bluuebunny/crossref_metadata_2025 huggingface dataset:
High-frequency vibrations of a piezomagnetic plate
Authors: Altay Gulay , Dokmeci M. Cengiz
Published: September 2013

This paper deals with a consistent derivation of the hierarchic system of two-dimensional approximate equations of a piezomagnetic plate at high frequency where the wavelength is of the order of magnitude or smaller than the plate thickness. To begin with, a generalized variational principle is reported for piezomagnetism, and the field variables are represented by the power series expansions in the thickness coordinate. Next, with the aid of the variational principle together with the series expansions, the system of plate equations is derived in invariant, differential and fully variational forms. The system of equations that may be readily expressed in a particular coordinate system most appropriate to the plate geometry is capable of predicting all the types of vibrations at both low and high frequency. Also, the uniqueness is investigated in solutions of the system of plate equations, and the conditions are enumerated for the uniqueness. Further, certain cases involving special geometry, material properties and types of vibrations are indicated. The resulting equations agree with and generalize some of earlier plate equations [cf. the authors, Int. J. Solids Struct. 40, 4699–4706 (2003)]. [Work supported by TUBA.]
Free flexural vibrations of super elliptic plates
Authors: Altekin Murat , Altay Gulay , Dokmeci M. Cengiz
Published: September 2013

This paper deals with a direct problem of the free flexural vibrations of a plate with rounded corners on the basis of the theory of thin plates. The plate of uniform thickness is made of linear elastic, isotropic materials, and its periphery is given by a super elliptic function with a power. The super elliptic power defines the shape of the plate ranging from an ellipse to a rectangle and indicates the degree of roundness. The method of solution is based on the method of separation of variables together with certain methods of weighted residuals (i.e., the method of moments, and the Galerkin and least squares methods). The shape functions are chosen in the form of double series polynomials, and they satisfy either a simply supported or a clamped boundary condition. Some numerical results are reported for the vibration frequencies in the case of both symmetric and antisymmetric mode shapes of the plate. The results are compared with the existing literature, and the convergence of solutions is discussed. [Work supported in part by TUBA.]
Voice onset time and global foreign accent in mature Japanese–English bilinguals
Authors: Riney Timothy J.
Published: September 2013

Experiment 1 investigates to what degree the phonetic category established in childhood for an L1 sound may evolve gradually [Flege, Speech Learning Model (1995)]. VOT is assessed in two groups of five bilingual (English and Japanese) speakers, one L1 English and the other L1 Japanese, ages 35–60 with little or no L2 exposure before age 15, but working in the L2 regularly for 15–35 years in adulthood. Both groups read lists of English and Japanese words containing word initial /p/, /t/, and /k/; 880 tokens (10 speakers × 2 languages × 44 tokens per language) were examined. The findings for both groups were that (a) the L1 VOT values did not change much over time and (b) the L2 VOT values were halfway between the L1 and target language values. Experiment 2 investigates the relationship between individual VOT and accent. The ten speakers were asked to read five Japanese sentences, now digitized. Ten additional L1 Japanese participants will rate these sentences for accent in March 2004. The prediction is that the American speakers who have the most Japanese accents will also have VOT values that are closest to L1 Japanese values.
Phonetic specifications in infant-directed speech
Authors: Sundberg Ulla
Published: September 2013

In contrast to the overspecification of prosodic aspects and the expansion of the vowel space typically observed in infant-directed speech (IDS), VOT measurements of voiceless stop consonants occurring in Swedish mothers’ speech to their 3-month-old infants revealed surprisingly lower values in IDS than in the mothers’ adult-direct speech (ADS). Since the mothers’ underspecification of consonantal contrasts in early IDS, while at the same time exaggerating prosodic and vocal contrasts, may indicate an adjustment to the phonetic aspects that they perceive to be adequate to the infant’s developmental level, the present study of VOT in IDS towards 12-month-olds was carried out in order to determine the age interval within which mothers may start to adopt adult-like VOT contrasts in their IDS. The VOT measurements from the IDS aimed at their 12-month-olds showed instead significantly longer durations than in ADS. It is hypothesized that this age-dependent use of consonantal specifications in IDS may reflect the mothers’ adjustments to their perception of the infants’ communicative capabilities, from dominating phatic function, conveyed by deeply modulated speech and exaggerated vowel contrast in early IDS, towards a focus on lexical content by the end of the first year of life.
Perception of Spanish, Parkinsonian speech by English listeners
Authors: Fraas Michael , Boyce Suzanne
Published: September 2013

