bluuebunny/crossref_metadata_2025 huggingface dataset:
Ongoing experience with laboratory-based subject-fit REAT methods for measuring hearing protector attenuation
Authors: Berger Elliott H. , Kieper Ronald W.
Published: July 2012

As data have accumulated indicating the difficulty in basing estimates of field-delivered (i.e., real-world) protection for groups of users upon classical laboratory-derived optimum attenuation data, more attention has been directed towards standards intended to provide better simulations of the real world. The development of ANSI S12.6-1997 Methods for Measuring the Real-Ear Attenuation of Hearing Protectors, is one approach towards addressing this problem. The standard includes both experimenter-supervised fit and subject-fit methods. The latter method, designated as Method B, requires the use of audiometrically experienced subjects who are naive in the use of hearing protection. This method is intended to approximate the upper limits to the attenuation that can be expected for groups of occupational users. It yields mean attenuation values, more so for earplugs than earmuffs, that are substantially lower and standard deviations values that are higher than previously found using ANSI standards. This paper will present the latest Method-B test data, review ongoing studies designed to further evaluate the Method-B protocol, and will comment on efforts to more widely disseminate Method-B data and the associated noise reduction rating (Subject FIT) [NRR(SF)] which can be derived from such values.
Measuring the noise attenuation of shotblasting helmets
Authors: Patel Jacqueline A.
Published: July 2012

European Standard EN 271: 1995 deals with the construction of air-fed shotblasting helmets. It specifies minimum requirements for face, eye, and respiratory protection and tests the noise generated by the breathing air supply. However, it does not test the helmet’s ability to attenuate the very high levels of noise generated by the shotblasting process. This is a major omission. A test method was developed for measuring the noise attenuation provided by shotblasting helmets against typical shotblasting noise. It involved objective measurements using the head and torso simulator (HATS) currently prescribed by EN 271, fitted with miniature microphones. Using such a HATS was shown to give attenuation values that correlate well with those measured using human subjects. Results from this project showed: the HATS already used by manufacturers to show compliance of their product with EN 271 can also be used to provide information on the helmet’s noise attenuation; and the same HATS can be used, in place of human subjects, to measure the air supply noise according to the method defined in EN 271. The findings from this work will be used to try to influence future revisions of EN 271 so that the noise attenuation of shotblasting helmets is considered.
Noise attenuation of an insertion-type hearing protector by mathematical model and experimental verification
Authors: Gerges Samir N. Y. , Bavastri Elizabete Y. N. , Tenenbaum Roberto A.
Published: July 2012

The experimental real ear attenuation at threshold (REAT) method is based on the standards ANSI S12.6-1997 and ISO 4869-1990 which consider measurements on qualified subjects, in a qualified acoustic chamber. The REAT method is very expensive, time consuming, and has a very poor frequency resolution. Mathematical and numerical models, such as the one-dimensional plan wave model, finite-element method, and boundary-element method offer cheap, quick, and high-resolution results, especially for comparison and product development. In this paper, the outer ear canal is considered as a straight tube with an open end and the other end closed with an eardrum membrane of human acoustic impedance. For the open ear canal case (without hearing protector on), plan acoustic waves are considered as incident and reflected waves. In the case of a blocked ear (with the insertion hearing protector on), a model of three mediums is considered; air hearing protector air. In this model only one longitudinal wave propagation is considered. Material density and speed of sound are the only parameters considered. The noise insertion loss is calculated as the difference of the sound pressure level at the eardrum without and with the protector on. The results are compared with controlled experimental measurements.
Measurements of wineglass resonance using a fiber-optic probe
Authors: Piacsek Andrew A.
Published: July 2012

A fiber-optic probe (MTI-2000 Fotonic Sensor) is used by Central Washington University physics students to measure the peak displacement of such vibrating surfaces as acoustically driven wineglasses, parametrically shaken liquids, and soap films. This presentation will consist of a brief description of the fiber-optic measurement system, a discussion of its advantages and limitations, and sampling of some recent data obtained by students.
An analytical solution for the self and mutual radiation resistances of a rectangular plate
Authors: Li W. L.
Published: July 2012

It is widely accepted that, for an arbitrary acoustic wave number, the radiation resistance of a simply supported rectangular plate has to be calculated through numerical integration. In this study, an analytical solution for the self and mutual radiation resistances is obtained in the form of the power series of the nondimensional acoustic wave number. Unlike the previous analytical or asymptotic solutions, it is not subject to any of the restrictions usually imposed upon the acoustic wave number. A few numerical examples are given simply to verify the solution and elucidate the reliance of the self and mutual radiation resistances on the acoustic wave number and the plate aspect ratio. It is shown that the present formulae are extremely efficient by cutting the CPU time by orders of magnitude in comparison with the traditional numerical integration scheme. This investigation successfully fills the long-existing gap in solutions for the moderate wave numbers that are often of primary concerns in an acoustic analysis.
A new finite/infinite scheme to model acoustic trim under realistic working conditions
Authors: Coyette Jean-Pierre , Lielens Gregory , Migeot Jean-Louis
Published: July 2012

