bluuebunny/crossref_metadata_2025 huggingface dataset:
Test of the Validity of a Shell Theory for the Reflection of Sound from Thin Shells
Authors: Goodman R. R.
Published: September 2005

In 1943 Epstein introduced a method for obtaining differential equations for the deformations in an elastic shell. This method only requires assumptions concerning the thickness of the shell and the analytic properties of the deformation and stress components. Earlier methods involve additional assumptions. In 1953 Kennard reformulated the Epstein method in a more standard form and included the possibilities of nonvanishing boundary conditions for the components of stress. Using the method in the original Epstein approach, but including non-zero boundary conditions, the author has obtained an expression for the amplitude of a plane wave incident on an infinite plate immersed in a fluid. The results have been found to be identical with the exact reflection coefficient in the limit kd≪1, where k is the wave number of a transverse wave in the plate and d is the thickness of the plate. Details of the development will be presented.
Progress in Developing a Method of Analyzing the Mechanical and Acoustic Response of Complex Structures
Authors: Penhallow William S. , Brigham Gerald A.
Published: September 2005

In order to develop a method of analyzing complex structures one must know the valid criteria in comparing two different structures. As a beginning three criteria are considered: (a) point and transfer mechanical impedance, (b) radiation efficiency, and (c) radiation directivity. Work to date has centered around two test structures designed to have the same collapse strength. One is a 1/7 scale of an engine room compartment and other a proposed design called the Quad Hull. Both structures are approximately 412 ft in over-all diameter and 612 ft in length and are terminated in heavy end plates. Resonant frequencies of the circular hull are calculated and compared with data taken in air. The shift in resonant frequencies due to the mass loading is predicted and compared with data taken in the water. Radiation patterns using the point source technique are predicted and compared to patterns obtained in water. Finally the total radiated power as measured in the water is correlated with that predicted by the point source method. In general good agreement exists between theory and experiment. The approach therefore looks encouraging.
Bistatic Scattering from Totally Reflecting Flat Plates
Authors: Ankerman P. W. , Rubega R. A.
Published: September 2005

This paper deals with an investigation of the characteristics of the scattering of sound from a flat plate five wavelengths long. The scatter patterns were calculated based on the simplifying assumption of total reflection and experimentally checked by echo ranging in air. Agreement was found to be reasonably good although some interesting deviations in the side lobe structure were observed. Patterns calculated and experimentally obtained include bistatic backscatter patterns as well as the scatter patterns for a given incident wave.
Electrical Model of the Middle Ear
Authors: Zwislocki J.
Published: September 2005

In the physiological studies of the ear the emphasis has shifted from the mechanics to electrical and chemical phenomena. Nevertheless, sound transmission in the ear is not yet known to a degree where it would become possible to calculate the stimulus transformation between the entrance to the auditory canal and the sensory cells. Such a calculation appears desirable from the point of view of an integrated theory of hearing. In an effort to decrease the existing gap, an electrical analog has been constructed that matches an average middle ear element by element. The analog was derived from impedance measurements on normal and pathological ears and from known anatomical data. It duplicates the acoustic impedance at the ear drum and the transmission characteristic of the middle ear within the experimental error. It also facilitates the study of pathological changes. On the basis of analog analysis and actual impedance measurements, it became possible to give the ear surgeon pre- and postoperative indications concerning the state of the middle ear ossicles. (Investigation supported by a research grant PHS B-1559 from the National Institute of Neurological Diseases and Blindness, Public Health Service.)
External Spiral Innervation of the Cochlea
Authors: van Bergeijk Willem A.
Published: September 2005