It is well established that when two languages differ in voicing patterns for obstruents, listeners are likely to misidentify obstruents in a non-native language according to the patterns of their native language. It has also been established that the normal patterns that distinguish voiced and voiceless stops in English are disrupted in speakers with Parkinson’s disease. Accordingly, English-speaking clinicians not familiar with the voicing characteristics of another language, e.g. Spanish, run the risk of erroneously interpreting the utterances of clients who speak that language as natives. In a study of the voice-onset time characteristics of stops spoken by Spanish speakers with Parkinson’s disease and a matched set of control Spanish speakers (Fraas, 2002; Pan-American/Iberian Meeting on Acoustics), we determined that Spanish speakers with PD produce shorter VOTs for voiced stops and longer VOTs for voiceless stops as compared with Spanish-speaking controls. These longer VOTs were judged to be appropriate by English listeners, although they are not characteristic of normal Spanish production. These results imply that English-speaking clinicians are likely to err in not identifying voicing as a target of remediation for Spanish speakers with PD.
Contrastive voicing acquisition in 2-year-old children: Preliminary data
Authors: Hitchcock Elaine R. , Koenig Laura L.
Published: September 2013

Earlier studies using voice-onset time (VOT) as the acoustic marker of contrastive voicing acquisition in English have differed widely in method and statistical procedures. Research in this area has shown three primary patterns of voicing acquisition for English stop consonants. One report indicates children demonstrate discrete voicing categories with adult-like VOT values as early as 2 years old. Other reports suggest a subperceptual distinction of the voicing contrast, followed by an exaggerated voicing contrast with evidence of more adult-like discrete categories by 3 years old. Still other reports suggest no distinction between the voicing categories until approximately 3 years. This work investigates voicing acquisition in three typically developing, English-speaking 2-year-old children. The subjects were recorded every 2 weeks for 4–6 months. Approximately 15–20 tokens were elicited for four target utterances containing initial /b p t d/. Frequency distribution, measures of central tendency, and skewness will be calculated for every recording session of each child. Discussion will focus on the development of contrastive VOT categories and their stability over time. These data will contribute to our understanding of laryngeal timing for English stop consonants in young children.
Acoustic communication systems and space/time processing
Authors: Baggeroer Arthur B.
Published: September 2013

Acoustic communication research for the last three decades has concentrated on point-to-point systems. Efforts are now evolving which exploit the spatial aspects of the underwater channel. First, there are systems with array for transmitters and/or receivers. Because the ocean randomizes the propagation, information can be received over many ‘‘paths;’’ for this beamforming and, more generally, singular value decomposition methods have been used to increase channel capacity. With multiple nodes in a distributed system, the problems of (i) time latency due to the relatively slow speed of sound and (ii) range, or multipath, spread become much more problematic; consequently, the space/time architecture of using time, frequency and space becomes very important and this differentiates underwater systems from cellular phone technology. The network structure, e.g., centralized or link connected leads to different signaling protocols and the potential for complicated interaction and interference. Nevertheless, many advances including both space/time diversity and coding are now popular research topics which will lead to more reliable and higher data rate acoustic communication systems.
Adaptive instant record signals applied to shallow water detection
Authors: Folégot Thomas , de Rosny Julien , Prada Claire , Fink Mathias
Published: September 2013

Time reversal arrays are becoming common tools whether for detection, tomography or communication. These applications require the measurement of the response from the array to one or several receivers. The most natural way to record different impulse responses between several points is to generate pulses successively from each emitting point and directly record all the impulse responses on the recording points. However, this method is very time consuming and inefficient in terms of signal-to-noise ratio. Hence, in this work, we propose an original way of sending continuous signals simultaneously from all the sources, recording all the pressure fields on the receivers and processing them in order to extract the exact impulse responses by matched filter. To this end, the signals are adapted to the environment and, more specifically, to highly dispersive media. These adaptive instant records signals (AIRS) are used experimentally to detect targets using the time reversal operator decomposition method. The quality of the 15×15 transfer functions acquired simultaneously, and therefore, the detection capability is demonstrated in shallow water in the presence of bottom absorption and reverberation. Finally, the connection of AIRS with CDMA and FDMA that are two coding techniques used in telecommunication is shown.
The effect of internal waves on low-frequency underwater acoustic communications
Authors: Yang T. C.
Published: September 2013

Internal waves are abundant in coastal waters and are known to have a significant impact on acoustic signal propagation. The effect includes significant signal fading to loss of signal coherence depending on the acoustic signal frequencies. This paper presents the analysis results using binary phase-shifted keying signals for underwater acoustic communications (ACOMMS) during the SWARM95 experiment. As reported in the open literature, the acoustic data were strongly affected by the presence of internal waves. For example, at 200–400 Hz, the signal characteristics changes drastically at the scale of ∼2–6 min. The most noticeable changes include the depth where the signal intensity peaks, the multipath arrival (time) pattern, and the signal amplitude and phase at a fixed depth. At these frequencies, the ACOMMS packet length for a reasonable amount of data will be long (due to the limited bandwidth) and comparable to the signal coherence time. The bit error rate of a packet varies depending on the temporal coherence within a packet (intrapacket). We report the temporal coherence measurements as a function of packet transmission time and relate that to the performance of the channel equalizer. [Work supported by the U.S. ONR.]
Approximate methods for time-reversal processing of large seismic reflection data sets
Authors: Berryman James
Published: September 2013