The paper presents a finite-element scheme modeling all aspects of the behavior of acoustic trim: insulation, absorption, and damping. The models can combine different materials (viscoelastic, poroelastic, incompressible), acoustic fluid, and include complex effects like visco-thermal dissipation in thin air layers. Unbounded acoustic regions are modeled using stabilized conjugated infinite elements that present exceptional convergence properties. The structure can be subjected to a number of different excitations: kinematical (fixed motion), dynamical (discrete or distributed forces) or acoustical. An incident diffuse sound field or distributed pressure fluctuations corresponding to aerodynamic boundary layers can also excite the structure. The presentation will be organized as follows: (1) a brief review of the techniques involved: finite-element method for the structure and the acoustic near field, infinite elements for the acoustic far field; (2) material models considered: viscoelastic, poroelastic, incompressible, acoustic (including viscothermal effects); (3) excitation models: kinematical, dynamical, acoustical, aerodynamic; (4) validation of the approach; (5) three application cases: comparison of the dynamic behavior of a treated and untreated shell, acoustic transparency of an insulating sandwich, evaluation of the acoustic impedance of a porous layer.
Conversational Interfaces: Today and Tomorrow
Authors: Zue Victor
Published: July 2012

For more than a decade, the Spoken Language Systems Group at the MIT Laboratory for Computer Science (with members made up of four generations of Ken Steven’s disciples), have been conducting research leading to the development of conversational interfaces that enable users to access and manage information using spoken dialogue. Our research has been heavily influenced by Ken’s teaching and research, ranging from acoustic landmark detection, acoustic-phonetic modeling, hierarchical phonological modeling using subword units such as syllables and features, lexical access strategies, and speech synthesis. While we are far from being able to develop systems capable of carrying on unrestricted conversations with users, we are beginning to field systems that have restricted domain expertise. For example, users can now speak to computers over the telephone, and receive weather, flight arrival–departure, and traffic information. One can even conduct air travel planning, and receive flight and fare information, all by simply speaking to the computer. This talk will highlight some of our recent work, and speculate on the future. [Work supported by DARPA and NSF.]
Retrieving distinctive features and segments from variable acoustic cues
Authors: Stevens Kenneth N. , Keyser Samuel J.
Published: July 2012

It is assumed that words are stored in memory as sequences of bundles of distinctive features. Accessing words from the acoustic signal requires that these features be identified and organized into segments. Variability is a major obstacle to this process. Accounting for this variability requires a clear understanding of how variability arises when an utterance is generated by a speaker. It is proposed that variability arises from the operation of two principles: (1) Conservation: some of the defining gestures for a feature in a given segment may overlap with gestures from adjacent segments, causing weakening or masking of certain acoustic cues. (2) Enhancement: depending on the segmental and prosodic environment in which a feature occurs, additional gestures not directly specified by the feature may be introduced to enhance its perceptual salience. Conservation and enhancement provide a basis on which to select acoustic cues that reflect the gestures that produced them. Selection of acoustic cues for the features of consonant place, voicing, and nasality will be described and it will be shown that combinations of these cues can lead to feature identification with low error rate. [Work supported in part by grants from NIDCD.]
Blind source separation and blind deconvolution in experimental acoustics
Authors: Roan Michael J. , Erling Josh
Published: July 2012

In active noise control, vibration control, and noise analysis, observed signals are typically a mixture of many sources, possible convolved with an unknown filtering function. A new area of research in the area of blind source separation and blind devonvolution (which has had application on the area of wireless communications) has promising application in noise and vibration control, radar/sonar, and noise analysis. The area of research exploits information theoretic criteria (rather than higher statistics) for blind source separation (BSS) and blind deconvolution (BDC). In this paper, several algorithms for BSS and BDC are presented. These algorithms are applied to experimental data. Experimental work in the areas of BSS has been with the separation speech signals from several speakers, and BDC work has been with speech signals convolved with artificial filters. It is shown through experimental results that several real acoustic filters (i.e., driven duct, driven duct with expansion chamber, and driven duct with Helmholtz resonator sidebranch) can be deconvolved. It is shown that application of the learned inverse filtering functions to the measured time series removes the effect of the filtering function. Finally methods for applying the algorithms for noise source identification, noise/vibration control, and noise analysis are presented.
Blind separation of L sources from M mixtures of speech signals
Authors: De Leon Phillip , Ma Yunsheng
Published: July 2012

In many real-world applications of blind source separation, the number of mixture signals, L, available for analysis often differs from the number of sources, M, which may be present. In this paper, we extend a successful and efficient kurtosis maximization algorithm used in speech separation of two sources from two linear mixtures for use in problems with arbitrary numbers of sources and mixtures. We examine three cases: underdetermined (ML). In each of these cases, we present simulation results (using the TIMIT speech corpus) and discuss separation matrix initialization issues and observed algorithm limitations. We find that in the critically determined case, the algorithm performs well (20–40 dB SIR) at separating four sources from four mixtures. For the other cases, our results are mixed. In the overdetermined case (two sources, three mixtures), the algorithm performs well (20–40 dB SIR) and we find that the extra mixtures do not result in better SIR measurements. In the underdetermined case (three sources, two mixtures), we are able to separate out at least one source (sometimes two) with the other output signals each containing pairs of the remaining sources.
Speech privacy in office spaces
Authors: Roy Kenneth P.
Published: July 2012

