bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Recruitment on Speech Perception—A Simulation for Normal Listeners
Authors: Villchur E.
Published: May 2012

It has been suggested that one cause of the loss of intelligibility in perceptive deafness is the radical change, brought about by recruitment, in the normal loudness relationships among the acoustical elements of speech. This hypothesis is explored through an analogy in which deaf-subject loudness relationships are transposed to the normal span of hearing. The limiting frequency/amplitude coordinates of amplified speech are plotted relative to the average measured hearing span of five deaf subjects (the span between threshold and an equal-loudness contour at preferred speech level), and are projected to proportionate positions relative to the corresponding normal span. The loudness distortion of these deaf subjects can be represented by the response of an electronic model, a bank of fast-acting expanders with frequency-dependent expansion ratios, followed by a treble attenuator. Speech with and without interference has been processed by such a model, to simulate deaf-subject loudness relationships for normal listeners, and will be demonstrated. Experimental hearing-aid processing will also be demonstrated. The model predicts that frequency-dependent amplitude compression followed by frequency equalization will benefit intelligibility much more than would be indicated by the limited benefit of either process used separately.
Development of the Organ of Corti of the Newborn Mouse in Culture
Authors: Sobkowicz Hanna M. , Bereman Barbara , Rose Jerzy E.
Published: May 2012

Differentiation and afferent innervation of the organ of Corti were studied in 152 cultures. If an unopened turn of the cochlear duct and its complement of spiral neurons are explanted, the culture retains the compact arrangement of innervated hair cells which are the only differentiated elements at birth. During the following two weeks in culture supporting elements, reticular plate, and tunnel spaces differentiate. Development of tectorial membrane is observed. Innervation pattern in a differentiated culture is basically similar to that at birth even though the innervation derives only from locally present neurons. Fibers collect into radial bundles; some terminate immediately upon the inner hair cells; others form the inner spiral band; still others cross the tunnel to form external spiral fibers. Different events occur at injured edges, or in entire explant if during explantation the cochlear duct is torn. No differentiation of supporting cells occurs. Hair cells spread outward, acquiring a ghost-like appearance. Nerve fibers follow the degenerating cells and may form spirally oriented bundles. Some leave the disorganized hair-cell region, growing freely for several millimeters. [Supported by USPHS Grants NS-08626, NS-03360, and NS-06225.]
Electrical Impedance Measurements of Walls of the Guinea Pig Cochlea Channels Using Sinusoidal Currents
Authors: Sitko Steve , Honrubia Vicente , Strelioff David
Published: May 2012

Electrode pairs for current injection and recording of the resulting potentials were introduced in the scala media, scala vestibuli, and scala tympani of the first turn of the guniea pig cochlea and in the neck muscles. The potential difference between each combination of pairs of recording electrodes was determined for sinusoidal currents over the frequency range from 1.5 Hz to 5.0 kHz. When current was passed between the perilymphatic scalae, the potentials dropped at only 1 dB/decade over the entire frequency range. In contrast, when current was passed through the walls of the scala media, the resulting potentials dropped by 3 dB at frequencies between 50 and 100 Hz and then continued to drop at 6 dB/oct. These results suggest that there is an equivalent capacitance of approximately 0.1 microfarad between the scala media and the perilymphatic spaces.
Absolute Threshold, Noise-Induced Hearing Loss, and Cochlear Pathology in the Chinchilla
Authors: Clark William W. , Clark Carolyn S.
Published: May 2012

Absolute thresholds were determined in the chinchilla using a new behavioral procedure. The animal was reinforced with a 45-mg pellet (Noyes) for depressing and holding a key 1–7 sec and either releasing it during a 2-sec tone presentation or not releasing it during a 2-sec catch trial. Using a tracking procedure, thresholds were determined at 9 to 15 frequencies during each daily 1-hour session. Thresholds are compared to those obtained by conventional shock-avoidance techniques, and the advantages and disadvantages of the procedure are considered. Following threshold determinations, two of the animals were exposed to a 123-dB two-octave band of noise (710–2800 Hz) for 15 minutes. The animals were sacrificed 7 and 28 days post exposure, respectively and their cochleas prepared for examination under the light microscope by the surface preparation technique. The correlation between the amount of hearing loss present and the cochlear pathology is examined, and these results are compared to those obtained by Ward and Duvall [Ann. Otol. 80, 881 (1971)]. [Research supported by NIH research and training grants.]
Durational Relations between Connected Text, List Sentences, and Carrier Sentences
Authors: Molter Marion O.
Published: May 2012

For experimental convenience, it is customary in speech studies to use lists of independent short sentences, or of words substituted into a repeated carrier phrase. Little is known, however, about the degree to which such .material is or is not representative of continuous text. This paper reports a comparison of temporal effects in three forms of material. Two speakers read first a list of 86 test sentences, disordered and mixed with irrelevant sentences; then a list of 252 words taken from the test sentences and embedded in the carrier phrase “say — instead”; and finally, the test sentences in their original form, a coherent narrative. Measurements of the data show that the durations of whole sentences and of individual content words average 7% longer in listed sentences than in connected text. Words in the carrier sentence range from the same duration to twice as long as those in continuous text, with an average increase of 45% or 140 msec. The report presents details of these differences at the phoneme and word levels, and attempts to interpret them in terms of pause, intonation, and stress changes and at higher levels of structure.
A Methodology for Assessing Potential Community Impact Resulting from Noise Emitted by Railroad Yard Operations
Authors: Swing J. W. , Pies D. B.
Published: May 2012

