bluuebunny/crossref_metadata_2025 huggingface dataset:
Evoked response study tool software for single and multiple evoked potential measurements in animals.
Authors: Finneran James J.
Published: October 2010

The Evoked Response Study Tool (EVREST) is an integrated, portable hardware/software system designed for field measurement of evoked potentials. The software component of EVREST is a Windows-based application that is used for generating and calibrating sound stimuli and recording and analyzing evoked responses. The software has been used by a number of investigators to measure auditory evoked potentials in fish, marine mammals, and primates. The software features a graphical user interface and is compatible with a variety of commercial off-the-shelf data acquisition hardware. Options for sound stimuli include arbitrary waveforms loaded from disk or sums of up to 16 individual waveform components consisting of clicks or amplitude/frequency modulated tones. Evoked response data are averaged/displayed in real-time and also streamed to disk, allowing post-acquisition changes to analysis parameters. Objective response detection procedures include the F test, magnitude-squared coherence, and phase coherence. An adaptive staircase procedure is included for automated threshold measurements at multiple frequencies. In this talk, the operating principles and capabilities of the EVREST software are reviewed and example evoked potential data from dolphins and sea lions are presented. [Work supported by ONR.]
Software for viewing and checking automatic detections.
Authors: Mellinger David K. , Nieukirk Sharon L. , Heimlich Sara L. , Klinck Karolin , Klinck Holger
Published: October 2010

Automatic detection of animal vocalizations is now used widely for handling long-duration recording. Automatic detection methods inevitably make some errors—both false positive (wrong detection) and false negative (missed call) errors. Here a system is described for checking these errors. The MATLAB system “Osprey” allows viewing spectrograms, manipulating their parameters, and making various measurements of the displayed sounds. Another program, “checkDetections”, takes a log file that was output by an automatic detection software and systematically displays the detected sound in Osprey, allows a user to indicate whether the detection is correct, and then skips to the next detection in the log. This allows for rapid checking of detected sounds and calculation of the false-positive (wrong-detection) error rate. A second system, “checkMissedCalls”, displays random segments of sound in which no calls were found and allows the user to check whether there really were calls. This allows the user to estimate the false-negative (missed-call) error rate. Together these programs can be used to characterize a detector and arrive at a more accurate estimate of the number of calls present. Both of the programs are parametrized so that they can easily work with multiple data sets.
A system for tracking frequency-modulated bowhead whale calls on vector sensors in the presence of seismic exploration activity.
Authors: Thode Aaron , Kim Katherine H. , Blackwell Susanna B. , Greene Charles R. , Macrander Michael
Published: October 2010

A group of software tools has been developed for automated detection and localization of bowhead whale sounds with arbitrary frequency-modulated tones. The software is a mixture of JAVA, UNIX C-shell scripts, and MATLAB components, and consists of six sequential components: an incoherent spectral band event detector that yields time and bearings of transient events; an interval estimator to remove weak airgun signals; a feature extractor that processes an input spectrogram to yield a 23-element feature vector; two feed-forward neural network classifiers that sequentially winnow non-biologic signals and pinnipeds; a linking procedure to combine signals detected on sensors several kilometers apart; and a localization method that uses a maximum-likelihood procedure for estimating a position from a series of bearings. The software has been applied to data collected between 2007 and 2009 from at least 35 vector sensor autonomous recorders deployed over a 280-km swath in the Beaufort Sea. The largest dataset (2008) logged 1.35 × 106 calls at 386 000 locations over 54 days across 40 recorders and took 24 days to compute using a single 2.66-GHz processor. Seven recorders consumed over 50% of the processing time. [Work supported by Shell Exploration and Production Company.]
Equipartition and retrieval of Green’s function.
Authors: Weaver Richard L.
Published: October 2010

Research on retrieval of Green’s function by correlation of ambient noise has seen enormous growth in recent years, in particular in seismology, exploration geophysics, and ocean acoustics, and in general whenever receivers are convenient while active sources are not. As such it resembles various other methodologies such as daylight imaging, sound shadows, and correlations with noisy sources which are, in fact, different in principle. Retrieval has its theoretical origin in the concept of wave equipartition and the fluctuation dissipation theorem of statistical thermal mechanics. Proof that the Greens function is retrieved from the correlations of noise is the simplest and most elegant in the thermal case, but acoustic noise is rarely thermal and those proofs do not always apply. Nevertheless, diffuse acoustic wave fields will sometimes approximate equipartition (it is routinely assumed in room acoustics and statistical energy analysis), and retrieval is often strikingly feasible even where that approximation is weak. This talk will review some of the history of retrieval in acoustics, particularly its analytic proofs and its successful applications. Rates of convergence, the effect of non-stationarity of noise, and the practical effect of imperfect equipartition, will also be discussed.
Ambient noise in the Mariana Trench.
Authors: Barclay David R. , Buckingham Michael J.
Published: October 2010

