bluuebunny/crossref_metadata_2025 huggingface dataset:
Distributed source localization in a wireless sensor network
Authors: Williams Stephen M. , Schmidt Peter L. , Frampton Kenneth D.
Published: October 2013

This work concerns experimental implementation of distributed acoustic source localization with a wireless sensor network. The envisioned application is the distribution of hundreds or thousands of small, semi-disposable, wireless sensor nodes (possibly by airdrop). These nodes would form an ad-hoc communications network and monitor and track acoustic events within the array. Centralized processing of such data would be prohibited by the excessive communications and complexity of calculations. Furthermore, localization with a network of randomly placed sensors is not suited to use of traditional array theories due to irregular placement of sensors and the unknown sensitivity and phase relationships between sensors. Therefore, a fully distributed localization algorithm was developed in which nodes organize themselves into groups which collaborate to locate sources. Acoustic event time-of-arrival information is shared among group members and the source locations were determined using Tikhonov regularized inversion. Small scale localization experiments (with 10 sensor nodes) were conducted to validate the performance of the method. Results are discussed, along with limitations of the method discovered during conduct of the experiments. In addition, a comparison is made between this method and traditional matrix solution methods.
Higher moment estimation for shallow water reverberation
Authors: LePage Kevin
Published: October 2013

Shallow water reverberation is characterized by clutter which causes false alarms in sonar systems. In previous work we have estimated the non-Rayleighness of shallow water reverberation time series predictions obtained by the R-SNAP model. Here we extend the R-SNAP model to the closed form estimation of the second moment of reverberation intensity, allowing the estimation of pdf fits for the two parameter K distribution as a function of system and channel characteristics and time after shot. This work is intended to theoretically guide the selection of clutter-robust system characteristics. [Work supported by ONR.]
Comparison of measured buried target backscatter levels with high-order predictions: Rippled interface effects
Authors: Lim Raymond , Lopes Joseph L. , Sammelmann Gary S.
Published: October 2013

Controlled sonar measurements with buried spheres and cylinders have demonstrated diffraction by bottom ripple can significantly improve target detection performance with sonar operated at grazing angles shallower than the critical grazing angle. Furthermore, buried target scattering models based on low-order perturbation theory to handle sound transmission through bottom roughness confirm that a significant enhancement in detection performance can be expected. But comparisons between measurements and model predictions have not always produced good agreement. As the bottom ripple height increases, discrepancies have been noted in comparisons with the predicted backscatter levels from a buried sphere, suggesting a failure of low-order perturbation theory to properly account for high-amplitude roughness effects. Recently, a recursive algorithm to generate arbitrary-order perturbation corrections for transmission and reflection through an idealized sinusoidal ripple was formulated and incorporated into our existing buried target scattering codes. The resulting higher-order predictions indicate previous discrepancies were not necessarily due to the neglect of high-order corrections. Calculations show model inputs such as bottom attenuation can influence backscatter levels significantly and measurement of these parameters may need to be performed more carefully. We demonstrate this through a presentation of data and model comparisons. [Work supported by ONR and SERDP.]
Lip and jaw closing gesture durations in syllable final voiced and voiceless stops
Authors: Warren Willis , Jacks Adam
Published: October 2013

It is generally assumed that the longer vowel durations in voiced final consonant contexts can be attributed to longer vowel steady state durations wherein the jaw remains stable for a longer period of time (see diagrams in Chen, 1970; Summers, 1987). Chen (1970) argued that the rate of closure duration was the best explanation for the vowel length effect. However, the closure durational differences he reported were very small relative to the reported differences in vowel duration with an average of 17 ms to 92 ms. Lip and jaw movements for two speakers were measured and synchronized with acoustic data in the CSD department at the University of Texas using the head-mounted lip-jaw movement transducer (HMLJMT) of Barlow et al. (1983). This study provides much stronger evidence for Chen’s hypothesis, suggesting that there is a more dynamic arc to the jaw. While Chen (1970) gave data showing the closing gesture accounted for less than 20% of the overall difference, the data given here, shows that the duration of the closing gesture can account for 80% of the total vowel durational differences, and the remainder can be accounted for in the opening gesture and the relative timing of vocal cord cessation.
Relations between speech sensorimotor adaptation and perceptual acuity
Authors: Villacorta Virgilio , Perkell Joseph , Guenther Frank
Published: October 2013