A method for prediction of community noise exposure in the vicinity of a railroad yard, knowing its operations and layout, has been developed. Requirements of the technique were (1) applicability to a yard of arbitrarily defined operation and layout, (2) ability to accurately measure existing noise levels for use as reference data, and (3) consistency of methodology with possible government regulatory monitoring procedures. The method selected involves development of noise contours based upon the average maximum A-weighted noise levels of individual events projected in the community. This method satisfied the needs for a workable noise prediction technique within the current state-of-the-art. The advantages of this technique are as follows: (1) it may be accurately tailored to any yard configuration by a building block approach which allows inclusion of all significant sources of noise; (2) it utilizes easily measured quantities (in dBA) which are largely independent of the variables which affect noise output by virtue of usage of average maximum noise levels for each operation; (3) it does not require precise location of specific noise sources-but rather assigns certain operations to broad areas of tracks over which these operations would logically occur; (4) it accounts for level of yard operation activity, and (5) it provides a conservative working instrument for railroads to assess the potential impact of their yard operations on the surrounding community. Supporting data were taken at four railroad yards in the Los Angeles area representing a broad range of yard activity.
Prediction of Click Responses of Cochlear Nerve Fibers from Responses to Sinusoidal Stimuli
Authors: Little-Field Warren M. , Pfeiffer Russell R. , Molnar Charles E.
Published: May 2012

A method for deriving tuning curves of single cochlear nerve fibers based upon a phase-locking response criterion [Littlefield el al., J. Acoust. Soc. Am. 51, 93 (1972)] yields gain and phase information as a function of the frequency of the stimulating tone. For a range of low-level and low-frequency stimuli, the response of cochlear nerve fibers has been shown to be consistent with a number of criteria for linearity [Littlefield el al., J. Acoust. Soc. Am. 54 (1973) (in press)]. If system linearity is assumed, measurements of gain and phase at discrete frequencies n/T, where n is a positive integer, can be used to predict the Fourier series of the response to any periodic stimulus of period T. By this method, we have calculated theoretical responses of low CF cochlear nerve fibers to periodic click trains, using gain and phase measurements taken within the range of stimulus conditions that have been found to produce responses consistent with a linear system hypothesis. Examples of gain and phase curves and click responses calculated from them will be presented and compared with directly obtained click responses. These comparisons may assist in evaluating linear and nonlinear properties of neural excitation. [This research was supported by PHS research grants from the National Institutes of Health.]
Differential Response of Neurons of the Cochlear Nucleus to TTS-Producing Tones
Authors: Salvi R. J. , Henderson D. , Hamernik R. P.
Published: May 2012

The I/O functions of neurons in the chinchilla cochlear nucleus were measured before and after exposure to 8 min of a 95-dB-SPL tone at the characteristic frequency of the neurons. The exposure produced virtually no change in whole nerve AP but produced 14–19-dB shifts in auditory evoked response thresholds. “Flat primary” and “chopper” neurons showed a general decrease in spontaneous activity (SA), an 8–12-dB decrease in sensitivity, and no truncation of the neuron I/O function. “Pauser” and “primary” units showed little, if any, shift in sensitivity with relatively no change in SA. “On” neurons had higher SA after.exposure; their I/O function was depressed at low intensities and elevated at high intensities relative to the pre-exposure I/O. During the exposure, the activity of “on” neurons dropped below SA, while all other classes of neutrons showed marked increases in activity over the SA rate.
A Behavioral Paradigm for Determining the Effect of Attention on the Activity of Single Units in the Monkey's Auditory Cortex
Authors: Heffner H. , Hocherman S. , Goldstein M. H.
Published: May 2012

Rhesus monkeys have been trained to respond to either the auditory or visual component of a stimulus in order to determine the effects of attention on the responses of single units in auditory cortex to sound. The monkeys are trained to make a two-choice discrimination using either auditory or visual cues. Both cues are then presented simultaneously and the animal's response brought under control of only one of the cues—the relevant cue—by the following procedure: The animal is given trials in which only the relevant cue is presented. This is followed by trials in which both cues are presented, but the irrelevant cue either indicates the incorrect response or else is programmed randomly with respect to the correct response. By comparing the temporal pattern of sound-evoked spike activity of a given auditory unit when the behavioral response of the animal is under control of the sounds with the pattern produced when the behavioral response is under control of the lights, it is possible to study the changes in single unit activity corresponding to changes in attention. [Research supported in part by NIH Grant NS-05143.]
Propagation through an Anisotropic Random Medium I. The Single Scatter Region
Authors: Beran M. J. , McCoy J. J.
Published: May 2012