Lack of speech privacy in office spaces is an issue that has been inadequately addressed for decades. Now may be the time to reconsider the consequences of not properly designing our work spaces, since ever increasing noise intrusions are having more adverse effects on knowledge worker productivity. Both lab and field tests were performed to characterize the acoustic environment in closed work spaces, and acoustic performance was determined on the basis of the speech privacy index (PI). The goal was to develop an integrated design solution for closed offices spaces based on signal-to-noise performance.
Comparison of Alaskan and Hawaiian humpback whale song at the song-unit level
Authors: Frankel Adam S. , Straley Jan
Published: July 2012

Humpback whale songs were recorded in Hawaii and Alaska in 1991, 1994 and 1998. Songs from both areas showed the typical hierarchical theme structure. Strong differences between years were noted, as expected. Songs in Alaska tended to be shorter than those recorded in Hawaii, as previously reported. A unit-level analysis was conducted using an automated measurement program. The program reports >100 descriptive variables. The size of the variable set was reduced using principal components analysis. The resulting principal components (PC) set that accounted for 80% of the variance was tested with discriminant analysis for differences between recordings (nominal individuals) and region. Preliminary analysis indicates that the songs were similar between regions at the theme level. There were no significant differences between the two regions at the unit level of analysis. These results support earlier acoustic and visual-resight data that the two regions are both part of the same population. The small size of the Alaskan sample leaves open the possibility that regional differences exist, but were not detected with this sample.
Geographic variations in the whistle repertoire of Hawaiian spinner dolphins (Stenella longirostris)
Authors: Bazua-Duran Carmen , Au Whitlow
Published: July 2012

Studying geographic variations in the whistle repertoire of Hawaiian spinner dolphins (Stenella longirostris) will increase our understanding of the population structure of this species. In the present work, groups of spinner dolphins off the Islands of Oahu, Lanai, and Hawaii, were studied. The dolphin whistle repertoire of each island was used to search for geographic variations. Two methods were used: (1) spectrogram information extraction and (2) zero crossing. For the first method, frequency and time information was extracted from the spectrogram of each whistle. Results show that geographic variations exist in the whistle repertoire of Hawaiian spinner dolphins. Statistically significant differences were obtained by using discriminant function analysis: Wilks lambda=0.576; F(22,1866)=26.93, p<0.00001, N(Oahu)=314, N(Lanai)=293, and N(Hawaii)=339. Greater differences were found between the Oahu and Hawaii groups (3.413), intermediate differences were found between the Oahu and Lanai groups (2.200), and Lanai and Hawaii were the least different groups (0.560). These results indicate that looking for geographic variations in the whistle repertoire will help us in understanding the population structure of Hawaiian spinner dolphins. The results of the zero-crossing method will be compared to the spectrogram information extraction results. [Work supported by Leonida Memorial Scholarship, UH Seed Money Grant, UH Foundation Grant, Fulbright-GarcaRobles-CONACyT and DGAPA.]
Autoregressive synthesis of bottlenose dolphin whistles
Authors: Huang Xiaozhou , Buck John R.
Published: July 2012

The signature whistle hypothesis proposes that most of the whistles bottlenose dolphins (Tursiops truncatus) produce are individually distinctive, and that bottlenose dolphins can identify the signature whistles of the other dolphins from the fundamental time-frequency contour. This hypothesis has not been tested directly. One major obstacle has been the need to modify the whistles so that scientists can quantitatively control the acoustic parameters of the whistles. Buck, Morgenbesser, and Tyack [J. Acoust. Soc. Am. 108 (2000)] proposed a model for synthesizing whistles using a sum of harmonically related sinusoids. Some synthetic whistles produced by this method sound artificial. The objective of the current research is to develop an alternative technique for modifying and synthesizing these whistles using autoregressive (AR) modeling. An important property of the AR model is that if the synthesis filter is excited by the residual signal from a prediction filter, the original signal is perfectly reconstructed. Using the residual signal as the excitation for a synthesis filter with modified AR parameters should produce more realistic-sounding modified whistles. [Work supported by NSF Ocean Sciences.]
Broadband amplitude enhancement of a transducer using parametric excitation
Authors: Ginsberg Jerry H. , Nguyen Phillip H.
Published: July 2012

A paper by Larson et al. [J. Acoust. Soc. Am. 103, 1428–1441 (1998)] suggests that it is possible to use piezoceramics to construct a transducer with a time-variable spring constant. The present work explores the response of such a transducer, modeled as a one-degree-of-freedom system, when the stiffness is varied with a fixed period either sinusoidally or as a square wave. Such variation represents a parametric excitation whose effect strongly modifies the conventional forced response. Transient solutions of the equations of motion are obtained by numerical integration, and verified in the square wave case by an analytical solution that exploits the piecewise linear nature of the equations. It is shown that the response amplitude is increased by as much as 20 dB over a range of excitation frequencies from DC to twice the nominal resonant frequency when the period of the parametric excitation is set substantially below the natural frequency.
A modal Pritchard approximation for computing array element mutual impedance
Authors: Scandrett Clyde L. , Day Joe L. , Baker Steven R.
Published: July 2012

