificial neural network, 150 signals for rumbling sound are synthesized. The interior sounds of 16 vehicles are tested by using the trained artificial neural network. The output of artificial neural network becomes the rumbling index and has 90% correlation with the subjective results for interior sounds of 16 vehicles. [Work supported by BK21.]
MRI structure borne noise, in and out
Authors: Hoover K. Anthony
Published: October 2013

MRI equipment typically requires very low levels of ambient floor vibration. However, this same equipment often generates levels of vibration that are sufficient to cause complaints of excessive MRI noise in nonadjacent rooms. This paper will review two projects. The first investigates levels of floor vibrations caused by flyovers of medivac helicopters. The second investigates a structural floor slab designed to satisfy MRI ambient-vibration criteria, but, as predicted, allowed for excessive structure borne MRI noise. Difficulties with standard vibration isolation of MRI equipment will be discussed.
Environmental noise issues associated with medical facility HVAC equipment
Authors: Carnes Ted N. , Pelton Howard K. , Saenz Daniel W.
Published: October 2013

Medical facilities comprise a variety of types of buildings from research facilities to hospitals to professional office buildings to name but three. Many new hospitals are being located in close proximity to residential housing. Furthermore, as hospitals expand the buildings are closer to residential communities. Thus, the community noise aspects of these facilities are of even more importance than ever. This paper will examine how community noise intrusions can occur without proper planning, and how this can be avoided by knowing the community noise criteria, working closely with the design team to assist them with the proper planning and noise control design. Case histories will be presented that will include a hospital expansion with large rooftop equipment, new cooling towers and how these can be modeled as part of the overall hospital campus model to determine the community noise impact. In addition, a new chiller plant expansion adjacent to the residential areas will be examined, and how this can be modeled to show the various aspects of the community noise impact.
Resonant self-pumped thermoacoustic heat transfer
Authors: Swift Greg , Backhaus Scott
Published: October 2013

As a thermoacoustic engine or refrigerator is scaled up to higher power, it generally needs heat exchangers of a larger cross-sectional area. Constrained to lie adjacent to a stack or regenerator, large heat exchangers must use intricate geometries to interweave the thermoacoustic working gas and an external fluid (e.g., ambient cooling water or hot combustion gas) to bring them into intimate thermal contact. Such heat exchangers have many thermoacoustic passages in parallel, often entailing many parts and many joints that must be leak tight. Resonant self-pumped thermoacoustic heat transfer is a new alternative in which the thermoacoustic-to-external heat-transfer surface area is in the form of one long tube (or a few) extending far from the associated stack or regenerator. With a resonant sound wave in the tube and with diode-like nonlinear flow elements near the wave’s velocity maxima, a strong time-averaged circulation of the working gas carries the heat. This concept will be described and preliminary experimental results will be presented. [Work supported by DOE’s Office of Science and by Praxair, Inc.]
Driver parameter characterization method for a thermoacoustic cooler
Authors: Paek Insu , Mongeau Luc , Braun James E.
Published: October 2013

The efficiency of transducers used in electromechanically driven standing wave thermoacoustic coolers is governed by six parameters. The maximum efficiency is obtained around the frequency at which the total electrical input reactance is zero. The parameters in a linear circuit representation of the dynamic behavior of the driver are often frequency and amplitude dependent. This nonlinear response is due to the large acoustic power delivered and the resonant nature of the acoustic load. A method was developed to determine quickly and accurately driver equivalent parameters from independent measurements of the input voltage and current, as well as the piston acceleration and pressure. A system identification technique was used. Transfer function measurements were performed for a few driving frequencies close to the optimal operating condition of the thermoacoustic cooler. The data were used to calculate driver parameters off-line. Parameter values obtained for low piston force and displacement amplitudes were found to be significantly different than their values for larger amplitudes. The method can be used to find the optimal driver parameters for target operating conditions of a particular thermoacoustic cooler.
Numerical simulation of hydrodynamic and thermal effects around a 2-D stack plate in a thermoacoustic refrigerator
Authors: Marx David , Blanc-Benon Philippe
Published: October 2013

Two-dimensional Navier–Stokes equations for an unsteady and compressible flow are solved around a 2-D stack plate of a thermoacoustic refrigerator. The computational domain is a resonator slice including the resonator end but not the acoustic source. The standing wave is sustained in the domain using the characteristics method. The same methods were already used for the simulation of the coupling between stack plates and heat exchangers (AIAA Paper No. 2003-3150). The oscillating flow above the 2-D plate induces a periodic vortex creation at the ends of the plate. Numerical results will be compared to PIV measurements. The effect of the acoustic Mach number and geometrical parameters are studied. The temperature difference between the ends of the plate is also investigated and compared to linear theory. Some deviations can be attributed to the difference between the mean temperature gradient in the plate and the mean temperature gradient in the fluid. A streaming flow is also observed above the plate. [Work supported by DGA.]
Investigation of harmonic generation in thermoacoustic engines
Authors: Parker James E. , Hamilton Mark F. , Ilinskii Yurii A.
Published: October 2013