The descriptions of the external spiral innervation of the cochlea by various anatomists are incomplete; important data such as length of fibers, number of side branches, and direction in which fibers run (to apex or base) are not accurately known. About the function of this type of innervation only speculation exists. Branching nerve fibers in which impulses converge to the main fiber have interesting logical properties. At the branching point the refractory time constant can cause impulses from either branch to be blocked. Thus branching points become summing points where impulses from branches add in such a manner that output rate is generally less than the sum of input rates, but greater than either of the input rates. Using simple nerve analogs, a model of the spiral innervation was built; it was driven from a cochlear analog. Different hypotheses of anatomists were tested, such as direction and length of fibers and spacing of branches. Results indicate that the spiral innervation may serve to extend the dynamic range of the ear. The results also suggest a method to establish neurophysiologically the length of the spiral nerves, direction of their course, location along the basilar membrane, and perhaps the number and location of side branches.
Averages of Responses Evoked by Tonal Stimuli in the Auditory Cortex of the Cat
Authors: Sandel T.
Published: September 2005

Because of the variability of responses evoked by auditory stimuli in the auditory cortex of the cat, it is difficult, if not impossible, to quantify responses to tonal stimuli without resorting to techniques which alter the physiological state of the nervous system being studied. Such techniques include the use of deep barbiturate anesthesia and the local application of strychnine at the recording sites in order to potentiate the responses, making them visually detectable. In the present study, a digital computer has been used to average large numbers of responses evoked at various locations on the auditory cortex, without the complications of either deep anesthesia or strychnine. Data obtained using this technique are presented showing the organization of responses to tonal stimuli over the surface of the primary auditory areas of the cortex. [This work was supported in part by the U. S. Army (Signal Corps), the U. S. Air Force (Office of Scientific Research), and the U. S. Navy (Office of Naval Research).]
Siren Design Procedure
Authors: Allen Clayton H. , Watters Bill G.
Published: September 2005

A simplified design procedure for efficient, high-intensity sirens will be presented in which several of the more useful physical relations have been put into chart form. Consideration is given to the limitations imposed by finite amplitude effects in the choice of the operating pressure and the design of an acoustic matching section for the siren.
Improved Directional Distribution from Horn Arrays
Authors: Veneklasen Paul S.
Published: September 2005

Use of vertical arrays of multicell horns provides more uniform sound distribution over their frequency range, corresponding to the cell configuration at high frequencies, and to the diffraction characteristics of the rectangular envelope at lower frequencies.
Submarine Shock Motions Resulting from Underwater Explosions
Authors: Belsheim R. O.
Published: September 2005

When a depth charge is exploded in the vicinity of a submerged submarine, damage of two kinds may result from the compression wave. This paper discusses, in qualitative terms, the motions of the submarine which may lead to shock damage of equipment installed or carried inside the boat. Damage to the boat itself is not considered here. These motions, often called shock motions, are approximate inputs to equipments being analyzed for shock response. Because of the behavior of the underwater explosion three rather distinct types of submarine motions are observed. Equipment response to each of these is dependent upon the relation between the “characteristic frequencies” of the input motions and the responding systems. A convenient measure of the damage potential of these shock motions is the shock spectrum, and the usefulness of this plot in response analyses is briefly discussed.
Utilization of the Dynamic Mechanical Properties of Rubber-Like Materials in Vibration Control
Authors: Snowdon J. C.
Published: September 2005

Literature concerned with the problems of vibration control frequently disregards the importance and value of considering the frequency dependence of the elastic modulus and the damping factor of rubber-like materials. Such a consideration has been found valuable in the following ways. Firstly, it enables criteria which define a good antivibration mount material to be determined. Secondly, it shows that a dynamic absorber utilizing a material with a stiffness proportional to frequency and a constant damping factor can reduce the resonant vibration of machinery and mounted equipment considerably. Its performance is superior to that of the classical dynamic absorber where the absorber mass is attached to the mounted item with a spring. Thirdly, it indicates that a mounting composed of natural and a high damping synthetic rubber in parallel can suppress resonant foundation motion nearly as effectively as a mount of the high damping rubber alone, yet offer much greater isolation at intervening frequencies. (This research was supported in part by the Bureau of Ships and the Office of Naval Research.)
Random Vibration
Authors: Morrow Charles T.
Published: September 2005