In November 2009, ambient noise measurements were made in the Mariana Trench from the surface to a depth of 9000 m using the instrument platform Deep Sound. Deep Sound is a free-falling acoustic recorder designed to descend from the ocean’s surface to a pre-assigned depth where it drops an iron weight and returns to the surface under its own buoyancy. The ascent and descent rate is 0.6 m/s, resulting in an 8 deployment time to 9 km. The instrument recorded the continuous ambient noise time series over the bandwidth 5 Hz–30 kHz on four hydrophones mounted with vertical and horizontal spacings. Environmental data were recorded on a CTD and were used to calculate the local sound speed. Power spectra of the ambient noise were calculated as a function of depth, while vertical and horizontal coherence were calculated and used to infer information on the directionality of the noise field. The spectral levels of ambient noise over the measured range of frequency were found to increase with depth. [Work supported by ONR and the UC Ship fund.]
Ocean acoustic thermometry with ambient noise.
Authors: Godin Oleg A. , Zabotin Nikolay A. , Goncharov Valery V.
Published: October 2010

Diffuse acoustic illumination, provided by ambient and shipping noise in the ocean, can be used as a probing signal to characterize the environment in a cost-effective and non-invasive manner. Valuable quantitative information about sound speed and, hence, temperature fields in water is contained in acoustic travel times between spatially separated receivers. The travel times can be retrieved from cross-correlations of noise recorded by the receivers. Practical applications of noise interferometry to ocean thermometry face a number of obstacles, the main challenge being the need to achieve very high accuracy of passive sound-speed measurements in a dynamic environment with a complex noise field. This paper reviews the theoretical background of wave interferometry in inhomogeneous media with non-perfectly diffuse noise from the viewpoint of ocean remote sensing. Feasibility of ocean acoustic thermometry is illustrated using noise recordings of opportunity, which were obtained in the North Pacific Ocean as a by-product of a long-range sound propagation experiment. Requirements to future dedicated passive acoustic systems for long-term observations of variations in the ocean heat content are discussed. [Work supported by ONR.]
Mapping of the ocean wind by ocean acoustic interferometers.
Authors: Voronovich Alexander , Penland Cecile
Published: October 2010

Air-sea interaction is driven mainly by the wind blowing over the ocean surface, and its monitoring is an important task. Using ambient noise for the wind speed retrieval was suggested long ago; however, the proposed approaches rely usually on the local measurements with bottom-mounted hydrophones. We present another approach based on measurements of directivity of the ambient noise in the horizontal plane at low frequencies of the order of a few tens of hertz. Such measurements would be done with the help of ocean interferometers, which represent a couple of long vertical line arrays separated by a distance of the order of a few tens of kilometers and coherently measuring the ambient noise. In contrast to the methods of wind measurement based on local measurements, our approach relies on measurements of distant noise sources. The method principally allows mapping ocean wind over vast areas of the order of 1000 km in horizontal scale with resolution of the order of 10 km. A time of averaging required to overcome statistical variability of the noise field was estimated to be of the order of 3 h. The results of numerical simulations will be presented for propagation conditions typical for North Atlantic.
Micro-Doppler ultrasound in monitoring cancer therapy responses.
Authors: Czarnota Gregory J.
Published: October 2010

A number of cancer therapies including radiation, chemotherapy, and anti-vascular treatments act by causing endothelial cell death, leading to microvascular destruction within tumours. We have been using high-frequency (20–40 MHz) power Doppler micro-ultrasound to study the effects of a variety of anti-cancer therapies on tumor blood micro-vessels. Using breast and prostate xenograft tumors in mice with radiation alone, large doses above 8 Gy appeared to diminish the vascular by up to 40%–60%. Radiation given in the presence of a basic fibroblast growth factor did not have this effect. The anti-angiogenic Sutent suppressed vascular growth and enhanced radiation effect, but tumor vasculature exhibited a rebound effect when therapy was stopped. In contrast, novel anti-vascular microbubble based therapies induced a greater synergistic tumor cell kill due to vascular disruption. Tumor cell kill increased when microbubbles were used in conjunction with radiation, with increases of cell kill from 5% to over 50% with combined single treatments linked to destruction of the micro-vasculature. In summary, power Doppler micro-ultrasound can be used quantitatively to assess the effects of anti-cancer therapies on tumor micro-vasculature. Effects of anti-angiogenic agents and newer anti-vascular therapies and their rebound effects can be monitored non-invasively and longitudinally in preclinical models.
The wall-filter selection curve method for objective tuning of power Doppler clutter filter cutoff velocity.
Authors: Lacefield James C. , Pinter Stephen Z.
Published: October 2010