One factor limiting the efficiency of thermoacoustic engines and refrigerators is the generation of harmonics. Not only do thermoviscous losses increase in relation to the generation of higher frequencies, but the stack is not designed to optimize thermoacoustic processes at these frequencies. We describe here a semi-analytical investigation of nonlinear effects associated with harmonic generation. The approach is based on a regular perturbation expansion of the acoustical quantities, combined with the assumptions and methodology underlying the linear theory developed by Rott. At first order, Rott’s equations for the pressure and particle velocity are obtained and solved numerically. The second-order system consists of Rott’s equations for the second harmonic driven by a forcing function containing products of the first-order solutions. The goal is to solve the third-order system, given by Rott’s equations for the fundamental driven by products of the first- and second-order solutions, to determine the nonlinear correction to the fundamental component. The investigation was not completed at the time of writing, and we therefore present here the intermediate results for second-harmonic generation. These results provide partial explanations of how harmonic generation influences thermoacoustics. [Work supported by ONR and ARL:UT IR&D.]
Interpreting electrically evoked emissions using a finite-element model of the cochlea
Authors: Deo Niranjan V. , Grosh Karl , Parthasarathi Anand
Published: October 2013

Electrically evoked otoacoustic emissions (EEOAEs) are used to investigate in vivo cochlear electromechanical function. Electrical stimulation through bipolar electrodes placed very close to the basilar membrane (in the scala vestibuli and scala tympani) gives rise to a narrow frequency range of EEOAEs, limited to around 20 kHz when the electrodes are placed near the 18-kHz best frequency place. Model predictions using a three-dimensional inviscid fluid model in conjunction with a middle ear model [S. Puria and J. B. Allen, J. Acoust. Soc. Am. 104, 3463–3481 (1998)] and a simple model for outer hair cell activity [S. Neely and D. Kim, J. Acoust. Soc. Am. 94, 137–146 (1993)] are used to interpret the experimental results. To estimate effect of viscosity, model results are compared with those obtained for a viscous fluid. The models are solved using a 2.5-D finite-element formulation. Predictions show that the high frequency limit of the excitation is determined by the spatial extent of the current stimulus. The global peaks in the EEOAE spectra are interpreted as constructive interference between electrically evoked backward traveling waves and forward traveling waves reflected from the stapes. Steady state response predictions of the model are presented.
Effect of loudness on the haptic force-feedback perception in virtual environments
Authors: Altinsoy M. Ercan , Blauert Jens , So Richard H. Y.
Published: October 2013

Due to increasing usage of the haptic modality in virtual reality applications, the perceptual aspects of the interaction between haptic and auditory modalities is becoming more important. In our daily life, force-feedback which we perceive in our hands after beating a drum as well as the loudness of the drum sound give us the required information about how much force we have applied when playing a drum. In this study, psychophysical experiments were conducted to investigate the effect of loudness on the haptic force-feedback perception (strength) by playing a virtual drum. Subjects were presented (1) only haptic force-feedback information, (2) only auditory information, and (3) auditory and haptic information together. In each experiment, subjects were asked how much force they had applied when playing the virtual drum. The results show that the magnitude of strength increases with increasing loudness in spite of no change in force-feedback as generated by a virtual drum and applied to the subject’s hand. These results contribute to our knowledge on how to effectively combine haptic and auditory information in virtual environments. [Work supported by IGSN, Ruhr University Bochum.]
Exposure smart hearing protector for reducing noise-induced hearing loss
Authors: Nykaza Ed , Frank Tom
Published: October 2013

The Exposure Smart Hearing Protector (ESHP) is a new device that can be used for measuring noise exposure levels (NELs) and the prevention of noise induced hearing loss (NIHL). The ESHP consists of two microphones, located in a right and left earplug, that are connected to a dosimeter. In practice, the user wears the ESHP. When the noise level exceeds a safe dose a warning light comes on. The user then inserts the earplugs. If the earplugs are correctly inserted and the noise level in the user’s earcanal is below a safe level the warning lights go off. As a result, the ESHP measures the user’s total daily noise exposure (unprotected and protected). To increase the efficiency of using the ESHP for preventing NIHL, the user downloads the information stored in the ESHP via a scanner into user friendly-software. The software can be used not only to record a user’s daily NELs, but more importantly to determine if the user needs intervention because the NELs exceed a safe level. The purpose of this poster session is to demonstrate the ESHP and software, and to report the results of a pilot study. [Work supported by NIOSH/CDC Grant No. U60/CCU 315855.]
Probabilistic neurotransmitter release for dynamic synapse neural networks and its application on pure tone recognition
Authors: Dibazar Alireza A. , Namarvar Hassan H. , George Sageev , Berger Theodore W.
Published: October 2013