There is at present a great interest in random vibration as a special aspect of shock and vibration, especially in relation to effects on equipment. An attempt will be made to explain to members of the Acoustical Society of America (particularly those concerned with shock and vibration) what is meant by random vibration as opposed to other excitations that might be confused with it, what is involved in random vibration testing, what the corresponding objectives are, why there is controversy about these general subjects, and how some of the controversies may be resolved.
Effect of High Pressure on Sound Absorption in a Water-Dioxane Solution of Magnesium Sulfate
Authors: Fisher F. H.
Published: September 2005

Measurements have been made of the effect of high pressure on sound absorption at ∼500 kc in a 0.5 molar solution of magnesium sulfate with a water-dioxane sulfate 25% by weight dioxane. It was found that the change in solvent from water to water-dioxane (decrease in dielectric constant from 78.5 to 56.5) produced little change in absorption at atmospheric pressure or in the pressure dependence of absorption. The relaxation frequency increased slightly at atmospheric pressure for the water-dioxane solution.
Absorption of Ultrasonic Waves in Rotational Isomer Liquids of the Ring Type
Authors: Pedinoff Melvin E.
Published: September 2005

The ultrasonic pulse technique has been extended to lower frequencies by the use of solid dielectric transducers and has been used here for the determination of the anomalous absorption of sound in several organic liquids over a frequency range of approximately 150 to 3500 kc/sec. The principal liquid studied, methylcyclohexane, has a large anomalous sound absorption which can be attributed to the irreversible perturbation of an equilibrium between two of its rotational isomers by the sound wave. An experimental evaluation of the temperature dependence of the anomalous absorption per wavelength and the ultrasonic relaxation frequency has yielded the free energy difference between the two isomers and the activation energy barrier between these two states. Values of 1.9 kcal/mole for the free enthalpy difference between the isomers, and 6.4: kcal/mole for the activation enthalpy of the higher energy state, indicate that a monomolecular reaction between the polar substituted and the equatorial substituted chair configurations of methylcyclohexane is responsible for the ultrasonic absorption anomaly. Values for the entropy differences between the low-energy, high-energy, and activated states yield insight into the nature and structure of the activated state. (This research was supported in part by the Office of Naval Research.)
Determination of the Equation of State of Solids by Ultrasonic Methods
Authors: Anderson O. L. , McSkimin H. J.
Published: September 2005

Most of the published data on the equation of state of solids pertain to high-pressure, high-temperature transient events. There are few accurate data in the low-pressure, low-temperature range comparable to that known for liquids and gases, even though data in this range are of considerable theoretical importance. High-frequency ultrasonic techniques can be used to determine the equation of state of solids with at least the same accuracy as that which exists for gases. Using a phase balance ultrasonic technique the equation of state for vitreous silica has been determined in the range 75°K–300°K, 1–3500 atmospheres. The thermodynamic derivatives (of the third order) have been determined as p → 1 and T → 0. These derivatives have been very instructive in understanding several anomalies of vitreous silica which are: this solid has a larger volume at absolute zero than at room temperature; it gets stiffer as the temperature increases, and softer as the density decreases.
Characteristics of Typewriter Noise
Authors: Sapega A. E.
Published: September 2005