The goal of this research is to study the auditory component of feedback control in speech production. This experiment investigates auditory sensorimotor adaptation (SA) as it relates to speech production: the process by which speakers alter their speech production in order to compensate for perturbations of normal auditory feedback. Specifically, the first formant frequency (F1) was shifted in the auditory feedback heard by naive adult subjects as they produced vowels in single syllable words. Results presented previously indicate that the subjects demonstrate compensatory formant shifts in their speech. The current study investigates the relationship between compensatory adaptation and speaker perceptual acuity. Subjects from the SA study were tested for their ability to discriminate vowel tokens differing in F1 frequency. Preliminary results indicate that subjects with greater perceptual acuity also demonstrated greater ability to adapt, with a significant cross-subject correlation (p less than 0.05). The relation between these experimental findings and DIVA, a neurocomputational model of speech motor planning by the brain, will also be discussed. [Work supported by NIDCD Grant R01-DC01925.]
Nasals and nasalization: The interplay between segmental duration and coarticulation
Authors: Sefton Samantha E. , Beddor Patrice S.
Published: October 2013

Two experiments were conducted on English to test the hypothesis that the temporal extent of coarticulatory nasalization is inversely related to the duration of the source of coarticulation. Experiment 1 investigated patterns of carryover (NVC) and anticipatory (CVN) vowel nasalization, and the overall timing of nasalization across the syllable. Acoustic analysis of CVN and NVC words (e.g., seen/niece, pin/nip, tame/mate, ten/net) produced by five speakers showed that, although vowel nasalization is temporally more extensive in CVN than in NVC sequences, N is shorter in CVN than in NVC, so that there was no significant overall difference in total nasalization between the two syllable types. Experiment 2 tested similar timing patterns in CVNC syllables, where N duration varied as a function of the voicing of the following C (e.g., wince/wins, sent/send, can’t/canned). Acoustic measures of productions of five English speakers again showed that the shorter the N, the temporally more extensive the vowel nasalization. Findings for selected other languages (Thai, Italian) provide further evidence of the inverse relation. These findings have implications for theories of coarticulation and theories of phonological change. [Work supported by NSF.]
Intensity variation in vowels across acoustic and auditory spectra
Authors: Jacewicz Ewa , Fox Robert Allen
Published: October 2013

Changes to vowel intensity are affected primarily by an increased physiological effort of the speaker. A second source of intensity variation comes from immediate consonant environment of the vowel as a result of coarticulation [House & Fairbanks, J. Acoust. Soc. Am. 22, 105–113 (1953)]. Variation in intensity distribution across the vowel spectrum was measured for eight American English vowels in ten symmetrical CVC environments (consonants included both stops and fricatives) at four different locations (at the vowels rms peak and at points corresponding to 20%, 50%, and 80% of the vowels duration). Three types of spectral intensity distribution were examined: (1) the relative amplitudes of formants F1-F4; (2) the summed intensity in four contiguous frequency bands of 0–0.5, 0.5–1.0, 1.0–2.0 and 2.0–4.0 kHz [Sluijter and Van Heuven, J. Acoust. Soc. Am. 100, 2471–2485 (1996)]; and (3) the intensity distribution following three stages of auditory processing (using an auditory filter bank consisting of 33 filters, equal loudness pre-emphasis, and intensity-loudness compression). The nature and size of the effects of spectral intensity variation as a function of consonant environment in the acoustic spectrum (formants) and in auditory pre-processing of the acoustic spectrum will be compared. [Work supported by NIDCD R03 DC005560-01.]
Extracorporeal shock wave therapy for non-unions and delayed fracture healing
Authors: Schaden Wolfgang , Fischer Andreas , Sailler Andreas , Karadas Ender
Published: October 2013

Although the primary management of fractures is highly developed in Central Europe 1% of fractures develop a non-union. After successful pilot studies the Traumacenter Meidling started in December 1998 to treat non-unions regularly with shock wave therapy. From December 1998 to August 2004, 1153 patients with non-union and delayed healing fractures were treated. The results of 755 patients are available up to September 2004. The patients consisted of 250 (33%) female and 505 (67%) male. The mean age was 44.1 years (10; 90). The mean age of the non-union was 15.5 months. In 74 (10%) osteomyelitis was present before shockwave therapy. Out of 755 non-unions 593 (79%) achieved bony healing. As expected, the subgroup of 284 delayed unions (shockwave therapy 3–6 months after the trauma or the last surgery concerning the bone) showed the best results. 245 (86%) healed. Out of 471 non-unions being older than 6 months 348 (72%) achieved bony healing. Because of the efficacy and the lack of complications as well as the economic advantage in comparison to surgery, shockwave therapy is considered as therapy of first choice in the treatment of non-union and delayed healing fractures.
Experience with extracorporeal shock wave therapy (ESWT) in the United States
Authors: Furia John P.
Published: October 2013