Seismic reflection data sets, whether collected on land or at sea, contain very large amounts of data even by modern standards. These data are typically sampled regularly in time but irregularly in space. So, temporal Fourier transforms are straightforward, but spatial transforms can be problematic, and very often require special efforts to resample the data onto a uniform grid in space. On the other hand, time-reversal processing of such data requires only the temporal Fourier transform, which is easy for these data. Accounting for data reciprocity, a complex square transfer matrix can be constructed at each frequency, and standard methods can then be used—at least in principle—to find singular values and singular vectors (SVD) of this large matrix. Once those singular vectors having the largest singular values are known, it is relatively straightforward to reconstruct the scattering surfaces giving rise to the data matrix. The biggest leap in this data processing scheme comes from the need to find the SVD for very large complex matrices. But iterative schemes using Krylov space methods can be applied to resolve this difficulty and produce a relatively small number of singular vectors containing the most relevant information.
Utilization of the interference invariant for geoacoustic parameter inversion in shallow water
Authors: Daly Peter M. , Mikhalevsky Peter N.
Published: September 2013

S. D. Chuprov’s interference invariant, or β parameter, characterized broadband striation patterns as a function of range and freuencey. Puchenkina and Salin proposed using the β parameter to estimate geoacoustic bottom parameters. Further work by Baggeroer, Rousseff, and Spindel recommended characterizing β as a probability distribution instead of a discrete quantity. the authors of this presentation will illustrate use of the β distribution to perform geoacoustic parameter inversion in shallow water, using simulated annealing methods. This inherently broadband process utilizes ships of opportunity combined with a priori range information to provide high-SNR input signals to the inversino process. [Work sponsored by DARPA Advanced Technology Office, Contract N00024-01-C-6319.]
The diffraction of leaky Rayleigh waves at the extremity of a fluid-loaded plate
Authors: Declercq Nico F. , Teklu A. , Breazeale M. A. , Briers Rudy , Leroy Oswald , Degrieck Joris
Published: September 2013

This study reveals that leaky Rayleigh waves, when scattered at the extremity of a thick plate swamped in water, generate leaky Rayleigh waves that propagate around the corner. Furthermore, it is experimentally proved that leaky Rayleigh waves are stimulated by the borders of a Gaussian-bounded beam and not by the interior of the beam. A comparison between the scattering of leaky Rayleigh waves and the scattering of Scholte–Stoneley waves at the extremity is also outlined and shows that leaky Rayleigh waves on the vertical edge at the extremity of the plate are best stimulated by means of incident leaky Rayleigh waves and not by means of Scholte–Stoneley waves. [Work supported by The Flemish Institute for the Encouragement of the Scientific and Technological Research in Industry (I.W.T.) and by a NATO Collaborative Linkage Grant.]
Fluid-filled spheres: Theoretical and measured scattering response
Authors: Deveau David M.
Published: September 2013

Investigation into the scattering nature of surfaces or other physical objects often requires the use of measurement systems which cannot always be well controlled. This lack of control can be compensated for by calibrating the resulting measurements against a known target. While these targets can be any object, the goal is to use a target that has a stable scattering response and is independent of angle. The ideal shape is that of a sphere, but even this can be improved with the addition of internal fluids that focus and temperature stabilize the scattering response. A scatter response model of a sphere has been developed and used to design four thin-walled spheres, each with a different diameter and filled with a focusing fill fluid (Fluorolube). One pair of spheres was measured in an ocean environment, while the second pair was tested in a controlled test tank from 5–50 kHz but using shorter continuous wave pulses. While the ocean-measured spheres closely matched the model, the test-tank measurements showed a marked difference from the model. Changes to the model will be explored to determine if theoretical minimums for pulse length are insufficient for targets of this density or focusing capability.
Scattering from bubbles rising in a vertical line—Comparison between theory and experiments
Authors: Nikolovska Aneta , Ooi Andrew , Manasseh Richard
Published: September 2013

In this paper, the experimental data from the sound field around similar sized air bubbles rising in a vertical chain are analyzed. The data reveal a strong anisotropy in the acoustic field. The transition from individual to continuum behavior in a bubble chain is not correctly described with classical theory especially when the bubbles are uniformly sized, discretely populated, and the frequency of interest is close to the natural frequency of the individual bubbles. Single compact scatterers initiated at frequencies near their resonant frequency in isolation act preliminarily as monopole sources, amplifying the local pressure field by a factor of order 1/(k*a), a being the scattering radius and k the wave number at the resonant frequency in the surrounding material [Tolstoy, 1986]. A laboratory investigation used air bubbles in fresh water and varied the bubble sizes and separation by carefully controlling bubble production rates. A linear coupled equation method was developed to explain the result. The model reproduced the acoustic pressure anisotropy along the chain and the change in pulse waveform along the chain. The results suggest that the enhancement of sound intensity along the chain can be explained by bubbles acting as resonant scatterers retransmitting the acoustic energy.
Optimal passive source localization in a fluctuating ocean waveguide based on an analytic model for the mean field and covariance
Authors: Ratilal Purnima , Bertsatos Ioannis , Chen Tianrun , Zanolin Michele , Makris Nicholas C.
Published: September 2013