Measurement of noises of short-time duration, such as typewriter noise, is not satisfactory when carried out using conventional sound level meters. Availability of an Impact Noise Analyzer allows measurement of peak levels and decay-time constants of typewriter noise. The measurement and evaluation of typewriter noise using this instrumentation is reported in this paper. Peak sound power levels due to type impact were found to be 90±5 db, with an average decay-time constant of 2–3 msec. Investigation of typewriter noises using this instrument also reveals that the decay-time constant is as important a parameter characterizing a short-time duration noise as is its peak level. Decay-time constants of noises due to different typewriter operations were found to vary from 2 msec to over 300 msec. Octave and third-octave band analyses of typing noise were also carried out using the Impact Noise Analyzer. The most important frequency bands of noise due to type impact were found to be those above 1200 cps. Relative energy of the noise in octave bands indicates that type impact noise, and the noise generated in the desk supporting the typewriter, are the most important sources of noise in typing. (This work was carried on in the General Research Laboratory of the Underwood Corporation, Hartford, Connecticut.)
Noise Surveys of Cocktail Parties
Authors: Legget R. F. , Northwood T. D.
Published: September 2005

This paper discusses and enlarges on a recent theoretical paper by W. R. MacLean on the acoustics of cocktail parties. The discussion is supported by experimental evidence accumulated during the past two years. MacLean's analysis suggests that there is a critical density of participants above which a “quiet” cocktail party becomes abruptly “noisy.” It would appear that one might actually plan a quiet or noisy party as required (assuming control over the number of participants). Unfortunately the cases studied experimentally do not show this quiet-noisy transition, and it is believed that factors not considered in the theory result in a blurring of the distinction. Indications are that there is a gradual increase in sound level to a saturation value that is independent of the properties of the room, of the beverages served, and of the number of participants. There is, however, dependence on the sex of the participants.
Speech Intelligibility in Low-Frequency Noise
Authors: Pickett J. M.
Published: September 2005

Speech intelligibility was tested in a low-frequency noise. Various conditions of speech and noise suppression below 1200 cps were employed, chosen so as to test the relative effects of direct low-frequency masking and upward spread of masking to higher frequency regions. The basic unfiltered noise spectrum was approximately parallel to the speech spectrum above 300 cps (−5 to −8 db per octave); below 300 cps the noise spectrum had a slope of −1.5 db per octave. Tests were carried out at three noise spectrum levels which corresponded to over-all levels of 85, 105, and 115 db when the noise was unfiltered. The results showed significant increases in intelligibility as the noise energy was progressively removed between 20 and 300 cps. The speech between 20 and 300 cps provided no significant contribution to intelligibility under any noise condition tested. Thus we concluded that the low-frequency energy in the noise produced upward spread of masking. The spread of masking had more effect at the higher noise levels and also at lower speech-to-noise ratios (noise held constant). Implications for calculating noise interference are discussed.
Performance of High-Frequency Barium Titanate Transducers for Generating Ultrasonic Waves in Liquids
Authors: McSkimin H. J.
Published: September 2005

A study is made of high-frequency (10 mc/sec) barium titanate transducers radiating into water, with band width and efficiency being of principal concern. Optimum electrical damping alone is considered; however, it is demonstrated that the introduction of an intermediate 14-wavelength-thick composite mechanical element results in superior performance. Of the units constructed, the best exhibited a frequency band width (half-power points) of 44% with 4 db midband loss (equivalent insertion loss on a 2-transducer basis). Focusing, as well as plane, radiators were tested.
Free Edge Disk with Water Load
Authors: Kritz Jack
Published: September 2005

The free edge disk as a high-efficiency transducer into air previously has been reported. Its operation in a seawater medium is now analyzed. The choice of an aluminum-lead zirconate titanate composite is made. The equivalent mass and stiffness is deduced, and the damped frequency as well as radiation loading is evaluated. The curves of loaded Q vs thickness to radius ratio are presented for the composite and compared to an all aluminum disk. The transformer in the equivalent circuit is also evaluated. A sample calculation is made for a high-power high-efficiency underwater transducer. Values of size, weight, bandwidth. efficiency, and input impedance are given. Power capability is estimated for both a prestressed and unstressed condition of the ferroelectric portion of the composite. Efficiencies of 90% with input impedance levels of the order of 100 ohms at 99% power factor are shown to be possible. Power capabilities in the megawatt range appear feasible at the low audio-frequencies.
Method for Measuring Ultrasonic Wave Velocities in Solids
Authors: McSkimin H. J.
Published: September 2005