The purpose of this presentation is to summarize the literature and to report on single treatment, high-energy ESWT for the treatment of chronic plantar fasciitis and lateral epicondylitis. Fifty-three patients (60 heels) were treated with 3800 shock waves. Sixteen patients (19 heels) were active, 21 (22 heels), were moderately active, and 16 (19 heels) were sedentary. Twelve weeks post treatment, mean visual analog scores (VAS) for the entire group improved from 9.2 to 2.4 (p<0.05), RAND-Physical Functioning score improved from 40.4 to 91.5 (p<0.05), and RAND-Pain score improved from 33.3 to 90 (p<0.05). Fifty heels (83.3%) were assigned an excellent or good result. Thirty-six patients with chronic lateral epicondylitis were treated with 3200 shock waves. There were 9 workers compensation and 27 non-workers compensation patients. Twelve weeks post treatment, the mean VAS for the entire group improved from 8.0 to 2.5 (p<0.05), and the mean RAND-Physical Functioning score improved from 65.6 to 88.0 (p<0.05). Twenty-eight elbows (77.8%) were assigned an excellent or good result. In both trials, outcome was similar for each subgroup. There were no significant complications in either trial. Using the therapeutic parameters applied, ESWT is a safe and effective treatment for chronic plantar fasciitis and lateral epicondylitis.
The disruption of tissue structure using high intensity pulsed ultrasound
Authors: Fowlkes J. Brian , Parsons Jessica E. , Xu Zhen , Cooper Michol , Tran Binh C. , Hall Timothy L. , Roberts William W. , Cain Charles A.
Published: October 2013

Recent investigations of pulsed ultrasound at high acoustic intensities have revealed a regime in which significant breakdown of tissue structure can be achieved. This therapeutic modality, which might be termed histotripsy, is dependent on the presence of highly active cavitation evidenced by significant temporal fluctuations in acoustic backscatter. In the presence of tissue interfaces, erosion can result yielding, for example, well-defined perforations potentially useful in creating temporary shunts for the treatment of hypoplastic left heart syndrome. When applied in bulk tissue, the process results in a near emulsification with little structural integrity remaining or chance of cellular survival. In each case, the process is dependent on acoustic parameters of the field to not only produce damage for a given pulse but also to sustain the cavitation nuclei population for subsequent pulses. Fluctuations in acoustic backscatter indicate both initiation and extinction of the appropriate cavitation activity during application of therapeutic ultrasound, which leads to a potential feedback mechanism to minimize acoustic exposure. This presentation will discuss the observed tissue damage as affected by acoustic parameters and the ability to monitor the presence of cavitation activity expected to be responsible for these effects. [Work supported by NIH grants RO1 RR14450.]
Secondary shock wave emissions from cavitation in lithotripsy
Authors: Chitnis Parag V. , Cleveland Robin O.
Published: October 2013

We investigate the role of secondary shock waves (SSWs) generated by cavitation in lithotripsy. Acoustic pressure was measured with a fiber optic probe hydrophone and cavitation using a dual passive cavitation detector (PCD) consisting of two confocal transducers. An artificial stone (∼7 mm diameter and ∼9 mm length) was placed at the focus of an electrohydraulic lithotripter. The fiber was inserted through a hole drilled through the stone so that the tip was at the proximal surface. SSWs were identified by matching the time of arrival to that of the inertial collapse signature acquired by the PCD. Measurements of SSWs were obtained for 50% of SWs fired at 20 kV and 1 Hz. The peak positive pressure for the SSW was p+=33.7±14.8 MPa, which was comparable to the pressure induced by the incident SW (p+=42.6±6 MPa). The peak pressure in water was p+=23.2±4.4 MPa. The PCD also recorded acoustic emissions from forced collapse of pre-existing bubbles caused by the incident SW. We propose that both the reflection from the semi-rigid stone boundary and SSW from the forced collapse contribute to the observed increase in the peak pressure of the incident SW in presence of a stone. [Work supported by NIH.]
Psychoacoustic evaluation of a low-parameter modal model for synthesizing impact sounds
Authors: Lutfi Robert A. , Storm Eileen , Alexander Joshua M. , Oh Eunmi
Published: October 2013

Three experiments were conducted to test the viability of a low-parameter modal model for synthesizing impact sounds to be used in commercial and psychoacoustic research applications. The model was constrained to have 4 physically-based parameters dictating the amplitude, frequency and decay of modes. The values of these parameters were selected by ear roughly to match the recordings of 10 different resonant objects suspended by hand and struck with different mallets. In Exp. 1, neither 35 professional musicians nor 187 college undergraduates could identify which of the 2 matched sounds was the real recording with better than chance accuracy, though significantly better than chance performance was obtained when modal parameters were selected without the previously imposed physical constraints. In Exp. 2, the undergraduates identified the source corresponding to the recorded and synthesized sounds with the same level of accuracy and largely the same pattern of errors. Finally, Exp. 3 showed highly-practiced listeners to be largely insensitive to changes in the acoustic waveform resulting from an increase in the number of free-parameters used in the modal model beyond 3. The results suggest that low-parameter, modal models might be meaningfully exploited in many commercial and research applications involving human perception of impact sounds.
Extracting a carrier-independent version of the syllabic message: The principles
Authors: Patterson Roy D. , Walters Thomas C. , Irino Toshio
Published: October 2013