High-frequency power Doppler ultrasound is commonly used to assess vascularity in small-animal cancer models, but quantitative images can be difficult to obtain in the presence of clutter artifacts. To improve vascular quantification, the color pixel density (CPD) in a region of interest can be plotted as a function of wall-filter cutoff velocity to produce the wall-filter selection curve. A mathematical model based on receiver operating characteristic statistics was developed to guide the interpretation of wall-filter selection curves. Mathematical predictions were tested using a VisualSonics Vevo 770 system with a 30-MHz transducer and a flow phantom containing four 200–300-μm-diameter vessels. The phantom mimicked vessel configurations observed in micro-CT images of a transgenic mouse prostate cancer model. Selection curves characteristically include a plateau whose CPD may correspond to either the total vascular volume fraction or to the volume fraction of a subset of vessels in the region. The flow-phantom data indicate that the plateau provides a reliable estimate of total vascularity if the plateau begins at a cutoff velocity <2 mm/s and is longer than 0.5 mm/s. The wall-filter selection curve may enable adaptation of scanner settings to changing flow conditions as a tumor progresses during a longitudinal study.
Improved method for objective selection of power Doppler wall filter cut-off velocity for microvascular imaging.
Authors: Elfarnawany Mai , Pinter Stephen Z. , Lacefield James C.
Published: October 2010

The wall-filter selection curve method has been enhanced to improve detection and interpretation of color pixel density (CPD) plateaus. The improved algorithm was developed by analyzing data acquired from three fields of view in a four-vessel flow phantom using a 30-MHz swept-scan transducer. An N-point maximum envelope peak search applied to the first difference of CPD detects selection curve plateaus by incorporating criteria that identify intervals of minimum variation in CPD. Selection curves for regions of interest (ROIs) containing multiple vessels can be difficult to interpret, so the algorithm subdivides the image into small ROIs, constructs selection curves for each ROI, and sums the resulting vascularity estimates. The lower limit on ROI size is constrained by a need to avoid ROIs that are completely filled by blood. A multiple-step decision algorithm was designed that considers the number, length, and slope of each plateau to identify the cutoff velocity that yields the best vascularity estimate. At high (> 5 mm/s) flow velocities, the decision algorithm yielded a summed CPD that was within 5% of the vascular volume fraction in each field of view. These improvements are an initial step toward automating wall-filter cutoff settings in a power Doppler system.
Estimating fetal heart rate from multiple Doppler ultrasound signals.
Authors: Voicu I. , Girault J.-M. , Kouame D. , Fournier-Massignan M. , Perrotin F.
Published: October 2010

In utero, monitoring of fetal well being or suffering is today an open challenge due to the high number of clinical parameters to be considered. An automatic monitoring of fetal activity, dedicated for quantifying fetal well being, becomes necessary. For this purpose and in a view to supply an alternative for the Manning test, we used an ultrasound multitransducer muligate Doppler system. One important issue is the accurate estimation of fetal heart rate (FHR). An estimation of the FHR is obtained by evaluating the autocorrelation function of the Doppler signals for ills and healthiness of the fetus. However, this estimator is not robust enough since about 20% of the FHR is not detected in comparison to a reference system. These non-detections are principally due to the fact that the Doppler signal generated by the fetal movement is strongly disturbed by the presence of several other Doppler sources (mother’s movement, pseudo breathing, etc.). By modifying the existing method (autocorrelation method) and by proposing new estimators used in the audio’s domain, we reduce to 5% the probability of non-detection of the fetal heart rate. These results are really encouraging, and they enable us to plan the use of automatic classification techniques in order to discriminate between healthy and suffering fetus.
Measuring tendon velocities using vector tissue Doppler imaging.
Authors: Eranki Avinash , Sikdar Siddhartha , Stanley Christopher , Prosser Laura , Bellini Lindsey , Bland Daniel , Alter Katharine , Damiano Diane
Published: October 2010

We have developed a vector tissue Doppler imaging (vTDI) method to quantify the magnitude and direction of tissue motion. The goal of this study was to quantify the repeatability of vTDI in measuring the contraction velocity of the tibialis anterior (TA) tendon in patients with cerebral palsy and foot drop (impaired dorsiflexion). vTDI was implemented on Ultrasonix Sonix Touch ultrasound system with a 5–14-MHz linear array transducer. The array was electronically split into two transmit and two receive apertures to estimate velocity vectors. Transmit and receive beams were steered by ±15 deg. We conducted 42 trials on 7 subjects. Our preliminary results show that TA tendon velocities measured using vTDI have a strong linear correlation with the joint angular velocity estimated using a conventional 3-D motion capture system. We observed a peak velocity of 5.20±1.58 cm/s during dorsiflexion and 8.45±2.06 cm/s during the gravity-aided passive relaxation phase. The R2 values for all 42 trials were 0.77±0.10. A second velocity measurement was made on three subjects after an interval of 4 weeks. We obtained repeatable velocity estimates with the standard deviation of the radius of action less than 0.13 cm. This demonstrates that vTDI is a feasible and reproducible method for measuring tendon velocities.
Development of a master program in acoustics and vibration.
Authors: Arenas Jorge P.
Published: October 2010

