bluuebunny/crossref_metadata_2025 huggingface dataset:
Chemistry of ultrasound. III. The irradiative behavior of simple aliphatic amines
Authors: Fayter Richard G. , Spurlock Langley A.
Published: October 2005

The ultrasonic irradiation of water was effected under an argon atmosphere with an 800-kHz transducer at several intensities. The rates of hydrogen peroxide formation were followed by spectrophotometric analyses. The results were utilized to relate intensity to reaction rate for standardization purposes. Irradiations of several alkyl amines in aqueous solution or suspension were next accomplished under conditions similar to those applied to pure water. Products included aldehydes, an alcohol, amines, an N-oxide, methane, ethane, ethylene, carbon monoxide, and hydrogen. The products and their ratios were dependent on the structure of the amine used in the reaction. Reaction rates were only slightly different when an oxygen atmosphere was used instead of argon. The reactivity order for the amines was observed to be primary > secondary > tertiary. Methylamines reacted somewhat faster than did n-butylamine.
Transverse vibrations of shallow shells by the method of constant-deflection contours
Authors: Jones R. , Mazumdar J.
Published: October 2005

A method for the analysis of vibration of shallow shells is presented. The method is based upon the concept of iso-amplitude contour lines on the vibrating surface of the shell. The problem of transient axisymmetric vibrations of shallow elliptical dome is investigated. It is shown that in the limiting case, when the elliptical dome reduces to the spherical dome, Reissner's well-known result is obtained.
Performance of a class of reactive mufflers with a volume constraint
Authors: Karnopp Dean
Published: October 2005

Reactive mufflers with N resonant chambers but with constant total muffler volume and total internal piping length are studied. The ratio of outflow to inflow for periodic inflow is studied as a function of frequency. It is shown that, although the sharpness of the high-frequency attenuation is increased by increasing the number of resonant chambers, the cutoff frequency and the highest resonant frequency also increase.
NEF contours for continuous spread of flight paths
Authors: Mansbach Peter
Published: October 2005

NEF contours for aircraft noise have generally been computed assuming three or four well-defined flight paths from a given runway. In fact, a whole continuum of flight paths normally exists. In this paper, methods are developed to treat this continuum of flight paths. Simplifications are also suggested which provide realistic approximations and which allow preliminary calculation of NEF values without the need for major computer programming. These have the form NEF = NEFC + correction, where NEFC assumes all flights are overhead, and a (negative) correction term is added for the splayout. Results of the conventional discrete path computations are contours shaped like fingers. Using a continuous spread of paths results in a single fanned-out contour. We feel the latter is more realistic.
Noise of police firearms
Authors: Weissler Pearl G. , Kobal Michael T.
Published: October 2005

In an effort to provide guidelines for law enforcement personnel to protect their hearing, the peak pressure level and signal duration (A and B duration) of eight popular firearms were measured and compared with the requirements of OSHA (1970), CHABA DRC (1968), and EPA levels (1974). Small condenser microphones and a storage oscilloscope were used to record the blast wave signatures from a 9-mm automatic, 0.357-cal. Magnum revolver, 0.41-cal. Magnum revolver, 0.22-cal. revolver, 0.45-cal. automatic, 0.44-cal. Magnum revolver, 12-gauge shotgun, and 0.22-cal. rifle. Measurements were made at the ear of the person shooting and at the approximate position of a neighbor at a firing range. Some measurements were also made at a practice firing range. A portable tape recorder was found useful for recording gun signals and measuring B durations. The peak pressure levels of the signatures of all the firearms tested exceed the OSHA maximum of 140 dB. It was found that in an anechoic environment the noise from five of the handguns exceeded the CHABA DRC (1968), while the noise from all of the firearms tested, except the 0.22-cal. rifle, exceeded the EPA levels (1974). At a sound-insulated firing range, the noise from all the firearms tested, except the 0.22-cal. rifle, exceeded the CHABA DRC (1968), while all the firearms tested exceeded the EPA levels (1974).
Transmission of sound through sandwich panels
Authors: Dym Clive L. , Lang Mark A.
Published: October 2005

An analysis of the transmission of sound through sandwich panels (consisting of lightweight, flexible cores between relatively stiff skins) is presented here. First, previously given results for the free vibrations of such panels are analyzed and unified. Then, a traveling-wave analysis is used to obtain impedances and transmission-loss formulas, which are in turn compared with previously published experimental data. The comparison is relatively good, and confirmation of a symmetric coincidence effect is obtained. Further, the numerical results indicate that this symmetric coincidence generally occurs at a much lower frequency than does antisymmetric (shear wave) coincidence.
Apodization in numerical holography
Authors: Kramer D. B. , Anand D. K.
Published: October 2005

Apodization, a process in which the energy in a diffraction pattern is redistributed among the main lobes and the side lobes, has proved its usefulness in optical imaging systems and in linear sonar arrays. It can also make the numerical reconstruction of holograms more adaptable to varying requirements. To demonstrate, the hologram of a rectangular slot is first reconstructed numerically in the conventional manner. It is then reconstructed after apodizing the diffraction pattern contained in the hologram. One type of apodization led to a reconstructed image that accentuated the discontinuity at the edge of the slot. Another type gave an image with a concentration of energy at the center of the object, thus minimizing interference from nearby objects. It is expected that the method can be extended to other objects by expressing them as summations of rectangular slots.
Dependence of middle-ear parameters on body weight in the guinea pig
Authors: Funnell W. R. J. , Laszlo C. A.
Published: October 2005