An investigation into the applicability and accuracy of Pritchard’s approximation for closely packed transducer arrays is undertaken. A new, ‘‘modal’’ Pritchard approximation is developed, based upon normal modes of the acoustic medium, and is tested for arrays of acoustically hard spheres to ascertain its accuracy in determining the mutual acoustic radiation impedance between array elements. For ka≊1, it is found that the modal Pritchard approximation works quite well in approximating the mutual radiation impedance of a two-element array, even for relatively close spacing, but for arrays of three or more scatterers in close proximity, the approximation may have relatively large errors. The effect of neglecting interelement scattering is analyzed for the monopole-to-monopole scattering of various configurations of a three-element array and a 16-element double-line array. [Work supported by ONR.]
Directivity of conformal-baffled cylindrical transducers
Authors: Welch John , Reinhart Lawrence , Oishi Tetsuro , Aronov Boris , Brown David A.
Published: July 2012

The theoretical and experimental directivity patterns, radiation impedance, and source levels of piezoelectric cylindrical rings with conformal acoustic baffles will be presented. A model was implemented with matlab to simulate the directivity response of various baffled cylindrical piezoelectric transducers. The cylinder is modeled by assuming a vibrating cylindrical element with constant surface velocity as outlined by Morse [Vibration and Sound, 3rd ed.] and adding complications due to effects of the conformal acoustic baffle. A number of devices of practical importance have been fabricated and tested. Results for conformal baffles ranging from 180 to 250 deg of coverage are presented and are compared with experimental results using different baffle designs and at various frequencies.
Hysteresis effects in high-power ultrasonic transducers
Authors: Mortimer Bruce J. P. , Green Alex , du Bruin Tertius , de Vries Ian , Tapson Jon T.
Published: July 2012

It is well known that ultrasonic piezoelectric transducers can be difficult to drive at high power levels. Transducers usually have high Qs, which implies a narrow driving bandwidth and characteristics that may change with temperature, component wear, or variations in the load. Some method of feedback control is usually required to lock onto the optimum transducer driving frequency. Small-signal parameters are usually used in the design of both the control and the amplifier matching system. In this work we have measured the characteristics of several sandwich transducers coupled to water at significant drive levels (50–250 V) by measuring the drive current, voltage, and phase. Increasing the drive level shows a decrease in optimum operating-point frequency. In addition, both the Q and admittance at the driving point decreases. This creates a practical problem as the matching of transducers done on the basis of small-signal values will be inaccurate. Increasing the power levels also results in an abrupt transition to a lower impedance value after the onset of cavitation. Decreasing the power levels is shown to exhibit a hysteresis effect which is thought to be due to the persistence of gas bubbles in the liquid.
Sonic band-gap materials as acoustical components
Authors: Cervera F. , Sanchis L. , Martínez-Sala R. , Rubio C. , Sánchez-Pérez J. V. , Meseguer F. , López C. , Caballero D. , Sánchez-Dehesa J.
Published: July 2012

Sonic band-gap (SBG) crystals can be made by periodic distributions of scatterers. In particular, it was found that two-dimensional (2D) arrays of rigid cylinders in air do have acoustic band gaps that could be of application in acoustic devices related to control and filtering of sound. Here, it is pointed out that this type of SBG crystal can be used as custom-made acoustical components in the linear region well below the gap. This idea is supported by the fact that sound velocities in these materials are smaller than that of air. Also, it was previously measured that their transmittance is high; i.e., they exhibit low reflectance [J. V. Sánchez-Pérez et al., Phys. Rev. Lett. 80, 1208–1212 (1998)]. Both features guarantee the practicality of sonic crystal lenses and other optical components. Finally, 2D SBG crystals based on triangular and square arrays are classified as acoustically uniaxial or biaxial. [Work supported by CICyT of Spain.]
A comparison between one-channel time reversal and phase conjugation in random media and in reverberant cavities
Authors: Fink Mathias , Tourin Arnaud , de Rosny Julien , Derode Arnaud
Published: July 2012

In this paper, we are interested in time-reversal experiments conducted with only one omnidirectional transducer. Focusing through random media or inside chaotic reverberant cavities is shown to be possible when broadband pulses are used. A comparison with phase-conjugated experiments shows that this result is not obtained for monochromatic waves. It will be shown that the time-reversal focusing quality depends on the pulse bandwidth and on the statistical decorrelation of the wave fields for different frequencies. A set of experiments conducted through multiple scattering media of different thickness and through closed cavities will be presented. Self-averaging properties of time-reversed fields will be discussed for these various configurations.
Effects of low-pass and high-pass filtering on the identification of environmental sounds
Authors: Gygi Brian , Watson Charles , Kidd Gary
Published: July 2012