The frequently used pulse method of measuring ultrasonic wave velocities in solids involves a high-frequency quartz crystal transducer cemented to one end of a specimen having parallel end faces. The phase shift for waves reflected from the transducer must be considered for highest accuracy. It is shown that combining several measurements of phase delay with a theoretical analysis of the reflection phase angle makes possible a determination of velocity to within 1 part in 5000 for round-trip delays greater than 5 μsec. Indirectly the approximate thickness of the cement bond between transducer and specimen can be determined. Experimental procedures are discussed, and illustrative data for fused silica and germanium are presented. Measurements were made at 10 and 20 Mc/sec.
Microbubble Persistence in Fresh Water
Authors: Turner W. R.
Published: September 2005

Preliminary research confirms that microbubbles become stabilized in a body of water and persist for long periods of time in contradiction of classical theory. The evidence was obtained by generating bubbles at the bottom of a water tank and then measuring the decay of ultrasonic attenuation as bubbles of various sizes rose to the surface. Comparison of experimental and classical decay curves disclosed persistence that appeared to be a function of the solid particle content of the water and indicated that bubbles may stabilize at sizes as large as 30 μ radius in water of high particulate content. In waters of low particulate content persistence lasted over 100 hr. Substantial persistent abnormal attenuation was detected in all fresh tap water measured, amounting to a minimum 44% over that of distilled water (at 5.125 Mc/sec) and is believed due to stabilized bubble nuclei somewhat less than 0.7 μ in size. An interesting discovery was that attenuation rose in an uncovered test basin but fell in a covered basin, indicating that microbubbles may enter water on dust particles. Hypotheses are developed to explain the stabilization phenomena and the dust particle effect.
Quieting the Air-Conditioning Equipment for a Large Hotel Ballroom
Authors: Goodfriend Lewis S. , Ostergaard Paul B.
Published: September 2005

A large metropolitan hotel grand ballroom was to be modernized and enlarged. All the air-conditioning fans and coils were to be installed over the translucent ceiling approximately 12 ft over the guests. The architect and owner did not want these fans to be noticeable in the occupied space. The recommendations made specified that the fan-coil sections should be vibration mounted on a large concrete slab and that 4 in. of acoustical material be applied to the ceiling and walls of the mechanical space. Also octave-band sound pressure level specifications were drawn up for the noise radiated from the casings of the fan-coil units. The fan-coil units were installed as specified and were not audible in the space below. It was necessary to install small lined elbows on the ventilating louvers to the motors of the fan-coil units. All the ducts were installed with the joints in the sheet metal sealed to avoid high-frequency whistles.
Effect of Sonically Induced Microstreaming on the Development Rate of a Photographic Emulsion
Authors: Jackson Francis J. , Nyborg Wesley L.
Published: September 2005

Recent studies have indicated that the presence of small-scale acoustic streaming, or “microstreaming,” near a solid-liquid boundary can have a considerable effect on reactions occurring at such a phase interface. Results to be discussed here represent an extension of those earlier studies with emphasis on a particular interface reaction, namely, chemical development of a photographic plate. Employing a rather simple experimental system, which permits precise and controllable generation of microstreaming in the ambient developer at the emulsion surface, it is possible to produce highly localized changes in the reaction rate. An advantage of the particular system employed is that the associated acoustic fields, both first- and second-order, recently have been studied in considerable detail. Observed photographic effects thus may be discussed readily in terms of known characteristics of these fields. By carrying out all sonic exposures at a relatively high static pressure, it has been possible in most cases to suppress completely gaseous cavitation and its associated spurious effects which often mask the orderly streaming action. Photographs of irradiated emulsions will be shown, along with densitometer recordings, illustrating the extent of reaction at various points on the emulsion. Results indicating the dependence of the reaction rate on various experimental parameters will be compared with predictions based upon features of the microstreaming. [This work supported in part by the National Institute of Health (Biophysics Section) and in part by the U. S. Air Force Office of Scientific Research.]
Scattering of Sound by Sound
Authors: Dean L. W.
Published: September 2005