At the heart of each syllable of speech is a vowel; the wave consists of a stream of glottal pulses, each with a resonance attached. The vowel contains three important components of the information in the larger communication: the glottal pulse rate (the pitch), the resonance shape (the message), and the resonance scale (the vocal tract length). Recent experiments on the perception of vowels show that variability in glottal pulse rate and vocal tract length has surprisingly little effect on the humans ability to recognise the vowel or discriminate speaker size, despite the variability it imparts to the spectra of these sounds. We appear to have an automatic normalization process to scale vowels and extract the message independent of the carrier. Many animal calls are like syllables in form and duration, and normalization is essential here as well if animals are to correctly identify the species of the sender and not be confused by changes in pulse rate and resonance scale that simply indicate a size difference. This talk describes how neural firing patterns produced by vowels and animal calls could be normalized to produce a carrier independent version of the message of the syllable. [Work supported by UK MRC.]
The perception of size in musical instrument sounds
Authors: van Dinther Ralph , Patterson Roy D.
Published: October 2013

There is size information in natural sounds. For example, as humans grow in height their vocal tract increases in length, and this produces a predictable decrease in formant frequency. Recent studies have shown that listeners can judge the relative size of two individuals with considerable precision, and they can recognize vowels scaled well beyond the range normally experienced. This paper reports two psychophysical studies designed to extend the research to musical instrument sounds. The first showed that listeners can discriminate the relative size of instruments reliably, although not quite as well as for voices. The second showed that listeners can recognize instrument sounds scaled in size and pitch well beyond the range of normal experience. The research supports the hypothesis that the auditory system applies some kind of active normalization to all input sounds. [Work supported by the U.K. Medical Research Council (G9901257, G9900362), and ONRIFO (Grant N00014-03-1-1023).]
Source reconstruction of sensory and cognitive evoked potentials
Authors: Ponton Curtis W.
Published: October 2013

Cortical activity reflected in auditory-evoked potentials (AEPs) is often evaluated using only a small subset of all the recorded data. Conclusions based on this approach can be misleading, with no utility in identifying the underlying neural generators of the scalp recorded activity. Techniques that make use of all of the AEP data range from relatively simple methods, such as global field power, to more advanced approaches including independent components analysis (ICA), dipole modeling, and current density reconstruction. The objective of this presentation is to describe analysis of the component-structure of AEPs using these advanced techniques. Results of the ICA analysis will be used to generate spatial filters characterizing the specific scalp distribution associated with each ICA pattern. The cortical origin of each ICA scalp distribution will then be determined using current density reconstruction. The analysis will be applied to standard AEPs as well as the mismatch negativity in normal hearing and cochlear implant users. The results will demonstrate the unique suitability of neuroimaging based on AEPs for understanding the effects of cochlear implant use on cortical activity associated with cognitive processing in children and in adults.
Assessing the future of green building
Authors: Cole Raymond J.
Published: October 2013

As the realities of resource depletion and global environmental degradation become more evident, we can anticipate a maturing and strengthening of the public’s concern and knowledge on environmental issues. This will translate into an expectation for greater environmental responsibility and, as with other sectors, the building industry will be increasingly scrutinized for its environmental actions. The adoption of environmental strategies has been accelerated by the emergence of building environmental assessment methods that have provided both a definition and common language for green buildings as well as a means of communicating performance improvements. Whereas the current focus is on ‘‘green’’ design—reducing or mitigating the environmental consequences of buildings—the future concerns will embrace mitigation, adaptation to the new conditions and restoring previous adversely impacted regions and human settlements. This presentation will provide an overview of the evolution of green building practices to set a context for understanding emerging issues in building acoustics. Since the adoption of green building practices is a function of the context that shapes political and public priorities, the presentation compares and contrasts several short and long-term scenarios some certain, others more speculative and their direct and indirect consequences for environmental progress building design.
Post-occupancy evaluation and acoustics in green buildings
Authors: Hyde Rosamund
Published: October 2013

Post-occupancy evaluation is a process for discerning whether completed buildings are delivering to their occupants and owners the benefits which were set as goals in the design process. Both resource consumption and occupant satisfaction are assessed. Evaluations of seven green buildings in British Columbia have been carried out, including buildings with a range of occupancies and climates. These studies have highlighted acoustics as an area where occupant satisfaction could be improved. This presentation will address three questions. First, what have we learned about acoustics from post-occupancy evaluation of green buildings? Results of the seven post-occupancy evaluations of green buildings will be discussed. Second, what questions do designers have about decisions related to acoustics in green buildings? Third, how can we improve post-occupancy evaluation processes to better address those questions?
New single echo detection methods for shallow water fishery acoustics
Authors: Balk Helge , Lindem Torfinn , Kubecka Jan
Published: October 2013

