bluuebunny/crossref_metadata_2025 huggingface dataset:
A Community Noise Monitor
Authors: Cook Bill D. , Farley Lawrence I.
Published: May 2012

A low-cost device has been built for obtaining a histogram of community noise levels. Signals from a sound level meter or tape recorder are appropriately rectified and level sensed by ten comparators. From the output of the comparators and a logic network, currents are furnished to a bank of electrolytic storage cells, known as E-cells. The charge imposed on a cell is a measure of the time that the sound level is within some preestablished bounds. After a period of sampling, the E-cells are removed from the device and the charge read by a commercial instrument.
Reaction Time as a Measure of Threshold and Suprathreshold Hearing. I. Normal Man and Monkey
Authors: Pfingst B. E. , Hienz R. , Miller J.
Published: May 2012

Reaction time to auditory stimuli has been suggested as a measure of loudness in nonverbal animals [Stebbins, J. Exp. Anal. Behav. 9, 135 (1966)]. The reaction time task can also be used to measure threshold. We have compared the relationship of this measure to other psychophysical measures of loudness and threhsold hearing in man, and have compared hearing in man and monkey under similar experimental conditions. Absolute sensitivity functions derived from human reaction time data closely matched clinical threshold measures and were an average of 5 dB above thresholds measured by a forced-choice method. Human equal-reaction time contours matched closely equal-loudness contours derived in the same subject by loudness matching. The human and monkey equal-reaction time contours are similar throughout the overlapping hearing range of the two species. The results of this study support the suggestion that response latency can be used as a measure of threshold hearing and loudness and have application to the study of mechanisms underlying hearing in the animal model. [Work supported by PHS Grants NS 08181, RR 00166, NS 50637, and NS 05082.]
Modern Methods in Data Collection and Analysis of Surface Reverberation and of the Associated Water Waves
Authors: Horton C. W.
Published: May 2012

The problem of quantitative relationships between surface reverberation statistics and the statistics of the associated water waves has great current interest. Reverberation is a nonstationary process and the surface wave motion may be either stationary or nonstationary, so that the only reliable statistical averages are ensemble averages. The Applied Research Laboratories have developed an extensive set of sampling techniques and computer programs which are now applied routinely to all collections of stochastic processes that are analyzed. These calculations include validation tests to establish statistical homogeneity, first-order statistics, and covariance functions and their associated intensity spectra. Quadrature samples are used for narrow-band signals to reduce the number of sample values needed. These tests are described and examples are given of their application to surface and bottom reverberation and to wind waves on a lake surface. The relationship between the statistics of reverberation and of surface waves are discussed.
Statistical Analysis of Multipath Transmission
Authors: Yacoub Kamal , DeFerrari Harry A.
Published: May 2012

The statistics of the rate of transmission fluctuation in the ocean are examined theoretically for multipath single-tone processes. The mean and standard deviation of the rate of change of envelope, as well as the mean and absolute deviation of the rate of change of phase and the rate of change of logarithmic measures such as transmission loss are expressed in terms of the mean and standard deviation of the rate of change in travel time and log amplitude for each of the independent paths. The distribution of the rate of change of transmission loss and the rate of change of phase are shown to be of the form 12 (1 + x2)−12. The mean-square bandwidth or its equivalent is calculated for the envelope, the phase, and the transmission loss as well as the total received signal. In particular it is shown that the central mean-square bandwidth of the received signal is twice the mean-square bandwidth of the envelope. In other words, half the signal bandwidth is due to amplitude modulation and half is due to phase modulation regardless of the ratio of travel time fluctuations to log amplitude fluctuations of the independent rays.
Interaction of Ultrasound with Discontinuities in Metal
Authors: Yee B. G. W. , Chang F. H. , Couchman J. C.
Published: May 2012

The energy partition coefficients were calculated for plane shear and longitudinal waves incident on a thin, parallel separation containing air and water within a metal. It may be shown that the reflected, mode-converted, and transmitted energy coefficients are highly dependent on the ratio of interface separation t to the wavelength λ in the separation, as well as the angle of incidence. Resonances occur for values of “t” equal to integral multiples of half-wavelength of sound within the medium of the separation. The values of the energy coefficients change markedly near these resonances as a function of both the angle of incidence and t/λ. The energy coefficients exhibit large changes near the second critical angle when shear waves become surface waves. Calculations were made for titanium with the separation containing air and water. These calculations show that the energy coefficients are relatively constant over a wide range of values of t/λ, permitting possible correlation between ultrasonic response and flaw cross-sectional area. There are regions of t/λ, however, where the energy coefficients are not constant and no correlation is possible between ultrasonic response and flaw size.
Dispersion of Rayleigh Waves to Measure Property Gradients near Surfaces
Authors: Tittmann B. R.
Published: May 2012