This paper discusses the interaction of two sound beams traveling at right angles to each other. In the case of two perfectly collimated beams the solution is obtained by solving an inhomogeneous, wave equation in the region of intersection, solving a homogeneous wave equation outside this region, and fitting the two solutions at the boundary. Scattered waves appear at various angles which are the same as the angles predicted by U. Ingard and D. C. Pridmore-Brown [J. Acoust. Soc. 28, 367 (1956)]. The generalization to cases where the boundary of the region of intersection of the two beams is not sharply defined is also discussed. [This work was supported in part by the U. S. Navy (Office of Naval Research), the U. S. Army (Signal Corps), and the U. S. Air Force (Office of Scientific Research, Air Research and Development Command).]
Time vs Intensity in Sound Localization
Authors: Whitworth Randolph H. , Jeffress Lloyd A.
Published: September 2005

In 1927 Banister wrote, “If the intensities at the two ears are not equal, an observer may judge that the tone of low pitch is localized … (toward the louder side) … but with more careful observation, two sounds will, as a rule, be discriminated. …” Like many a sage remark, this one has gone unnoticed, and we continue to trade time and intensity. Or we let the second sound go unlocalized and complain when it causes variability in our data. The present study is concerned with this second sound. Subjects adjusted a delay line until a 500-cps tone (the pointer) supplied to them through it (and earphones) matched in localization another 500-cps tone (the signal). The two tones were presented alternately. Various combinations of interaural time and intensity differences for the signal tone were used. Two experienced subjects performed during one phase of the experiment and several naive subjects during another. The experienced subjects were able, after some practice, to respond at will to either of the two localizations. Their “time response” data closely resemble the data presented by Moushegian and Jeffress for one subject, and their “intensity response” data resemble in many respects (but not all) the data for two others. The findings are not explainable in terms simply of a peripheral “trading relation” between time and intensity. (This work was supported by the Bureau of Ships.)
Temporary Threshold Shift from Acoustic Pulses
Authors: Ward W. Dixon , Selters Weldon , Glorig Aram
Published: September 2005

Although some empirical laws relating temporary threshold shift (TTS) to various parameters of continuous noise (intensity, duration, temporal pattern) recently have been devised, little is known about the TTS produced by impulsive noises such as gunfire. Some preliminary studies using impulses are described. Repetitive impulses of 140- to 150-db peak SPL were generated by (a) a toy known as a “cricket” which generates acoustic pulses when a piece of metal snaps from one position to another, and by (b) a high-intensity Altec driver through which a condenser was discharged. Comparison of TTS produced by the two types of pulses shows that peak pressure, although important, is not the only relevant parameter. The correlation between the TTS produced in individual ears by the impulses and that produced in the same ears by steady noise was not significantly different from zero. This fact underscores the futility of trying to devise a simple test for “susceptibility to acoustic trauma.” (This research was supported by a research grant from the National Institutes of Neurological Diseases and Blindness, Public Health Service.)
Auditory Facilitation Following Stimulation at Low Intensities
Authors: Rubin Herbert
Published: September 2005