Acoustic target detection is commonly carried out with parametric single echo detectors. These detectors test one ping at a time and look for echoes fulfilling a set of criteria such as echo duration and shape. In shallow water, noise phenomena can distort echoes from fish and false fish echoes can be generated. This causes the parametric detector to produce fractionated tracks from fish surrounded by numerous noise detections. Parametric detectors utilize only small portions of the information available in a split beam echogram. By including information from more than one ping and from the background reverberation, a more robust fish detector has been designed. This detector, called the Cross Filter Detector (CFD), has now been further improved by applying the variance in the angle measurements.
Echo characteristics of two salmon species
Authors: Nealson Patrick A. , Horne John K. , Burwen Debby L.
Published: October 2013

The Alaska Department of Fish and Game relies on split-beam hydroacoustic techniques to estimate Chinook salmon (Oncorhynchus tshawytscha) returns to the Kenai River. Chinook counts are periodically confounded by large numbers of smaller sockeye salmon (O. nerka). Echo target-strength has been used to distinguish fish length classes, but was too variable to separate Kenai River chinook and sockeye distributions. To evaluate the efficacy of alternate echo metrics, controlled acoustic measurements of tethered chinook and sockeye salmon were collected at 200 kHz. Echo returns were digitally sampled at 48 kHz. A suite of descriptive metrics were collected from a series of 1,000 echoes per fish. Measurements of echo width were least variable at the −3 dB power point. Initial results show echo elongation and ping-to-ping variability in echo envelope width were significantly greater for chinook than for sockeye salmon. Chinook were also observed to return multiple discrete peaks from a single broadcast echo. These characteristics were attributed to the physical width of chinook exceeding half of the broadcast echo pulse width at certain orientations. Echo phase variability, correlation coefficient and fractal dimension distributions did not demonstrate significant discriminatory power between the two species. [Work supported by ADF&G, ONR.]
Tissue response to modified shock wave profiles
Authors: Zhong Pei , Zhou Yufeng , Cocks Franklin H. , Marguet Charles , Preminger Glenn M. , Madden John
Published: October 2013

We have upgraded the original Dornier HM-3 lithotripter with a reflector insert to modify the lithotripter pulse profile and a piezoelectric annular array (PEAA) generator to produce microsecond tandem pulse lithotripsy. In this talk, we will present results from in vivo animal experiments using a swine model with or without surgically implanted artificial stones in the renal pelvis. Using this animal model, we have compared in vivo stone comminution and tissue injury, respectively, produced by the original versus the upgraded HM-3 under clinically relevant output settings. It was found that the upgraded HM-3 could produce significantly improved stone comminution with substantially reduced tissue injury, compared to the original HM-3. The underlying mechanisms that may contribute to the improved performance and safety of the upgraded HM-3 will be discussed. [Work supported by NIH DK52985 and DK58266.]
Study of a tissue protecting system for clinical applications of underwater shock wave
Authors: Hosseini S. H. R. , Takayama Kazuyoshi
Published: October 2013

Applications of underwater shock waves have been extended to various clinical therapies during the past two decades. Besides the successful contribution of extracorporeal shock waves, tissue damage especially to the vasculature has been reported. These side effects are believed to be due to the shock wave-tissue interaction and cavitation. In the present research in order to minimize shock wave induced damage a shock wave attenuating system was designed and studied. The attenuating system consisted of thin gas packed layers immersed in water, which could attenuate more than 90% of shock waves overpressure. Silver azide micro-pellets (10 mg) were ignited by irradiation of a pulsed Nd:YAG laser to generate shock waves. Pressure histories were measured with fiber optic probe and PVDF needle hydrophones. The strength of incident shock waves was changed by adjusting the distance between the pellets and the layers. The whole sequences of the shock wave attenuation due to the interaction of shock waves with the dissipating layers were quantitatively visualized by double exposure holographic interferometry and time resolved high speed photography. The attenuated shock had overpressure less than threshold damage of brain tissue evaluated from histological examination of the rat brain treated by shock waves.
A model for damage of microheterogeneous kidney stones
Authors: Szeri Andrew J. , Zohdi Tarek I. , Blake John R.
Published: October 2013

In this paper, a theoretical framework is developed for the mechanics of kidney stones with an isotropic, random microstructure—such as those comprised of cystine or struvite. The approach is based on a micromechanical description of kidney stones comprised of crystals in a binding matrix. Stress concentration functions are developed to determine load sharing of the particle phase and the binding matrix phase. As an illustration of the theory, the fatigue of kidney stones subject to shock wave lithotripsy is considered. Stress concentration functions are used to construct fatigue life estimates for each phase, as a function of the volume fraction and of the mechanical properties of the constituents, as well as the loading from SWL. The failure of the binding matrix is determined explicitly in a model for the accumulation of distributed damage. Also considered is the amount of material damaged in a representative non-spherical collapse of a cavitation bubble near the stone surface. The theory can be used to assess the importance of microscale heterogeneity on the comminution of renal calculi and to estimate the number of cycles to failure in terms of measurable material properties.
Future directions in musical acoustics education
Authors: Rossing Thomas D.
Published: October 2013

