bluuebunny/crossref_metadata_2025 huggingface dataset:
Segmentation of Speech into Syllables
Authors: Stowe Arthur N.
Published: November 2005

A computer program to segment speech into syllables is now a part of the Lincoln Laboratory speech-recognition system. It is intended to facilitate processing of polysyllabic words spoken in isolation, and, eventually, connected speech. The program does not attempt to fix boundaries precisely in time. Evaluation of the results is made with reference to the aural impression that a sequence of speech sounds makes on the investigator, the aim being to insure agreement between program and investigator for those segments at which the latter is certain that there is or is not boundary, and to confine disagreements to those segments at which the investigator is uncertain. Decisions are made at 3 levels, the easiest being made at the first level. Syllable boundaries are first marked at transitions from voiced to voiceless segments, voicing being determined according to the ratio of amplitude in a lowpass band to the total speech amplitude. Then the stretches of continuously voiced speech thus marked are processed. Dips in the over-all amplitude large enough to indicate unambiguously a syllable boundary are marked as boundaries. At the third level, the voiced segments defined by the boundaries thus far determined are further processed. More-detailed characteristics of the spectrum are used to make decisions in the most difficult cases, vowel-semivowel-vowel combinations and the monosyllabic diphthongs.
Pitch, Intensity, and Spectrum Stereotypes in Vocoder-Analysis Data for Readings of Phonetically Balanced Wordlists
Authors: Smith Caldwell P.
Published: November 2005

An 18-channel vocoder system using a conventional pitch extractor was used to analyze intelligibility-test recordings consisting of talkers reading Harvard PB wordlists in the carrier sentence “You will write (test word) now.” Digital-output data from the analyzer were segmented to separate the test-word items from the carrier sentences. Distributions of the fundamental pitch frequency, intensity level, and spectrum data were compiled for the segments and analyzed to permit a comparison of the test-word items and the carrier sentences, and with data from connected-speech samples from the same talkers.
Rate of Information Transmission for 1-, 2-, and 3-Dimensional Acoustic Stimuli
Authors: Studdert-Kennedy Michael , Liberman Alvin M. , Rosov Robert J.
Published: November 2005

Three sets of 8 acoustic stimuli, each lasting 1 sec, were prepared. The 3 bits of information in each set were coded into 1 (pitch), 2 (pitch and loudness) or 3 (pitch, loudness, repetition rate) dimensions. Six listeners learned the randomly assigned numerical names of the members of a given set. They were then asked to identify these members under time pressure without knowledge of results: stimuli were presented at intervals of 4, 2, 1, 12, and 14 sec, permitting maximum information transmission rates of 0.60, 1.00, 1.50, 2.00, and 2.40 bits/sec. Reaction times to the stimuli presented at 1-sec intervals were also recorded. Previous work has shown that listeners may learn more rapidly to identify stimuli and may identify them more accurately as the number of coding dimensions increases. The present study supported these findings, and further showed that (1) for a given stimulus set, the rate of information transmission increased as time pressure, within the limits specified above, the percentage gain in rate being somewhat less for the 3- than for the 1- or 2-dimensional sets; (2) for a given presentation interval, the subjects' computed transmission rate increased as the number of coding dimensions. Median reaction times did not differ significantly across the 3 sets. [This investigation was supported in part by the Prosthetic and Sensory Aide Service, Veterans Administration, under research contract V1005M-1253, and in part by the National Science Foundation under grant G-23633.]
Impact-Noise Recommendations for the FHA
Authors: Schultz T. J.
Published: November 2005

Because of increasing complaints of disturbance from impact noise in multifamily dwellings, the Federal Housing Administration plans to include in their Minimum Property Standards some recommendations for the control of this noise. A study of the existing noise codes and of several surveys of public reaction to household noise has led to the recommendation of a criterion of acceptability for floor/ceiling constructions in multifamily dwellings; a listing of floor/ceiling structures commonly used in the U.S.A., classified as to their ability to meet the criterion; and a set of recommendations and suggestions regarding typical structural details, intended to help the architect realize the fullest benefit from the type of structure he selects. This paper gives the results of that study and tells how they were arrived at.
Rupture of Canine Erythrocytes in Ultrasonic Fields in which Cavitation Has Been Suppressed
Authors: Ackerman Eugene
Published: November 2005

Canine blood was diluted with isotonic Rous-Turner solution at pH 5.8 or at 7.0. The suspended erythrocytes were exposed to ultrasonic energy at 495 kc/sec with cavitation either occurring or being suppressed by excess pressure. The same power was applied to the transducer whether or not cavitation was occurring. The rupture of the cells was measured spectrophotometrically. In addition, the osmotic fragility of the exposed cells was compared with that of control cells. The results were analyzed and graphed, using an IBM-1620 computer. These studies indicated that (1) canine erythrocytes can be ruptured in the absence of cavitation, albeit more slowly; (2) mechanical strength as determined ultrasonically is not simply related to osmotic fragility; (3) the changes of osmotic fragility after ultrasonic treatment were different from those after heating; (4) the destruction not due to cavitation occurred at intensities between those used for surgery and those used for physical therapy. [This work, performed with the technical assistance of N. Nolder, A. Hildestad, and L. C. Gatewood, was aided by National Institutes of Health grants GM 08299-02 and FR-00007.]
Decibel vs Hearing Cell
Authors: Angeluscheff Z.
Published: November 2005