Auditory thresholds may become lower (improve) following stimulation by sound of low intensity. This shift in threshold was determined by comparing the reference threshold of a test pulse, presented alone, to the threshold for the test pulse preceded by a stimulating pulse. Duration, intensity, and frequency of the stimulating pulse were controlled, as were duration and frequency of the test pulse and duration of the interval between pulses. For pulses of 1000 cps, facilitation, or a lowering of the threshold, consistently follows stimulation by sound of 25 db SL or less: the lower the stimulating intensity, the more widespread the facilitation over the various poststimulatory intervals tested. Facilitation reaches a maximum of 5 to 7 db 160 msec after the termination of the stimulating pulse, although some negative shift in threshold occurs after the longest interval (2 sec). Stimulation by white noise may depress the threshold for a pure tone, though a pure tone seems to have no effect upon the threshold for a white noise. When the stimulating pulse is a 1000-cps tone, facilitation occurs for test tones between 500 and 2000 cps. The maximal shift is at 160 msec for all test tones except 2000 cps. The nature of the facilitatory process, auditory or attentional, and its locus, whether peripheral or central, are questioned.
Design of Arrays Giving Prescribed Radiation Patterns
Authors: Rowlands R. O.
Published: September 2005

The Dolph-Chebishev method of designing a broadside array pattern with equal minor lobes is well known. The first part of this paper is concerned with an extension of the method to the design of end-fire, broad-beam, and split-beam array,. The second part of the paper considers the limitations of the above method and discusses an alternative Fourier Synthesis method. It is shown, however, that instead of attempting to approximate an ideal rectangular pattern, it is better to find desirable patterns which may be synthesized accurately with only a few elements. Such patterns and the procedure for synthesizing them are described.
Resolution of Underwater Sound Transducers in the Near and Far Fields
Authors: McKinney Chester M.
Published: September 2005

It is sometimes desirable to use the same underwater sound transducer at ranges which vary from the near field to the far field. If the transducer is focused at infinity, there is an optimum size transducer for maximum resolution for operation at a given range. This paper presents the results of measurements made on a variety of different types of transducers (lines, circular pistons, rectangular pistons, and curved-face units) to illustrate this point. Some of the information should be useful in designing transducers for specific applications in sonar. The requirements for far-field transducer calibration also are discussed. (This work was supported by contract with the Bureau of Ships.)
Diffraction of Light by Ultrasonic Waves of Various Standing Wave Ratios
Authors: Cook B. D.
Published: September 2005

The theory for the diffraction of light by plane ultrasonic waves of various standing wave ratios is derived. The medium disturbed by the ultrasound is considered to act as an optical phase grating. By evaluating the diffraction integral for the light amplitude. expressions for the time dependent and time average light intensities are found for the diffraction spectrum. Experimental measurements of these intensities indicate the theory is valid. (This work was supported by the Office of Ordnance Research, U. S. Army.)
Diffraction of Light Passing through Two Adjacent Ultrasonic Progressive Waves of Different Frequency
Authors: Hargrove L. E.
Published: September 2005

The theory for the diffraction of light by plane progressive ultrasonic waves of sinusoidal or arbitrary waveform has been developed for both wide and narrow light beams [L. E. Hargrove, K. L. Zankel, and E. A. Hiedemann, J. Acoust. Soc. Am. 31, 1366–1371, (1959)]. The author has reported [L. E. Hargrove, J. Acoust. Soc. Am. 31, 849 (A) (1959)] experimental verification for the case of a narrow light beam and a sinusoidal ultrasonic wave. Agreement between theory and experiment for wide light beams and sinusoidal waves is well known. The present paper is concerned with a light beam passing successively through two adjacent sound beams of different frequency. As the optical effects add vectorially, the light diffraction is the same as would be produced by superposition in space of the two waves. Experimental results obtained for 3 and 6 Mc in water are discussed in terms of the theoretical predictions. Both wide and narrow light beams are used for various relative phases between the fundamental and second harmonic ultrasonic components. (This work was supported by the Office of Ordnance Research, U. S. Army.)
Critical Frequencies Occurring in the Propagation of Elastic Pulses in Wires
Authors: Meitzler Allen H.
Published: September 2005