In 2008 a new master program on acoustics and vibration became part of the graduate offerings at the Univ. Austral of Chile. This program—the first graduate course on this topic to be offered in the country—evolved from the undergraduate one on Acoustical Engineering that has been offered for several decades in the university. Its set of courses is offered through the Institutes of Acoustics, Materials, Mechanics, Physics, Electronics, and Mathematics of the university. Its curriculum was planned taking into account the strongest areas of research in our university. It has been designed into three core courses: Vibroacoustics, Instrumentation, and Mathematics. These courses give the students the basic theoretical background. Then, there is a pool of optional courses on forensic acoustics, advanced signal processing, acoustic sensors, acoustic emission, environmental acoustics, advanced theory of vibrations, finite elements in vibrations, machinery diagnostics, parametric modeling, materials engineering, and heat transfer. After completion of the courses, the students have to elaborate a thesis work including a final dissertation. The duration of the program is three semesters for a full-time student. After 2 years of offering this program, a great success has been achieved in the advancement of the acoustic knowledge of the country.
Description of the National Polytechnic Institute acoustics program.
Authors: Beristain Sergio
Published: October 2010

At the National Polytechnic Institute in Mexico City there has been, in the last 35 years, the teaching of the major in acoustics within the Communications and Electronics Engineering BSc studies. Thanks to the vision of Eng. Tomas Guzman Cantu, and the support of all the lecturers and the students, there are now over 1000 students graduated in this area. In the last promotion, there are over 90 students about to graduate, most of them have gone to the audio business in recording studios and broadcast centers, However, there are also graduated people in the areas of noise, hospitals and clinics, architectural acoustics, machinery vibration and structures, animal bioacoustics, speech and audiology, designing and evaluation of musical instruments, etc. Details of the studies are presented.
Acoustics at University of Texas: History and current introductory course in physical acoustics.
Authors: Blackstock David T.
Published: October 2010

As an academic discipline at the University of Texas, acoustics began in the 1930s under C. Paul Boner in Physics and Lloyd A. Jeffress in Psychology. World War II saw Boner and many physics graduate students go to Harvard for “war work,” largely in underwater acoustics. When the war ended, Boner returned and founded the Defense Research Laboratory, later named Applied Research Laboratories. Interest in acoustics grew in Physics during the postwar years but eventually waned in the 1950s and 1960s. Acoustical activity developed in the 1960s in the College of Engineering, chiefly Electrical Engineering and Mechanical Engineering. Today physical and engineering acoustics is a strong interdisciplinary program at Texas, with faculty in several departments in Engineering and still a vestige in Physics. In addition, much work on speech, hearing, and music is done in other parts of the University. Engineering features two basic courses in physical acoustics, Acoustics I and II, and five specialty courses, which are described in an accompanying paper. Here we concentrate on Acoustics I and II, which provide an introduction to propagation, reflection and transmission, refraction, normal modes, horn theory, propagation in stratified fluids, absorption and dispersion, waveguides, directional radiation, diffraction, and arrays.
The use of information technology and communication in the teaching of acoustics in the National Polytechnic Institute.
Authors: Becerra García Jorge , Ramírez Rangel Patricia Lorens , García Alvarado Dagoberto
Published: October 2010

The IPN-ESIME Zacatenco has been making major changes in the educational field, since the goal is that technological education is kept at the forefront of the learning processes of their graduates in the various schools of IPN. The ESIME with its acoustics specialty does not remain outside this fact and promotes the redesign of its processes of teaching each of the subjects to students in an era of a more competitive knowledge society. To achieve this, graduates of the specialty must have more elements of judgement in carrying out their professional activities. The institute promotes further that students graduate and leave with more modern learning tools.
New methods for acquiring a Bachelor of Science level in the National Polytechnic Institute careers.
Authors: Lizana Pablo , Rabadan Itzala
Published: October 2010

The main problem for the Bachelor of Science (BSc) students at the National Polytechnic Institute (IPN) is the lack of the BSc certificate, which sets them at a disadvantage compared with students of other institutions of the same level, locally and abroad. After several years of discussion, the Advisory Board of the IPN Mexico was able to incorporate a new way for getting the certificate, in order to reduce that problem, but the experience has shown that even having the same quality as the traditional way, some students and lecturers show resistance to the change to the establishment. The main problem is the lack of time the students have in order to develop their thesis within the allocated time frame.
Modeling the piano string as a mass-spring chain.
Authors: Kuroda Junji , Smith Julius , Perng Jack
Published: October 2010

The mass-spring chain allows accurate modeling of vibrating strings in all three spatial dimensions. [Rowland and Pask, Am. J. Phys. (1999)]. This presentation describes striking one or more adjacent masses of such a string model with a forcing function corresponding to the piano hammer [http://www.ioc.ee/stulov/PUB.htm]. An advantage of striking a mass-string model, in which each mass may move in three dimensions, is that coupling from transverse to longitudinal modes of vibration are naturally provided.
Analysis and digital enhancement of “brassiness”.
Authors: Cooper Charles M. , Abel Jonathan S. , Erdol Nurgun
Published: October 2010