The human ear, gate to human mind and emotions, conveys vibrations to the brain. Signals such as the ticking of a watch, humming of mosquitos, etc., provoke nerve activity even during sleep. Low frequencies (0.5–10 cps) of 1×10−7 V are perceptible and recorded on an encephalogram. Energy of 0.1 W/cm2 (20 kc/sec) breaks down the nervous cell, disrupts the molecular structure, and alters its physiological function. Chronic stimulation (noise) causes formation of (Purkinje) cells, indication of failing functional capacity of enzymes. The cell is filled with granulations of inert RNA (nucleic acid), a sign of denaturation of polymer protein. The cell is deprived of its physiological capacity. Overtaxation by noise of the nerve cell in day and night over physiological threshold has disastrous effects. Sustained acoustical energy over 60 dB (10 μW) promotes pathology in the nerve cell: e.g., busy street—70 dB, rock drill—110 dB, riveting hammer—120 dB, jet motor—140 dB, supersonic jet—180 dB, and the sonic boom and sharp thunderlike noise clap that follows the aircraft and hits the ground along the entire flight path within a “boom carpet” the width of 90 miles. Nova-Boosters (500 MW, all with the hidden range of harmonics) are gloomy harbingers for human hearing and mind.
Plate-Edge Point Impedances
Authors: Eichler Ewald
Published: November 2005

The response of a thin semiinfinite plate driven through a stud attached to its edge has been calculated assuming simple-stress distributions along the edge. The transverse motion and the two in-plane rotatory motions of the stud are related to the corresponding force and moments by an input-impedance matrix. The elements of the impedance and admittance matrices are presented for a Poisson ratio σ=0.3 and for different stud widths. For small stud widths, the phase angles of the admittance-matrix elements are independent of frequency. [This research has been supported in part by the Aeronautical Systems Division.]
Multistate Dissociation and Sound Absorption in MgSO4 Solutions
Authors: Fisher Frederick H.
Published: November 2005

The following measurements have been made on MgSO4 solutions: (1) the effect of pressure and dielectric constant on sound absorption for 0.5 molar solutions; (2) the effect of pressure on electrical conductivity at concentrations from 0.0005–0.5 molar. These measurements support the multistate dissociation concept. The observed large decrease of sound absorption as a function of pressure is inconsistent with the simple dissociation model used by Bies. Work is in progress to determine the ΔV̄ values and concentrations of species associated with the multistate model. The object is to develop a model of acoustic absorption that is consistent with conductivity and density data. [This work represents results of research carried out under the U. S. Office of Naval Research, Contract Nonr 2216(05).]
Sound-Absorption Characteristics of Auditorium Seats, with and without Audience
Authors: Veneklasen Paul S. , Christoff Jerry
Published: November 2005

Desired absorption characteristics of auditorium seats were specified by reverberation-chamber tests on a group of eight units. Correction of the usual excessive absorption in the 250-cps region was required. Correlation of chamber measurements with measurements in the completed auditorium is reported.
Modal Vibration Testing of Aircraft with Low-Power Shakers
Authors: Baker Jackson C.
Published: November 2005

A comparison is made of the two different types of vibration testing: modal and environmental. Their application to the determination of the flight-safety characteristics of a flight vehicle is discussed. A brief history is included of the development of the equipment and techniques for modal or resonance vibration testing, which is so important before first flight. An example is given of a modal vibration test on an unusually complex aircraft structure, the Lockheed WV-2E, that shows the problems of separation of modes closely spaced in frequency and the difficulties in obtaining all of the modes, clean. The significance of mode shapes, location of mode lines, and mode-frequency ratios are discussed as to how they affect dynamic responses and flutter susceptibilities.
Pitch-Information Rate for Connected Speech
Authors: Shaffer Harry L.
Published: November 2005

An information-theory approach is used to evaluate the information rate necessary to accurately transmit the pitch information of connected speech. An IBM-1620 is programmed to scan experimentally obtained pitch data and evaluate transitional probabilities, which are used to determine the conditional entropy. The conditional entropy decreases monotonically as higher-order transitional probabilities are considered. For transitional probabilities of sufficiently high order, the minimum entropy for the pitch signal is obtained. Numerical values for the pitch-information rate, based on experimental data, are presented as a function of the transitional probabilities. [The work reported was sponsored by the National Science Foundation under grant GP-590.]
Pitch and Formant Shifts Accompanying Changes in Speech Power Level
Authors: Harris Cyril M. , Weiss Mark R.
Published: November 2005