The ocean acts as an enormously complex channel for signal transmission. It is characterized by temporal fluctuations and spatial variabilities that often lead to significant randomization of the measured field. Signal processing techniques must be derived from fundamental physical models to attain statistical optimality in such an environment. Here we present such an analysis with a new analytic model [Ratilal and Makris, J. Acoust. Soc. Am. 114, 2428 (2003)] for the mean field and its covariance after propagation through a fluctuating ocean waveguide based on the first principles of waveguide scattering theory. The model is advantageous because it includes the primary physical effects of attenuation, dispersion, and coupling of modal energy due to multiple forward scattering in a convenient and intuitive form that is well suited to analytic manipulations. An example will be presented for passive source localization in range and depth in a fluctuating ocean waveguide by nonlinear matched field inversion. The necessary conditions on sample size and signal-to-noise ratio (SNR) for unbiased and minimum variance (optimal) estimates of source postion are then derived using asymptotic statistical inference theory [Naftali and Makris, J. Acoust. Soc. Am. 110, 1917–1930 (2001)]. Degradation in performance by environmental uncertainties are quantified within this statistical framework.
Some interesting features in pulse propagation for environments with structured velocity profiles
Authors: Field R. , Werby M.
Published: September 2013

On a diurnal time scale the velocity profiles in some shallow water environments can change enough to modify signal detection features. In particular, if a vertical array is used to collect data, then contour plots of the detected signals relative to time and vertical distance can reflect features of the environment that are readily interpreted and therefore reveals some details of interest. Two features are investigated here. One pertains to surface ducting, which may be present over some limited time scale on a daily basis. The other feature is a rather pronounced variation in bottom ducting diurnally. At suitable frequencies (1 KH–5 KH) contour plots indicate discrete time arrivals due to sound waves trapped in the surface duct that reflect fast early (precursor) group arrivals. This effect has been studied earlier by H. DeFerrari and can be useful in extracting environmental features. Broad bottom ducts manifest themselves as broad group fronts characterized by almost vertical initial arrivals. This pattern varies on a daily basis. Thus these contours offer a simple method for diurnal duct variations and ought to be of interest for passive detection.
Passive acoustic localization for Sciaenid habitat in coastal water of Taiwan
Authors: Tu Chang , Wei Ruey-Chang , Chan Hsiang-Chih
Published: September 2013

There are many Sciaenid species found in coastal water of Taiwan, and most of them can generate sound in the spawning season. However, due to overfishing, the populations of these high economic value fishes have been greatly decreased. To study and protect Sciaenid, whose habitat should be identified, seasonal protection zones should be set up. In this study, easy and low-cost measure of using passive sonar is proposed to map the habitat in the field. Measurement and analysis of Sciaenid sound were performed to investigate its acoustic characteristic, and frequency range was found to be 350 to 1500 Hz. The statistical distribution of sound levels can be built up by enough field measurement; therefore source levels can be defined in this method. In addition, the transmission loss of in-site shallow water was studied to compute the real decaying factor (TL=n*logR) of the survey site. By using three sonobuoys, with known source level distribution and transmission loss, the distance of possible habitat can then be inverted. Through enough measurements, the map of coastal habitat of Sciaenid can be generated with efficiency and accuracy.
Auditorium acoustics evaluation based on simulated impulse response
Authors: Wu Shuoxian , Wang Hongwei , Zhao Yuezhe
Published: September 2013

The impulse responses and other acoustical parameters of Huangpu Teenager Palace in Guangzhou were measured. Meanwhile, the acoustical simulation and auralization based on software ODEON were also made. The comparison between the parameters based on computer simulation and measuring is given. This case study shows that auralization technique based on computer simulation can be used for predicting the acoustical quality of a hall at its design stage.
Concert hall acoustics
Authors: Schroeder Manfred
Published: September 2013

I will review some work at Bell Laboratories on artificial reverberation and concert hall acoustics including Philharmonic Hall (Lincoln Center for the Performing Arts, New York). I will also touch on sound diffusion by number-theoretic surfaces and the measurement of reverberation time using the music as played in the hall as a ‘‘test’’ signal.
Room acoustic impulse responses estimation: Challenges and opportunities
Authors: Benesty Jacob , Huang Yiteng (Arden) , Chen Jingdong
Published: September 2013

The estimation of room acoustic impulse responses in real-time plays a major role in many important applications such as dereverberation, echo and feedback cancellation, noise reduction, etc. This task is very challenging. In this talk, we will discuss different scenarios of estimation, depending on the application. We will see that when this estimation is reliable, the related applications can give good performances. However, in many applications it is very difficult to have a good estimate of the impulse responses. As a result, performances are usually very poor even with very clever tricks. We will see that opportunities are endless if good progress is made in this important area.
Artiodactyl and Perissodactyl acoustics: Identifying distress calls by farm animals
Authors: Browning David G. , Scheifele Peter M.
Published: September 2013