The desire to understand sound production by musical instruments, transmission of musical sound to the listener, and the perception of musical sound has been a strong motivator for students to learn acoustics, and will no doubt continue to be. We briefly describe past and present practices in teaching musical acoustics and attempt to predict how the subject may develop in the future.
Acoustics in the elementary classroom
Authors: Hansen Uwe J.
Published: October 2013

The need for increased science exposure at all educational levels continues to be acute. Science is almost universally perceived as difficult, and its ability to raise the quality of life in the presence of apparently insurmountable social problems is increasingly suspect. Over the past 15 years we have conducted teacher workshops, visited classrooms, have organized hands-on demonstration sessions, judged science fairs, and mentored high school students in research efforts, all in an attempt to raise the level of enthusiasm for science. A look ahead suggests that the need continues. Elementary school teachers all too often limit their own science skills to plants and animals, and thus physics concepts do not get the exposure needed to generate the necessary excitement for the physical sciences. Workshops for Elementary grade teachers will be described, which are aimed at preparing teachers to use music as a vehicle to introduce basic physics concepts in the upper elementary grades.
The elastodynamic Poynting vector bridges the gap in student understanding of complex wave phenomena
Authors: Dean Cleon E. , Braselton James P.
Published: October 2013

The advent of powerful graphic desktop computers and software allows the modern physics or engineering student to be shown dynamic physical processes formerly considered too complicated to present at the introductory level. For some time now desktop computers have been capable of showing intricate patterns of time evolving physical systems. As a simple example, students can be shown the energy flux of surface guided waves in both time averaged and time animated forms. Both vacuum and fluid loaded examples in various geometries are considered as examples. In an introductory wave phenomena class that considers electromagnetic, acoustic, and elastodynamic waves, a consistent approach using the Poynting vector field serves to bridge the gap between understanding of wave behavior for the three different types.
Field studies in architectural acoustics using Tablet PCs
Authors: Boye Daniel
Published: October 2013

Core requirements for the sciences within the liberal arts curriculum challenge students to become directly involved in scientific study. These requirements seek to develop scientifically literate leaders and members of society. Formal laboratory periods are not usually associated with these courses. Thus, conceptual discovery and quantitative experimentation must take place outside of the classroom. Physics 115: Musical Technology at Davidson College is such a course and contains a section dealing with architectural acoustics. Field studies in the past have been an awkward and cumbersome activity, especially for non-science majors. The emerging technology of Tablet PCs overcomes many of the problems of mobile data acquisition and analysis, and allows the students to determine the locations of the rooms to be studied. The impulse method for determining reverberation time is used and compared with calculations based on room size and absorption media. The use of Tablet PCs and the publicly available freeware Audacity in field studies investigating architectural acoustics will be discussed. [Work supported in part by the Associated Colleges of the South through their Technology Fellowship program.]
Spectral resolvability of iterated rippled noise
Authors: Yost William A.
Published: October 2013

A forward-masking experiment was used to estimate the spectral ripple of iterated rippled noise (IRN) that is possibly resolved by the auditory system. Tonal signals were placed at spectral peaks and valleys of IRN maskers for a wide variety of IRN conditions that included different delays, number of iterations, and stimulus durations. The differences in the forward-masked thresholds of tones at spectral peaks and valleys were used to estimate spectral resolvability, and these results were compared to estimates obtained from a gamma-tone filter bank. The IRN spectrum has spectral peaks that are harmonics of the reciprocal of the delay used to generate IRN stimuli. As the number of iterations in the generation of IRN stimuli increases so does the difference in the spectral peak-to-valley ratio. For high number of iterations, long delays, and long durations evidence for spectral resolvability existed up to the 6th harmonic. For all other conditions spectral resolvability appeared to disappear at harmonics lower than the 6th, or was not measurable at all. These data will be discussed in terms of the role spectral resolvability might play in processing the pitch, pitch strength, and timbre of IRN stimuli. [Work supported by a grant from NIDCD.]
Temporal and spectral resolution of hearing in patients with precipitous hearing loss: Gap release of masking (GRM) and the role of cognitive function
Authors: Vestergaard Martin D.
Published: October 2013