Propagation through a random medium with horizontal correlation lengths that are orders of magnitude larger than vertical correlation lengths is studied. In this first paper we consider a horizontal time-harmonic plane wave to be incident on a finite scattering volume. The spatial distribution of the scattered intensity is obtained using the single scatter theory, or Born approximation. The most significant result is the demonstration that for λ≪lHm and λ≫lVM, where λ is the acoustic wavelength, lHm is the minimum horizontal correlation length, and lVM is the maximum vertical correlation length; the energy is essentially forward scattered. The angular dependence of the scattered energy measured in a vertical plane is not controlled by the vertical correlation lengths, as one might intuitively expect, but is controlled by the larger horizontal correlation lengths. This suggests that the resolution limitation caused by the scattering of low-frequency acoustic signals by the ocean temperature microstructure will be considerably less than might be intuitively suspected.
A Mathematical Analysis of a Free-Flooded Finite-Length Radiating Magnetostrictive Shell. II
Authors: Hanish S. , Baier R. V. , King B. J. , Rogers Peter H. , Sinsky J. A.
Published: May 2012

The analysis of Part I, “A Mathematical Analysis of a Free-Flooded Finite Length Radiating Magnetostrictive Shell,” is continued. Acoustic radiation from a finite-length free-flooded circular cylinder is analyzed by numerical integration of applicable Helmholtz-type integral equations. By matching acoustic boundary conditions, the modal vibration of the shell is integrated into the elastic and magnetostrictive response provided by Part I. For an input set of dimensions, electric drive, and required frequency range, the computer program delivers surface velocities, electrical and mechanical motional impedances, nearfield and farfield acoustic radiation, and acoustic power developed for a water-loaded shell. Typical examples of computer output are given together with discussions. Comparison is made with selected experimented results.
Low-Frequency Acoustic Radiation from Free-Flooded Ring Transducers Driven through the Circumference, Thickness, or Height
Authors: Zalesak J. F. , Rogers Peter H.
Published: May 2012

The normal velocity distribution of the surface of a free-flooded ring transducer completely determines its radiation characteristics in a given medium. The SHIP program is an algorithm for rapidly predicting the radiation characteristics of a free-flooded ring when the known surface velocity distribution is axisymmetric. The character of the radiation at low frequencies is extremely sensitive to the details of the velocity distribution which, in turn, depends not only on the geometry of the ring, but also on the manner in which the ring is driven and on the electromechanical parameters of the ring material. Gross differences in the directivity patterns predicted for different drive conditions occur at frequencies well below the first radial resonance for typical rings. Directivity patterns were obtained for a number of rings fabricated for different commonly encountered drive conditions (circumference, thickness, or height) and compared with patterns predicted by the SHIP program using simple models for the velocity distribution appropriate to each drive. Good agreement was obtained between the measured and predicted directivity patterns.
A Transient Resonant Rod Technique for the Determination of Extensions! Velocity in High-Q Materials
Authors: Betts D. A. , Nelson R. A.
Published: May 2012

A resonant-rod technique to determine the extensional velocity of sound, using the transient capture mode of a real time spectrum analyzer, is presented. The rod is excited by striking one end, and the resulting ringing is picked up by a microphone and fed to the analyzer to determine the fundamental longitudinal resonant frequency. Results of this method on aluminum bar samples are compared to results obtained on the same bars using a ceramic driven half-wave resonator and an ultrasonic pulse-echo overlap technique. This comparison reveals the technique to be a fast and accurate one.
Comparison of Reverberation Measurement Signal Processing Methods
Authors: Walker Bruce E.
Published: May 2012

The presently accepted method for measurement of the decay of sound in an enclosure calls for decay from “steady state” excitation by bandlimited noise, measured with rms pressure sensing instrumentation. Other methods, such as the rms Pressure Impulse Response scheme used by Knudsen and Delsasso in several studies and Schroeder's Integrated Pressure-Squared procedure, have not found widespread use, even in view of the time savings which can be realized. In this study, the decay of sound in several diverse acoustical environments had been measured by five different signal processing techniques, including the three mentioned above. The results of the measurements are shown and differences and similarities analyzed.
Pitch Rules for the Synthesis of Simple Declarative English Sentences
Authors: Olive Joseph P.
Published: May 2012

A recent experiment by Olive and Nakatani [J. P. Olive and L. H. Nakatani, “Rule-Synthesis of Speech by Word Concatenation: A First Step,” J. Acoust. Soc. Amer. 54 (1973) (to be published)] has shown that when telephone numbers were synthesized by rule by splicing together numbers which were spoken in isolation, the proper adjustment of pitch was more important than adjustments of amplitude, duration, and between-word-coarticulation, for making these spliced numbers sound as if they were spoken continuously. This experiment also showed that in the case of telephone numbers, pitch adjustments were sufficient for providing synthesis by rule of quality comparable to the quality of natural speech which was processed by an analysis-synthesis procedure. This paper describes the next step in our research of rule synthesis: the study of sentences instead of the more restricted telephone numbers. Methods for studying pitch contours of naturally spoken sentences are discussed; some pitch rules for synthesizing short English sentences are derived; and the validity of these rules was tested by incorporating them into a computer program for speech synthesis.
Adaptive Preprocessing for Linear Predictive Speech Compression Systems
Authors: Makhoul John , Viswanathan R.
Published: May 2012