There is growing concern for the welfare of farm animals. Vocal signals are discernable in a herd, generally carry over relatively long ranges, and, as Jahns has shown, can be easily automatically detected. Analysis of vocalizations from the two principal farm animal families show, however, that only a few, a pig’s squeal, for example, meet Morton’s classic criteria for distress. In general, Artiodactyls (cows, sheep, goats, etc.) have tonal bellows or bleats where apparently one vocalization fits many emotional situations. Duration and repetition, as Grandin has suggested, may be the important criteria in indicating stress. In contrast, Perissodactyls vary frequency during some vocalizations, such as a horse whinny, but no direct connection between frequency change and stress has yet been determined. The apparent reliance of Perissodactyles (with keen eyesight) on visual detection of body language appears to limit to some degree the amount of vocalization.
Measurement of Lombard-like response in the beluga whale
Authors: Scheifele Peter M.
Published: September 2013

Noise pollution has become recognized as a potential danger to marine mammals in general, and to the St. Lawrence beluga (Delphinapterus leucas) in particular. One method to determine whether noise is having an effect on an animals auditory ability is to observe a natural and repeatable response of the auditory and vocal systems to varying noise levels. This can be accomplished by observing changes in animal vocalizations in response to auditory feedback. A response such as this observed in humans and some animals is known as the Lombard vocal response, which represents a reaction of the auditory system directly manifested by changes in vocalization level. This response is known in humans, songbirds, and some primates. In this research a population of belugas in the St. Lawrence River Estuary was tested to determine whether a vocalization-as-a-function-of-noise phenomenon existed by using hidden Markhov classified vocalizations as targets for acoustical analyses. Correlation and regression analyses of signals and noise indicated that the phenomenon does exist and results of a human subjects experiment along with results from other animal species known to exhibit the response strongly implicate the Lombard vocal response in the St. Lawrence population of beluga.
Comparative sensitivity analysis of transmission loss in beaked whale environments
Authors: Wezensky Eryn M. , Miller James H. , Tyce Robert C.
Published: September 2013

Scientific literature states that anthropogenic sound, such as mid-frequency sonar, may cause a behavioral response in marine mammals. The degree of response is highly variable and dependent upon many factors, including how sound transmission is influenced by environmental features. The physical parameters of the ocean medium, such as sound speed profile and bathymetry, are important controls of underwater acoustic propagation. Determining the acoustic propagation loss of the ocean environment is an application used to identify and correlate influential environmental factors. This study investigates the sensitivity of acoustic propagation loss based on specific physical characteristics found in five different sites representing beaked whale environments. These sites were chosen with regards to existing data on beaked whale distribution, historical mass stranding records, and presence of mid-frequency sonar activity. A range-independent, ray-tracing acoustic propagation model was used to generate a two-dimensional sound field over a range of 30 km. From the results of this experiment, the acoustic importance of bathymetry and sound speed profile of the five beaked whale environments were identified. Preliminary results from the experimental study will be presented.
Acoustic hemostasis
Authors: Crum Lawrence , Andrew Marilee , Bailey Michael , Beach Kirk , Kaczkowski Peter , Martin Roy , Vaezy Shahram , Khokhlova Vera
Published: September 2013

The application of HIFU to tissue can result in rapid temperature elevations, so much so that protein denaturization can occur. Not only can these elevated temperatures and denatured proteins induce coagulative necrosis, but they can also result in the cessation of blood supply to a particular region. Indeed, when applied to a site of active bleeding, hemostasis can be induced. A group of us at the University of Washington have considered the application of HIFU to active bleeding and have developed methods and devices that offer considerable promise for use in clinical medicine. A brief review of our work in this area will be presented, including our most recent results. [Work supported in part by the U.S. Army and the NIH.]
Interstitial ablation and imaging of soft tissue using miniaturized ultrasound arrays
Authors: Makin Inder R. S. , Gallagher Laura A. , Mast T. Douglas , Runk Megan M. , Faidi Waseem , Barthe Peter G. , Slayton Michael H.
Published: September 2013

A potential alternative to extracorporeal, noninvasive HIFU therapy is minimally invasive, interstitial ultrasound ablation that can be performed laparoscopically or percutaneously. Research in this area at Guided Therapy Systems and Ethicon Endo-Surgery has included development of miniaturized (∼3 mm diameter) linear ultrasound arrays capable of high power for bulk tissue ablation as well as broad bandwidth for imaging. An integrated control system allows therapy planning and automated treatment guided by real-time interstitial B-scan imaging. Image quality, challenging because of limited probe dimensions and channel count, is aided by signal processing techniques that improve image definition and contrast. Simulations of ultrasonic heat deposition, bio-heat transfer, and tissue modification provide understanding and guidance for development of treatment strategies. Results from in vitro and in vivo ablation experiments, together with corresponding simulations, will be described. Using methods of rotational scanning, this approach is shown to be capable of clinically relevant ablation rates and volumes.
Real-time motion correction combined with electronic beam steering strategies optimized for large tumors: First in-vitro HIFU experiments in large moving targets
Authors: Pernot Mathieu , Tanter Mickael , Fink Mathias
Published: September 2013