Listeners’ abilities to identify environmental sounds under high-pass and low-pass filtering was determined using a constant-stimulus method. The goal was to determine the degree to which listeners rely on information in various frequency regions when attempting to identify naturally occurring sounds. In experiment 1, 70 environmental sounds were low- and high-pass filtered with cutoff values ranging from 300 to 4800 Hz in octave steps. Subjects identified the sounds after an initial familiarization stage in which all sounds were presented without filtering. With low-pass filtering, performance improved from 57% to nearly 100% correct as the cutoff frequency increased. Performance with high-pass filtering was better, with percent correct identification above 70% for all cutoff values. Importance functions derived from these results were used to develop articulation index-like predictions for the identification of a representative set of environmental sounds. [Work supported by NIH.]
Visualization and auralization of sound quality
Authors: Daniel Peter , Mundt Harald
Published: July 2012

VIPER, a new tool for the VIsual PERception of sound quality, will be presented. Requirement for the visualization of sound quality is a signal analysis modeling the information processing of the ear. The first step of the signal processing implemented in VIPER calculates an auditory spectrogram by a filter bank adapted to the time- and frequency resolution of the human ear. The second step removes redundant information by extracting time- and frequency contours from the auditory spectrogram in analogy to contours of the visual system. In a third step, contours and/or auditory spectrograms can be resynthesized, confirming that only aurally relevant information was extracted. The visualization by contours allows the intuitive grasp of the important components of a signal. Contributions of parts of a signal to the overall quality can be easily auralized by editing and resynthesizing them. Resynthesis of time contours alone allows, e.g., auralization of impulsive components separately from the tonal components. Further processing of the contours determines tonal parts in form of tracks. Audible differences between two versions of a sound can be visually inspected in VIPER through the help of auditory distance spectrograms. Applications are shown for interior noises of cars and for speech.
Time course of word identification and semantic integration in spoken language
Authors: Van Petten Cyma , Rubin Susan , Parks Marjorie , Plante Elena , Coulson Seana
Published: July 2012

Human speech consists of a nearly continuous stream of auditory input, so that the semantic message formed by combinations of words must be analyzed as the input continues. The minimum duration signal necessary to identify a set of words was established via the gating technique: Subjects were asked to identify (or guess) words after hearing only the initial 50, 100, or 150 ms, etc. Results showed that most words were identified before their acoustic offset: Average word duration was 600 ms, but identification accuracy was close to 90% after 350 ms of input. The isolation points established in the gating experiment were compared to the time course of semantic integration evident in event-related brain potentials (ERPs). The gated words were used as congruous and incongruous sentence completions (in their full-duration versions). Differential ERP responses to contextually appropriate and inappropriate words were observed by 200 ms after word onset, before the acoustic signal was sufficient to uniquely identify the words. These results indicate that semantic integration can begin to operate with only partial, incomplete information about word identity. If time allows, the talk will also describe similarities and differences between the semantic processing of words and environmental sounds.
Array design and motion effects for matched field processing
Authors: Tracey Brian , Lee Nigel , Zurk Lisa , Ward James
Published: July 2012

While matched field processing (MFP) algorithms have most commonly been applied to data collected on vertical line arrays, there is increasing interest in applying MFP to more general array geometries. One challenge for novel array design is to determine the fundamental performance of volumetric arrays in a shallow water channel. To address this issue, recent work by Tantum and Nolte [J. Acoust. Soc. Am. 107, 2101–2111 (2000)] has been extended to allow more general array geometries, including horizontal arrays steered away from endfire. The correlation among acoustic modes across the array can be related to MFP resolution and sidelobe levels. Another trend in underwater array design is the consideration of larger arrays which provide additional array gain. However, large arrays are susceptible to the effects of motion [Zurk et al., Oceans 99]. A new time series simulation that rigorously treats source and receiver motion is used to quantify the effects on adaptive MFP. Simulation results are compared to data from the Santa Barbara Channel experiment (SBCX). [This work was sponsored by DARPA under Air Force Contract F19628-95-C0002. Opinions, interpretations, conclusions, and recommendations are those of the authors and are not necessarily endorsed by the United States Air Force.]
Incoherent beamforming with interference patterns
Authors: D’Spain Gerald L. , Berger Lewis P. , Hodgkiss William S. , Kuperman William A. , Spiess Fred N.
Published: July 2012

A conventional coherent plane wave beamformer exploits the phase evolution of the wave field across the array aperture, using the phase at one element as reference, to obtain information on source location. Alternatively, in a multipath environment, the phase of one mode or multipath can be used as reference for the phase evolution of the other multipaths in the wave field. This ‘‘intermode interferometry’’ is the basis of an incoherent beamformer presented here. It involves summing together individual element autospectra, after performing a frequency-domain dilatation/contraction operation based upon a hypothesized source location. Because it uses autospectra rather than element time series, this processing provides no gain of signal over background noise. Therefore, its usefulness in its basic form is restricted to localization of strong signals. However, it is not limited to line arrays with equal element spacing, and the array element positions need only be known to a fraction of an interference wavelength rather than an acoustic wavelength. Examples of the incoherent beamforming results from simulation and actual ocean acoustic data collected during the shallow-water (200 m) SWellEx-3 experiment will be presented. Emphasis is placed on 2D passive synthetic aperture applications. [Work supported by ONR, Code 321US.]
Stabilizing Rietschs signal estimation technique against noise for multipath mitigation in shallow water transient classification
Authors: Smith George B. , Larue James P.
Published: July 2012