The surface properties of a solid can sometimes be different from the bulk properties because of near surface gradients in such variables as chemical composition, metallurgical microstructure, degree of cold work, etc. Since surface or Rayleigh acoustic waves sample the surface elasticity to a depth comparable to the wavelength, these waves can be used to determine such a property gradient in a nondestructive way by measuring the velocity of propagation as a function of frequency. A theoretical expression relating the frequency dependence of the wave velocity to the gradient in elastic constants and density has been derived using perturbation theory, and several cases of practical interest have been calculated. Experiments on quench-hardened steel in which the property gradient is the hardness have been carried out to verify the theory.
Power Flow and Energy Relations in a Cello-Stage-Air System
Authors: Nelson D. L. , Crandall S. H.
Published: May 2012

The power flow and energy relationships between a cello, the stage supporting it, and the air in a reverberant room are experimentally investigated by measuring the power flowing into the cello from a shaker attached at the cello bridge, the power flow through the cello endpin into the stage, and the acoustic radiation from the cello and the stage. The objective of the study is to evaluate the significance of radiation from the stage relative to the radiation from the cello alone to determine the feasibility of enhancing the total radiated sound by altering the cello-stage coupling and/or changing the stage radiation properties. Experimental techniques employed include direct measurement of power flow between the two structures and acoustic power measurements in 13-octave bands. Four different stage configurations are investigated including a concrete floor, simple unbaffled wooden panel, a baffled panel of the same dimensions, and a special soloist's podiu m which incorporates a sounding board connected to the podinto top by a sound post. [This research has been supported by the National Science Foundation.]
Harmonic Structure of an Aging Guitar String
Authors: Allen J. B.
Published: May 2012

By application of various signal processing means, namely FFT, linear estimation, and digital filtering, impulse responses of new and old guitar strings were analyzed to determine the important differences. These measurements were compared to the theoretical results derived from the generalized string equation operator ε∇4+∇2+k2, using appropriate boundary conditions. Results are discussed and synthetically generated samples will be played.
Reed Cavity and Neck Proportions in Conical Woodwinds
Authors: Benade A. H. , Gebler J. M.
Published: May 2012

Stable pitch and good attack in the low register (also good octaves) require accurate harmonicity of the lower two air column resonances under playing conditions. This implies a particular impedance pattern, as viewed from the main bore into the oboe reed staple, bassoon bocal, or saxophone neck. At low frequencies the impedance must be nearly that of a cavity of volume V0 equal to the missing part of the cone. The impedance then falls to its first zero and turns mass-like at resonance frequency ω0 such that x0 = half-wavelength (x0 = missing length to apex). These basic points determine the total equivalent volume Ve, of reed plus staple, etc., including effects from the yielding reed wall (Weber, 1830), and also determine the frequency ωe, of the reed cavity-plus-(staple, bocal, or neck) played alone with normal embouchure. If the tone-hole lattice cutoff frequency is low (as on the tarogato), then ωe>ω0. Departures from exact conicity also require changes in Ve and ωe. Attention to strength of second harmonic in the tone (plus octave consistency) guides adjustment of impedance function for all ω via changes in proportions: e.g., Vienna oboes require a shorter staple, broader reed, and lower ωe than Conservatory oboes. Reeds, staples, and bocals are correctly predicted for baroque, classical, and modern oboes and bassoons. Useful saxophone neck and mouthpiece modifications have been devised and are in use.
Tone Radiation from Electroacoustic Pipes for Organ
Authors: Martin Daniel W. , Stein John L.
Published: May 2012

An acoustically realistic method of tone radiation was needed in order to complement a unique Baldwin optoelectronic system for the retrieval of photographically stored, computer-generated facsimiles of pipe organ tones. A study of the radiation patterns of tubular sources and arrays led to the invention of “electro-acoustic pipes” for the purpose. Each pipe is a vertical tubular enclosure for a loudspeaker located at and radiating chiefly from the upper end of the tube. Conically tapered absorption within the lower end and internal absorptive rings prevent either the axial or the transverse modes of the tube from coloring the tone spectrum. A port near the conventional pipe-mouth location resonates with the enclosure to enhance low-frequency tone radiation. Various sizes and lengths can be used in arrays resembling conventional organ pipes acoustically, and even visually if desired.
Electroanatomy of the Lateral Wall of the Cochlea of the Guinea Pig
Authors: Prazma J.
Published: May 2012

Glass microelectrodes with very small tips were filled with 3 M KCl or procion yellow and were introduced through the lateral wall of the cochlea with the help of a piezoelectric vibrator. Steady potentials were recorded by an X-Y plotter. The position of the electrode was plotted on the X axis, and the value of the potentials on the Y axis. The reference electrode was placed into the mandibular muscles. Certain areas of interest were marked in the tissue by procion yellow, and the position of the area was established later under a microscope after the tissue had been embedded into paraffin and cut by microtome. During penetration of the Iigamentum spirale only small negative values were recorded; however, further penetration through the stria vascularis usually revealed a positive potential and only rarely a small negative value. [Research supported by an NIH grant.]
Cochlear Microphonic Interference Effects in the Guinea Pig
Authors: Ferraro John A. , Dallos Peter
Published: May 2012