A method for tracking in realtime the 3D motion of tissues is combined with a 2D high-intensity focused ultrasound (HIFU) multichannel system in order to correct for respiratory motion during HIFU therapy. Displacements estimation is based on an accurate 3D ultrasonic speckle tracking technique. A correction is achieved in real time by adjusting the transmit delays of each channel of the HIFU system. In vitro HIFU experiments combined with motion correction are performed in fresh biological tissues. The accuracy of the HIFU targeting is clearly improved. Moreover, this technique permits an important reduction of the treatment time for moving tumors. To generate large thermal lesions, the focus is scanned electronically over a large region. Different heating strategies are investigated in moving tissues: the shot-by-shot treatment interleaved with cooling periods, and the continuously scanned treatment of the whole region. The temperature distribution and the thermal dose are computed using a 3D thermal diffusion code combined with a 3D wave diffraction algorithm and compared to experimental results. Using motion correction, the necrosis threshold is achieved 3 times faster than without motion correction. This should lead to an important time reduction for the treatment of abdominal tumors.
Therapy/imaging array-based system and technology for intense ultrasound surgery
Authors: Barthe Peter G. , Slayton Michael H. , Jaeger Paul M. , Makin Inder R. S. , Gallagher Laura A. , Mast T. Douglas , Runk Megan M. , Faidi Waseem
Published: September 2013

Minimally invasive, miniature (2.2- × 50-mm aperture, 3.3-mm diameter) dual-mode linear arrays have been developed into low-cost disposable probes with high acoustic power output (120 W/cm2 at the source), high transmit efficiency (>65% typical), and good imaging performance (50% fractional bandwidth, >100-mm-deep field of view). These therapy/imaging probes have been integrated into a flexible intense ultrasound surgery platform which also includes conventional diagnostic imaging probes. A system architecture has been developed which includes a 64-channel therapy driver with software selection of array aperture and phasing (λ/16), frequency (0.5–8 MHz), drive amplitude (5 W/channel, nominal), rotational steering (±180 deg), and temporal sequencing/switching of imaging/therapy/monitoring modes. System software includes graphical and text-based script mode control of therapeutic treatment. Real-time monitoring of electric power per channel, temperature sensors, and thermal effects provide a range of feedback and safety. Numerous system and probe technological issues such as electrical interconnect and matching, acoustic coupling, thermal control, and maintaining probe efficiency have been addressed. The array-based imaging/therapy system has produced encouraging results in preclinical studies of bulk tissue ablation and imaging.
A model-based noninvasive temperature estimation technique for monitoring HIFU therapy using backscattered ultrasound
Authors: Anand Ajay , Kaczkowski Peter J.
Published: September 2013

A new noninvasive temperature estimation technique using the bioheat transfer equation (BHTE) to constrain inversion of ultrasonic travel time data has been developed for HIFU therapy monitoring. Initial estimates for BHTE parameters and ultrasonic travel time temperature dependence δτ(T) are noninvasively obtained in situ using ultrasound backscatter signals acquired during two probe heating exposures performed prior to therapy: one to obtain medium thermal parameters, the other to estimate the magnitude of the local HIFU heat source. These estimates are used in BHTE simulations and compared to local travel time changes measured periodically during therapy using a medical ultrasound imager. Quantitative 2-D temperature maps are obtained by constrained data fitting. Preliminary results obtained from in vitro experiments in tissue mimicking phantoms will be presented. Temperature maps are computed throughout therapy delivery and posttreatment cooling periods, and validated against independent temperature measurements obtained using thermocouples placed close to but not at the HIFU focus. This model-based technique permits temperature estimation throughout the entire therapeutic range and is completely noninvasive, and is thus a departure from previously reported techniques. This ultrasound-based approach could serve as an alternative to MRI-based temperature estimation methods in a clinical setting.
Rudolph Koenig’s workshop of sound
Authors: Pantalony David A.
Published: September 2013

Rudolph Koenig’s workshop was a busy meeting place for instruments, ideas, experiments, demonstrations, craft traditions, and business. Starting around 1860 it was also the place in Paris where people discovered the new science of sound emerging from the studies of Hermann von Helmholtz in Germany. Koenig built Helmholtz’s ideas into apparatus, created new instruments, and spread them throughout the scientific and musical world. Through his own research, he also became Helmholtz’s strongest critic. This paper looks at the activities of this unique space, and, in particular, how it contributed to the protracted disputes over an elusive acoustical phenomenon called the combination tone. Many of these instruments became standard teaching and demonstration apparatus.
Harmonic analysis utilizing a Phonodeik and an Henrici analyzer
Authors: Fickinger William J. , Hanson Roger J. , Hoekje Peter L.
Published: September 2013