This paper presents quantitative information concerning the shifts in pitch that occur when a talker changes the power level of his voice from “normal” to “loud” or from “normal” to “soft” under natural speaking conditions; in addition, data are given of the shift in frequency of the first formant (F1) for an increase in speech power level. The shifts were measured for the following sets of words: (1) a group of recordings of the same word, each spoken by a different talker, and (2) a group of different words spoken by the same talker. For each word, the shifts accompanying the change in speech power level were computed for five points along the pitch and formant tracks—from the beginning to the end of the word. For a change in speech power level from “normal” to “loud,” the average change in pitch for all of the data was approximately 40%, and the change in F1 was approximately 12%. For a change in speech power level from “normal” to “soft,” the over-all average decrease in pitch was approximately 12%.
Talker-Recognition Procedure Based on Analysis of Variance
Authors: Pruzansky Sandra , Mathews Max V. , Britner P. B.
Published: November 2005

This paper describes a talker-recognition procedure that selects a small subset of features from a much larger body of data and bases recognition on this subset. The subset is chosen as those features having small variation between utterances of a given talker as compared to the variation among utterances of different talkers. This procedure is applied to materials consisting of quantized spectrographic information from a group of ten talkers uttering 10 different words seven times each; modified materials averaging the spectrographic information are also used for recognition. Results are computed as a function of the number of features used. These results are compared with those obtained by simple pattern matching and by a procedure that selects features by means of multidimensional analysis of variance. Although we have treated talker recognition only, this procedure is general and can be applied to other recognition problems where it is desirable to use a simple, cheap, and fast method to select a few important features from a much larger set that can be in the thousands.
Propagation of Broad-Band Signals in a Random Medium
Authors: Laval R.
Published: November 2005

The propagation of a monochromatic wave in a medium containing random inhomogeneities is generally described in terms of amplitude and phase fluctuations. Is is shown in this paper that the method can be extended to broadband waves by considering the correlation of the fluctuations between elementary frequency bands. The relation between the correlation function of the fluctuations in the frequency domain and the waveform distortion of a broad-band signal is established. The method is applied to a medium where the fluctuations in refractive index are small and have a Gaussian correlation function in space. Waveform distortion of short pulses propagating in such a medium is studied.
Acoustic Rays in an Ocean with Heat Source or Thermal-Mixing Zone
Authors: Lugt Hans J. , Ugincius Peter
Published: November 2005

The eikonal equation of ray acoustics is discussed for the general case, with the index of refraction a function of the three space coordinates. Two examples illustrating the influences of a two-dimensional heat source and a thermal-mixing zone on the acoustic-ray paths in an ocean are presented. Numerical results show that, for long-range acoustical ray-tracing, inhomogeneities of the ocean in the horizontal plane can cause refraction effects that are not negligible in comparison with effects due to vertical inhomogeneities. Rays, which travel in the vicinity of a heat source, can be refracted as much as 6°. Thermal-mixing zones can increase the ranges of shadow zones near the ocean surface up to 50%. Even new shadow zones can be formed.
Some Recent Attenuation-Loss Measurements in the Sub- and Low-Kilocycle Region
Authors: Thorp W. H.
Published: November 2005

An experiment is described that was conducted to provide an empirical evaluation of attenuation in sea water in the frequency decade of 354 to 3540 cps. Recordings were made of SOFAR shots detonated every 5 miles along a 500-mile track employing receiving elements located near the axis of the SOFAR channel. An analysis is outlined both in terms of received energy spectrum and transmission loss as a function of range. The experimental data have been statistically fitted by least-squares methods to a number of mathematical models of the general form Nw=H0+10n log R+aR, where H0 represents the transmission loss in excess of a geometrical spreading specified by 10n logR. A selection made from these various results on the basis of significance in terms of ray acoustics is finally compared with other published results.
Some Remarks on SOFAR Time Dispersion
Authors: Hirsch Peter
Published: November 2005

It is a well-known characteristic of SOFAR propagation that measurements of time, distance, and acoustic speed in the propagating medium show that the pulse that arrives last travels the shortest distance. This seeming paradox is explored by assuming that the acoustic speed near the sound-channel axis varies as c2=c02/(1–2|αz|β), where c0 is the axial speed, x is the vertical distance from the axis, and α and β are free parameters. It is shown that by using this assumption a value of β<2 can be found that will yield the observed time dispersion of the SOFAR arrivals. The axial arrival time is predicted according to the formula T=Rc0{1+β−2β+2[αRΓ(1+1β)⧸(2π)12NΓ(12+1β)]2β/(2−β)}. Here, T is the travel time from source to receiver, and N is the number of axis crossings that the ray makes in the range R. [This work was supported by the Bureau of Ships, U. S. Navy.]
Experiment for the Study of Short-Term Variations in the Ocean's Sound-Velocity Depth Profile
Authors: Piip Ants
Published: November 2005

The sound-velocity depth profiles in the oceans are subject to considerable variations, even at sound-channel axis depths. Previous work, generally directed towards obtaining “typical” profiles, indicates large, short-time variations in these profiles. An experiment to investigate the short-time spatial and temporal variations of the profiles has been designed and is in progress. An instrument package containing depth gauges and two velocimeters is continuously lowered and raised from a stationary ship for tens of hours at a time. The single-conductor, armored, suspension cable carries power and programming instructions down and telemeters the FM sensor outputs to a recording station on shipboard. Continuous, consecutive profiles are thus obtained at selected sites. A description of the design of the experiment is given, and results are shown and analyzed. [This program was supported by the U. S. Office of Naval Research's Acoustics Programs.]
Recovery from Auditory Adaptation
Authors: Canahl Kathryn Dunn , Small Arnold McC.
Published: November 2005