We have investigated the dependence of several anatomical parameters of the guinea-pig middle ear on body weight, and thus on age. In particular, the volumes of the tympanic and epitympanic cavities are found to increase with age, with the tympanic cavity growing somewhat more slowly. The mass of the incus appears to be independent of body weight. These results are important for establishing the values of parameters used in mathematical models of the middle ear. They are also relevant to theoretical considerations of the significance of middle-ear resonances.
Intensity discrimination in a rapid sequence of tone bursts
Authors: Moray Neville , Fitter M. J.
Published: October 2005

Listeners monitored a rapid series of tone bursts to detect intensity increments in a 1000-Hz tone presented in continuous white noise. The data were analyzed using TSD statistics and suggest that performance was close to that observed in more conventional paradigms. Possible violations of TSD assumptions are discussed and it is concluded that TSD may be used to analyze the performance of people listening to rapid trains of tone bursts as well as when discrete trials are used.
Intensity discrimination of noise in the presence of band-reject noise
Authors: Viemeister Neal F.
Published: October 2005

Weber's law holds over at least an 80-dB range for intensity discrimination of 200-msec bursts of noise. Weber's law holds over a comparable range when information regarding intensive differences is effectively restricted to a limited frequency region by the addition of a relatively intense band-reject noise. In particular, no failure of Weber's law is observed at intensities for which the discharge rates of fibers innervating the frequency region of the stopband are presumably saturated. These results do not support the generally accepted notion that a spread of excitation along the cochlear partition with increasing intensity is necessary for the auditory system to maintain its large dynamic range.
Effect of ring scatterers on the directivity pattern of a small sonar transducer at an air-water surface
Authors: Sugar R. J. , Stumpf F. B.
Published: October 2005

The effect of ring scatterers on the directivity pattern of a small sonar transducer at an air-water surface was studied. The rings were made of styrofoam and brass. The soft (styrofoam) ring narrows the pattern significantly whereas the hard (brass) ring seems to have much less effect. This pattern narrowing may make the ring a useful device in reducing the acoustic interaction between sonar array elements.
Use of sine-wave calibration in the frequency domain
Authors: Braun S.
Published: October 2005

Sine-wave calibration in the frequency domain may result in large errors in case of digital signal processing. A practical approach based on spectrum weighting is shown to result in reasonable accuracy.
Coherent analysis of ray propagation with moving source and fixed receiver
Authors: Flanagan R. P. , Weinberg N. L. , Clark J. G.
Published: October 2005

Ray propagation has been analyzed coherently for a moving-source-fixed-receiver system by taking into account source motion from the results of a fixed model in which spreading loss, travel time, boundary losses, and boundary phase shifts are calculated. Specific examples of the amplitude and phase time series are given for a source moving at 5 knots from 500 to 520 km radially from the receiver. These time series are given for sampling intervals of 1 min and in shorter sections for 0.2 sec, indicating the effects on phase of the source motion. The data clearly indicate the effect of multipath and the usefulness of this technique in the study of spatial variations in the medium. It is demonstrated that multipath interference due to source motion in the medium is a major contributor to transmission fluctuations in both phase and amplitude.
Low-frequency power radiation from a flat plate into an acoustic fluid
Authors: Warren William E.
Published: October 2005

The power transmitted into an acoustic fluid by a periodically supported flat plate vibrating with low frequency is investigated. Utilizing a direct analysis of the field equations, closed-form expressions for radiated power and oscillation amplitude are obtained. It is shown that several null power frequencies can exist which are distinct from the null midspan amplitudes of oscillation of the plate. These null power frequencies are strictly a low-frequency effect, while the null midspan amplitude frequencies will occur over the entire frequency spectrum. Numerical results for a steel plate clamped at its periodic supports and in contact with water are obtained and presented graphically.
Absorption of sound waves by chemical equilibria occurring in solution
Authors: Garland Frank
Published: October 2005

Expressions previously developed by Tabuchi for the velocity and absorption of sound waves in a liquid in which a reversible chemical reaction is occurring are corrected, taking into account the effect of pressure on the chemical equilibrium.
Measured jet noise compared to California noise codes and health limits
Authors: Lane S. R.
Published: October 2005

In December 1971, maximum allowable limits on aircraft noise at California airports became effective in the Public Utilities Code (PUC). Noise-exposure limits are specified in terms of a base parameter, Single Event Noise Exposure Level (SENEL), which is an integration of A-weighted noise level with time. Measurements of conventional jet aircraft landing-noise levels at Los Angeles International Airport (LAX) were made and compared to the PUC SENEL limits, to the “standard” SENEL values used for mapping community noise exposure zones, and to noise limits for hearing and health conservation. The measurement survey indicated that at 1 NM from landing threshold, the standard SENEL limits were exceeded by 5 to 15 dB 50% of the time, and the California SENEL limits were exceeded about 50% of the time. Data from special flight tests for the FAA indicated that the implied SENEL limits would be violated about 35% of the time. If violators were cited according to the PUC ($1000 per violation), the resulting fines for landing operations would be about $200,000 per day, or $70 million per year, at LAX.
Effect of Sampling procedure upon the performance of an electrical model of auditory detection
Authors: Gaston Audley D. , Jeffress Lloyd A.
Published: October 2005