The purpose of this experiment was to measure temporal acuity and spectral resolution of hearing in new hearing-aid users over a period of time post-fitting, and to demonstrate the extent to which performance might change over time. For one-octave wide maskers with and without spectral and temporal gaps, masking was measured repeatedly over 3 months post-fitting. GRM was characterized as the release from masking under the gap conditions. The cognitive skills of the participants were assessed with two tests for measuring working memory capacity and lexical vigilance. The results showed that while the masking by one-octave wide noise maskers without any gaps was constant over time, GRM increased over time for maskers involving a temporal gap. Moreover, at low frequencies where the subjects had normal hearing-threshold levels, they performed as hearing-impaired for the spectral-gap condition. For the temporal-gap condition, they performed as normally hearing at both low and high frequencies. These results suggest that patients with precipitous hearing loss do not maintain normal spectral resolution through the low-frequency region, in which the hearing threshold levels are otherwise normal. Surprisingly, the results also showed moderate though highly significant correlation between lexical vigilance and GRM. [Work supported by the William Demant Foundation.] a)Currently at CNBH, Dept. Physiol., University of Cambridge, CB2 3EG Cambridge, UK.
A signal delection theory-based analysis of American English vowel identification and production performance by native speakers of Japanese
Authors: Lambacher Stephen , Martens William , Kakehi Kazuhiko
Published: October 2013

The identification and production performance by two groups of native Japanese of the American English (AE) vowels /æ/, /a/, /■/, /■/, /■/ was measured before and after a six-week, identification training program. A signal detection theory (SDT) analysis of the confusion data, as measured by d′, revealed that all five AE vowels were more identifiable by the experimental trained group than the control untrained group. The d′ results showed that /■/ was less identifiable than /■/ in the pretest, even though the percentage identification rate for /■/ was slightly greater than that for /■/. Both groups productions of a list of CVCs, each containing one of the target AE vowels, were presented to a group of native AE listeners in a series of identification tasks. The d′ results revealed that the AE listeners could more sensitively identify the experimental groups post-test vowel productions than they could the control groups. SDT analysis also clarified an additional potentially confusing result: /■/ was somewhat less identifiable than /■/, despite the fact that the percentage identification rate for /■/ was higher. Overall, the SDT-based analysis served to change the pattern of results observed for L2 vowel identification and influenced the interpretation of the data.
The development of vowel spaces in English- and Korean-learning infants’ speech
Authors: Lee Soyoung
Published: October 2013

A previous study (Yang, 1996) revealed that the vowel spaces of adult speech differ between English and Korean. This study longitudinally investigated whether vowel spaces of English- and Korean-learning infants’ speech demonstrated similar patterns to their ambient languages. Speech samples of English- and Korean-learning infants were collected at 12 and 24 months and transcribed by either native English- or Korean-speakers, respectively. First and second formants of each vowel were measured using LPC, spectral peak value, and spectrographic formant mid points. The vowel spaces between the two groups displayed similar patterns at 12 months although the frequency of occurrence of each vowel differed (e.g., [i] occurs more frequently in English than in Korean). However, the vowel spaces showed different patterns at 24 months. F2 values for front vowels [i, e] were higher in English-learning infants’ speech than those in Korean. [a] in Korean was located at a central position of vowel space while it was located at a back position in English. These patterns were similar to the adult vowel space of Korean and English. This study suggests that infants form vowel space similar to their own languages at around 24 months.
Spanish listeners’ perceptual patterns for English /i/ and /I/
Authors: Morrison Geoffrey Stewart
Published: October 2013

Spanish has five monophthongs which differ only in spectral properties. General Canadian English has ten monophthongs which differ in steady-state spectral properties and duration, and many nominal monophthongs have substantial diphthongization. Unlike Spanish, Canadian English also uses duration as a cue to postvocalic obstruent voicing. The present study investigates L1-English and L1-Spanish L2-English listeners perception of a Canadian English /bIt, bit, bId, bid/ continuum varying in steady-state spectral values and duration. Several patterns emerge in the L1-Spanish listeners data, including a contrary pattern in which duration is used in the same direction as L1-English listeners but spectral properties in the opposite direction. With respect to /i/ and /I/ perception, these patterns are generally consistent with the stages of learning proposed by Escudero [Unpublished Masters Thesis, Edinburgh University, 2000]: L1-Spanish listeners cannot initially perceive the difference, next they use duration properties, later they begin to use spectral properties, and finally they have L1-English-like primary use of spectral properties and secondary use of duration. Production data adds additional insight into the relationship of the perceptual patterns to the stages of learning.
Subjective and objective assessments in classrooms following acoustical renovation
Authors: Astolfi Arianna
Published: October 2013