One of the possible weaknesses of earlier studies of recovery from auditory adaptation involves the restimulation of the adapted ear during the recovery process. In the present study, recovery was investigated by means of simultaneous dichotic loudness balances and, in order to keep restimulation to a minimum, test durations of 0.3 sec were used. A 1000-cps tone, 45 or 90 sec in duration at 60, 80, or 100 dB SPL, was used as the adapting signal. Recovery curves for each SPL-duration combination were determined by measuring the amount of adaptation at 0.1, 0.4, 1.0, 4.0, 10.0, and 40.0 sec following cessation of the adapting signal. The results indicated that recovery from adaptation is a simple exponential function. In addition, the results appeared to indicate that rate of recovery depends primarily upon the amount of adaptation from which recovery is taking place. The relationship between the amount of fatigue, which was also measured in the present study, and adaptation at particular points on the recovery curves is discussed.
Auditory Masking by Multiple Tones
Authors: O'Leary G. C.
Published: November 2005

The masking of a single sinusoid by two other pure tones was measured monaurally by the Békésy technique. The maskee was pulsed slowly at the rate of one pulse per second. The maskers were on continuously. Ten pairs of maskers were chosen to cover the range 300 to 2300 cycles. The masking was measured two ways: (1) as a function of the frequency of the maskee, holding the frequency and level of the maskers constant; and (2) as a function of the frequencies and levels of the maskers holding the frequency of the maskee constant. Data from four subjects were obtained. An empirical model for describing the masking function is presented. In an effort to link the masking effect to speech perception, the experiment was extended to consider the masking of one spectral line by all other frequency components in a synthetic speech sound. A vowel synthesizer was arranged with a phase-locked frequency divider so that a prescribed spectral line could be controlled in amplitude and phase. Intensity limens for individual components located at formant peaks and in valleys between formants were determined. These data are described for three vowel sounds and are related to the two-tone masking model.
Effect of Auditory Fatigue upon Frequency Discrimination and Binaural Diplacusis
Authors: Elliott D. N. , Frazier L. , Sheposh J.
Published: November 2005

Utilizing the method of adjustment, repeated binaural-pitch matches were obtained under normal conditions and under conditions in which one ear was fatigued. Mean adjustments and intrasubject variances were computed for normal and fatigue conditions as indices of the effect of fatigue upon discrimination and upon the ear's “tuning.” Fatiguing tones were 2000 and 4000 cps, and test frequencies for these two fatiguing frequencies were, respectively, 2800 and 5600 cps. There was evidence of an upward shift in the perceived pitch at both test frequencies. No statistically significant changes in discrimination were obtained.
Difference Limen for Frequency in the Presence of Masking
Authors: Brandt John F. , Small Arnold McC.
Published: November 2005

The monaural differential threshold for frequency at 1000 cps in the presence of wide-band masking was investigated in 26 listeners, using the method of constant stimulus differences. Enough masking was introduced into the same ear as the 1000-cps tone to raise the absolute threshold of the sinusoid 10 or 45 dB. Four SL's relative to masked threshold were investigated (5, 15, 25, and 35 dB SL). The DL was also obtained under quiet conditions at the four SL's listed above. The results indicate that the introduction of masking simultaneously with the sinusoid simply translated the function relating the DL to SL along an intensity dimension. That is, when SL is referred to either absolute threshold under conditions of quiet, or to masked threshold under conditions of masking, the DL functions are identical. Loudness and over-all SPL were found not to be of particular importance per se.
Pitch Perception and Structure of Pulse Sequences
Authors: Lowy Karl
Published: November 2005

Extending an observation by Seebeck and others in which there was a slight temporal shift between even and odd clicks in a series, an additional phenomenon was observed, which is demonstrated. Several experiments performed to determine the origin of the perceptual phenomenon are described. They seem to indicate that the shift in pitch can be accounted for in terms of cochlear action.
On the Limits of Binaural Interaction
Authors: Robinson Donald E. , Deatherage Bruce H.
Published: November 2005

Several combinations of dichotic stimuli have been investigated in an attempt to place limits on the conditions under which binuaural fusion can be obtained. Deatherage, in 1961, found that his subjects could obtain fusion (a unitary click image) when the stimuli to the ears differed greatly in frequency content. When the frequency difference was large, however, they obtained two click images of different pitch that could be independently brought to the median plane of the head. The present study is an extension of this work. Other combinations of clicks and of tone bursts and clicks are employed at various sensation levels. For the tone bursts, various rise and fall times are used, also. As in the earlier paper, the results indicate that fusion can be obtained under a wide variety of dichotic stimulus conditions. The effects of rise time of the stimulus of higher frequency is found to be of some importance, with a lesser effect shown by fall time. Under some conditions, however, two images are obtained when the rise and fall times are different. Data for these and other dichotic stimulus conditions are presented. [This work was supported by a contract between the U. S. Office of Naval Research and TRACOR, INC.]
Ultrasonic Relaxation in Molten Boron Trioxide
Authors: Buarque de Macedo P. , Litovitz T. A.
Published: November 2005