Data for an electrical model of auditory detection were obtained using two different methods of sampling. One used as the sample the voltage at the termination of the signal; the other selected the largest amplitude peak that occurred during the observation interval. Results showed that while detection performance for the end-of-signal samples plateaued at about 200 msec and showed no further improvement with duration, detection based on peak samples showed continued improvement in performance out to 2 sec. It is suggested that the continued improvement with duration exhibited by human subjects may be due to their use of amplitude peaks.
Spectral cues used in the localization of sound sources on the median plane
Authors: Hebrank Jack , Wright D.
Published: October 2005

The spectral cues used for median-plane localization are described by three experiments. First, the frequency spectrum necessary for localization is measured by noting the accuracy of subjects localizing low- and high-pass-filtered white noise. Second, several high-pass, low-pass, bandpass, and bandstop filters are associated with the subjective impression of direction by observing what directions are most frequently perceived by subjects localizing white noise colored by each filter. Third, the frequency responses of several artificial ears are measured for different angles of median-plane sound incidence. Results show that sound spectra from 4 to 16 kHz are necessary for localization. Frontal cues are a 1-octave notch, with a lower-frequency cutoff between 4 and 10 kHz and increased energy above 13 kHz. The “above” cue is a 1/4-octave peak between 7 and 9 kHz, with a high-frequency cutoff at 10 kHz. The “behind” cue is a small peak from 10 to 12 kHz. Increases in frontal elevation are signaled by an increase in the lower cutoff frequency of the 1-octave notch. This notch appears to be generated by time-delayed reflections off the posterior concha wall interfering with sound directly entering the external auditory canal.
Pure-tone, third-octave, and octave-band attenuation of ear protectors
Authors: Waugh R.
Published: October 2005

Experimental confirmation is shown of the practical identity of measuring ear-protector attenuation for pure tones and for 1/3-octave bands centered at the same pure-tone frequencies. In typical broad-band industrial noise, variations of spectrum shape have a negligible influence on an ear protector's octave-band attenuation. The use of pure-tone attenuation values at octave-band center frequencies as estimates of octave-band attenuation can lead to errors exceeding 10 dB. In the octaves centered at 500 Hz and above, ear-protector attenuation should be measured at 1/3-octave center frequencies.
Identification of speakers by use of nasal coarticulation
Authors: Su Lo-Soun , Li K.-P. , Fu K. S.
Published: October 2005

A new approach, based on the statistical properties of the nasal spectra, has been used to quantitatively study the coarticulation of nasal consonants, with the vowels following them in isolated /hə′CVd/ utterances. The spectral differences between the mean spectra of nasals followed by front vowels and those of nasals followed by back vowels were used as the acoustic measure of the coarticulation of [m] and [n] with the following vowel [V]. The coarticulation between [n] and [V] was found to be only about one-third of that between [m] and [V]. The coarticulated nasal spectrum, particularly between [m] and [V], was found to have strongly idiosyncratic characteristics, which are not likely to be modified in natural speech. A method was therefore developed by which the coarticulation between [m] and [V] was taken as the acoustic clue and the speaker was identified by use of a correlation decision criterion. Coarticulation was found to give more reliable clues than the nasal spectrum alone, which had earlier been found to be one of the best acoustic clues for identifying speakers.
Mode conversion relation for elastic waves scattered by a cylindrical obstacle in a solid
Authors: Lewis Timothy S. , Kraft David W.
Published: October 2005

A simple relation shown by White to exist between plane shear and compressional elastic waves undergoing mode conversion when normally incident upon an empty or fluid-filled cylindrical scatterer is extended to include the case of a solid scatterer. The obstacle is assumed to be an infinitely long cylinder embedded in an infinite isotropic solid medium. A sign error in White's result is corrected.
Listener reliability for a dichotic task
Authors: Ryan William J. , McNeil Malcolm
Published: October 2005

Test-retest relationships for several measures of dichotic listening performance were studied. All measures showed a relatively high degree of test-retest agreement. Nevertheless, individual listener variability was of sufficient magnitude to indicate caution when attempting to predict a given subject's dichotic performance on the basis of his previous performance or from averaged group scores.
Vibrational Relaxation in Carbon Dioxide/Helium Mixtures
Authors: Lewis J. W. L. , Shields F. D.
Published: October 2005