In this paper, we propose a probabilistic neurotransmitter release for dynamic synapses neural network (DSNNs). The capabilities of DSNNs have already been investigated in the processing of spatio-temporal patterns of action potentials [J.-S. Liaw and T. W. Berger (1996)]. The deterministic model of synapse is substituted by probabilistic Markov model. The action potentials generated by auditory system are the inputs of the model. The probability of neurotransmitter release is then estimated from the model. In general, the aim of this study is to present a robust pure tone recognition system based on DSNN. To generate action potential from music tone we have employed pulse code modulation method. The action potentials are plugged into the DSNN for recognition purpose. Our simulation results showed that the DSNN based on probabilistic release has 4% better recognition performance with respect to the deterministic model [A. A. Dibazar et al., SFN 2002]. [Work supported in part by DARPA-CVS, NASA, and ONR.]
Computation of scattering by high-aspect ratio spheroids using a new wide-angle on-surface radiation condition approach
Authors: Calvo David C.
Published: October 2013

In a previous study [Calvo et al., IEEE Trans. Antennas Propag. (2003)], a wide-angle on-surface radiation condition (OSRC) was introduced to compute scattering by hard and soft elliptical cylinders. This OSRC was based on a rational approximation of the exact Dirichlet-to-Neumann map for a circular cylinder. As a result of the wide-angle accuracy, exceptional results were obtained for scattering by hard elliptical cylinders when a plane wave was incident end-on with the target. In this talk, the form of the rational approximation is economized and the OSRC is extended to the case of three-dimensional convex bodies (spheroids). A comparison of scattered fields using the OSRC and the BEM methods shows excellent agreement. Owing to the tridiagonal form of the differentiation matrices appearing in the rational approximation, computational costs scale only linearly with frequency making this technique ideal for mid-to-high frequency target scattering computations for orientations where diffraction effects may be important.
Correlation of acoustic and vibration signatures of faulty bearings
Authors: Jillella Nagarjuna , Darvennes Corrinne , Pardue Sally
Published: October 2013

The use of acoustic based measurements for machinery health monitoring of rolling element bearings is explored. Acoustic data was taken with several types of microphones placed very close to the bearings, to minimize the effect of background noise. Accelerometer measurements were also made on the system. A frequency spectrum analysis of acoustic and vibration data was done. The experimentation was performed on a Machine Diagnostics Trainer unit. The shaft is driven by a motor and supported by two bearings that can be easily replaced to incorporate known defects. Three bearings were used to make measurements: a good bearing, a bearing with an inner race defect, and a bearing with an outer race defect. Frequency spectrums and rms values will be presented showing the effects of the transducer type and location, and of the bearing defects.
‘‘The perceptual bases of speaker identity’’ revisited
Authors: Voiers William D.
Published: October 2013

A series of experiments begun 40 years ago [W. D. Voiers, J. Acoust. Soc. Am. 36, 1065–1073 (1964)] was concerned with identifying the perceived voice traits (PVTs) on which human recognition of voices depends. It culminated with the development of a voice taxonomy based on 20 PVTs and a set of highly reliable rating scales for classifying voices with respect to those PVTs. The development of a perceptual voice taxonomy was motivated by the need for a practical method of evaluating speaker recognizability in voice communication systems. The Diagnostic Speaker Recognition Test (DSRT) evaluates the effects of systems on speaker recognizability as reflected in changes in the inter-listener reliability of voice ratings on the 20 PVTs. The DSRT thus provides a qualitative, as well as quantitative, evaluation of the effects of a system on speaker recognizability. A fringe benefit of this project is PVT rating data for a sample of 680 voices. [Work partially supported by USAFRL.]
Auditory color constancy
Authors: Kluender Keith R. , Kiefte Michael
Published: October 2013

It is both true and efficient that sensorineural systems respond to change and little else. Perceptual systems do not record absolute level be it loudness, pitch, brightness, or color. This fact has been demonstrated in every sensory domain. For example, the visual system is remarkable at maintaining color constancy over widely varying illumination such as sunlight and varieties of artificial light (incandescent, fluorescent, etc.) for which spectra reflected from objects differ dramatically. Results will be reported for a series of experiments demonstrating how auditory systems similarly compensate for reliable characteristics of spectral shape in acoustic signals. Specifically, listeners’ perception of vowel sounds, characterized by both local (e.g., formants) and broad (e.g., tilt) spectral composition, changes radically depending upon reliable spectral composition of precursor signals. These experiments have been conducted using a variety of precursor signals consisting of meaningful and time-reversed vocoded sentences, as well as novel nonspeech precursors consisting of multiple filter poles modulating sinusoidally across a source spectrum with specific local and broad spectral characteristics. Constancy across widely varying spectral compositions shares much in common with visual color constancy. However, auditory spectral constancy appears to be more effective than visual constancy in compensating for local spectral fluctuations. [Work supported by NIDCD DC-04072.]
Grammatical judgments and phonetic reality: A study of internal constraints in phonological variation
Authors: File Richard , Diaz-Campos Manuel
Published: October 2013