Dayton C. Miller of the Case School of Applied Science assembled a series of instruments for accurate analysis of sound [D. C. Miller, J. Franklin Inst. 182, 285–322 (1916)]. He created the Phonodeik to display and record sound waveforms of musical instruments, voices, fog horns, and so on. Waveforms were analyzed with the Henrici harmonic analyzer, built in Switzerland by G. Coradi. In this device, the motion of a stylus along the curve to be analyzed causes a series of spheres to rotate; two moveable rollers in contact with the nth sphere record the contributions of the sine(nx) and cosine(nx) components of the wave. Corrections for the measured spectra are calculated from analysis of the response of the Phonodeik. Finally, the original waveform could be reconstructed from the corrected spectral amplitudes and phases by a waveform synthesizer, also built at Case. Videos will be presented that show the motion of the gears, spheres, and dials of a working Henrici analyzer, housed at the Department of Speech Pathology and Audiology at the University of Iowa. Operation of the Henrici analyzer and the waveform synthesizer will be explained.
Evaluation of the performance of the blast analysis and measurement system
Authors: Luz George A.
Published: September 2013

In the years since the introduction of the C-weighted day–night average sound level (DNL) to assess the noise of military explosives, Army practice has evolved to incorporate linear peak sound-pressure level into the evaluation of military training noise. Although the DNL remains as the method of choice for National Environmental Policy Act (NEPA) documentation and for land-use planning, peak level is used by firing range operators for day-to-day complaint management. Several different monitoring system designs are being used at Army installations to provide range operators with real-time feedback on blast noise levels in nearby residential areas. One of these, the Blast Analysis and Measurement (BLAM) system, is a modified version of a sonic boom monitor designed by the U.S. Air Force. Data collected from two BLAM units located near a 120-mm tank gunnery range were evaluated in terms of hit rate and false-alarm rate over a range of 94 to 140 decibels linear peak. Hit- and false-alarm rates are compared with hit- and false-alarm rates reported for other blast noise monitoring system designs.
A linear independence method for system identification/secondary path modeling for active control
Authors: Kim Benjamin , Swanson David
Published: September 2013

A novel method for noninvasive system identification/secondary path modeling has been developed for single- and multi-channel filtered-x LMS-based active noise control (ANC). The problem of on-line secondary path modeling is recognized as one of linear dependence associated with an underdetermined system, a one-equation/two-unknown problem in which the highly correlated primary source and secondary source contributions to the error signal are not readily distinguishable. The method resolves this uniqueness issue by introducing a second equation with similar unknowns. The critical linear independence of the two equations, hence the proposed designation, is achieved with a single perturbation of the control filter output thereby making the system solvable. This new secondary path modeling strategy was implemented using a novel real-time DSP control architecture and tested on a novel transducer-less system devised to investigate the behavior of ANC algorithms. Results of narrow-band, broadband, and multi-channel tests reveal estimates of exceptional accuracy, in both magnitude and phase; any bias in the secondary path estimate, whether introduced by the primary noise source or other secondary sources in the system, is eliminated using this method. Its quickness as well contributes significantly to the stability and performance of filtered-x LMS-based controllers. [Work supported by ONR.]
Hybrid feedforward-feedback active noise control for circumaural headsets
Authors: Streeter Alexander D. , Ray Laura R. , Collier Robert D.
Published: September 2013

Traditional stability-performance tradeoffs pose limitations on active noise reduction (ANR) using feedback control, which are evident in circumaural communication headsets. In these systems, the cavity resonant behavior necessitates low feedback gains, redcing performance. Feedforward ANR using a Lyapunov-tuned least-mean-square filter dramatically enhances noise reduction performance compared with feedback ANR [Cartes et al., J. Acoust. Soc. Am. 111, 1758–1771 (2002); Collier et al., NOISECON (2003)]. However, feedforward performance is sensitive to the noise source stationarity, and the frequency-dependent forward path gain reduces stability margins. This paper presents experimental results for a hybrid feedforward-feedback ANR system, which enhances performance and gain margins for both stationary and nonstationary noise. Algorithms are optimized and measurements are performed with Thayer’s rapid prototyping system and associated low-frequency acoustic test cell using a circumaural hearing protector. In the frequency range 50–800 Hz, the hybrid system provides an average of 27 dB active noise reduction (40 dB total) for tonal noise and 17 dB reduction (32 dB total) for nonstationary noise. Performance below 100 Hz improves by as much as 15 dB over that of individual control components, and gain margin of the hybrid system improves substantially over individual feedforward or feedback components.
Aircraft interior ANC with light-weight actuators
Authors: Gerner Christian , Sachau Delf , Breitbach Harald
Published: September 2013