Sound-absorption and -dispersion measurements have been made using the tube method on gas mixtures of carbon dioxide and helium over the temperature range 25° to 191°C. The data obtained indicate a single relaxation-time process, and the maximum absorption per wavelength agreed, within experimental error, with the theoretical values. The reciprocal of the relaxation time of the mixture was found to be a linear function of the mole fraction of helium. The number of CO2/He collisions necessary to de-excite the deformation mode vibration was found to decrease linearly when plotted versus T−13 from 3222 at 25°C to 1376 at 191°C.
Measurement of the Attenuation Constant in a Tube Having Uniform Cross Section
Authors: Rogers Joseph W.
Published: October 2005

The theory and the experimental technique for measuring the attenuation constant in a tube are given. No moving parts are required, nor is there any need to calibrate the couplings of any microphones. The attenuation constant is found to be 2π⋅Δf/c, in which Δf is the difference in frequency to be measured and c is the speed of sound in the tube.
Integration of the Energy in Repeated Tone Pulses by Man and the Goldfish
Authors: Offutt George C.
Published: October 2005

A basic difference is shown to exist between the hearing of man and that of the goldfish. The goldfish possesses a direct relationship between the sound energy (percent of time that the tone is on) and its threshold, which is lowest with continuous tones. In humans, however, the threshold is dependent upon the duration of each tone pulse. With long-tone pulses, the human threshold is lower than with continuous tones. It is hypothesized that this difference is due to a lack of adaptation in the goldfish auditory nerves, whereas the human has increased nervous activity at the beginning and end of each tone pulse. Thus, the level of sensation in the human appears to depend on the amount of nervous activity produced in the receptor by a stimulus pulse. These findings show that the fish are relatively better adapted to hearing the kinds of sounds found in their natural environment than is the human observer. Some ideas are presented as to how the determination of tone-pulse thresholds could aid in certain clinical investigations.
Normalized Numerical Solutions for Rayleigh's Frequency Equation
Authors: Potter D. S. , Leedham C. D.
Published: October 2005

In this paper, limiting forms of a transcedental-frequency equation, attributed originally to Lord Rayleigh, are derived. The limiting forms are examined and their roots are used to find the exact normalized roots the original equation in the complex plane. A comprehensive collection of roots, considerably more extensive than that currently available, is tabulated for a range of normalized frequency.
Accumulation Theory of Binaural-Masked Thresholds
Authors: Schenkel K. D.
Published: October 2005

Two models describing binaural-masked thresholds (the delay-line model and the EC model) are checked by extended experiments. They prove only a limited validity. Therefore, a new model, the accumulation model, is proposed, one that does not use any delay at all and that is, therefore, able to process interaural differences on a more general basis. It is in full agreement with former calculation schemes for monaural-masked thresholds. This model explains all effects in binaural masked thresholds known so far. Binaural-masked thresholds computed according to this model are in good agreement with experimental data.
Frequency Discrimination as Measured by AB and ABX Procedures
Authors: Saslow Michael G.
Published: October 2005

It is often reported that difference thresholds for frequency when measured by an ABX procedure are at least twice as great as those measured by an AB procedure. The relationship has always been rationalized in terms of the greater phsyical and judgmental complexity of the ABX procedure. The present experiment was performed at 120 cps, 70 dB SPL, with two practiced subjects. For frequency differences of plus or minus 0.3 cps, or 0.25%, responses were 95% correct for ABX, and 82% correct for AB. This result contradicts the usual findings, and suggests a need for a new analysis of frequency-judgment mechanisms.
Variation of Shear Viscosity and Ultrasonic Absorption for Compressed Water
Authors: Eden H. F. , Horne R. A.
Published: October 2005

Recent measurements of μs, the shear viscosity of compressed water, are in poor agreement with older values. These discrepancies can affect the interpretation of measurements of ultrasonic absorption in compressed water. Calculations of the behavior of excess absorption with varying temperature and pressure differ considerably, according to which values of μs are used.
Technique for Correcting Helium Speech Distortion
Authors: Stover W. R.
Published: October 2005

Some qualitative data on the nature of the speech distortion caused by respiration of a helium-oxygen atmosphere are presented. Previous corrective-processing techniques are discussed, and an advanced technique that overcomes their disadvantages described. The experimental system is based upon time-domain speech-processing methods and is capable of retaining the natural pitch rate of the speaker's voice while correcting the formant shifts caused by the helium-rich atmosphere. This system uses digital-processing methods and is capable of operating on continuous speech in on-line applications. It promises a practical solution to the problem of providing normal voice communication in a helium environment.
Improved Transfer Standard for Vibration Pickups
Authors: Jones E. , Lee D. , Edelman S.
Published: October 2005

This paper describes a vibration transfer standard designed to provide comparison calibrations of pickups with minimum degradation. Features of the design are the use of a ceramic housing of a stiff, light, lossy material; provision of a means for evaluating the quality of the motion by the use of three integral accelerometers oriented parallel to the nominal direction of motion; and design of the geometry to minimize differences in motion between the pickup being calibrated and the standard. The useful frequency range is 10–10 000 Hz.
Transient Response of an Elastic Shell in Plane Strain
Authors: Keer L. M. , Fleming J. F. , Herrmann G.
Published: October 2005