Previous investigations analyzing phonological variation in Spanish have pointed out that phonetic context is an important factor for predicting different variants of /s/. In many studies (Cedergren, 1973; Poplack, 1979, 1980, 1986; Ranson, 1993; Samper Padilla, 1990; Terrell, 1977, 1978, 1979, 1986, etc.), it is claimed that /s/ aspiration is more likely to happen word-internally, preceding a consonant, while elision is more likely to happen word-finally preceding a pause. The methodology used in those studies relies on grammatical judgment for performing the analysis of phonetic context, which could present a perceptual bias that could misrepresent the reality of the realization of the segments. The present investigation examines the phonetic cues that might have an effect in the perception of syllable-final /s/ including the duration of the preceding vowel as well as the following context. Preliminary results show that when the preceding vowel had a shorter duration, retention was easily perceived, whereas when the preceding vowel was longer in duration, the perception of aspiration was favored. The results suggest that for a segment with the same degree of aspiration, deletion was perceived before a pause more often than before a consonant, especially when the preceding vowel was shorter in duration.
Shifts in the perceived voicing boundary of bilingual listeners
Authors: Garcia-Sierra Adrian , Champlin Craig A , Rivera-Gaxiola Maritza
Published: October 2013

Three groups of listeners, American-English monolinguals, Mexican-Spanish monolinguals, and Mexican-Spanish bilinguals, identified synthetic /ga/–/ka/ syllables varying in VOT. In order to induce a language set in the bilingual listeners, they were asked to produce syllables and phrases in either English or Spanish prior to the identification task. Bilinguals identification of the VOT stimuli varied depending on the language set condition, with the voicing boundary in each case shifting in the direction of values characteristic of monolingual listeners. This effect of language set replicates earlier findings [L. Elman, R. Diehl, and S. E. Buchwald, J. Acoust. Soc. Am. 62, 971–974 (1977)]. Bilinguals velar consonant productions showed a corresponding shift in VOT values across the two language conditions. A Mismatch Negativity paradigm will be used in an attempt to record preattentive discrimination of the language-set-induced phonemic boundary shift in bilingual listeners. [Work supported by the Department of Communication Sciences and Disorders Univ. of Texas–Austin.]
Otoacoustic emissions measured in children diagnosed with attention-deficit/hyperactivity disorder
Authors: McFadden Dennis , Westhafer J. Gregory , Pasanen Edward G. , Tucker David M. , Carlson Caryn L.
Published: October 2013

Attention-deficit/hyperactivity disorder (ADHD) is generally acknowledged to be more prevalent in males than in females. Further, some precursors to ADHD appear early in life. Together these facts suggest that ADHD may be influenced by androgenic mechanisms operating early in development. This reasoning raises the question of whether the otoacoustic emissions (OAEs) of children with ADHD are masculinized. Click-evoked OAEs were measured for one click level in 8 boys and 3 girls diagnosed as ADHD/Combined, in 11 males and 5 females diagnosed as ADHD/Inattentive (IA), and in 17 male and 18 female controls. The ages of these samples ranged between 7 and 15. As in adults, the CEOAEs of the control males were weaker than those of the control females. Further, the CEOAEs of the ADHD/IA males were weaker than in the control males (a hypermasculinization) and the CEOAEs of the IA females were weaker than in the female controls (a masculinization). The CEOAEs of the Combined groups were slightly stronger (feminized) than those of the control males and females. One interpretation is that the IA subgroup of ADHD boys and girls (but not the Combined subgroup) was exposed to higher-than-normal levels of androgens sometime early in development. [Work supported by NIDCD.]
The Ganong paradigm: Converging evidence supporting initial phoneme weighting
Authors: Tracy Erik C. , Pitt Mark A.
Published: October 2013