Extraction of a transient signal received on a hydrophone array at tactical ranges in shallow water is made difficult by distortions caused by dynamic multipath. Blind deconvolution techniques can adapt the processing to the environment. Rietschs algorithm [E. Rietsch, Geophysics 62(6), 1931–1946 (1997)], which is an exact algebraic solution to the blind deconvolution problem, performs exceptionally well when no noise is present in the data. In this work, progress with attempts to stabilize Rietschs algorithm using noisy simulated data is presented. [This work was supported by the Office of Naval Research and the Naval Research Laboratory.]
Subjective assessment of stage environments for chamber music
Authors: Wang Weichun , Chiang Weihwa , Chen Shih Tang
Published: July 2012

Stage acoustics were evaluated in four halls regarding chamber music performances. Sensations about hearing oneself, hearing others, ease of ensemble, and overall impression were expressed by players of violin and piano sonata, piano trio, and brass quintet. Evaluations were taken at two locations with and without detached reflectors in each hall. Subjects in the audience were asked about the balance among players. In additional to the well-accepted support factor (ST1), calculated measures included a similar parameter early-to-direct energy ratio (ED80), where the energy integrated from 20 to 100 ms was substituted by the energy from 7 to 80 ms since recital halls were normally smaller than symphony halls. As a result, most acoustical environments were acceptable to the players. Overall impression was significantly correlated with all of the subjective attributes and there was a strong relation between hearing others and ease of ensemble (r=0.921). The players of brass quintet favored higher ED80 values than did the others. For the audience, significant variances of perceived strength were found in cello for piano trio and in horn for brass quintet. On-going research is conducted to collect data in other halls. [Work supported by the National Science Council of Taiwan.]
Nonlinear seismoacoustic land mine detection and discrimination technique
Authors: Donskoy Dimitri , Ekimov Alexander , He Jianhui
Published: July 2012

The paper presents further development [D. Donskoy, Proc. SPIE 3392 (1998); ibid. 3710 (1999)] of the innovative seismoacoustic technique for detection and discrimination of artificial objects, such as mines, pipes, containers, etc., buried in the ground. The present paper discusses a physical model to explain land mine detection and discrimination using acoustic waves and presents results of laboratory and field tests validating the model. At low frequencies (below 1 kHz) the model treats the soil–mine system as a lumped-element system, which includes the mass and stiffness of the soil on top of the mine and the stiffness of a mine diaphragm as the governing parameters. The model explains both: linear and nonlinear dynamic behavior of buried mines, observed in numerous laboratories and field tests. Thus, the developed model helps to evaluate the mine detection capabilities of seismoacoustic techniques based on mine type, burial depth, and soil condition.
Measurements of the induced pore pressure in packings of glass beads due to an incident airborne acoustic wave
Authors: Hickey Craig J. , Sabatier James M. , Goddard William E.
Published: July 2012

The Biot theory predicts the existence of two P waves (referred to here as type I and type II) and one S wave. In a previous experiment where airborne sound was incident upon an air-filled packing of sand, it was postulated that the signal detected by microphones at shallow depths was due to the type II P wave whereas at the deeper depths the signal is associated with the type I P wave [C. J. Hickey and J. M. Sabatier, J. Acoust. Soc. Am. 102, 128–136 (1997)]. In this presentation we discuss the results of measurements obtained in packings of glass beads. Four different packing were respectively made with 304 (30–40 mm), 405 (40–50 mm), 507 (50–70 mm) and 1014 (100–140 mm) size glass beads. A smaller bead size increases the flow resistivity of the packing, thereby increasing the attenuation of the type II P wave. If the previous interpretation is correct then the depth at which the signal is dominated by type I or type II P wave should change with glass bead size.
Perceptual identification training of American English /r/ and /l/ by Japanese speakers generalizes to novel stimuli and tasks
Authors: Doeleman Tobey L. , Conley Ryan J. , Pruitt John S. , Iverson Paul , Kuhl Patricia K. , Stevens Erica B.
Published: July 2012

This study investigated the extent to which results from /r/ and /l/ perceptual identification training generalized to identification of novel natural stimuli and discrimination of synthetic stimuli in ten native Japanese speakers. A behavioral training software program was used which incorporated factors known to affect the acquisition of phonemic distinctions, including bimodal speech cues, stimulus variability, and subject-controlled stimulus presentation with immediate feedback. Natural speech tokens were digitally manipulated to create three levels of acoustic exaggeration. These levels, and other stimulus characteristics such as the number of talkers, vowel contexts, and syllable structure, varied during each training session as a function of listener’s performance. Pre- and post-training identification tasks measured generalization to natural tokens of novel talkers and vowel contexts. In addition, pre- and post-training discrimination tasks measured generalization to novel tasks and synthetic stimuli. Same–different and AXB paradigms were used to measure and compare performance on the trained non-native (/r/–/l/) contrast as well as a native (/b/–/d/) contrast using synthetic CV and VCV tokens previously identified and judged good exemplars by American English listeners. Both identification and discrimination results show generalization of learning to novel stimuli and tasks. [Work supported by NICHD HD37954 to P.K.K.]
Training Mandarin and Cantonese speakers to identify English vowel contrasts: Long-term retention and effect on production
Authors: Wang Xinchun
Published: July 2012