Ultrasonic velocity and absorption was measured in molten boron trioxide in the frequency range 30 kc/sec to 11 Mc/sec, in the temperature range 350° to 1450°, which corresponds to the viscosity range 6×107 to 31 poise. Thus, viscoelastic relaxation values were obtained in both the Arrhenius region (where the log of the viscosity follows a 1/T law) and the non-Arrhenius regions of boron trioxide. In the Arrhenius (high-temperature) region, a single relaxation was observed, while, as the viscosity departed from the Arrhenius temperature behavior, a distribution of relaxation times appeared, whose width progressively increases with decreasing temperature. This is in agreement with McDuffie and Litovitz's postulates, which relate the origin of the distribution of relaxation times in liquids to the origin of the non-Arrhenius (or W.L.F.) behavior of the temperature dependence of the viscosity. [Research supported by the U. S. Atomic Energy Commission.]
Ultrasonic Bubble Detector
Authors: Mitchell Richard L. , Heisig Charles G.
Published: November 2005

The principle of operation and unique design of an ultrasonic bubble-detector system for general application and utilization in the process industries is presented. The primary element is made of an unaltered pipe with the transducer elements epoxied directly to the pipe o.d. surface. The cell is isolated from external effects and limited in active length by absorbing sheathing. The major effects of gradual temperature, viscosity, and other fluid property changes are circumvented by the secondary (electronic) circuitry, thereby resulting in a system sensitive primarily to bubbles. Although the resulting output is primarily a qualitative indication of bubble presence, experience has shown that a good quantitative calibration can be empirically established for a particular application.
Ultrasonic Measurement of Elastic Moduli at Elevated Temperatures, Using Momentary Contact
Authors: Carnevale E. H. , Lynnworth L. C. , Larson G. S.
Published: November 2005

The elastic moduli of several materials have been determined by momentarily coupling 1-mc/sec longitudinal- and shear-wave pulses through a sample, and measuring the transit time. The temperature range has been from room temperature to beyond 1000°C. Measurement of longitudinal and shear-wave velocity is accurate to about 1%, permitting the moduli and Poisson's ratio to be computed to a comparable accuracy. Comparison of results with published data for 4340 steel, fused-quartz, and aluminum 6061-T6 is excellent up to the highest temperatures at which data are available. The test sample is a cylinder five wavelengths in diameter by several inches long. Dimensional requirements are easily met. Accordingly, sample preparation and moduli determinations are relatively simple. Momentary coupling of longitudinal waves is achieved by employing a suitable couplant. Shear waves are coupled dry by using special probes. At room temperature, these probes have been used to measure shear-wave velocity in copper, aluminum (up to 60-ft pathlength), brass, lucite, steel, fused silica, glass, and thoriated tungsten. Mode conversion by reflection or refraction has also been used to measure shear-wave velocity, but this is not required. The momentary contact method is amenable to production-line inspection and quality-control situations where measurements of material integrity, temperature, or flaws are required at room or elevated temperatures. [This work was supported by the U. S. Office of Naval Research.]
Ultrasonic Determination of Temperature and Transport Properties in a High-Temperature Gas
Authors: Carnevale E. H. , Larson G. S. , Lynnworth L. C.
Published: November 2005

An extension of the ultrasonic-pulse technique described previously [E. H. Carnevale, H. L. Poss, and J. M. Yos, “Ultrasonic Temperature Determinations in a Plasma,” in Temperature—Its Measurement and Control in Science and Industry (Reinhold Publishing Corp., New York, 1962), Vol. 3, Part 2, p. 959] has been used in determining the temperature profile in a high-temperature argon rf plasma. In addition, preliminary sound-absorption measurements have been made in order to determine the transport properties, viscosity, and thermal conductivity. In an ideal gas, measurement of the sound velocity yields the temperature (V2=γRT/M). Simultaneous measurements of the sound absorption yields the transport properties (classical equation of Stokes and Kirchoff). In the earlier technique [Carnevale et al., loc. cit.], an average gas temperature was measured. In the present experiments, the variations in transit time and amplitude were measured as a function of probe separation. From these measurements, both the temperature profile and the transport properties can be determined. Temperatures in the range 5000° to 10 000°K have been measured. These temperatures are in reasonable agreement with spectroscopic determinations for similar plasmas. Preliminary attenuation measurements have been obtained at 1 and 2 mc/sec. Ultrasonic-velocity and -absorption measurements in argon at room temperature are in excellent agreement with the values obtained by Tempest and Parbrook. A discussion of the experimental apparatus, method of measurement, experimental results, and analysis is given. [This research was supported by the National Aeronautics and Space Administration.]
Study of the α-β Phase Transformation in Plutonium, Using Ultrasonics
Authors: Peterson Ronald G. , Rosen Moshe
Published: November 2005