In the present experiment we investigate whether the initial phoneme is given more weight in word recognition [W. D. Marslen-Wilson and A. Welsh, Cognit. Psych. 10, 29–63 (1978)] or if all phonemes in a word are weighted equally [C. M. Connine, D. G. Blasko, and D. Titone, J. Mem. Lang. 32, 193–210 (1993)]. Using the Ganong paradigm [W. F. Ganong, JEP:HPP. 6, 110–125 (1980)], participants were instructed to categorize a final ambiguous fricative in the target items, which included both words and pseudowords. Pseudowords were created by changing either the initial or a medial phoneme within the words. For example, the word diminish was altered to create the pseudowords timinish and dimimish. In addition, initial and medial phonemes were altered by either one or three distinctive features. The differences in the labeling of the final ambiguous fricative in the target items led to the conclusion that the initial phoneme is weighted more heavily. [Work supported by NIDCD.]
The rotating rake fan mode measurement system
Authors: Sutliff Daniel
Published: October 2013

An experimental measurement system was developed and implemented by the NASA Glenn Research Center in the 1990s. The system is a continuously rotating radial rake immersed into the duct. This rotating rake provides a complete map of the acoustic duct modes present in a ducted fan and has been used on a variety of test articles: from a low-speed, concept test rig to a full-scale production turbofan engine. The rotating rake has been critical in developing and evaluating a number of noise reduction concepts as well as providing experimental databases for verification of several aero-acoustic codes. This paper will describe the physical theory (Sofrin) and the analytical techniques (Moore) upon which the rotating rake is based will be described. Data processing and analysis as well as implementation issues will be discussed. Several Rotating Rake systems have been custom built for 3 facilities. In order of complexity of the turbo machinery test article, these are (1) the Advanced Noise Control Fan, (2) various 22-inch fan rigs in the NASA Glenn 9×15 wind tunnel, and (3) a full scale turbofan, the Honeywell TFE-731-60. Descriptions and measurement achievements of these systems will be provided (Heidelberg, Sutliff).
Methodologies for duct liner impedance eduction
Authors: Parrott Tony L. , Jones Michael G. , Watson Willie R. , Smith Charles D.
Published: October 2013

Methodologies and techniques are reviewed that are currently employed at Langley Research Center to educe (from primitive measurements) the impedance of acoustically absorbing liner structures. These structures are of interest for suppressing noise emission from aircraft engine nacelles. The accuracy and precision of the primitive measurements and their impact on the educed impedance of liners when exposed to high speed grazing flows is of special interest for aircraft engine nacelle applications. The test setups range from the classical standing wave tube for which the primitive measurement is a complex transfer function between two judiciously chosen locations, to an elaborate grazing flow duct arrangement (the Langley Grazing Incidence Tube) for which the primitive measurements (acoustic pressure and phase) are compromised by increased flow noise contamination due to high speed grazing flows up to a Mach number of 0.5. Results of different techniques/methodologies are compared on the basis of how the primitive measurements are processed and mapped into impedance spectra for different test setups. The results are compared on the basis of bias and precision errors that are specific to the impedance eduction methodology employed.
In situ evaluation of aircraft interior noise reduction technologies
Authors: Klos Jacob , Palumbo Daniel L.
Published: October 2013

In order to quantify the performance of interior noise treatments under flight conditions, it is desirable to evaluate the noise reduction due to treatment of a limited portion of an aircraft fuselage. However, radiation from the untreated areas of the fuselage can corrupt an intensity measurement in front of the treated area. In the past, this problem of corrupting noise has been solved by acoustically isolating the treated area from the rest of the fuselage. In this presentation, a method to evaluate the performance of an acoustic treatment applied to an aircraft fuselage in situ using correlation analysis is documented. The insertion loss of the acoustic treatments is estimated from the ratio of the intensity, correlated to reference transducers, measured with and without the treatment applied. The formulation is presented for both single and multiple reference transducers. Several experimental studies and numerical simulations have been conducted, and the results are documented. Through these case studies, it is demonstrated that this method can be used to evaluate the insertion loss of fuselage treatments without having to acoustically isolate the treated area.
Multiresolution analysis of noise generated by aircrafts during landing/take-off operations
Authors: Caligiuri Luigi Maxmilian , Sabato Adolfo
Published: October 2013

The evaluation of noise impact generated by aircrafts is usually realized by means of indicators such as Lden and/or by indexes obtained opportunely combining the values of single event levels relative to the events occurred within the measurement time interval. In any case is fundamental, to ensure the validity of result, to properly find and characterize the noise events produced by aircrafts landing/take-off operations, in particular distinguish them from that produced by other sources. Since the traditional analysis techniques are generally inadequate to describe these nonstationary signals, its necessary to employ time-frequency or time-scale based techniques. In this paper it will be shown the application of multiresolution time-scale and time-frequency analysis techniques, based on Wavelet (WT) and smoothed Wigner Ville transforms (SWVT), to noise signals related to aircrafts landing/take-off operations, also comparing the result with those obtained using a Windowed Fast Fourier Transform (WFFT). The effects of changing the parameters related to the smoothing WVT windows and to the WT base functions atoms will be investigated, showing that an adequate choose of such parameters will allow to us to properly analyze and characterize these noise events in order to quantify their impact.
Electronic architecture: An acoustician’s approach
Authors: Jaffe J. Christopher
Published: October 2013