Synthesized hVd vowel stimuli and naturally produced CVC minimal pairs by multiple talkers were used to train native Mandarin and Cantonese speakers to identify the English /i/–/I/, /u/–/U/, and /E/–/Q/ contrasts. In the pre- and post-tests, subjects took the identification tests on synthesized and natural stimuli, and were also recorded producing the target vowel contrasts. Results showed that subjects relied on duration cues for the /i/–/I/, contrast more consistently than they did for the other two contrasts. Training effectively shifted their attention from duration to spectral cues. Trainees’ perceptual performance on natural tokens improved significantly from pretest to post-test on all three contrasts. Accuracy in generalization to new words produced by new talkers was comparable to new words by familiar talkers. The effect of perceptual learning was retained 3 months later after the training was completed. Improvement in production was observed but performance differences between pre- and post-test did not reach significance. The findings suggest that increased perceptual accuracy in identifying L2 vowel contrasts through perceptual training may not be sufficient for significant improvement in production accuracy. Future studies may look at combination of simultaneous production and perceptual training for better results.
Aipotu: Simulation from Nucleotides to Populations and Back Again
Authors: White Brian T.
Published: July 2012

Aipotu, the IBI Prize–winning module, creates a world where students manipulate the DNA of virtual organisms and examine resulting effects.
Explosive Backpacks in Old Termite Workers
Authors: Šobotník J. , Bourguignon T. , Hanus R. , Demianová Z. , Pytelková J. , Mareš M. , Foltynová P. , Preisler J. , Cvačka J. , Krasulová J. , Roisin Y.
Published: July 2012

As
Neocapritermes taracua
termites age, they develop a suicidal toxic apparatus that bursts during aggressive encounters.
The Structure and Catalytic Cycle of a Sodium-Pumping Pyrophosphatase
Authors: Kellosalo Juho , Kajander Tommi , Kogan Konstantin , Pokharel Kisun , Goldman Adrian
Published: July 2012

View of a Sodium Pump

Membrane-integral pyrophosphatases (M-PPases) found in plants, protozoans, bacteria, and archaea, link pyrophosphate hydrolysis or synthesis to sodium or proton pumping and contribute to generating an electrochemical potential across the membrane.

Kellosalo
et al.

(p.
473
) report the structure of the sodium pumping M-PPase from
Thermotoga maritima
in the resting state with product bound. The structures reveal the conformational changes that are likely to accompany pyrophosphate binding and provide insight into the ion-pumping mechanism.
Planetary Science Is Busting Budgets
Authors: Kerr Richard A.
Published: July 2012

A predictable escalation of the exploration of Mars has collided with limited funding, pushing Mars science into the arms of the astronauts.
Texas Wildflower's Red Keeps It a Species
Authors: Pennisi Elizabeth
Published: July 2012

An evolutionary biologist has unearthed evidence that differences in hue between phlox species persist because they help keep hybrids from forming between the annual and pointed phlox.
Phase IIa Study of the Immunogenicity and Safety of the Novel Staphylococcus aureus Vaccine V710 in Adults with End-Stage Renal Disease Receiving Hemodialysis
Authors: Moustafa Moustafa , Aronoff George R. , Chandran Chandra , Hartzel Jonathan S. , Smugar Steven S. , Galphin Claude M. , Mailloux Lionel U. , Brown Elizabeth , DiNubile Mark J. , Kartsonis Nicholas A. , Guris Dalya
Published: July 2012

Bacteremia is the second leading cause of death in patients with end-stage renal disease who are on hemodialysis. A vaccine eliciting long-term immune responses against
Staphylococcus aureus
in patients on chronic hemodialysis may reduce the incidence of bacteremia and its complications in these patients. V710 is a vaccine containing iron surface determinant B (IsdB), a highly conserved
S. aureus
surface protein, which has been shown to be immunogenic in healthy subjects. In this blinded phase II immunogenicity study, 206 chronic hemodialysis patients between the ages of 18 and 80 years old were randomized to receive 60 μg V710 (with or without adjuvant), 90 μg V710 (with adjuvant), or a placebo in various combinations on days 1, 28, and 180. All 201 vaccinated patients were to be followed through day 360. The primary hypothesis was that at least 1 of the 3 groups receiving 2 V710 doses on days 1 and 28 would have a ≥2.5 geometric mean fold rise (GMFR) in anti-IsdB IgG titers over the baseline 28 days after the second vaccination (day 56). At day 56, all three groups receiving 2 doses of V710 achieved a ≥2.5 GMFR in anti-IsdB antibodies compared to the baseline (
P
values of <0.001 for all 3 groups), satisfying the primary immunogenicity hypothesis. None of the 33 reported serious adverse experiences were considered vaccine related by the investigators. V710 induced sustained antibody responses for at least 1 year postvaccination in patients on chronic hemodialysis.
Cerebral cavernous malformation: a diagnostic challenge in a young patient with intracerebral haemorrhage
Authors: Milinis Kristijonas , Mohammed Mohammed , Dyer James Edward , Sutton Paul Anthony
Published: July 2012