In any vocoder, the process of parameter quantization is crucial for reducing the transmission rate while maintaining the quality of the synthesized speech. We have observed that, for linear predictive vocoders, the short-time spectral dynamic range of the speech signal is the single most important factor that affects the quantization properties of transmission parameters, irrespective of the particular choice of parameters. We describe two preprocessing methods by which the spectral dynamic range is reduced, thereby improving quantization properties. In the first method, adaptive optimal (linear predictive) preemphasis is applied either directly to the speech signal or more easily to the autocorrelation coefficients through convolution. Experiments indicate that an appropriate set of preemphasis filters can be pre-selected; for any speech segment being analyzed, the filter from this set that is closest to the optimal choice can be used for preemphasis. The advantages of such a scheme as well as the effect of first- and second-order preemphasis on quantization and speech quality are discussed. The second method of preprocessing (the SIGMA method) involves multiplying the impulse response of the inverse linear prediction filter by an exponential window. Some preliminary results obtained using this method are reported.
Speech Compression by Spectral Decomposition
Authors: Arcese A. , Goldberg A. J.
Published: May 2012

In this paper, we consider compressing speech using diagonalization transformations which include predictive coding as a special case. The algorithm determines the autocorrelation matrix pitch synchronously, producing a circular Toeplitz matrix under stationarity assumptions. Next, we find a diagonalization transformation involving both the eigenvalues, which for this matrix is the spectrum, and the eigenvectors, which depend only on the dimension of the matrix and are independent of the eigenvalues. This transformation then operates on the speech waveform, producing a random sequence that is then quantized and transmitted along with parameters characterizing the autocorrelation matrix. The synthesizer calculates the inverse transform exactly by Fourier transforms and then reconstructs the waveform. This paper presents results illustrating these processing operations.
Real-Time All-Digital FFT Vocoder
Authors: Cohen A. , DeLellis J. , Freudberg R. , Ross M. , Shaffer H.
Published: May 2012

In this paper, we describe a real-time all-digital spectrum channel vocoder implemented on a programmable signal processor. The vocoder system efficiently utilizes a radix four, 64-point FFT algorithm for spectral analysis, while the pitch extractor selects the pitch period using decision logic on the average magnitude difference function (AMDF) of the input speech. The receiver linearly interpolates both the pitch period and the synthesized impulse response which is generated by using the inverse Fourier transform. The vocoder frame updating rate is 22 msec, and the input speech sampling rate is 7040 samples/sec. The configuration of the vocoder and the logic of the AMDF pitch extractor is discussed and the system demonstrated with audio tapes.
Speech as an Error-Resistant Digital Code
Authors: Coker C. H.
Published: May 2012

Distinctive features, dominant perceptual cues—indeed many concepts of linguistics equate redundancy with waste. In doing so, they ignore an important principle of communication—that noise resistance derives from duplication. The remarkable indestructability of natural speech is well known. Doubtlessly that error resistance results from worthwhile redundancy. This paper presents a treatment of speech as the transmission of discrete units (words) coded as varying-length sequences of smaller elements (phonemes) over a noisy acoustic channel. This is, in every respect, a problem in coding theory, and the literature on error recovery in Huffman-like codes is extremely pertinent. In such codes, the dominant error problem is to maintain synchronism between sender and receiver. With poor codes, a single error can propagate to the end of the message, with the receiver never again correctly determining where one word ends and another begins. In practical codes, the mean time to recover from error is shortened by frequent occurrence of sequences that clearly signal the location of a boundary. In this presentation we review some of the coding literature. We argue that intonation and durational gestures, and consistent allophone variation at boundaries all serve an indispensable role: synchronization cues for error resistance.
Noise Control in Production Metal Machining and Forging Operations
Authors: Heymann Roger W.
Published: May 2012

Noise control programs in production metal machining and forging operations produced significant reductions of noise levels. Interaction with production engineering personnel contributed very much to the achieved successes. Operator exposure to high noise levels was the result of overlapping intermittent sources. Principal noise offenders were airjets, hydraulics, steel impact on steel tables and conveyers, furnace airjets, metal machining, TEFC electric motors, and fans. Management strived to meet 85 dBA (U. S. Army Tech. Bull. MED 251) and 90 dBA (OSHA) levels without regard for exposure time. Operator exposure and source identification was obtained by taping and statistically analyzing noise levels at operator positions. Thorough testing was undertaken before implementation. In the cases studied, increased room absorption was of little value regardless of distance. This was determined through studies of sound field from portable sound sources, impulse techniques, and standard calculations. Reductions of 20 dBA were achieved by installing small resistive and dispersive mufflers on pneumatic controls. Steel impact noise was reduced 15 dBA with combined low durometer rubber and unconstrained viscoelastic damping. Furnace fan noise was reduced by using low-pressure mufflers on the fan intake, and by relocating fans. Directional electric motor fan noise was reduced by using mufflers.
The Masking of Tones by Broad-Band Noise in the Goldfish: Critical Masking Ratios
Authors: Fay R. R.
Published: May 2012