Interference of the cochlear microphonic (CM), i.e., the effect whereby the CM response to one tone is suppressed when a second tone is introduced, was studied in the first, second, and third turns of the guinea pig cochlea. In each turn, probe tones (tones whose CM was subject to interference) were presented at various frequencies at a constant stapes displacement of 1 Å. At each probe frequency, the interfering tone's frequency was varied while its level was maintained at constant stapes displacement of 10 Å. It was found that the frequency of maximal interference (dip-frequency) was a function of both probe frequency and electrode location. In all turns, dip frequencies occurred within a relatively narrow range and were affected (i.e., raised) within this range by increasing the probe frequency. This limited region where effective interference took place was found to be dependent upon electrode location and existed at and above the area of the best frequency of the electrode site. The double-lobed interference functions that have been recently reported by Legouix et al. [J. P. Legouix, M. C. Remond, and H. B. Greenbaum, “Interference and Two-Tone Inhibition,” J. Acoust. Soc. Am. 53, 409–419 (1973)] were not confirmed in the present investigation and it is not appearent why our results are in conflict.
Hearing-Aid Design and Evaluation for a Presbycusic Patient
Authors: Pascoe D. P. , Niemoeller A. F. , Miller J. D.
Published: May 2012

An octogenarian male with gently sloping audiograms with average hearing threshold levels (0.5, 1.0, 2.0 kHz) of 56 dB was tested extensively with a two-channel master hearing aid. Each channel includes a headworn microphone and a button receiver in a fitted earmold. The electronics consist of laboratory-quality amplifiers and 13-octave-band equalizers. Speech-reception tests were conducted in an acoustically absorbent room with a closed set of 100 monosyllables presented live by a female talker in quiet and noise. In a single mini-experiment, three or four frequency responses were compared in two to four sessions of 1 hour with a counterbalanced and randomized design that allowed frequent rest periods. When the field-to-eardrum transfer function is matched in the hearing-aid over a bandwidth of 6.5 kHz, reception of monosyllables is superior to competing curves by 6%–15%. Competing curves have included: those of a good quality commercial hearing aid; high-frequency pre-emphasis of +8 dB/octave defined at the eardrum ; curves with less than +18 dB relative gain in the 2–4 kHz region; curves with bandwidth less than 6.5 kHz; and so on. Finally, it is suggested that the role of frequency distortion in the design of hearing aids may be understood by relating aided and unaided audibility curves for sound fields to measures of speech reception.
Possible Importance of Head-Diffraction and Ear Canal Resonance for Speech Perception and Hearing-Aid Design
Authors: Miller J. D.
Published: May 2012

The results of recent measurements of the spectrum of spoken English and of the effect of frequency response on speech reception by a hard-of-hearing patient at Central Institute for the Deaf are related to the literature on speech, acoustical cues for speech, earmold design, and optimal speech transmission systems. This review suggests the hypothesis that the normal field-to-eardrum transfer function plays a special role in speech reception with regard to the audibility and discriminability of friction sounds and the processing of transitions of the second formant.
The Role of Anchors and Category Scale Labels in Speech Quality Rating
Authors: Pierce Linda
Published: May 2012

Although there is widespread use of category scales for the evaluation of speech quality, the labeling and instructions to subjects about the use of such scales has frequently been intuitively selected. In this experiment, subjects rated speech stimuli varying in volume and circuit noise level on a verbal (“Unsatisfactory”-“Excellent”) or a numerical (1–5) scale. Subjects using the verbal scale were instructed either to define the endpoints of the scale as equal to the highest and lowest signal/noise ratios in the experiment (external anchors) or to use their telephony experience to define the scale (internal anchors). The subjects using the numerical scale used external anchors only. On the verbal scale, the internal anchoring resulted in a higher mean rating and more peaked response distribution than the external anchoring; this indicates that subjects can apply this scale somewhat independently of the stimulus distribution. In comparing the verbal and numerical scales, the response distributions show that there are small differences in category boundaries between the two scales. In general, the results suggest that anchoring plays a more important role than scale labeling in determining the subjects’ response distributions.
Inter-Speaker versus Intra-Speaker Variability of Glottal Pulse Shapes
Authors: Curtis T. H.
Published: May 2012

Glottal volume velocity waveforms have been obtained by passing segments of voiced speech through an all-zero filter representing the inverse of the vocal tract for that segment. The poles of the vocal tract were obtained by finding the roots of the linear prediction coefficient polynomial and selecting out the formants. Selected glottal pulses for a given speaker were time normalized and averaged over an utterance, and compared to similarly averaged glottal pulses for a different speaker. The purpose of the work is to explore the feasibility of using glottal pulse shapes for a speaker classification system.
The Invalidity of FAA-Aircraft Industry Standard EPNL Data for Rating Jet Noise in Communities
Authors: Lane S. R.
Published: May 2012