The effectiveness of an expensive acoustical intervention in an old Italian high school building has been assessed in this work. The school building has fifty classrooms, the majority of which were acoustically renovated. A subjective survey and measurements were performed in both the renovated and non renovated classrooms. With the competence of some psychologists from Turin University, a questionnaire was set up for the subjective analysis. The questionnaire, validated after numerous pilot tests, was submitted to all the students and the teachers in two periods of the year. The questions on acoustical features included questions on annoyance from room noise, reverberation, speech comprehension, overall acoustical satisfaction and the consequences of bad acoustical conditions. Apart from the acoustics, other aspects of environmental quality, such as the thermal and visual environmental features and IAQ were investigated. The statistical analysis of the subjective answers allowed aggregated information to be obtained on the users and different data to be correlated. The aim of the statistical correlation was to determine any significant relationships between the objective and subjective data, and between the overall satisfaction scores and the different environmental factors. The effects of bad environmental conditions and their influence on learning capacity were also examined.
Electrophysiological methods for hearing assessment in pinnipeds
Authors: Reichmuth Kastak Colleen , Kastak David , Finneran James J. , Houser Dorian S. , Supin Alexander
Published: October 2013

Studies of auditory sensitivity in marine mammals generally rely on behavioral psychophysical methodologies. While these studies are the standard for hearing assessment in marine mammals, data are limited to only a few individuals representing a small proportion of species. Accumulating research on dolphin auditory physiology has resulted in the refinement of electrophysiological methods appropriate for odontocete cetaceans and an increase in available audiometric information. Electrophysiological methods have also been used with pinnipeds, but there are significant gaps in our understanding of pinniped auditory physiology that must be addressed before such appoaches can be broadly applied to investigations of pinniped hearing. We are taking a bottom-up approach to developing suitable methods for evoked potential audiometry in pinnipeds, including technology transfer from studies of cetaceans and other mammals, mapping of response amplitude with respect to recording positions on the skull, characterization of responses in relationship to various stimulus types and presentation parameters, and determination of whether useful frequency-specific data can be reliably obtained using electrophysiological methods. This approach is being taken with representative pinniped species including California sea lions (Zalophus californianus), harbor seals (Phoca vitulina), and northern elephant seals (Mirounga angustirostris) using both training and chemical immobilization techniques. [Work supported by NOPP.]
Communications performance of an undersea acoustic large-area network
Authors: Kriewaldt Hannah A. , Rice Joseph A.
Published: October 2013

The U.S. Navy is developing Seaweb acoustic networking capability for integrating undersea systems. Seaweb architectures generally involve a wide-area network of fixed nodes consistent with future distributed autonomous sensors on the seafloor. Mobile nodes including autonomous undersea vehicles (AUVs) and submarines operate in the context of the grid by using the fixed nodes as both navigation reference points and communication access points. In October and November 2004, Theater Anti-Submarine Warfare Exercise (TASWEX04) showcased Seaweb in its first fleet appearance. This paper evaluates the TASWEX04 Seaweb performance in support of networked communications between a submarine and a surface ship. Considerations include physical-layer dependencies on the 9–14 kHz acoustic channel, such as refraction, wind-induced ambient noise, and submarine aspect angle. [Work supported by SSC San Diego.]
NEPTUNE Canada—status and planning
Authors: Bornhold Brian D.
Published: October 2013

Stage 1 of the joint Canada-U.S. NEPTUNE seafloor observatory has been funded by the Canada Foundation for Innovation and the British Columbia Knowledge Development Fund with an overall budget of $62.4 million. The network is designed to provide as close to real−time data and images as possible to be distributed to the research community, government agencies, educational institutions and the public via the Internet. Covering much of the northern segment of the Juan de Fuca Plate, this first phase of the NEPTUNE project is scheduled to be installed, with an initial suite of ‘‘community experiments’’, in 2008. As part of the planning, NEPTUNE Canada held a series of three workshops to develop the science plans for these ‘‘community experiments’’; these experiments have a budget of approximately $13 million. The experiments will cover the gamut of oceanographic science themes including various aspects of: ocean climate and marine productivity, seabed environments and biological communities, fluids at ocean ridges, gas hydrates and fluids on continental margins, plate tectonics processes, associated earthquakes and tsunamis. The next three years will be spent developing and testing the necessary instrumentation for deployment on the network.
Confocal microscopy movies of fibrin clots during ultrasound-accelerated thrombolysis
Authors: Everbach E. Carr , Chernysh Irina N. , Weisel John W.
Published: October 2013

Blood clots made of human purified fibrin (white clots) were insonified with 1 MHz pulsed ultrasound during observation by fluorescence confocal microscopy. A deconvolution microscope allowed extremely thin sheets (0.2 μm) of fibrin to be viewed at a resolution of 0.2 μm per pixel, and the clot microstructure visualized. Acoustic pressure amplitudes from 0.1 to 0.8 MPa (peak-to-peak) were inferred using the image blur of 0.6-μm-diameter polystyrene spheres coated with FITC fluorecent label present in the clots. Acoustic pulse widths of 1 ms and pulse repetition frequencies of 125 Hz reduced clot heating to less than 3°C during each 30-minute exposure. Still 100 μm by 100 μm images were recorded every 10 seconds during pauses in insonificaiton, to produce time-lapse movies that are compared with movies made during sham ultrasound exposures.