Tonal thresholds were measured for four goldfish (at 100, 200, 400, 700, and 1200 Hz) in quiet and under three levels of a flat acoustic noise spectrum extending between 50 and 2500 Hz. Signals and noise were generated within an air chamber enclosing a lucite water tank within which the fish was restrained. A classical respiratory conditioning technique was used in combination with the descending method of limits for the threshold determinations. Masking was found to be a linear function of noise level ( − 28, −38, − 48 dB re 1 dyn/cm2/cycle) at all frequencies. Signal-to-noise ratios (S/N) were lowest at 100 Hz (13 dB) and increased linearly with log frequency at a rate of 3 dB/octave. This function is remarkably similar to those for man and other vertebrates. The values at frequencies above 200 Hz lie about 2.5 dB above those for cat and, at 1200 Hz, considerably below that for rat. Below 200 Hz, however, the values fall below those reported for man. This sensitivity of the fish in detecting signals in noise provides some support for the notion that the operation of a mechanical filter at the periphery of an auditory system is not a necessary assumption in accounting for some aspects of frequency analysis.
Sensitive Acoustic Vibration Measurements by Optical Heterodyne Detection of Scattered Laser Light
Authors: Drag-Sten P. R. , Webb W. W. , Paton J. A. , Capranica R. R.
Published: May 2012

A sensitive method for measurement of small vibrations at acoustical frequencies has been devised using optical heterodyne spectroscopy to detect the Doppler shifts of laser light diffusely scattered from the vibration object. Beginning with the geometry of a Michelson interferometer, we replace one mirror by the scatterer and mix the reference and scattered beam on a small-area photomultiplier cathode. With only simple optical alignment, acoustic vibration spectra can be measured without perturbations even on very small-size objects, since no attachment such as an interferometer mirror is required. Vibration amplitudes as low as 0.01 nm and up to ∼100 nm can be detected with a precision of a few percent in a few seconds averaging time by phase sensitive detection of the optical beat note at the excitation frequency. Application to mechanically unstable subjects such as the auditory organs of living biological specimens is facilitated by incorporation of low-frequency feedback control of the optical path length and provision for continuous amplitude calibration. The complete system has been used in measurements of tympanal membrane movements of acoustic receptor organs. [Supported by NSF and NIH].
Sensory Processing in the Peripheral Auditory System of Treefrogs (Hyla)
Authors: Moffat A. J. M. , Capranica R. R.
Published: May 2012

Responses to various sounds were recorded from single fibers in the auditory nerve of the green treefrog (Hyla cinerea) and the barking treefrog (H. gratiosa). Based on their sensitivity to tones, units fall into one of three distinct classes. In H. cinerea, one class is most sensitive to low frequencies 100–500 Hz; a second class is most sensitive to 500–1200 Hz; the third class responds best to 3100–3800 Hz. In both species, responses of low-frequency fibers can be inhibited by addition of energy in the corresponding mid-frequency range. This inhibition originates in the inner ear; it is not due to efferent activity. Responses of the other fibers cannot be inhibited. Most units in each class are spontaneously active. Thresholds within each class vary over a wide range; firing rates of individual fibers increase monotonically over an intensity range of about 40 dB. Fibers in each class can “follow” pulse repetition rates up to 250–400/sec. Our results suggest that the peripheral auditory system of treefrogs is well-suited to detect signals of species-specific significance. [Supported by NSF Grant GB-18836 and NIH Grant NS-09244.]
A Simplified Description of Distant Shipping Noise for Sonar Response Applications
Authors: Burroughs C. B. , O'Connor J. C. P.
Published: May 2012

Many current ambient noise measurement and modeling programs are aimed at improved estimates of the spatial properties of ambient noise fields. One application of these studies is the development of models for predicting sonar array response to anisotropic ambient noise. The purpose of this paper is to present a simple model developed in closed form for sonar applications, and yet which reflects the dependence on important environmental parameters. A simple model which describes the vertical directionality of distant shipping noise above and below the horizontal is derived from a model presented by-Talham [J. Acoust. Soc. Am. 36, 1531 (1964)]. Combining this model with a previously derived simple model for the vertical directionality of wind-generated noise [J. Acoust. Soc. Am. 53, 353(A) (1973)] yields a simple model which is applicable at most frequencies of interest to sonar array designers. Comparisons to more accurate and comprehensive models and measurements show that the model satisfactorily describes the substance of these environmental factors. [Study supported by NAVSHIPS, PMS 302–44.]
A Comparison between Laboratory Measurements and Truck Drive-By Measurements of a Diesel Engine Enclosure
Authors: Crocker Malcolm J. , Tree David R. , Jones Steven R. , Towers David A.
Published: May 2012