During unfunded noise surveys in communities beneath aircraft flight paths for Los Angeles International Airport (LAX), 50% of the jet aircraft noise measurements were 5 to 15 dB higher than the FAA-Aircraft Industry standard EPNL values used for rating jet noise in communities. In addition, the survey results indicated that the NEF −40 and −30 contours (unacceptable noise zones) extended twice as far from LAX as the FAA published contours. Unfortunately, neither the development of the EPNL rating nor the sources of data for the FAA-Industry standard EPNL values for commercial aircraft have been fully reported. The JASA Cumulative Indices for 1948 to 1972 do not show any published papers on jet noise surveys in specific airport communities, or about jet noise data used for the FAA standard EPNL values. Thus, there has been little critical evaluation of EPNL data and rating procedures by investigators independent of the government-aircraft industry complex.
On the Hearing of Residents Near Airports
Authors: Nagel David C. , Parnell John E.
Published: May 2012

Over the last decade, many residents near major airports have been exposed to intense intermittent noise levels. Although maximum sound pressure levels in these residential communities are in many cases quite intense, the noise exposure patterns are sufficiently different from commonly studied industrial noise environments to make the application of existing damage risk models for predicting hearing loss of the residents difficult or impossible. Nonetheless, noise exposures in certain areas appear great enough to preclude ruling out the possibility of hearing loss due to aircraft noise exposure. Audiograms and other data relative to ear condition and noise exposure were obtained from residents drawn from two neighborhoods in the greater Los Angeles area. The two communities were chosen to be similar in all respects other than aircraft noise exposure, one representing a severe aircraft noise impacted area and the other a more typical surburban residential community. Results from these measurements are reported and suggestions made as to the proper interpretation of the data. [Research performed under contract to the U. S. Public Health Service, funded by a PHS-FAA interagency agreement.]
Aircraft Noise and the Community
Authors: Evans Marjorie W.
Published: May 2012

Noise levels declared to be acceptable and tolerable by local California noise ordinance and by several studies and hearing reports are compared to both (a) actual levels of aircraft/airport noise, and (b) levels stated to be acceptable and tolerable by acoustical firms employed to prepare environmental impact reports. The author will comment unfavorably on style, clarity, and quality of EIRs prepared by acoustical firms for local governing bodies such as city councils. Results of the Aircraft/Airport Noise Study by an Environmental Protection Agency Task Force in the Spring of 1973 to assist EPA in the preparation of its report to Congress on that subject are discussed. The author was a member of the Task Force Study Group.
Comparison of inside and outside Noise Measurements in Various Urban Environments
Authors: Bishop Dwight E. , Simpson Myles A.
Published: May 2012

Simultaneous measurements of the inside and outside noise environment for periods of up to 24 hours were obtained in urban areas exposed to heavy street traffic, freeway traffic, aircraft, and construction activity, as well as at a “quiet” residential location. The measurements were made using unmanned instrumentation which sampled the A-weighted noise level at half-second intervals continuously throughout the measurement period. The data, recorded in digital format on magnetic tape, were processed to yield the cumulative distribution of noise levels as well as the hourly variation of the equivalent continuous level and of various percentile levels. Consistent among the data from each location is the poor correspondence between inside and outside noise levels during periods of human activity inside, due to inside sources of noise. At other times, such as during nighttime hours, there is reasonably good correspondence between outside and inside levels. Thus, to infer inside noise levels solely from measurement of exterior noise levels and knowledge of the outside-to-inside noise level reduction of a building introduces a serious underestimate of the inside noise environment to which people are actually exposed. [This study was supported by the Office of Noise Abatement, Department of Transportation.]
Two-Tone Suppression in Cat Auditory-Nerve Fibers: Comparison of Frequencies above and below Fiber CF
Authors: Abbas P. J. , Sachs M. B.
Published: May 2012

Responses of cat auditory-nerve fibers to two-tone stimuli have been measured. One tone was always at the fiber's characteristic frequency (fc). The other tone (at frequency f2) was always such that it could produce two-tone suppression when presented at an appropriate sound level. We concentrate on cases where f2 does not produce a change in rate when presented alone. We define “fractional response” to be the average rate to the sum of the two tones divided by the rate to the CF tone presented alone. The dependence of fractional response on stimulus parameters for f2 >fc was different from its dependence for f2<fc. In one series of experiments the ratio of the sound levels of the two tones was held constant; i.e., sound pressure was given by p(t) = P0 (sin2πfct +D0 sin2πf2t), D0 = constant. Fractional response was measured as a function of P0. For f2>fc, fractional response was approximately constant (less than 1) for P0 between fiber “threshold” and saturation; for higher Po fractional response increased, in some cases to 1. However, for f2<fc, fractional response was a monotonically decreasing function of P0. [Supported by the National Institutes of Neurological Diseases and Stroke and General Medical Sciences and the U. S. Air Force Office of Scientific Research.]
The Role of Phase-Locked Auditory-Nerve Discharges in Pitch Perception
Authors: Chesnutt Bekner , Dallos Peter
Published: May 2012