An 18-year-old Caucasian man presented with a sudden onset right hemiparesis. On examination, he had objective evidence of an upper motor neuron lesion affecting the right side of his body. CT scan showed a left thalamic haemorrhage. MRI, gradient echo and cerebral angiogram showed no structural lesion and the cause of the bleeding was ultimately attributed to the use of cocaine. During the subsequent 2 years the patient had two further similar episodes, with an MRI eventually demonstrating a cerebral cavernous malformation. This was excised using frameless stereotactic surgery, following which the patient made an uneventful recovery.
Small cell carcinoma of gastro-oesophageal junction with remarkable response to chemo-radiotherapy
Authors: Matsunaga Mototsugu , Miwa Keisuke , Noguchi Tsuyoshi , Sasaki Yasutsuna
Published: July 2012

Small cell carcinoma of the gastrointestinal tract is rare, and no effective strategy has yet been established. On the basis of regimens reportedly effective for small cell lung cancer, we performed chemotherapy with cisplatin plus etoposide in combination with radiotherapy to relieve obstruction, in a patient with small cell carcinoma of the gastro-oesophageal junction. Chemotherapy was switched to carboplatin plus etoposide due to renal toxicity. No distant metastases were detected and lesion spread was limited. A complete response, with no evidence of recurrence to date, was achieved. Curative resection was suggested but refused by the patient. He has been closely followed up in our outpatient clinic for more than a year and has shown no evidence of recurrence since the completion of treatment. Although cisplatin plus etoposide is a standard chemotherapy regimen for small cell carcinoma, carboplatin plus etoposide may be effective in cases in which cisplatin is contraindicated due to renal toxicity.
The stone man disease: fibrodysplasia ossificans progressiva: imaging revisited
Authors: Verma Amit Kumar , Aga Pallavi , Singh Shailesh Kumar , Singh Ragini
Published: July 2012

Fibrodysplasia ossificans progressiva (FOP) is a rare, disabling connective tissue disorder of unknown aetiology. Its occurrence is usually sporadic but may be an inherited autosomal-dominant condition with wide range of expression. FOP is characterised by congenital malformations of the great toes and abnormal progressive heterotopic ossification of striated muscles, tendons, ligaments, fascia and aponeuroses of the trunk and extremities leading to painful swellings. The ossifications typically appear within the first decade of life, resulting in progressive morbidity and severe disability. So far, there has been no effective treatment or prevention. In the early localised phase of disease it may be misdiagnosed, hence the role of correct diagnosis through imaging is essential. Herein, we report a case of a 10-year-old female who was evaluated radiologically and diagnosed as a case of FOP. The findings of plain radiography are described and the role of CT is highlighted.
The usefulness of rapid point-of-care creatinine testing for the prevention of contrast-induced nephropathy in the emergency department
Authors: You Je Sung , Chung Yong Eun , Park Jong Woo , Lee Woonhyoung , Lee Hye-Jeong , Chung Tae Nyoung , Chung Sung Phil , Park Incheol , Kim Seungho
Published: July 2012

Background

Renal dysfunction is the most important factor to consider when predicting a patient's risk of developing contrast-induced nephropathy (CIN). Measurement of creatinine (Cr) via rapid point-of-care blood urea nitrogen/creatinine testing (POCT-BUN/Cr) to determine CIN risk could potentially reduce the time required to achieve an accurate diagnosis and to initiate and complete treatment in the emergency department (ED). The aim of our study was to compare the results of POCT-BUN/Cr and reference laboratory tests for BUN and serum Cr.

Materials and methods

A retrospective analysis of suspected stroke patients who presented between November 2009 and November 2010, and had BUN and Cr levels measured by POCT-BUN/Cr, and the reference laboratory tests performed with the blood sample which was transferred to the central laboratory by an air-shoot system. Two assays were conducted on the whole blood (POCT) and serum (reference) by trained technicians. The time interval from arrival at the ED to reporting of the results was assessed for both assays via a computerised physician order entry system.

Results

The mean standard deviation (SD) interval from arrival at the ED to reporting of the results was 11.4 (4.9) min for POCT-BUN/Cr and 46.8 (38.5) min for the serum reference laboratory tests (p<0.001). Intra-class correlation coefficient (ICC) analysis demonstrated a high level of agreement (the consistency agreement) between POCT and the serum reference tests for both BUN (ICC=0.914) and Cr (ICC=0.980).

Conclusions

This study suggests that POCT-BUN/Cr results correlate well with those of serum reference tests in terms of BUN and Cr levels and, in turn, predicting CIN. POCT-BUN/Cr is easily performed with a rapid turnaround time, suggesting its use in the ED may have substantial clinical benefit.