Electronic architecture is a process for modifying the sound fields of an auditorium, concert hall, or theatre to recreate the sound fields of outstanding examples of individual performance spaces. This paper discuss how acousticians develop proper acoustic environments for specific program use in physical acoustic halls and how these design goals are incorporated into electronically enhanced facilities.
An electronic enhancement system for Silva Concert Hall
Authors: Gulsrud Timothy E. , Pfeiffer Scott D. , Swarte Frans H. H.
Published: October 2013

An electronic enhancement system and new orchestra shell have been designed for and installed in Silva Concert Hall, a 2500-seat multipurpose hall at the Hult Center for the Performing Arts in Eugene, Oregon. The enhancement system provided by Acoustic Control Systems B.V. features early reflection and reverberation modules in the house and a foldback system for performers on stage. The design considerations, interaction with the new shell, tuning, and in-hall measurements of the system are discussed, including reactions by musicians, administrators, and critical listeners.
Design and evaluation of a 63 element 1.75-dimensional ultrasound phased array for treating benign prostatic hyperplasia
Authors: Saleh Khaldon Y. , Smith Nadine B.
Published: October 2013

Focused ultrasound surgery (FUS) is a clinical method for treating benign prostatic hyperplasia (BPH) in which tissue is noninvasively necrosed by elevating the temperature at the focal point above 60°C using short sonications. With 1.75-dimensional (1.75-D) arrays, the power and phase to the individual elements can be controlled electronically for focusing and steering. This research describes the design, construction and evaluation of a 1.75-D ultrasound phased array to be used in the treatment of benign prostatic hyperplasia. The array was designed with a steering angle of ±13.5 deg in the transverse direction, and can move the focus in three parallel planes in the longitudinal direction with a relatively large focus size. A piezoelectric ceramic (PZT-8) was used as the material of the transducer and two matching layers were built for maximum acoustic power transmission to tissue. To verify the capability of the transducer for focusing and steering, exposimetry was performed and the results correlated well with the calculated fields. In vivo experiments were performed to verify the capability of the transducer to ablate tissue using short sonications. [Work supported by the Whitaker Foundation and the Department of Defense Congressionally Directed Medical Prostate Cancer Research Program.]
Factors affecting scatterer size estimation using a generalized ultrasound attenuation–compensation function to correct for focusing
Authors: Bigelow Timothy A. , O’Brien William D.
Published: October 2013

Over the years many different investigators have attempted to estimate the size of the principle scattering sites in materials by hypothesizing a model for the scattering and then fitting the power spectrum of the backscattered ultrasound signal to the model to obtain an estimate for the scatterer size. Traditionally, these models have assumed that a plane wave is incident on the scattering site limiting the measurement technique to unfocused or weakly focused ultrasound sources. In this investigation, the plane wave assumption was replaced by a model that assumed that the field of a focused source could be modeled as a three-dimensional Gaussian about the focus. Then, strongly focused sources could be used to obtain estimates for the size of the principle scattering sites provided that a generalized attenuation–compensation function was used to correct for the focusing. The improvement provided by the generalized attenuation–compensation function over traditional attenuation–compensation functions that neglected focusing was strongly affected by the type of scatterer being estimated. Also, the wavelength dependence of the axial beamwidth impacted how the improvement provided by the generalized attenuation–compensation function varied with increased focusing (i.e., going from f/1 to f/4). [Work supported by NDSEG Graduate Fellowship and Beckman Institute Graduate Fellowship.]
Characterization and differentiation of two mammary tumors using parametric imaging with ultrasound
Authors: Oelze Michael L. , O’Brien William D. , Zachary James F.
Published: October 2013

Two kinds of solid tumors were acquired and scanned in vivo ultrasonically. The first tumor series (fibroadenoma) was acquired from tumors that developed spontaneously in rats. The second tumor series was acquired by culturing a carcinoma cell line (4T1-MMT) and injecting the cells into Balb/c mice. The scatterer properties (average scatterer diameter and acoustic concentration) were estimated using a Gaussian form factor from the backscattered ultrasound measured from both kinds of tumors. Parametric images of tumors were constructed utilizing estimated scatterer properties for regions of interest inside the tumors and surrounding normal tissues. The average scatterer diameter and acoustic concentration for the fibroadenomas were estimated at 107±14 micrometers and 15.2±5 dB (mm−3), respectively. The average scatterer diameter and acoustic concentration for the carcinomas was estimated at 30±4.6 micrometers and 10.3±6.9 dB (mm−3), respectively. A comparison with light microscopic evaluations of the fibroadenomas showed cellular structures around 100 micrometers in size, and carcinomas showed cell nuclei with an average size of 12.5 micrometers in diameter (the total cellular size ranging from 50% to 200% larger than the nucleus size). [Work supported by NIH F32 CA96419 to MLO and by the University of Illinois Research Board.]
Traffic noise attenuation by scattering, resonance and dispersion
Authors: Tavossi Hasson M.
Published: October 2013