A possible frequency-pitch code is one wherein the timing information reflected in the structure of period histograms is information utilized by higher auditory centers in pitch perception. To test this model, period histograms were calculated from the discharges of guinea pig auditory single units in response to two-tone stimulation, the histograms being synchronized to various combination-tone frequencies. The list of combination-tone frequencies at which phase-locking occurs was compared with the list of those combination tones audible to human listeners. It was found that the response of auditory single units to two-tone stimulation is synchronous to all combination-tone frequencies through at least third order. There is no correlation between the combination-tone frequencies at which phase-locking is observed and the combination-tone frequencies that are audible. Thus, if the temporal information reflected in phase-locked period histograms were utilized in the perception of pitch, certain summation tones would be audible to humans- as are certain difference tones-and many more difference tones would be audible. The conclusion is that the brain does not process the temporal information contained in auditory-nerve discharges in a way analogous to calculating period histograms.
An Example of Uniform Approximation near a Caustic
Authors: Wood D. H.
Published: May 2012

In the region inside a caustic having two rays through each point, ray acoustics approximates a sound field due to a point harmonic source of frequency ω by e−Im(T1)[A1eiωT1+A2e(iωT2+ir/2) ]. When the caustic is smooth, Ludwig approximates the field everywhere by a constant times eiωθ[B1Ai(−ω23ρ)−iω−12B2Ai′(−ω12ρ)], where Ai is the usual Airy function. An example of Ludwig's approximation is presented in parameterless form for the unbounded, layered medium having speed c(z) = z−12. This approximation, of course, agrees with ray theory on the source side of the caustic, rises to a large but finite value near the caustic, and exhibits exponential decay on the other side of the caustic. For the record, the results are expressed in horizontal range x and depth z with the source at x = 0, z = z0: Tn = (23)[ζ + ( − 1)nγ]12[ζ − ( −1 )nγ/2], where ζ = z + z0 and r2 = 4zz0 − x2; An−2 = 2r(ζ + (− 1)nγ); 2ρ = ζ − R, where R2 = (z − z0)2 + x2, 3θ12 = ζ + R; B12 = 2ζρ13/(rR2) and B2 = ρ−12/R.
Measurement of the Radiation Impedance of a Transducer by a Single Sensor
Authors: Sinsky J. A.
Published: May 2012

A technique is described for measuring with any uncalibrated linear sensor the radiation resistance and reactance in a medium of any transducer whose motion can be approximated to be a single-degree-of-freedom damped harmonic oscillator. The measurement requires only a single velocity, acceleration, or displacement monitor on the transducer and its advantage over other measurement methods is that it does not require monitoring the pressure at the surface of the transducer, nor does it require an absolute measurement of velocity amplitude and phase at the transducer surface. The magnitude and phase of the output of the sensor on the transducer are measured in air and in the medium for the same frequency and driving force, and from the ratio of the results the radiation resistance and reactance of the transducer can be calculated. The mechanical impedance of the transducer, which is easily obtained by a variety of standard techniques, must also be known to perform the calculation. By using this procedure to first determine the self-radiation impedance of the transducer in a free field, the change in the radiation impedance of the transducer due to its position in an array or in a baffle can also be found by repeating the procedure.
Novel Technique for Measurement of Cross-Correlation Functions
Authors: Reader Wayne T.
Published: May 2012

A technique is presented for the direct measurement of the cross-correlation function of two mechanical quantities—at least one of which is measured with a passive-type transducer. The technique obtains measurements of the cross-correlation function without the sophisticated instrumentation normally utilized. Except for a suitable time delay unit, the necessary instrumentation is found in even the most basically equipped research laboratory. The paper describes the theoretical basis for the technique and discusses data resulting from application to measurement of the cross-correlation of the motion at two points on a slender beam. The beam is driven by sinusoidal and by bandlimited random excitation. Additional applications such as measurement of the cross-correlation between a sound field and the motion of an interacting structure are presented.
A New Device for Measuring Local Acoustic Power Output of Subsonic Jets
Authors: Yen J. T. , Siddon T. E.
Published: May 2012

Many devices have been developed for measuring noise intensity output from each volume element of a subsonic jet. However, none of these can measure, in a single operation, the total power output from the volume element. A new device will be proposed to fulfill this need with a good spatial resolution and a desirable frequency characteristic. We point out that in order to measure the power output in a single operation with a device of a manageable size, the device should operate in the spherical farfields (i.e., not in the plane wave fields) of the noise sources. Hence, our device will be made of many microphones mounted on a semispherical tubular skeleton. It will operate in the spherical farfield and will utilize the technique of interferometric phase-cancellation to achieve a good linear resolution (close to half-wavelength) and to measure the acoustic power output in a single operation with a good frequency characteristic (from 500 to 15 000 Hz), as confirmed by computer simulation and partially by experiments. Many microphones are needed to cancel out all the large sidelobes. Recently, a good and inexpensive electret microphone has become available with a weatherproof casing, to make the semispherical array economically feasible.
Speech Synthesis by Using Single Phons as Speech Elements
Authors: Endres W.
Published: May 2012