Results of laboratory insertion loss measurements on a full-scale prototype diesel engine enclosure are given. The measurements were obtained using loudspeakers and an engine “mock-up” in an anechoic room. Directivity measurements taken at positions around the engine-enclosure “mock-up” were used to make enclosure insertion loss predictions for the SAE J366a drive-by test, based upon a line-of-sight correlation. A practical complete engine enclosure was then designed and constructed on an IH CO-4070 A truck, with a 50-inch cab and an 8V-71 Detroit diesel engine. SAE J366a drive-by noise measurements were made with the enclosure equipped vehicle. Comparisons are presented between insertion loss predictions (based on laboratory results) and those measured by the drive-by. Also complete drive-by noise level predictions are compared with those actually measured. [Work supported by International Harvester, Fort Wayne, Indiana, under contract to the Office of Noise Abatement, Department of Transportation, Washington, D. C]
Formulation of a Noise Standard for Off-Road Vehicles
Authors: Harrison Robin T.
Published: May 2012

Current regulations covering the USDA Forest Service National Recreational areas require that all vehicles operated in the area be equipped with an adequate muffler. The adequacy of the muffler has been left to the discretion of individual Forest Service field personnel. In order to provide a more objective standard, several experienced recreation area personnel judged the noisiness of each of a fleet of dune buggies. This judgment was correlated with the A-weighted level, measured at 50 ft, of each buggy. The noisiness judgments were remarkably consistent, both from man-to-man and buggy-to-buggy. All vehicles in the fleet fell into three rather definite categories; clearly acceptable, marginally acceptable, and clearly unacceptable. Most, however, were clearly acceptable. The maximum acceptable level was found to be 85 dBA at 50 ft.
Acoustic Scattering by Turbulence in Typical Atmospheres
Authors: Hall F. F. , Gaynor J. E. , Neff W. D.
Published: May 2012

Acoustic scattering in the atmosphere is determined by velocity structure, Cv2, and temperature structure, CT2. A knowledge of these structure parameters is important in acoustic echo sounding, and in studies of noise propagation by scattering. Recent acoustic scattering measurements, wind variance studies, and in situ temperature difference measurements have provided a better understanding of Cv2 and CT2. Under convective conditions, the average value of Cv2 over prairie terrain in daytime is nearly constant with height for the first several hundred meters with a value at 100 m of 0.086 m4/3 sec−2. Although similarity theory predicts constant values of Cv2 within the convectively mixed boundary layer, measured values decrease with height from 0.096 at 75 m to 0.068 at 150 m. The standard deviation of Cv2 increases slightly with height, however. Typical CT2 values at 100 m under strong convection average to 0.004°C2 m−12, with values decreasing with height as z−4/3 as predicted by similarity theory. When these values are substituted into the acoustic scattering cross-section equation, it becomes apparent that the Cv2 term is several orders of magnitude more important in contributing scattered sound than CT2, especially for scattering in the forward direction.
Model Studies of Effects on Motor Vehicle Noise of Shapes and Arrangements of Buildings along Urban Streets. III. Roadside Barriers
Authors: Plane V. C. , Knudsen V. O.
Published: May 2012

This paper is Part III of a continuing investigation. Parts I and II were presented at the recent ASA Boston Meeting [J. Acoust. Soc. Am. 54, 341 (A) (1973)]. The adjustable model investigated since then relates to noise fields resulting from differing geometrical arrangements of roadbed and roadside reflective and absorptive materials-The model has inclined walls 12 ft × 6 ft hinged to the 12 ft × 16 ft floor. Walls and floor are 34-in. Masonite hardboard (absorption coefficient 0.02 at relevant frequencies); it thus simulates reflective roadbed and roadside boundaries. Noise reductions resulting from facing of floor and/or walls with 2-in. fiberglas (absorption coefficient 0.85 to 0.90) were measured for five upward inclinations of the walls between 0° and 90°. The sound source was 425–9600-Hz pink noise, located above the floor. Results are presented in curves showing sound pressure levels versus straight-line distance from source across floor, and up and above the inclined walls. A reference curve gives free-field levels and thus the curves reveal the increase in levels from reflective boundaries and the decrease from absorptive ones, which is very large at near grazing incidence. Applications to highway designing are discussed, including estimates of possible noise reductions.
The Measurement of In-Situ Absorption Coefficients Using Digital Correlation/Power Spectral Density Techniques
Authors: Barry Timothy M.
Published: May 2012

Using the theory of linear systems and stochastic processes, a model of the flat acoustic absorber was devised. By cross-correlating the system input and output, the cross-correlogram is shown to consist of the input autocorrelation function plus the input autocorrelation function convolved with the impulse response of the absorbing material. Proper truncation of the cross-correlogram, coupled with the standard frequency transform/system relations, makes possible the calculation of the frequency response function H(f). For white-noise inputs, the magnitude of H(f) is shown to have a simple relationship to the reflection coefficient, and hence enables the calculation of α, the absorption coefficient. Using a digital correlator whose correlation functions were Fourier transformed on the computer, system response functions for several common building materials were measured in an anechoic chamber. From these data, the reflection and absorption coefficients were calculated. Although the method is generally applicable to any angle, data are only presented for normal incidence. Measurements were also made in more complicated acoustic environments to test the general engineering applicability of the method.
Modified locus equations categorize stop place in a perceptually realistic time frame
Authors: Rhone Ariane E. , Jongman Allard
Published: May 2012