The purpose of this investigation is to analyze various techniques of sound attenuation which can be used to minimize traffic noise from heavy traffic circulation in urban areas, and to improve sound quality in these areas using selective absorption in specific frequency ranges, plus to reduce the degree of annoyance of traffic noise. This study covers uncontrollable noise sources such as trucks, automobiles and trains, in heavy traffic urban areas. Different methods of noise energy reduction are discussed, including sound attenuation by selective absorption, scattering and cavity resonance in the sound barriers. Multiple scattering on sound absorbing road and barriers are considered to increase noise energy dissipation in unwanted frequency ranges. The effects of dispersion and change in the frequency content of the noise with distance are studied. An elimination of the most disturbing frequency components of these uncontrollable noise sources improves sound quality from these sources and increases our overall capabilities in controlling noise pollution in the urban environment.
Evaluation of acoustical parameters of a Brazilian popular housing model
Authors: Ferreira Jos A. C. , Diniz Fabiano B. , Ferreira Andressa M. C. , Zannin Paulo T.
Published: October 2013

This article presents the results obtained from the evaluation of the acoustical insulation parameters determined in situ in a popular residence projected to offer an option to combat the housing deficit of the low income Brazilian population. This evaluation has been carried out according to the statements of the standards ISO 140-4 and 140-5, which state about this type of measurement. The results have shown that the surveyed house presents a satisfactory performance if compared to the standard of the Brazilian civil construction, but it is not adequate if compared to the demands of the international standards.
Residential reuse: Acoustics and making buildings livable
Authors: Ehnert Jesse J.
Published: October 2013

Adapting an existing facility, whether it is industrial, educational, or commercial in nature, to residential uses, such as condominiums and lofts, poses many challenges to the design team. Among other things, the process must include maintaining historic character while addressing current code issues in the context of becoming familiar with and utilizing existing architecture and building systems, which may not always be well-documented or obvious. Of the many unique issues encountered in such adaptive reuse projects, acoustic concerns often present themselves, especially in terms of sound and vibration isolation and noise control within and between residential units. Some of the paramount concerns and pitfalls will be discussed in the context of relevant examples and past experiences.
From manikin to microphone arrays development and application of binaural measurement devices
Authors: Mellert Volker
Published: October 2013

Ever since stereophonic systems were designed it was obvious to make the recording by two microphone channels which mimic the aural investigation of the acoustic environment by our two ears. Head-related stereophony aims at a subjectively optimal reproduction of a sound field, in particular with headphones, whereas the multi-channel synthesis of a sound field provides a listening condition which is more independent of the individual listeners acoustic properties (e.g., head size, near-field refraction pattern). Binaural measurement devices are comparatively less complex and costly and therefore in use for about 30 years for sound field investigations, as in concert hall acoustics or in the assessment of environmental and technical sounds. A review is given on the development of head-related stereophony for investigating (mainly) room acoustics. Concepts of future devices for the assessment of technical sound are presented. The classical head-shaped recording system (dummy head) is substituted by beam-forming microphone arrays.
Ultrasound attenuation as a quantitative measure of fracture healing
Authors: Gheduzzi Sabina , Humphrey Victor F. , Dodd Simon P. , Cunningham James L. , Miles Anthony W.
Published: October 2013

The monitoring of fracture healing still relies upon the judgment of callus formation and on the manual assessment of the stiffness of the fracture. A diagnostic tool capable of quantitatively measuring healing progression of a fracture would allow the fine-tuning of the treatment regime. Ultrasound attenuation measurements were adopted as a possible method of assessing the healing process in human long bones. The method involves exciting ultrasonic waves at 200 kHz in the bone and measuring the reradiation along the bone and across the fracture zone. Seven cadaveric femora were tested in vitro in intact form and after creating a transverse fracture by sawing through the cortex. The effects of five different fracture types were investigated. A partial fracture, corresponding to a 50% cut through the cortex, a closed fracture, and fractures of widths varying between 1, 2, and 4 mm were investigated. The introduction of a fracture was found to produce a dramatic effect on the amplitude of the signal. Ultrasound attenuation was found to be sensitive to the presence of a fracture, even when the fracture was well reduced. It would therefore appear feasible to adopt attenuation across a fracture as a quantitative measurement of fracture healing.
Investigation of ultrasonic properties of human hip bone: Relationship to bone mineral density (BMD) and micro-architecture
Authors: Jenson Frederic , Padilla Frederic , Laugier Pascal
Published: October 2013