As is known, continuous German speech can be synthesized using single phons, when connected by suitable transitional sounds. Recently we demonstrated that not only the /ə/, but also the /I/ and /ν/ ought to be used as transitional sounds. Their choice is dependent on the alleged phonetic environment. Additional investigations, using correlation methods in the time and frequency spheres, resulted essentially with the confirmation of this concept. The test material consisted of 196 German words spoken by one person. With a UNIVAC computer 1108, 16 characteristic normvowels of the German language were selected, and the degree of relationship between these normvowels-and then between the normvowels and the transitional sounds—was determined. As this synthesized speech should be used chiefly in automatic announcement and information services of the German Bundespost, it is important that the number of sound elements employed should be reduced. Simulated computer experiments, carried out in cooperation with the Heinrich-Hertz-Institut Berlin, showed that the character of certain vowels can be altered by shortening or lengthening their quasiperiodic parts. These results are demonstrated on tape.
Paragraph Synthesis by Word Concatenation
Authors: Olive Joseph P. , Spickenagel Nancy
Published: May 2012

This paper describes a scheme for the rule synthesis of speech in which words spoken in isolation were spliced after they were modified by rule. The input to this scheme consists of a typed text accompanied by phrase boundary information. The words spoken in isolation were recorded and analyzed into parameters from which these words can be synthesized after they have been modified. These modifications consisted of (1) a compression of word duration appropriate for continuous speech: however, the same shortened duration is used in all contexts; (2) minimal changes for amplitude and between-word coarticulation; and (3) pitch determined by context-dependent pitch rules. Pitch rules have been developed to deal with complex sentences whose phrase structure is known. The resulting paragraph is played as an example of the quality of synthetic speech.
Noise Control Feasibility Study in Meat Packing Plants
Authors: Niemiec K. , Commins D. E.
Published: May 2012

Numerous operations performed in the meat packing industry generate excessive noise levels. The size of the plants and the large number of employees involved create a severe problem if the requirements of the Occupational Safety and Health Act of 1970 are to be met. The poor acoustic qualities of the buildings and the restrictions put by the Department of Agriculture on construction materials used in food-processing plants limit the number of solutions available to the noise control engineer: acoustical materials generally contain dangerous substances such as lead, fiberglass, and asbestos and have physical characteristics which are incompatible with health regulations. A complete noise study of a large meat packing plant has been performed and noise sources have been identified and classified according to the noise generating mechanisms involved and to the severity of their impact. The noise control measures compatible with the processing of meat have been investigated and recommendations have been made for their implementation. Particular attention has been devoted to the noisiest machines, such as choppers, peelers, and injectors.
Gas Valve Noise—A Review of Current Knowledge
Authors: Sawley R. J. , White P. H.
Published: May 2012

Available information on valve noise is based largely on the results of experiments, with minimal interpretation with respect to the known behavior of fluid dynamic noise sources. This paper examines the potential for such interpretation and shows that it is possible to postulate different mechanisms of behavior for valves which should lead to improved normalization procedures. Measurements on valves with air flow suggest the presence of dipole noise, quadrupole noise, and shock-turbulence interaction. Different valve types exhibit differing mixes of these noise mechanisms.
Vertical Coherence of Ambient Noise at Different Depths at a Deep Water Location
Authors: Urick R. J.
Published: May 2012

Measurements of the ambient noise background have been made with a string of seven hydrophones 200 ft long. Data were collected at a number of depths throughout the water column at a deep water site north of St. Croix, Virgin Islands. The time delay correlograms obtained confirm a binary model for the sources of ambient noise: a low-frequency type arriving preferentially from near-horizontal directions, and a high-frequency type arriving from near-vertical directions. No variation in coherence with depth was observed. The correlograms constantly fluctuate in amplitude and peak time delay, indicating that the coherence and therefore the directionality are time-variable properties of the ambient background. Coherence measurements are an alternate, and in some ways a preferable, approach to obtaining the data needed for the optimum design of arrays to operate in the real-world noise background.
Detection of Fluctuating Sonar Targets
Authors: Gaun-Aurd G. C. , Urick R. J.
Published: May 2012

The effect of amplitude fluctuation on sonar detection can be expressed quantitatively by means of receiver operating characteristic (ROC) curves having a fluctuation index k as a parameter. The fluctuation-modified ROCs are found to be similar to conventional ROCs for non-fluctuating signals (k = 1), but on double-probability paper have a slope that depends on the value of k. A simple example with Gaussian statistics is developed where the time mean of a signal fluctuates Gaussianly about the ensemble mean. From this idea, the analytical expressions for the “tilted” ROCs, as well as their plots, are derived. Two extremes of slow and fast fluctuations are discussed.
Exact Evaluation of Delta Modulator Performance in Sonar Signal Processors
Authors: Wang H. S. C.
Published: May 2012