The velocities of longitudinal waves in α and in β plutonium are significantly different. Therefore, it is possible to monitor the progress of phase transformation by continuously observing the transit time of ultrasound through a plutonium specimen. The plutonium was first heated to a temperature at which the β phase is stable, then quenched to a temperature in the α-phase range. It was held at this temperature until the transformation was complete. This procedure was used at several different quenching temperatures. Sound was introduced into the sample as quickly as possible after it was put into the quenching bath. Since the samples were disks about one millimeter thick, and, since we used the pulse-echo technique so that we could measure both transit time and attenuation, we had to use very short sound pulses in order to resolve individual echoes. Our technique of using thick transducers excited by a short, high-voltage electrical signal, as well as results of the experiment, which gave the kinetics of the transformation, is described. [Work performed under the auspices of the U. S. Atomic Energy Commission.]
Ultrasonic Attenuation and Velocity in Three Transformation Products in Steel
Authors: Papadakis Emmanuel P.
Published: November 2005

Ultrasonic-attenuation measurements were made from 2 to 100 Mc/sec in the pearlitic-plus-ferritic, bainitic, and martensitic transformation products in S.A.E. 4150 steel, and in tempered martensite. Ultrasonic-velocity measurements were made at 10 Mc/sec in each case. To eliminate the question of grain size and grain-size distribution, three specimens were treated identically through the austenitizing operation. Then, they were cooled differently to produce the three transformation products. The attenuation can be expressed as Af4+Cf2, where f is frequency. Both A and C are strong functions of microstructure, and decrease in the order pearlite-plus-ferrite, bainite, martensite, tempered martensite. The ratio CT/CL (T=transverse waves, L=longitudinal waves) was a constant independent of microstructure and equal to 2.4. The large change in C on tempering (with CT/CL=constant) indicates that the interstitial carbon is involved. Pearlite-plus-ferrite has the highest velocities and density, while raw martensite has the lowest, with tempered martensite slightly higher.
Noise-Correlation Functions for Anisotropic Noise Fields
Authors: Talham Robert J.
Published: November 2005

Under certain conditions, the signal-to-noise gain of a hydrophone array can be expressed in terms of signal- and noise-correlation functions. When ideal propagation is assumed, the signal correlation is well-defined and the problem is reduced to establishing the noise-correlation function. Noise-correlation functions for two-dimensional and three-dimensional isotropic-noise fields are well-known: namely, the functions J0(X) and sinX/X. In this paper, an equation for the noise-correlation function is derived that is valid for any orientation of receiver elements and any distribution of background noise. Assuming a background-noise field whose power in a given direction is proportional to the radius vector of an oblate spheroid, an assumption in qualitative agreement with recent theoretical and experimental results, the noise-correlation functions for horizontal elements and for vertical elements are explored in detail. Quantitative results are given for noise fields of different anisotropy. [This work was supported by the Bureau of Ships, U. S. Navy.]
Calculation of the Generalized Load for Random Pressure Fields with Applications
Authors: Mayer Frank S.
Published: November 2005

The power spectrum of the generalized load for a structural mode of vibration is expressible in terms of the pressure power and the mode shape [A. Powell, J. Acoust. Soc. Am. 30, 1130 (1958)]. The calculation of the generalized load for any frequency band can be readily made, especially for sinusoidal modes, through expanding the correlation function as a Fourier series, much labor being saved by use of standard charts. The method is demonstrated in determining the characteristics of the load for beams and plates excited by acoustic fields and by boundary-layer pressures. These results infer features of the spatial correlation curve that are required for obtaining acceptable accuracy in calculation of the generalized loads. The most important characteristic is the distance between the zero crossings. Of lesser but equal importance are the number of zero crossings defining the curve and the maximum amplitudes of the curve between the zero crossings.
Scale-Model Acoustic Studies—624A SSLV
Authors: Shipman Robert , Van Ert Dan , Rader W. P.
Published: November 2005

A 1:33 scale model of the 624A SSLV solid-propellant booster was tested to determine the effects of flame-deflector configuration on launch acoustic levels. Aerothermodynamic and acoustic data were obtained from a series of firings in which exhaust-duct length, liftoff elevation, and exhaust-impingement distance were varied. The covered exhaust duct produces significant reductions in acoustic levels on the vehicle as compared to those occurring on an open flame deflector prior to and during vehicle liftoff. The model acoustic data were scaled in frequency by use of Strouhal numbers and the spectra were compared to predicted and measured data from large booster-engine firings. The relative reductions in sound-pressure levels achieved with the covered exhaust duct were then applied to the predicted launch-vibration environments for specific compartments in the vehicle.
Reynolds Stress near a Flexible Surface Responding to Unsteady Airflow
Authors: Ffowcs-Williams John E.
Published: November 2005

The stability of boundary-layer flows that are formed on flexible surfaces is known to be affected by the surface response. A study of the manner in which energy is exchanged between the mean flow, the perturbation, and the vibrating surface has called for more knowledge of the way in which the Reynolds stress is influenced by wall vibration. The reason is that mean flow energy is transferred to the perturbation by the action of Reynolds stresses, so any change brought about in their level, as a result of surface motion, could influence the energy balance and consequently the stability of the system. An analysis of the Reynolds stresses near a vibrating surface is described and it is shown that they are increased by at least an order of magnitude whenever the surface is allowed to vibrate. [This research has been supported by the David Taylor Model Basin.]
Effect of Room Absorption on Transmission-Loss Measurements
Authors: Northwood T. D.
Published: November 2005