The dynamic response of a circular, elastic shell in plane strain, when given an impulsive radial load, is studied. Inextensional bending is assumed and approximate solutions are obtained for the behavior at the wavefronts and for some time after the wave has passed. The method of Friedlander as applied by Payton to shells is used to study the wave propagation for relatively long times, and the bending-moment distribution is obtained.
Long-Range Sound Propagation in the South Tasman Sea
Authors: Kibblewhite A. C. , Denham R. N.
Published: October 2005

Experiments on long range propagation of sound in the South Tasman Sea were carried out by the New Zealand Naval Research Laboratory in July 1963 and April 1964. These appear to provide the first examples of RSR-type propagation in the southern hemisphere; convergence zones are observed with a spacing of from 32 to 33 nautical miles. In addition, changes in the characteristics of propagation may be associated with an oceanic front, the “subtropical convergence,” which is present in this area. North of this hydrological boundary, the convergence zones are much more sharply defined, and the attenuations are less than on the southern side.
Frequency Discrimination following Exposure to Noise
Authors: Brandt John F.
Published: October 2005

Measures of threshold and frequency discrimination were obtained at 1000, 2000, and 4000 Hz before and after exposure to wide-band noise. Two test-stimulus SPL's (sound-pressure levels) were used during the postexposure discrimination measures such that stimuli were presented at 10 or 40 dB SL (sensation level) re TTS3 (temporary threshold shift). The SPL remained constant throughout recovery during each experimental session. When test stimuli were equated in terms of SL, no differences between pre- and post-exposure jnd's (just-noticeable differences) were noted at 40 dB SL or greater at any frequency. At low stimulus SL's (10–20 dB), however, a differential effect on the jnd occurred owing to noise exposure that was not explainable in terms of TTS. At 4000 Hz (where maximum TTS occurred), there was little difference between pre- and postexposure jnd's. At 2000 Hz, a 10% impairment in the jnd existed in the latter stages of recovery. At 1000 Hz (no TTS), the postexposure jnd's were about 40% greater than pre-exposure jnd's and independent of recovery time. A paradox thus exists at low SL's between amount of threshold shift and frequency discrimination.
Stimulus-Oriented Approach to Detection Re-Examined
Authors: Jeffress Lloyd A.
Published: October 2005

The present paper is a reexamination of some of the conclusions of an earlier one. It is motivated by some new insights resulting from attempts to replicate experiments with human observers, through the use of an electrical model of the auditory system. It is concerned primarily with the effect of signal duration on detection in the presence of a continuous masking noise. The model, of those tried, that best fits human performance consisted of a bandpass filter obtained by subtracting the output of a 500-Hz sharp-cutoff, low-pass filter from another having a cutoff of 525 Hz. The filter was followed by a linear half-wave rectifier and it, in turn, by an integrator having a 100-msec decay time. The integrator can be thought of as a device that takes a running average of its input. The probability density distributions for N and SN yielded by the model lie between the Rayleigh Rice distributions on the one hand and a pair of normal distributions of unequal variance on the other. The exact shape of the two distributions depends upon both the bandwidth of the filter employed and the time constant of the averager.
Pitch of Noise Bands
Authors: Small Arnold M. , Daniloff Raymond G.
Published: October 2005

Ten subjects were asked to produce octave judgments, i.e., one octave above and one octave below a standard stimulus, with bands of low-pass and high-pass noise as well as sinusoids. For example, given a specific low-pass noise band as a standard, subjects adjusted the cutoff frequency of a second low-pass noise band so that its pitch was 1 oct above that of the standard. Results indicate that bands of noise have a pitch and that the pitch is correlated with cutoff frequency. For low-pass noise, there seemed to be a relatively linear relation between pitch and cutoff frequency from 80- to 10 000-Hz cutoff, whereas the linear relation for high-pass noise holds only for a restricted frequency range, 600–10 000 Hz. The pitch of both types of noise stimuli degenerates above 10 kHz, possibly because of limited earphone response and a rising threshold of hearing. More difficult to explain is the static and vague pitch of high-pass noise at low cutoff frequencies. A discussion of several mechanisms is included.
On the Frequency Spectrum of N Waves
Authors: Austin Michael E.
Published: October 2005

A set of curves is developed by means of Fourier analysis for determining the frequency content of N-shaped shock waves. The curves are generalized so that shock waves of any amplitude and duration can be analyzed.
ACOUSTIC FILTER APPLICATIONS IN LARGE, LIQUID, ROCKET-ENGINE-COMPONENT TEST SYSTEMS
Authors: Iwanicki L. R. , Nestlerode J. A. , Bugler G. J.
Published: October 2005

Large, liquid, rocket-engine-component tests demonstrated the effectiveness of an acoustic filter in decoupling propellant-feed-system oscillations from the combustion process in a gas-generator system. Test data are included. Reference is made to several other acoustic-filter applications.
Calculation of B/A for Water from Measurements of Ultrasonic Velocity versus Temperature and Pressure to 10 000 kg/cm2
Authors: Hagelberg M. Paul , Holton Gerald , Kao Samuel
Published: October 2005