Slope and y-intercepts of locus equations have previously been shown to successfully classify place of articulation for English voiced stop consonants when derived from measurements at vowel onset and vowel midpoint. However, listeners are capable of identifying English voiced stops when less than 30 ms of vowel is presented. The present results show that modified locus equation measurements made within the first several pitch periods of a vowel following an English voiced stop were also successful at classifying place of articulation, consistent with the amount of vocalic information necessary for perceptual identification of English voiced stops /b d g/.
Science Translational Medicine
Podcast: 23 May 2012
Authors: Edelman Elazer R. , LaMarco Kelly
Published: May 2012

In this podcast, Elazer Edelman discusses a new Commentary series on training and career challenges of early-career clinician-investigators and translational bioscientists.
Awakenings
Authors: Mashour George A.
Published: May 2012

The attention-deficit drug methylphenidate can reverse the effects of anesthesia.
Complete Genome Sequence of Streptococcus pneumoniae Strain ST556, a Multidrug-Resistant Isolate from an Otitis Media Patient
Authors: Li Guiling , Hu Fen Z. , Yang Xianwei , Cui Yujun , Yang Jun , Qu Fen , Gao George F. , Zhang Jing-Ren
Published: May 2012

Streptococcus pneumoniae
is a major pathogen causing bacterial infection in the middle ear of humans. We previously used
S. pneumoniae
strain ST556, a low-passage 19F isolate from an otitis media patient, to perform a whole-genome screen for ear infection-associated genes in a chinchilla model. This report presents the complete genome sequence of ST556. The genome sequence will provide information complementary to the experimental data from our genetic study of this strain.
Complete Genome Sequence of Riemerella anatipestifer Reference Strain
Authors: Wang Xiaojia , Zhu DeKang , Wang MingShu , Cheng AnChun , Jia RenYong , Zhou Yi , Chen Zhengli , Luo QiHui , Liu Fei , Wang Yin , Chen Xiao Yue
Published: May 2012

Riemerella anatipestifer
is an infectious pathogen causing serositis in ducks. We had the genome of the
R. anatipestifer
reference strain ATCC 11845 sequenced. The completed draft genome consists of one circular chromosome with 2,164,087 bp. There are 2,101 genes in the draft, and its GC content is 35.01%.
Complete Genome Sequence of Francisella philomiragia ATCC 25017
Authors: Zeytun Ahmet , Malfatti Stephanie A. , Vergez Lisa M. , Shin Maria , Garcia Emilio , Chain Patrick S. G.
Published: May 2012

Francisella philomiragia
is a saprophytic gammaproteobacterium found only occasionally in immunocompromised individuals and is the nearest neighbor to the causative agent of tularemia and category A select agent
Francisella tularensis
. To shed insight into the key genetic differences and the evolution of these two distinct lineages, we sequenced the first complete genome of
F. philomiragia
strain ATCC 25017, which was isolated as a free-living microorganism from water in Bear River Refuge, Utah.
Complete Genome Sequence of Mycobacterium xenopi Type Strain RIVM700367
Authors: Abdallah Abdallah M. , Rashid Mamoon , Adroub Sabir A. , Elabdalaoui Hafida , Ali Shahjahan , van Soolingen Dick , Bitter Wilbert , Pain Arnab
Published: May 2012

Mycobacterium xenopi
is a slow-growing, thermophilic, water-related
Mycobacterium
species. Like other nontuberculous mycobacteria,
M. xenopi
more commonly infects humans with altered immune function, such as chronic obstructive pulmonary disease patients. It is considered clinically relevant in a significant proportion of the patients from whom it is isolated. We report here the whole genome sequence of
M. xenopi
type strain RIVM700367.
The Draft Genome Sequence of Corynebacterium diphtheriae bv. mitis NCTC 3529 Reveals Significant Diversity between the Primary Disease-Causing Biovars
Authors: Sangal Vartul , Tucker Nicholas P. , Burkovski Andreas , Hoskisson Paul A.
Published: May 2012

We report the draft genome of the human pathogen
Corynebacterium diphtheriae
bv. mitis NCTC 3529. This is the first
C. diphtheriae
bv. mitis strain to be sequenced and reveals significant differences from the other primary biovar,
C. diphtheriae
bv. gravis.
A cross-sectional survey of attitudes to HIV risk and rapid HIV testing among clients of sex workers in Switzerland
Authors: Darling Katharine E A , Diserens Esther-Amélie , N'Garambe Chantal , Ansermet-Pagot Anne , Masserey Eric , Cavassini Matthias , Bodenmann Patrick
Published: May 2012

Objectives

To assess attitudes to HIV risk and acceptability of rapid HIV testing among clients of street-based female sex workers (FSW) in Lausanne, Switzerland, where HIV prevalence in the general population is 0.4%.

Methods

The authors conducted a cross-sectional study in the red light district of Lausanne for five nights in September of 2008, 2009 and 2010. Clients of FSW were invited to complete a questionnaire in the street assessing demographic characteristics, attitudes to HIV risk and HIV testing history. All clients interviewed were then offered anonymous finger stick rapid HIV testing in a van parked on-site.