The distinctive “brassy” timbre of instruments such as the trumpet and trombone has been variously attributed to spectral brightening of the mouthpiece excitation and to nonlinear wave-propagation effects, primarily shock waves, whose existence and importance are the subject of ongoing investigation. In the research presented here, spectral brightening at higher amplitudes—even at levels insufficient to produce shock waves—is explained analytically in terms of the known amplitude-dependent propagation speed of sound. This spectral-enrichment effect is experimentally demonstrated by acoustic measurements, analytically quantified in terms of phase modulation and the generation of harmonically related sidebands, and perceptually confirmed by digital simulation. Efficient discrete-time methods for implementing the desired signal-dependent delay or phase modulation, as well as shock formation, are described. This “brassification” effect can be used for synthesis of brass-like sounds or to increase the perceived brassiness of live or recorded instrument sounds.
Real-time computational audio scene analysis, transformation, and synthesis for active music listening.
Authors: Marchand Sylvain
Published: October 2010

Spectral models attempt to parametrize sound at the basilar membrane of the ear, thus permitting transformations closely linked to the perception. However, for high-quality real-time applications, these models require methods for a precise analysis and an efficient synthesis. When dealing with musical sound, that is, a polyphonic mix of non-stationary complex sounds, the main challenge is to extract these different sounds present in the musical mix. This can be done using (psycho) acoustical knowledge about the sound sources (computational auditory scene analysis approach). However, the quality is often not sufficient. When access to the compositional process is given, another option is to use some bits of this ground truth as additional information (informed analysis approach). This more precise analysis allows deeper transformations, and using psycho-acoustical considerations, efficient data structures, and algorithms, it is possible to re-synthesize the sounds from the model parameters in real time and with a high quality. This opens up new impressive applications, such as “active listening”, enabling the listener to interact with the sound while it is played. The musical parameters (e.g., loudness or spatial location) of the sound sources present in the musical mix can now be changed interactively.
Singing information processing: Concept and applications.
Authors: Goto Masataka , Saitou Takeshi , Nakano Tomoyasu , Fujihara Hiromasa
Published: October 2010

This paper describes recent research on singing information processing [Goto et al., Proc. of IEEE ICASSP (2010)], which is music information research for singing voices. Singing is one of the most important elements of music since a great number of people listen to music with a focus on singing, especially in the case of popular music. The concept of singing information processing systems is broad and still emerging, but three important categories are singing understanding systems, music information retrieval systems based on singing voices, and singing synthesis systems. Singing understanding systems have been developed for various tasks such as synchronizing lyrics to vocal music, singer name identification, singing skill evaluation, creating hyperlinks between phrases in the lyrics of songs, and detecting breath sounds. Music information retrieval systems based on similarity of vocal melody timbre and vocal percussion, as well as singing synthesis systems for speech-to-singing synthesis and singing-to-singing synthesis, have also been developed. Common signal processing techniques, such as techniques for extracting vocal melody from polyphonic music recordings and modeling the lyrics by using phoneme hidden Markov models for singing voices, are used in these systems. [This research was supported in part by CrestMuse, CREST, JST.]
Noise impact in a residential development in Zapopan Jalisco, Mexico.
Authors: Muñoz Aceves Cesar , Ortiz Garcia Juan Jose , Esparza Osuna Martha , Mendez Rodriguez Viridiana
Published: October 2010

Altagracia is a residential development in Zapopan Jalisco. Here noise due to stationary and mobile sources is an important environmental stressor, since the settlement is close to industry complexes and the major periphery road of the metropolis. As a way of getting knowledge about what noise sources contribute the most to the noise impact within the development, a noise environmental assessment was performed. 14 samples were taken to evaluate the contribution of mobile and stationary sources. Sampling sites were established as a result of a pilot experiment at which the highest noise levels were recorded. Data processing and analysis were performed taking into account national standards for stationary sources (NOM 081-ECOL-94), and mean values for the mobile sources, since there is not specific regulation for them. Results of the study, highlights mobile sources as the major contributor of noise impact within the residential area.
Study of noise, environmental quality, and health risks in an avenue of the city of Guadalajara, Jalisco, Mexico.
Authors: Galindo Barragan G. , Orozco Medina M. , Garcia Velasco J. , Gonzalez Hernandez A.
Published: October 2010

Unsuitable urban development plans prompt environmental problems that might seriously affect health such as stress, hearing impairment, and respiratory problems. According to the World Health Organization [WHO (2001)] air pollution is one of the leading causes of illness and reduced quality of life in general. This research examines the environmental quality in a critical area of Guadalajara City, taking into account physical and chemical parameters, as well as air microbiology, as an integrated approach to identify health problems in exposed population due to pollution. On this basis, the study suggests an attention proposal.
Environmental noise attached to an integral quality diagnostic on recreational public areas.
Authors: Chavez Rubio Loyda , Orozco Medina Martha , Hernandez Ramirez Gabriela , Hernandez Arellano David , Ramirez Trejo Gerardo
Published: October 2010