New measurements of the velocity of sound in water over a wide range of temperatures and pressures have been made and are used to calculate the nonlinearity parameter B/A in the temperature range from 0° to 80°C and at pressures to about 10 000 kg/cm2. It is found that, for low temperatures, B/A rises to a broad maximum at about 3000 kg/cm2 and then slowly decreases. At the highest temperatures, B/A decreases very slowly with increasing pressure. At 1 atm pressure, the B/A value for 0°C is the lowest calculated at any temperature and pressure, and B/A increases monotonically with temperature in the range covered. However, at 3000 kg/cm2, the B/A value for 0°C is the largest obtained, and B/A decreases with increasing temperature. The values of B/A range from a low value of 4.08 at 1 atm and 0°C to 6.80 at 3000 kg/cm2 and 0°C. B/A is found to be relatively insensitive to temperature and pressure. The usefulness of B/A measurements as a means of studying the liquid state is discussed.
Model Studies on the Scattering of Acoustic Waves from a Rough Surface
Authors: Horton C. W. , Mitchell S. K. , Barnard G. R.
Published: October 2005

A rough surface 32 in. by 32 in. in size was made of a pressure-release material. The relief of this surface was approximately Gaussian with a standard deviation of 0.6 wavelengths at 100 kHz. Experimental measurements were made of the scattering of acoustic waves in the plane of incidence at a frequency of 100 kHz for grazing angles of incidence of 20°, 40°, 45°, and 90°. The grazing angle of reflection was varied from 6° to 116° in each case. One set of measurements was made at 200 kHz. The statistical parameters of the surface were computed and these values were used in the theoretical formulas developed by Eckart. Close agreement between experiment and theory was obtained for all measurements except at an incidence grazing angle of 30°. In this case, it was necessary to introduce a correction to the mean-square surface relief in order to correct for the the shadowing effect. Theoretical results are presented for the scattering coefficient for directions not in the plane of incidence.
Monostatic Reflection from a Rigid Rectangular Plane
Authors: Neubauer Werner G. , Dragonette Louis R.
Published: October 2005

An approximate theory for the monostatic reflection from a rigid rectangular plane is given. Experimental measurements in water of far-field monostatic reflection from blocks made of a material of high specific acoustic impedance correspond with theory to within 2%, when sound is normally incident to one face. Good agreement between theory and experiment is also found in both far- and near-field situations, for angles of rotation of the reflecting face as large as 16°.
Auditory Nonlinearity
Authors: Goldstein J. L.
Published: October 2005

Combination tones (CT's) produced by two-tone stimuli (f1 and f2) at relatively low sound levels contradict the classical view that auditory mechanics is an essentially linear process that suffers significant percentage distortion only at high sound levels. CT level and phase behavior were measured extensively with pitch-cancellation and loudness-balancing methods. Relative level of the most prominant CT 2f1-f2 was nearly unaffected by stimulus level but decreased sharply with increasing frequency interval, being typically 15%–20% for f2/f1 = 1.10. In contrast, the difference tone was audible only for stimulus levels above 50 dB sensation level (SL), grew to 15% relative distortion only for estimated stimulus levels exceeding 100 dB SL, and was relatively insensitive to frequency interval. Other CT's of the form f1-n (f2-f1) were heard, and these decreased sharply in level with increasing integer n. The fact that CT's above the stimulus frequencies were inaudible is not caused by stimulus masking but rather reflects instead a mechanical frequency selectivity in the nonlinear source. Thus, although auditory mechanical analysis not essentially linear, the concept that the cochlea performs a limited resolution frequency-place transformation is supported. Physical studies of the cochlea should elucidate the nature of the hypothesized essential cochlear mechanical nonlinearity.
Comments on “Use of Sensation Level in Measurements of Loudness and of Temporary Threshold Shift” [W. D. Ward, J. Acoust. Soc. Am. 39, 736–740 (1966)] and On Courtesy in Writing
Authors: Zwislocki J. J. , Hellman R. P.
Published: October 2005

Response to an article by W. D. Ward entitled “Use of Sensation Level in Measurements of Loudness and of Temporary Threshold Shift” [J. Acoust. Soc. Am. 39, 736–740 (1966)] in which Ward disagrees with our conclusion that intersubject threshold differences are not accompanied by loudness recruitment. We attempt to show that Ward's demonstration of interfrequency recruitment in individual ears is irrelevant to our conclusion. We also take issue with the style of writing used by Ward.
Frequency Discrimination in Noise
Authors: Henning G. Bruce
Published: October 2005

Frequency-discrimination performance is measured as a function of the ratio of signal energy to noise-power density (ε-η0) for several values of frequency separation at 250, 1000, and 4000 cps. Discrimination performance at all frequencies and all frequency separations increases with increasing ε-η0 until ε-η0 reaches 40 dB. No further increase in performance was apparent with a further increase of 40 dB in ε-η0.
Analysis of Musical Instrument Tones
Authors: Freedman M. David
Published: October 2005