In propeller-driven aircraft the main source for internal noise is tonal disturbances caused by the propeller blades that are passing the fuselage. In a certain four-propeller military transport aircraft the maximum sound level in the cabin can reach up to 110 dB(A), not taking into account any noise control treatments. Inside the semiclosed loadmaster working station (LMWS) the sound level must be reduced down to 86 dB(A). It is proposed to reach this goal with an active noise control system, because passive solutions are too heavy at low frequencies. The optimal positions of the loudspeakers are found by finite-element calculations. These positions have been realized in a full-scale test bed. In the test bed a reduction of the sound-pressure level of more than 30 dB within a specified volume was achieved at a frequency of 100 Hz. In this test bed hi-fi speakers are used as secondary actuators. These speakers are heavy and of unsuitable geometric dimensions for an aircraft. Therefore, other actuators, e.g., flat panel speakers, will be investigated with respect to the application to a mock-up of the LMWS.
Acoustic feedback cancellation for active noise control in pipe
Authors: Liu Yun-Hui , Hung Chuan-Yu
Published: September 2013

In most practical applications of active noise control, acoustic feedback is a major problem that often interferes with the operation of the control system and even renders it unstable. The optimal collocated positions of secondary source and two microphones are studied and the theoretical equations that reduce the influence of acoustic feedback are developed based on plane-wave transmission theory of sound in a duct. The original signal of primary noise is obtained from the measured signals of reference microphone and error microphone, which are transformed to frequency domain by FFT and operated. In this study, the performance of the proposed method is compared with other traditional time-domain methods by means of simulation and analysis using LabVIEW programming language. The results showed that the proposed method can effectively reduce the influence of acoustic feedback. In practical application of active noise control in a duct, the adaptive control or other control method incorporating the proposed method in this paper will improve the stability and performance effectively.
Coupling of earphones to human ear and to coupler
Authors: Ciric Dejan , Hammershoi Dorte
Published: September 2013

The use of a standardized acoustical coupler should enable a calibration of audiometric earphones which ensures that the thresholds determined in the audiometry will be independent of the earphone type. This requires that the coupler approximates the average human ear closely. Nevertheless, the differences among earphones as well as between human ears and the coupler affect the results of audiometric measurements inducing uncertainty. The influence of these differences is examined by investigating the coupling of different earphones to human ears and to the standardized coupler. This is done by measurement of the transfer functions from input voltage of the earphone terminals to the entrance of the ear canal in two situations: (1) open, and (2) blocked. Similar measurements were carried out with the coupler, but since the ‘‘ear-canal entrance’’ is not well-defined for the coupler, the mentioned measurements were done at different depths in the coupler. The earphone’s coupling to (i) human ears and to (ii) the coupler, described in terms of the pressure division at the entrance of the ear canal, were compared. The results indicate that the coupling to the human ear and the coupling to the standardized coupler differ.
Using reflectance phase to estimate the acoustic response at the tympanic membrane
Authors: Keefe Douglas H.
Published: September 2013

A common problem in ear-canal acoustics is to estimate the SPL and acoustic transfer functions (ATFs) at the tympanic membrane (TM) based on a response measured at a distal probe location, but standing waves complicate interpretation above 1.5 kHz. Transmission is well approximated up to 8 kHz by modeling the ear canal as a rigid-walled cylindrical tube; the model transforms measurements at the probe tip to those at the TM. Based on SPL and ATFs measured at the probe in 42 normal-hearing and 18 conductive-impaired ears from 0.25–8 kHz, the equivalent SPL and ATFs at the TM are calculated for ambient and pressurized conditions in the ear canal. Tube area is calculated based on probe-tip size, while tube length from probe to TM is calculated from the group delay of the reflectance phase averaged from 6 to 8 kHz. In normal-hearing ears, the mean (±standard deviation) of the SPL difference at the TM re: probe has a maximum of 9.2±3.8 dB at 3.7±0.8 kHz. The equivalent TM admittance has a wideband shape similar to in vivo measurements of umbo velocity level at constant SPL at the TM [Ruggero and Temchin, 2003]. [Work supported by NIH.]
Relating psychophysical and otoacoustic emission suppression tuning curves
Authors: DiGiovanni Jeffrey J. , Zettner Erika M.
Published: September 2013

Psychophysical tuning curves (PTCs) are a well established method for estimating frequency selectivity in humans. PTCs are closely related to the shape of neural tuning curves. Furthermore, these two measurements are believed to represent frequency resolution processes primarily occurring in the cochlea. More recently, otoacoustic emission suppression tuning curves (STCs) have been measured and found to be characteristically similar in shape and tip frequency to PTCs (Abdala et al., 1996). STCs may represent an objective, noninvasive, measure of initial stages of cochlear tuning. The goal of this study was to compare and quantify the difference between transient evoked STCs (TE-STC) and PTCs. TE-STCs and PTCs were obtained in each normal-hearing subject with 4000-Hz probe tones. Preliminary data show that Q10 values and tip levels follow the same trend for both tuning curves. However, actual values of these parameters differ. Implications of methodological differences between these two paradigms will be discussed.