Environmental quality is one of the most important topics for the social well being and must be considered in order to have a healthy social system. Shopping malls have become an essential part of the daily life of Mexican society as recreational and leisure public areas as well as a strong source of employment and economic incomes. However, the shopping malls can also be a huge source of noise, urban waste, and traffic, among other impacts it can cause in the environment. The objective of this study is to recognize and analyze the environmental quality on recreational public areas, including the way these places are managed, and now they manage solid waste, water savings, energy consumption, and measuring the noise levels inside and outside of the building; the registered range was between 60 and 90 dB(A). Another analyzed aspect is the existence or absence of educational programs oriented to visitors. It is important to find applicable strategies to make these recreational areas a place with improved environmental quality.
Measurement time of urban noise in Montevideo (Uruguay) and Medellin (Colombia).
Authors: González Alice Elizabeth , Giraldo William
Published: October 2010

The duration of ambient noise measurements is one of the susceptible aspects regarding the correct design of a large measurement campaign, for example, to build an urban acoustic map. Previous work in Montevideo and Medellin lead to determine the stabilization time of the measurements with the aim of achieving accuracies from ± 1 to ± 3 dB in relation to the value of Leq,1h and Leq,d (Leq of the daytime). Montevideo data were taken at five points of the city, with traffic densities (IMH, time average intensity) from 200 to 1700 vph. Medellin data were taken in two monitoring stations, each equipped with a fixed sound level meter. In one of the stations, the IMH value is 1880 vph, while in the other one is 2120 vph except Sundays, when it is reduced to approximately 950 vph. Measured LA,eq,1h and Leq,d values are compared with those obtained for the same period with data corresponding to samples of 10, 15, 20, and 30 min. In both cases, the representativeness of the measurements increases with the enlargement of measurement time. Despite their great differences, both cities admit similar durations for measurements of urban noise to obtain representative data.
Measurement and prediction of urban noise spectrum at different heights and distances of the sound source.
Authors: Iasi Federico , Vechiatti Nilda , Armas Alejandro , Tomeo Daniel , Bontti Horacio , Velis Ariel , Gomez Pablo , Gavinowich Daniel , Ciccarella Pablo
Published: October 2010

To elaborate noise maps, national and international directives indicate that urban noise measurements must be carried out 4 m high, so as to obtain the map by the method of direct measurements, or for the calibration of mathematical models that predict sound levels. As a continuation of research plans to be carried out in the Acoustic and Lighting Laboratory of the Commission of Scientific Research, Province of Buenos Aires (LAL—CIC), and in the Acoustic and Electroacoustic Laboratory, Engineering Faculty of the University of Buenos Aires (LACEAC—FI UBA), and in order to estimate the error that will be committed using the prediction method rather than the direct measuring method, urban noise measurements were taken in surrounding areas in a quick access to La Plata City, at different heights and different distances from the sound source.
Enhancement and suppression of the response of a water-filled spherical shell resonator due to the interaction of modes.
Authors: Lonzaga Joel B. , Mobley Joel
Published: October 2010

In this paper we report on the suppression and enhancement of modal amplitudes in a water-filled, spherical shell resonator as a function of sound speed in water. The resonator, which has a 1-in.-thick wall and a 9.5-in. diameter, was driven by a transducer bolted to the external wall. The drive frequency was swept over specific resonant modes whose frequencies have different dependencies of the sound speed in the water. Theoretical analysis of the resonant modes revealed that the suppression or enhancement of the response occurs for specific values of the sound speed when the initially distinct resonant frequencies of two modes meet at a crossover point. Additional theoretical modeling shows that the suppression or enhancement is caused by the interaction between the two modes when their resonant frequencies intersect.
Inertial cavitation threshold dependence on static pressure.
Authors: Bader Kenneth B. , Raymond Jason L. , Mobley Joel , Church Charles C. , Gaitan D. Felipe
Published: October 2010

It is well known from observations in the ocean, as well as limited experimental measurements and theoretical predictions for spherical bubbles, that the threshold acoustic pressure for generation of inertial cavitation increases with hydrostatic pressure. However, the precise nature of the relationship between hydrostatic and acoustic pressures at threshold has not been well studied. We report here the results of a series of rigorous experiments designed to better define this relation and investigate the nature of the nuclei responsible for the cavitation events observed. The hydrostatic pres-sure dependence (up to 300 bars) of the inertial cavitation threshold in ultrapure water was measured in a radially symmetric standing wave field in a spherical resonator driven at a resonant frequency of 25.6 kHz. The results will be compared to an independent analysis of the particulate content of the liquid. [Work supported by Impulse Devices, Inc.]
Ultrasonic spectral analysis of cavitation bubbles in vegetable oils.
Authors: Doyle Timothy E. , Martini Silvana , Jensen Scott C. , Pichardo Ricardo J. T. , Hart Vern
Published: October 2010