A technique is presented for the analysis of musical instrument tones. The end result is a mathematical representation for the tone being investigated. Since no assumptions are made about the frequencies of the partial tones, inharmonic frequencies can be detected and accounted for in the representation. An analog-digital converter was used to present the signals to the ILLIAC II digital computer for analysis. Five tones were analyzed, resynthesized, and subjected to listening tests. The trumpet tone was characterized by a frequency change which, if omitted during synthesis, made the tone sound mechanical. The saxophone tone had a short-duration, inharmonic component which gave it the “bite” characteristic of a jazz tone. The other tones analyzed were produced by a violin, bassoon, and clarinet; and each, when resynthesized, still retained the tonal quality of the original; as examples, the wind tones sounded breathy and the violin sounded bowed. It was thus concluded that this analysis technique can be successfully applied to analyzing tones of the classes of instruments represented by these five tones.
Integral Equation Method for Radiation from Vibrating Bodies
Authors: Copley Lawrence G.
Published: October 2005

Physically realizable distributions of pressure and normal velocity over a vibrating surface submerged in an unbounded acoustic medium can not be independently prescribed, but must satisfy some acoustic relationship. The surface pressure and normal velocity can be obtained by solving an acoustic relationship simultaneously with an equilibrium relationship expressing dynamic equilibrium of the structure whose surface is vibrating. The present method uses as the acoustic relationship a regular integral equation derived from the classical Helmholtz integral. A numerical technique successful in solving the integral equation and economical of computational effort is described. It represents the solution functions in terms of their values at a set of mesh points but employs another, much larger, set of points for evaluating the integrals. The pressure at any field point is obtained by numerical quadrature in the Helmholtz integral of the calculated surface pressure and normal velocity. Results are presented of calculations for a spheroid and for finite capped cylinders, all with prescribed axisymmetric velocity distributions. The surface pressures calculated for the spheroid agree closely with an exact solution, while those for the cylinders are consistent with understood acoustical phenomena. The far-field directivities for the cylinders agree reasonably with an independent approximate solution.
Reflection and Transmission of Sound Waves by a Moving Fluid Laver
Authors: Yeh C.
Published: October 2005

The reflection and transmission of sound waves by a moving fluid layer are investigated theoretically and the reflection and transmission coefficients are determined. Numerical computations for the reflection and transmission coefficients as a function of the velocity of the moving medium are also carried out. It is found that the reflection and transmission coefficients are quite sensitive to the variation of the angle of incidence even if the layer is moving slowly. This fact suggests the possiblity of obtaining the speed of the moving fluid layer by measuring the reflection or transmission coefficient as a function of the angle of incidence.
Numerical Calculation of Some Response Statistics for a Linear Oscillator under Impulsive-Noise Excitation
Authors: Janssen R. A. , Lambert R. F.
Published: October 2005

Some response statistics of a linear oscillator under impulsive-noise forcing are examined from analytical as well as empirical viewpoints. Specifically, calculation of the first-order probability density and the crest (level crossing) statistics of the response of a narrow-band single-degree-of-freedom system under Poisson noise loading are considered. The inability to obtain numerical results from the Gram—Charlier (Type A) series is noted, despite the discovery of a convenient recursion relation between the moments and the semi-invariants of a random process. Under the simultaneous assumptions of a low impulse rate and high system Q, analytic expressions for the response first-order probability density and the response crest statistics are established that are in good agreement with experiment. Finally, a quantitative measure of the degree of deviation of the system random response from a Gaussian process is presented and discussed.
Array Gain for the Case of Directional Noise
Authors: Cron Benjamin F. , Shaffer Robert L.
Published: October 2005

Array-gain computations based on spatial-temporal correlation measurements in the 200–400-cps band and the directionality of the noise field for center frequencies of 112 and 178 cps are obtained. The results derived from spatial-temporal correlation measurements are compared with theoretical values for a directional noise field and vertical receivers, and the influence of sea conditions on the gain is demonstrated. For all element spacings of the eight-element array and all sea conditions considered, the gain varied from a low of 5 dB to a high of 12.5 dB. For the case of uncorrelated noise, a value of 9 dB is obtained for array gain from 10 log10 N, where N is the number of elements. The results based on directionality of the noise field are below those based on spatial-temporal correlation, and the same trend with increasing wind speed is observed. The data for this calculation were available only for the upper half-plane.
Some Materials for Ultrasonic Transducer Bonding at Cryogenic Temperatures
Authors: Bateman T. B.
Published: October 2005

Some techniques for bonding piezoelectric transducers to various materials at cryogenic temperatures are discussed. A number of bond materials are mentioned from the literature, along with a new material, di-2-ethylhexylsebacate (Plexol®). Factors involving the choice of transducer -i.e., expansivtiy, thickness, and finish—are discussed. Experimental data on the mechanical impedance of some of the materials are presented.
Anelastic Relaxation of Water and Hydroxyl Ions in Alkali Halides
Authors: Brugger K. , Fritz T. C. , Kleinman D. A.
Published: October 2005