The theory underlying measurements of airborne-sound-transmission loss assumes that diffuse sound fields exist in the source and receiving rooms separated by the test partition. This condition is desirable since (a) it is then possible to infer from simple measurements of sound level and reverberation time the ratio of incident to transmitted sound power, and (b) the test partition is then excited by a specific type of sound field, involving equal weighting of all angles of incidence. As one means of approaching this condition, the laboratory test procedure, ASTM E90-61T, specifies arbitrarily that the average absorption coefficient of the room surfaces be no greater than 0.05. Since many field situations and some laboratories depart drastically from this requirement, a systematic study of the importance of this parameter is needed. This paper reports measurements made with average absorption coefficients ranging from 0.03 to about 0.2. Small but systematic changes in apparent transmission loss were observed as room absorption and diffusion conditions were varied.
Impact Sound under Concrete-Floating-on-Wood-Joist Floor
Authors: Young R. W. , Gales R. S.
Published: November 2005

Impact sound generated under a wood-joist floor by a standardized tapping machine was measured in a two-story, wood-stud-and-dry-wall medical building. The original floor, covered with 18-in. vinyl asbestos tile, consisted of 58-in. plywood, nailed and glued throughout the entire second floor to 2×10-in. floor joists, 16 in. on center; the second-floor studs were erected on the plywood. There were glass-wool batts between the joists; the ceiling underneath consisted of 12-in. gypsum board. The net volume of each room was about 750 ft3. With a slight adjustment to 0.5-sec reverberation time, the impact-sound levels in the room underneath the tapping machine were 91, 90, 91, 84, 83, and 75 dB, respectively, in the octave bands centered on 125, 250, 500, 1000, 2000, and 4000 cps. After the installation of a 34-in. plywood floor on 1×3-in. battens floating on a 1-in. blanket of Fiberglas PF-615 (plus a thin rubber mat), the observed impact-sound levels were 84, 81, 72, 56, 47, and <42 dB. The floating raft was next replaced by reinforced concrete 134-in. thick poured over a 6-mil polyethylene membrane covering a 1-in. blanket of PF 614, and the floor surface finished with Plastifeutre 15-in. thick (a resilient material that can be scrubbed). The measured impact-sound levels were then 78, 73, 69, 59, 50, and 43 dB, respectively—values that come close to satisfying the recommendation of a “Impact Noise Control in Multifamily Dwellings” [FHA Rept. No. 750 (1963)]. Between rooms separated by the concrete floating floor, the airborne-sound isolations were 33, 41, 46, 53, 56, and 58 dB, respectively, even with some indication of flanking transmission.
Proper Application of Selective Absorption in Concert-Shell Design
Authors: Jaffe J. Christopher
Published: November 2005

Design criteria for the surfaces surrounding the space where orchestral sounds emanate are extremely limited. Observing the exceptionally fine qualitative results achieved through the use of materials that absorb sound below 100 cycles, as well as the predictable musical acoustic response of shells designed with flexible-wall and ceiling-panel positions, a three-year test-evaluation program was initiated in conjunction with the actual installation of 17 selective-absorption, tunable concert shells. The installations range from small theater-type auditoria to large municipal auditoria and university field houses. Included in the analysis are concert enclosures designed for major American symphony orchestras, as well as for music departments of colleges and universities. The paper reviews the qualitative results of the 17 shell installations, the important new concepts in shell design revealed by the test data and field experience, and explains how the theory of selective absorbtion can be applied to the design criteria of concert shells.
Energy-Decay-Rate Timer
Authors: Johnson Roger P.
Published: November 2005

A device is described for the measurement and automatic printout of the decay rate of reverberant sound energy or the damped vibration of structures. The design provides for a choice of decay ranges from 10 to 100 dB (in 10-dB steps), the point in the decay at which the timing starts (in 2-dB steps), and the number (up to 99) of decays to be measured and accumulated before printing. The signal to be measured is rectified and smoothed by a variable RC network, and then actuates a Schmidt trigger that starts and stops an electronic counter. The maximum measurable decay rate is better than 2000 dB/sec.
Cinéradiographic Studies of Speech: Procedures and Objectives
Authors: Öhman S. E. G. , Stevens K. N.
Published: November 2005

Simultaneous sound recordings and cinéradiographic films showing lateral views of the speech mechanism have been obtained for a variety of utterances generated by several speakers. Procedures are described for making frame-by-frame tracings from the films and for obtaining from these tracings quantitative data on the movements of the various speech-generating structures. Interpretation of these data is discussed in terms of several objectives: (1) obtaining further understanding of the relations between the positions of the articulatory structures, vocal-tract configurations, and acoustic outputs; (2) examining the dynamic properties of the various components of the articulatory mechanism and the interrelations among the movements of these components; and (3) gaining an understanding of the transformation from a discrete linguistic description of speech to the continuous motions of the articulatory structures. Attention in this paper is centered on the second of these objectives, and, in particular, data on the relative movements of various parts of the tongue and of the structures in the vicinity of the larynx for several vowel-consonant and consonant vowel combinations are presented and discussed. A short film is shown to illustrate certain features of the data.
Visarga Vowels
Authors: Bhimani B. V.
Published: November 2005