Ultrasound-induced cavitation in vegetable oils can be used to control the crystallization and resulting texture of food products such as shortenings. Cavitation in oils has not been explored as extensively as in aqueous systems, however. To more fully understand cavitation in vegetable oils, high-intensity ultrasound (HIU) and broadband 1.0-MHz transducers were used to generate and measure cavitation in soybean oil experimentally. To interpret the results, multipole-based models were used to simulate ultrasonic scattering from the cavitation bubbles in the 0.4–4.0 MHz range. Ultrasonic reflection spectra, transmission spectra, and velocities were simulated for spherical bubble clouds centered between two transducers. The size, concentration, and random configuration of the bubbles in the clouds were varied to find diagnostic features to correlate with experimental data. The models indicated that the configuration of the bubbles have unexpectedly large effects on the ultrasonic spectra even at dilute concentrations (0.2–5.0%). The simulated spectra additionally showed low-frequency (<2 MHz) and high-frequency (>2 MHz) features that correlated with bubble concentration and bubble size, respectively. The experimental results included spectral features that may be associated with turbulence in the oil and the persistence of low-frequency backscatter after stopping the HIU, indicating a slow decay in bubble concentration.
Nonlinear modifications and validation of the T. von Kármán and N. Moore model for ballistic shocks.
Authors: Aguilar Juan , Desai Sachi
Published: October 2010

The acoustical model of T. von Kármán and N. Moore is used to predict ballistic shocks produced by slender like projectiles traveling at supersonic speeds. This is a linear acoustics model which assumes the projectile as a linear distribution of point sources whose diameters vary according to the projectile shape profile. In this paper, an updated version of the T. von Kármán and N. Moore model which introduces nonlinear distortion of the N waves for describing shock overpressure and N wave duration is presented. Nonlinear distortions are introduced in the script in the form of the well known Whitham expression for N waves in the far field. Furthermore, the results of these computer simulations are validated using previously recorded waveforms obtained from real sniper weapons of different calibers.
Capabilities of the high-order parabolic equation to predict propagation in boundary and shear layers.
Authors: Malbequi Patrice , Simon-Christien Denis
Published: October 2010

The parabolic equation (PE) has proved its capability to deal with the long-range sound propagation in the atmosphere. It also represents an attractive alternative to the ray model to handle duct propagation in high frequencies for the noise radiated by the nacelle of aero-engines. It was recently shown that the high-order parabolic equation (HOPE), based on a Padé expansion with an order of 5, increases the aperture angle of propagation compared to the standard and the wide-angle PEs, allowing prediction close to the cutoff frequency of the duct. This paper is concerned with propagation using the HOPE in heterogeneous flows, including boundary layers above a wall and in shear layers. The thickness of the boundary layer is about dozens of centimeters; while outside it, the Mach number reaches 0.5. The boundary layer effects are investigated showing the refraction effects on a range propagation of 30 m, up to 4 kHz. On both sides of the shear layer, significant differences in the directivity patterns occur. Comparisons with the Euler solutions are considered, establishing the domain of application of the HOPE on a set of flow configurations, including those beyond its theoretical limits. [Work supported by Airbus-France.]
Efficient prediction of broadband radiation from vibrating panels in the high-frequency range.
Authors: Bliss Donald B. , Franzoni Linda P.
Published: October 2010

Broadband high-frequency panel radiation is shown to have simple directivity characteristics expressed analytically by a limited set of parameters. For subsonic structural waves, namely below coincidence, the far-field mean-square pressure is associated with radiation from the panel perimeter. For low structural damping, this edge radiation depends on the mean-square structural response of the panel and the reflection coefficients of structural waves at panel boundaries. The spatial transform of surface velocity can be expanded and inverted term-by-term in the radiating wavenumber region, giving an asymptotic result in physical space with singularity functions along the edges. The far-field is produced by monopole, dipole, quadrupole, etc., edge radiators with relative strengths that depend on surface-wave Mach number and wavefront orientation. Edge radiation cannot be explained simply in terms of uncanceled volumetric sources, as often stated incorrectly. The correct interpretation of the sub-coincidence radiation is provided in both physical space and transform space. High-frequency broadband radiation above coincidence is also examined. Then the panel behaves as a surface radiator and directional beaming is observed. The work gives insight into the role of uncertainty in boundary conditions, allowing the establishment of bounds on the radiated power and variation in directivity.
Vibrations, energies, and power flows in complex systems.
Authors: Xu Hongan , Li Wen L.
Published: October 2010