The goal of this study is to investigate the relationships between QUS measurements (transmission and reflection) and BMD and micro-architecture measured on human proximal femur. Thirty-eight 1-cm thick slices of trabecular bones were removed from fresh human proximal femurs. Two-dimensional scans were performed using 1-MHz focused transducers to measure QUS parameters: normalized BUA (nBUA), SOS and broadband ultrasonic backscatter (BUB). BMD was determined using QCT. Six hundred sixty non-overlapping ROIs were selected for quantitative analysis on both QUS and QCT images. Finally, 37 cylindrical cores were extracted from 31 specimens (8 mm diameter). Their micro-architecture was derived using micro-tomography. All QUS parameters were significantly correlated to BMD (nBUA: r2=0.7; SOS: r2=0.75; BUB: r2=0.44). Multiple regression models were tested with BMD and micro-architecture. SOS only was best explained by a combination of bone quantity (BV/TV) and micro-architecture parameters (SOS with BMD and structure model index: r2=0.93). No additional variability of nBUA and BUB could be explained by micro-architectural parameters in addition to BMD or BV/TV. These results suggest that QUS measurement at the hip may be relevant for fracture risk prediction.
Structural and elastic determinants of axial transmission ultrasonic velocity in the human radius
Authors: Raum Kay , Leguerney Ingrid , Chandelier Florent , Talmant Maryline , Saied Amena , Laugier Pascal , Peyrin Françoise
Published: October 2013

Accurate clinical interpretation of the sound velocity derived from axial transmission devices requires a detailed understanding of the propa-gation phenomena involved and of the bone factors that have an impact on measurements. In the low-megahertz range, ultrasonic propagation in cortical bone depends on anisotropic elastic tissue properties, porosity, and the spatial dimensions, e.g., cortical thickness. A subset of ten human radius samples from a previous biaxial transmission investigation was inspected using 50-MHz scanning acoustic microscopy (SAM) and synchrotron radiation computed tomography (SR-CT). Low-frequency axial transmission sound speed at 1 and 2 MHz was related to structural properties (cortical thickness C.Th, porosity POR, Haversian cavity density CDH) and tissue parameters (acoustic impedance Z, mineral density MD) on site-matched cross sections. Significant linear multivariate regression models (1 MHz: R=0.84, p<1E−4, 2 MHz: R=0.65, p<1E−4) were found for the combination of C.Th with POR and Z (measured in the external cortical quarter). A modified model accounting for the nonlinear dispersion relation with C.Th was also highly significant (R=0.75, p<1E−4, rmse=49.22 m/s) and explained (after adjustment for dispersion) 55.6% of the variance of the sound velocity by variations of porosity (15.6%) and impedance (40%).
Non-monotonic spectral transitions between successive phonemes
Authors: Dusan Sorin
Published: October 2013

In fluent speech one would expect that the transition between two successive acoustic targets would exhibit either a monotonic increasing or a monotonic decreasing trajectory in the time domain of each spectral parameter. Closer examination reveals that this is not always the case. This study investigates the existence of non-monotonic trajectories found in the acoustic spectral domain at the transition between some successive phonemes. This non-monotonic behavior consists of transitional regions that exhibit either increasing and then decreasing or decreasing and then increasing trajectories for some acoustic spectral parameters. Using the superposition principle, the training part of the TIMIT acoustic-phonetic database is used to build 2471 diphone trajectory models, based on the 61 symbols used in the database for phonetic transcription. Various non-monotonic trajectories are found in some of these models for some spectral representations including the linear prediction coding (LPC) parameters and the mel-frequency cepstral coefficients (MFCC). In some cases these spectral peaks or valleys between phonemes have significant amplitudes reaching approximately the standard deviation at the center, positions of the adjacent phonemes. These non-monotonic trajectories cannot be explained by the Stevens quantal theory of speech in which abrupt changes appear at transitions between two acoustic targets.
Evaluation of room acoustic qualities and defects by use of auralization
Authors: Rindel Jens H.
Published: October 2013

Auralizations generated by room acoustic computer modeling programs may be used as a tool for evaluation of acoustic qualities and defects, some of which are not easily detected by objective measures. Examples include reverberance, flutter echoes, perceived room size and distance, apparent source width, listener envelopment, and sound propagation in coupled rooms. In order to reach a sufficiently high level of realism in auralizations for such room acoustic applications, it is necessary that all parts of the chain are modeled with certain accuracy. In particular, it is found that the modeling of source directivity and the late room reflections (the reverberation tail) need careful consideration in order to achieve reliable and realistic-sounding results. However, when implemented in the software the practical use can be simple and quick.