Results

The authors interviewed 112, 127 and 79 clients in 2008, 2009 and 2010, respectively. All were men, average age 32–37 years old; 40–60% were in a stable relationship. History of unprotected sex was higher with non-commercial partners (33–50%) than with FSW (6–11%); 29–46% of clients had never undergone an HIV test. Anonymous rapid HIV testing was accepted by 45–50% of clients. Out of 109 HIV tests conducted during the three study periods, none was reactive.

Conclusions

On-site HIV counselling and testing is acceptable among clients of FSW in this urban setting. These individuals represent an unquantified population, a proportion of which has an incomplete understanding of HIV risk in the face of high-risk behaviour, with implications for potential onward transmission to non-commercial sexual partners.
Effect of Cathode Length on Electrical Characteristics of a Microhollow Cathode Discharge in Helium
Authors: Yamasaki Tsutomu , Namba Shinichi , Takiyama Ken , Nojima Hideo
Published: May 2012

The electrical characteristics of a microhollow cathode discharge (MHCD) have been measured over a wide range of helium gas pressures from 10 to 900 Torr, by using cathodes of 0.5 mm diameter and 0.5–3.0 mm length. A relatively high voltage of the Paschen minimum at high pressure for the shortest cathode and a conventional hollow cathode mode for longer ones were observed. These are explained by a change of the plasma loss owing to the difference in cathode length. The radial extent of the negative glow inside the cathode hole increased with discharge current, and eventually spread along the outer surface. The threshold current for the extension of the plasma outside the cathode hole increased in proportion to the cathode length and to the square of the gas pressure. Thus, the longer cathode provides a favorable condition for the generation of reactive MHCD plasma at high-pressure and high-current operation. On the basis of these results and spectroscopic observation, the sustaining mechanism of an MHCD is briefly discussed.
The cybersecurity risk
Authors: Garfinkel Simson L.
Published: May 2012

Increased attention to cybersecurity has not resulted in improved cybersecurity.
Security of the internet and the known unknowns
Authors: Hall Chris
Published: May 2012

Seeking answers to questions about Internet vulnerabilities.
Report on BooksOnline'11
Authors: Kazai Gabriella , Eickhoff Carsten , Brusilovsky Peter
Published: May 2012

The BooksOnline Workshop series aims to foster the discussion and exchange of research ideas and initiatives addressing challenges and exploring opportunities around large collections of digital or digitized books and complementary media. The fourth workshop in the series, BooksOnline'111 called for special attention to the role of social media and the phenomena of crowdsourcing in the context of online books, which are expected to be key in defining new user experiences in digital libraries and on the Web. The workshop boasted a high quality program, including keynote addresses by Ville Miettinnen, CEO of Microtask and Adam Farquhar, Head of Digital Library Technology at The British Library. From the accepted papers, two main themes became salient: 1) The role of relationships among authors, communities and books, and 2) Reading experiences and behaviours. This paper provides a summary of the workshop, its accepted contributions and the subsequent plenary discussion.
Evaluating retrieval models using retrievability measurement
Authors: Bashir Shariq
Published: May 2012

Evaluation is the main driving force in research, development and applications related to information retrieval (IR). In the traditional IR evaluation paradigm a list of query topics along with their relevance judgments are given. The main limitation of this kind of evaluation paradigm is that it focuses almost exclusively on a small set of judged documents and does not consider what influence the given retrieval models have on accessing all the relevant information in the collection. This is particularly important for recall oriented retrieval applications where we want to ensure that that everything relevant has been found.

In this thesis we analyze the effectiveness of retrieval models from the documents retrievability point of view. We focus particularly on the retrieval bias of different retrieval models, and try to examine to what extent this bias restricts the users in retrieving relevant information. We explore this research with the help of three factors. First, we analyze the relationship between different characteristics of queries and retrievability. This is important from the query generation point of view, since in case of exhaustive queries, it is practically infeasible to complete retrievability approximation in reasonable time. The strong correlation between retrievability and query characteristics allows us to approximate the retrievability score accurately with the help of a query subset without processing an exhaustive number of queries. After this, we examine to what extent the retrievability and other IR effectiveness measures are related to each other. This specifically helps us to understand to what extent it is possible to automatically rank the effectiveness of retrieval models on the basis of their retrieval bias. This also offers a basis for optimizing retrieval systems for specific collections without the need to provide manually annotated ground truth. This is particularly useful for those retrieval domains where it is difficult to obtain a sufficient amount of relevance judgments. At the end we investigate and devise different retrieval strategies for mitigating the effect of low retrievability of documents. These include collection partitioning and query expansion on the basis of improved pseudo relevance feedback selection.

The work present in this thesis provides an a novel approach for the evaluation and optimization of retrieval models particularly for recall oriented retrieval domains, where the focus is on retrieving all relevant information but not just retrieving a subset of relevant information. Available online at: http://www.ifs.tuwien.ac.at/~bashir/shariqbashir_phd_thesis.pdf.