A general numerical method, the so-called Fourier spectral element method, is described for the dynamic analysis of complex structures. When applied to structural problems, this method treats a complex structure as an assembly of fundamental structural components such as beams and plates. Over each component, the basic displacement is sought directly in the form of a modified Fourier series which is mathematically guaranteed to converge absolutely at every field or boundary point. The Fourier coefficients are considered as the generalized coordinates and determined using the Rayleigh–Ritz method. Since this method does not involve any assumption or simplification, it is broadly applicable to the whole frequency range usually divided into low-, mid-, and high-frequency regions. Additionally, because the system model is mesh- and grid-free, a smooth transition between the different frequency regions can be automatically accomplished by switching on/off the statistical processes and/or the spatial- and frequency-averaging features. This method is particularly suitable for mid-frequency dynamic analysis of complex systems. The relationships are investigated between component energies and power flows. It is shown that the spatial- and frequency-averaging processes may not be appropriate for the mid-frequency analysis because the important dynamic characteristics of a system tends to be eliminated.
Power transmission characteristics of a U-shaped plate structures withelastically restrained edges including in-plane vibration.
Authors: Chen Yuehua , Jin Guoyong , Du Jingtao , Liu Zhigang
Published: October 2010

An analytical study on the power transmission characteristics of a U-shaped configuration consisted of three rectangular plates is presented. Four groups of springs, to simulate the transverse shearing forces, bending moments, in-plane longitudinal forces and in-plane shearing forces separately, are distributed consistently along each edge of the model. With general boundary conditions of both flexural and in-plane vibrations taken into account by setting the stiffness of these springs, the double Fourier series solution to the dynamic response of the structure is obtained by employing the Raleigh–Ritz method. For model validation, the natural frequency and velocity response of the model are checked against existing literature results and the ANSYS data and good agreement is achieved. The influence of several relevant parameters on power transmission of the coupled structure is then studied in detail, including boundary conditions, coupling conditions, and locations of the external force. The results show that the power transmission of the structure can be significantly affected by altering the boundary condition without changing other parameters of the model. The location of the excitation will remarkably influence the power transmission. Once the excitation is imposed on the central symmetry point of the model, the power transmitted will show a symmetrical distribution. When the location deviates from the central symmetry point, the power circumfluence occurs.
Speckle subtraction imaging of structural vibrations.
Authors: Cannaday Ashley , Mahara Aditya , Zietlow Sarah , Moore Thomas
Published: October 2010

There are several optical methods that can be used for imaging structural vibrations; however, these often require expensive equipment and have significant limitations on the stability of the structure. We review some simple methods for imaging deflection shapes using inexpensive off-the-shelf components and introduce some modifications that make these methods even simpler. A simplified arrangement for electronic speckle pattern interferometry as well as a novel method that relies on the inherent threshold of the detection mechanism will be discussed.
Chloride detection in cement based materials by ultrasonic interferometry.
Authors: Cortez-Ortiz Eduardo , Pech Perez Andres , Cano Barrita Prisciliano F. de J. , Vazquez Feijoo Juan A.
Published: October 2010

Chloride ions play an important role in the corrosion of steel reinforcement in concrete structures. In northern countries, de-icing salts are a major factor in the deterioration of highways, and in many countries, chlorides from seawater exacerbate the deterioration process. In order to assess the chloride penetration as destructive, low spatial resolution methods are routinely used. A range of ultrasound based techniques are currently being used to characterize cement based materials. However, they are intended primarily to monitor changes in mechanical properties, cracking, position of stressing tendons, and corrosion of reinforcement. This paper will demonstrate the ability of an ultrasonic interferometry technique to monitor the capillary absorption of a 16.5% NaCl solution in cement paste and mortar cube samples. The results demonstrate that this technique is able to detect small changes in the properties of fluids penetrating the porous material. Future applications will include imaging of chloride penetration in cement based materials in laboratory and field conditions.
Auditory processing and speech production in children with typical development and developmental phonological disorders.
Authors: Liu Chang , Davis Barbara , Champlin Craig
Published: October 2010

The purpose of the study is to compare auditory processing of non-speech and speech sounds in children with developmental phonological disorders (DPDs) and children who are typically developing (TD). Basic auditory processing capacities of frequency selectivity, temporal processing, and speech perception for TD, and DPD children 4–6 years of age, were measured. Auditory filter bandwidth was examined at 4 kHz using the notch-noise method, and psychometric functions for gap detection and /b-p/ identification were measured. Preliminary results showed that DPD children had higher boundaries and shallower slopes in the psychometric functions of gap detection and /b-p/ identification than TD children, indicating that DPD children needed longer duration gaps for detection and longer voiced onset time for voiceless stop identification than TD children. There was no significant difference in auditory filter bandwidth between the two groups of children, although DPD children showed slightly higher detection thresholds than TD children. These results suggest that frequency selectivity was comparable between TD and DPD children, although DPD children have a lower central auditory processing efficiency. The relationship between auditory perception and speech intelligibility will also be discussed.