Two anelastic relaxation effects were found and studied ultrasonically in commercial alkali halide crystals. They are caused by (H2O)− and (OH)− impurities substituting for the halogen ions and orienting themselves along the six 〈100〉 directions. This degeneracy is lifted by elastic waves producing unequal strains along the cube axes. The resulting relaxation of the water ions is thermally activated with activation energies of E0 = 1.6 × 10−15 erg in NaCl and E0 = 3.7 × 10−15 erg in KCl. The high-temperature limits of the relaxation times are τ∞ = 2.5 × 10−11 and τ∞ = 2.2 × 10−11 sec, respectively. The relaxation of the hydroxyl ions does not depend on an activation energy. Relaxation times of the order of 10−8 sec are found in KCl crystals, in agreement with results from dielectric measurements. A simple model exhibiting all experimental features is presented.
Limits of Validity of Some Optical Ultrasonic-Waveform-Determination Methods
Authors: Hargrove L. E.
Published: October 2005

A successive-diffraction theory is assumed to be strictly valid and is used to calculate the diffraction of light by ultrasonic waves of the finite-amplitude type (odd symmetry waveform) for a range of parameters for which elementary (phase-grating) theory is almost valid. These calculated spectra are then used as “data” to calculate ultrasonic waveforms, using equations that are based on elementary theory. Comparison of the initially assumed waveforms with those calculated by this procedure illustrates errors that would result if elementary theory were used to calculate ultrasonic waveforms from light diffraction spectra under conditions for which elementary theory is not adequate.
Relaxation of Nitric Oxide in Mixtures with Argon
Authors: Kneser H. O. , Bauer H.-J. , Kosche H.
Published: October 2005

The variation of the relaxation rate of the rotational, electronic, and vibrational degrees of freedom of the nitric oxide molecule with the amount of argon admixed has been investigated by acoustic absorption measurements. The rotational and electronic relaxation show small influence of the argon content, so NO-Ar and NO-NO collisions are of similar efficiency in the deexcitation of the rotational and electronic degrees of freedom. In contrast to this, the measurements show a much lower vibrational transition probability for heteromolecular collisions as compared with the homomolecular ones. This confirms the assumption of a specific NO-NO interaction with respect to vibrational deexcitation that could result from the chemical affinity of two NO molecules.
Cavity Resonator for Piezoelectric Surface Excitation
Authors: Lamb J. , Richter J.
Published: October 2005

The three-dimensional problem of surface excitation of acoustic waves in a piezoelectric crystal is examined. For practical conditions, it is found that the excitation of a given acoustic mode is proportional to the scalar product of the exciting electric field and the “excitation vector,” which is determined by the material constants of the crystal. The direction of this excitation vector is evaluated for some common orientations in crystal quartz. Details are given of a new type of double-tuned cavity resonator, which, by suitable choice of one or the other of its two resonant modes, is capable of providing an electric field at the surface of the piezoelectric crystal that has a substantial component along any preferred excitation direction. A field-probe technique has been used to determine both the amplitude distribution of the exciting electric field in the cavity and the resulting acoustic wave in the crystal. It is found that constant phase of excitation over the cross section of the acoustic beam is a prerequisite for obtaining good exponential-decay patterns for successive reflection of many echoes in the crystal. Selection of the appropriate resonant mode of the cavity has enabled excellent results to be obtained for the decay patterns, using various orientations of crystal quartz.
Measurement of Very Small Changes in the Velocity of Ultrasonic Waves in Solids
Authors: McSkimin H. J. , Andreatch P.
Published: October 2005

Circuit improvements for a method of measuring ultrasonic delay times or velocities [H. J. McSkimin, J. Acoust. Soc. Am. 37, 864–871 (1965)] have resulted in attained resolutions of approximately one part in 107 for high-Q materials, and with compatible long-term stability. By way of illustration, some results are presented for delay-time variations as a function of low (<250 psi) uniaxial stress in single crystals of Si and Ge. For the latter, the data are combined with results obtained previously through use of hydrostatic pressure to yield the six 3rd-order stiffness moduli. The satisfactory agreement with literature values demonstrates the usefulness of the method for materials that might be damaged by large uniaxial loads.
Temperature Dependence of Ultrasonic Absorption and the Compressional Viscosity Due to Structural Rearrangement in Unassociated Liquids
Authors: Piercy J. E. , Rao M. G. Seshagiri
Published: October 2005

The ultrasonic absorption in carbon tetrachloride, toluene, chlorobenzene, cyclohexane, cyclohexanone, cyclopentane, and propane has been measured over a range of temperature that extends usually from the boiling to the freezing points. An empirical curve—based on the assumptions (1) that the vibrational contribution to the absorption is linear with temperature and (2) that the ratio of the structural component of the compressional viscosity ηc to that of the shear viscosity ηs is independent of temperature—has been fitted to the measurements. The derived ratio ηc/ηs for carbon tetrachloride is 2.5±1.5, toluene 1.7±0.2, chlorobenzene 1.6±1.0, cyclohexanone 0.4±0.1, cyclopentane <0.7, propane 1.1±0.1, and acetone <2. The empirical basis of the assumptions, the relationship of this method with others for determining ηc, the relationship of these values of ηc/ηs with theoretical and other experimental values are all briefly discussed. It emerges that (1) of the liquids that have been measured the three whose molecules have the most-spherical force fields have experimental values of ηc/ηs ≈ 1, which compares well with the theoretical value of 5/3 for rigid spheres, and (2) the common assumption that the viscous contribution to the absorption decreases with increasing temperature is true only for sufficiently low temperatures.