Single-bit delta modulation is increasingly being used or suggested for telemetry and beam-forming in sonar receiving systems. To evaluate its performance in these applications, an exact time-domain analysis appropriate for logic circuits practically used was formulated, which served as the basis for the development of a computer program for the simulation of the codec (coder-decoder). The essence of this formulation lies in a more rigorous calculation of the local decoder output voltage corresponding to an arbitrary coder output bit pattern in terms of the pole locations of the integrating network. The difference between the local decoder output and the analog input signal represents the quantization noise. Utilizing an 800-Hz sinusoidal signal as the analog input to the codec, local decoder output waveforms for a number of cases were calculated and displayed to show the decrease of quantization noise with increasing clock frequency and the improvement of codec performance with double integrating network. The average quantization noise power was also calculated from samples of noise waveform to illustrate the quantitative determination of the output SNR and the dynamic range of the codec. Further work directed specifically at sonar beamforming applications is being planned.
Vertical Directivity of Truck Noise
Authors: Commins D. E.
Published: May 2012

The effectiveness of highway noise barriers and the effect of highway noise on high buildings depend on the directivity of the noise source. An experiment was designed to determine the directivity pattern of trucks at highway speeds in a vertical plane. An array of microphones was placed on a vertical tower and was used to record the noise generated by trucks driving by on a nearby freeway. The speed was measured and the characteristics of each vehicle were noted. The results show that trucks exhibit an almost omnidirectional pattern, at least up to 45° from the horizontal, independently of the type of truck or type of exhaust. This conclusion is compatible with the results obtained elsewhere for passenger cars. [This study was supported by the National Cooperative Highway Research Program Project 3-7. The opinions and findings expressed or implied in this paper are those of the author. They are not necessarily those of the Highway Research Board, the National Academy of Sciences, the Federal Highway Administration, the American Association of State Highway Officials, nor of the individual states participating in the National Cooperative Highway Research Program.]
Attention of Acoustical Warning Signals near Highway-Railroad Intersections
Authors: Wilson G. A. , Oliver C. C.
Published: May 2012

Statistics of accidents involving motor vehicles and trains indicate that a high percentage of collisions occur in daylight hours when weather, road surface, and visibility conditions are considered good. Since visual warning signals such as blinking lights may be obscured during daylight, the effectiveness of acoustical signals such as bells and whistles is important. This investigation considers adverse meteorological conditions which lead to large excess attenuation of sound being transmitted from a moving source and a stationary source to a moving receiver. Wind speed, direction and gradient, and temperature at ground level and its gradient, are significant parameters—as are speeds of the moving source and receiver. The physical and mathematical models of the problem are presented and results of computer simulation studies are given. Meteorological conditions which lead to marginal or hazardous situations for a collision between a motor vehicle and a train are identified. Recommendations are given for field testing of the model and for improving acoustical warning devices near highway-railroad intersections.
Design Analysis of Highway Noise Barriers
Authors: Saurenman Hugh J.
Published: May 2012

Use of solid walls and earth berms as highway noise barriers is becoming more widespread. A survey of the methods generally accepted for use in acoustical evaluation and prediction of barrier performance indicates the following: First, most methods are based on the theory of Maekawa (diffraction by a semi-infinite screen). Second, the methods are either too complex to use except for final design evaluation, or they are too simplified for use except in preliminary design stage. This paper describes a method developed to bridge this gap. The method is based on the results of Maekawa and involves the analysis of a single truck pass-by. The vehicle is modeled as three incoherent noise sources representing stack, engine, and tire noise. The attenuation for each octave band is determined; then the octave bands are combined to give an A-weighted sound level. Evaluation of the effectiveness of the sound wall is done by comparing the noise signature with and without a barrier present. The method is simple enough to allow comparison of many barriers in a short period of time, but complete enough to be considered as accurate as the Maekawa results it is based on. Results from use of the method in the design and analysis of several projects are presented.
Model Study of the Propagation of Sound from V/STOL Aircraft into Urban Environs
Authors: Donavan Paul R. , Lyon Richard H.
Published: May 2012

The propagation of sound from elevated noise sources into urban environs was studied with a series of model experiments. The experiments included the modeling of previous urban propagation field studies, the measurement of sound enhancement and barrier effects in an urban region, and the determination of the significance of building facades in urban propagation. Results of the study were expressed in the difference in sound level observed between a particular urban source-receiver geometry and a corresponding open field geometry. The results expressed in this manner can be applied directly to many urban situations to predict sound levels from known noise sources. In addition to the model results, a more general method of sound level prediction based solely on urban geometries has been developed. With the model results and elementary psychoacoustic considerations, urban geometries which produce the most and least noise intrusion have been rank ordered for the specialized case of V/STOL aircraft. [Work supported by U. S. Department of Transportation.]
On Ranking the Impact Sound Transmission of Wood-Framed Floor-Ceiling Assemblies
Authors: Brittain F. H. , Heebink T. B. , Belmondo V. E.
Published: May 2012