Visarga is a class of vowels defined by Sanskrit phoneticians as ones that are coarticulated with “h” or aspiration. This class of vowels is not mentioned among most European and American vowel sounds and it has not been referred to in phonetic-acoustic studies. However, it could occur occasionally in any language, as in December spoken by an Englishman. For generation of visarga, the position of cheeks, tongue, and lips are the same as those for the vowel of its form. The only difference between a visarga and a normal vowel is that there is a steady flow of air from the vocal flaps for the former, whereas there is a significant periodic interruption of such a flow for the latter. The formant-frequency levels of both the above types of vowel sounds are expected to be approximately the same. However, the formant bandwidths of visarga vowels are wider than those of normal vowels, the energy in formants is lower for visarga than it is for normal vowels, and more fricative energy is expected with visarga than with normal vowels. [This work was supported by Air Force Cambridge Research Laboratories, U. S. Office of Aerospace Research, under contract No. AF 19(628)-2766.]
Rear-Axle Noise—Vehicle Sensitivity
Authors: Peithman H. W.
Published: November 2005

A high percentage of the axle-gear noise peaks in various unitized vehicle types have been traced to resonances of the drivetrain. Because of the close coupling between the bending and torsional modes, both bending and torsional characteristics of the drivetrain were investigated at resonance. The role of the rear-suspension components in transmitting axle-gear-excited vibration into the unitized body was studied. The discussion relates experimental techniques used to (1) make quantitative measurements of axle-noise levels in the vehicle, (2) determine major transmission paths into the body, (3) determine driveline and suspension dynamic characteristics. The utility of the mechanical impedance technique to analyze the torsional response of the driveline is demonstrated.
Measurement and Evaluation of Vehicle Noise
Authors: Fuchs G. L.
Published: November 2005

A critical review of methods and instrumentation used to date for objective measurements is followed by a discussion of the subjective evaluations and their applicability to legislation and control of noise. A method of quick computation based on S. S. Stevens' Mark VI is proposed to set up criteria for traffic and industrial noise. Possibilities of simpler checkup methods for restrictive purposes are explored in view of the uncertainties derived from sound-level-meter readings.
Backscattering of an Isotropic, Spherical, Acoustic Pulse of Arbitrary Shape from a Rough-Sea Surface
Authors: Saenger R. Alfred
Published: November 2005

When an isotropic spherical pulse generated by an underwater source at A reflects from a rough-sea surface S, the pressure p(A) subsequently measured at the backscatter point depends on the shape of the incident pulse and the displacement-slope properties of S. If A is at a large distance D from S and approximate boundary conditions appropriate to surfaces of small slope are assumed, then Kirchhoff's general integral formula can be transformed into the sum of two surface integrals over modified source distributions on the zero-level surface So. The first integral po reduces to an “image pulse” reflected from a mirror surface at D + ζo, where ζo is the vertical displacement of S from the specular point on So. The second integral ps is the scattered pulse that interferes with po and persists after the latter disappears. At time t, ps is composed of a superposition of pulselet contributions that have propagated to A from a limited portion So(t) of So. The functional form of the pulselet source at dSo(t) is generally quite different from that of the incident pulse since the “amplitude scattering coefficient” σ that determines the pulselet-source strength is actually a differential operator. Pulselet-source strength also depends directly on the slope of S near dSo(t). This approximate formulation gives physical insight into the causes of surface scattering and is convenient for treating certain problems that arise in underwater sound and model experiments. [Hudson Laboratories, Columbia University Informal Documentation No. 31. This work was supported by the U. S. Office of Naval Research.]
Experimental Investigation of Acoustic Scattering from Solid Elastic Cylinders of Varying Length
Authors: Diercks K. J. , Goldsberry T. G.
Published: November 2005

Experimental measurements are presented of backward and general scattering from vertically oriented solid aluminum cylinders in water. Cylinder lengths from 0.15 to 70λ—where λ is the wavelength of the incident sound—are considered. The ka range investigated is from 2 to 22. It is shown that the ratio L/a—where L is the cylinder length, and a is its radius—is the critical parameter in determining the cylinders' scattering behavior. Cylinders for which this ratio is greater than approximately 0.8 display similar backscattering (target strength) and general scattering patterns and echo-pulse forms regardless of incident wavelength; those for which the ratio is less than 0.8 are also similar in these measures but differ from the former group. The immediate conclusion is that two-dimensional analyses are applicable to cylinders appreciably shorter in length than the hitherto accepted value of L > 10λ. It is also shown that a halving of cylinder length yields more nearly a 5-dB rather than the expected 6-dB decrement in the measured target-strength values. [This work was supported by the U. S. Office of Naval Research.]