A masking procedure has been developed to rank apartment floor-ceiling systems in order of their resistance to the transmitted sound of footfalls. Results obtained subjectively show that the current international standard for rating impact noise transmission using a tapping machine incorrectly ranks some wood-framed floor-ceiling systems. When the described procedure is used to mask tapping machine noise, the floors are also incorrectly ranked. This inadequacy continued even though low frequencies, below the 89-Hz cutoff of the 100-Hz 13 octave, were included in the masking procedure. Because the masking procedure described is subjective, the problems associated with the development of an objective test are also discussed. A simple objective test method is suggested for future development.
The Theory of Flanking Transmission between Adjacent Rooms
Authors: Wakefield C. W. , Price A. J.
Published: May 2012

Statistical energy analysis (SEA) has been recently used to predict the sound transmission loss of single and double partitions [Price and Crocker, J. Acoust. Soc. Am. 47, 683 (1970)]. The present authors have applied a similar SEA technique to the problem of sound transmission between two adjacent rooms whose walls, floor, and ceiling are all structurally coupled. The model examined consisted of a rectangular box separated into two cavities by a dividing partition. The SEA model therefore consisted of five coupled resonant elements: the source room, the source and receiving room common sidewalls (assumed to be identical in each of the two rooms), the dividing partition, and the receiving room. The theory considers the effects of the material thickness and damping of both the dividing partition and the coupled sidewalls. Wave interaction at the structural junctions of the partition and the sidewalls was also examined and used to predict the required structural coupling loss coefficients. The theory was found to produce good agreement from 500 to 16 000 Hz (±2 dB) with experimental data obtained from a pair of model rooms. It is shown that by careful selection of system parameters, the effects of structure-borne flanking can be minimized.
Modeling the Dynamic Relationship Between HIV and the Risk of Drug-Resistant Tuberculosis
Authors: Sergeev Rinat , Colijn Caroline , Murray Megan , Cohen Ted
Published: May 2012

HIV-coinfected TB patients may be less likely to be affected by drug-resistant TB than others in their communities as resistance first emerges.
Comparative Genomics of Vancomycin-Resistant Staphylococcus aureus Strains and Their Positions within the Clade Most Commonly Associated with Methicillin-Resistant S. aureus Hospital-Acquired Infection in the United States
Authors: Kos Veronica N. , Desjardins Christopher A. , Griggs Allison , Cerqueira Gustavo , Van Tonder Andries , Holden Matthew T. G. , Godfrey Paul , Palmer Kelli L. , Bodi Kip , Mongodin Emmanuel F. , Wortman Jennifer , Feldgarden Michael , Lawley Trevor , Gill Steven R. , Haas Brian J. , Birren Bruce , Gilmore Michael S.
Published: May 2012

Methicillin-resistant
Staphylococcus aureus
(MRSA) strains are leading causes of hospital-acquired infections in the United States, and clonal cluster 5 (CC5) is the predominant lineage responsible for these infections. Since 2002, there have been 12 cases of vancomycin-resistant
S. aureus
(VRSA) infection in the United States—all CC5 strains. To understand this genetic background and what distinguishes it from other lineages, we generated and analyzed high-quality draft genome sequences for all available VRSA strains. Sequence comparisons show unambiguously that each strain independently acquired Tn
1546
and that all VRSA strains last shared a common ancestor over 50 years ago, well before the occurrence of vancomycin resistance in this species. In contrast to existing hypotheses on what predisposes this lineage to acquire Tn
1546
, the barrier posed by restriction systems appears to be intact in most VRSA strains. However, VRSA (and other CC5) strains were found to possess a constellation of traits that appears to be optimized for proliferation in precisely the types of polymicrobic infection where transfer could occur. They lack a bacteriocin operon that would be predicted to limit the occurrence of non-CC5 strains in mixed infection and harbor a cluster of unique superantigens and lipoproteins to confound host immunity. A frameshift in
dprA
, which in other microbes influences uptake of foreign DNA, may also make this lineage conducive to foreign DNA acquisition.

IMPORTANCE
Invasive methicillin-resistant
Staphylococcus aureus
(MRSA) infection now ranks among the leading causes of death in the United States. Vancomycin is a key last-line bactericidal drug for treating these infections. However, since 2002, vancomycin resistance has entered this species. Of the now 12 cases of vancomycin-resistant
S. aureus
(VRSA), each was believed to represent a new acquisition of the vancomycin-resistant transposon Tn
1546
from enterococcal donors. All acquisitions of Tn
1546
so far have occurred in MRSA strains of the clonal cluster 5 genetic background, the most common hospital lineage causing hospital-acquired MRSA infection. To understand the nature of these strains, we determined and examined the nucleotide sequences of the genomes of all available VRSA. Genome comparison identified candidate features that position strains of this lineage well for acquiring resistance to antibiotics in mixed infection.