The propagation of elastic pulses in metal wires of circular cross section has been studied for conditions in which pulses having carrier frequencies ranging from 0.5 to 4.0 Mc were transmitted in wires having diameters between 0.1 and 0.2 cm. The pulses used in the experiments were shaped to have relatively narrow frequency spectra. At certain frequencies herein called critical frequencies, pulses propagating in certain modes were observed to undergo pronounced distortion in which the peak amplitude of an affected pulse was reduced and the duration of the pulse was increased many times its original length. The experimentally observed frequencies at which these pulse distortions occur are in agreement with certain frequencies where, theoretically, the phase velocity in one mode is the same as the phase velocity in a different mode. Thus, for example, there is a critical frequency for pulses propagating in the first longitudinal mode at the frequency where the phase velocity in the first flexural mode with two nodal diameters (i.e., each displacement component has two nodal diameters in this mode) equals the phase velocity in the first longitudinal mode. Experimental and theoretical results will be given for wires made of an aluminum alloy and an isoelastic alloy. (This work was supported in part by the Ordnance Corps, U. S. Army.)
Experimental Case Study of a “Tone-Deaf” Individual
Authors: Tanner Wilson P. , Rivette Laurence
Published: September 2005

In an experiment started for another purpose, we encountered an observer who was unable to discrimate differences in frequencies of short bursts of sine waves. We then diverted our procedure to conduct an experimental case study comparing the “tone-deaf” observer to three observers with normal frequency discrimination under a variety of experimental conditions. In amplitude-discrimination experiments and experiments in which he is detecting pulses of sine waves he compares favorably. He far surpasses the other three observers when the signal is a sample of “white Gaussian” noise. The comparison of this observer's behavior under binaural and monaural listening conditions is also reported.
Sensitivity to Unidirectional Frequency Modulation
Authors: Sergeant Russell L. , Harris J. Donald
Published: September 2005

Eight subjects trained in listening were given a variety of taped programs of frequency glissando consisting of items which began at 1500 cps and proceeded at 50 phons either up or down in frequency. S's were required to judge “higher” or “lower.” Periods of glissando from 0.2 to 10 sec and rates of change from 0.5 to 100 cps/sec were used. Sensitivity to this type of frequency modulation is surprisingly good, and inter-subject variation is not excessive; thus it could well form one sensory input to certain man-machine systems, either on an absolute or a relative basis. One S, extremely poor on the more usual pitch test by the constants method, was not much worse than average on glissando. For most S's, a constant emerges at a total of about 5-cps change, such that sensitivity to 0.5 cps/sec change over 10 sec is about equally as difficult as 5 cps/sec change over 1 sec, and so on. This constant is in fact of the same order of magnitude as the traditional DL for pitch.
On the Matching of “Loudness.”
Authors: Creelman C. Douglas
Published: September 2005

A series of experiments examined the reliability of the method of adjustment, or loudness matching, as a means of measuring the subjective intensity of audio signals. The common procedure requires the observer to set the intensity of a “standard” 1000-cps tone of fixed duration to equality with the loudness of another signal. This procedure was compared to alternative procedures in which the observer has control of the intensity of the other signal and attempts to equate it to the loudness of the 1000-cps standard. Comparison data were taken with the same observers under different conditions of signal filtering, and under differing instructions. The initial aim of the study was a new assessment of the relation of subjective loudness to signal duration, and the conclusion is that loudness matching, by its very nature, cannot yield definitive answers regarding the nature of this relation. In order to make the conclusion more general and testable, a tentative model is presented for the loudness matching process. The model is of two independent processes, either of which might be identified with “subjective loudness,” but which are confounded in the usual matching procedure. (This work was done under a Postdoctoral Research Training Fellowship form the National Institute of Mental Health, and was supported in part by the Office of Naval Research.)
Miniaturized Glass Delay Lines With Improved Electrical Characteristics
Authors: Bieling C. A. , Thomas N. C.
Published: September 2005

There has been an ever increasing demand for short sonic delay lines in the range of 1–50 μsec. Early lines were large since they required temperature control to maintain close delay tolerances. In this paper data is presented showing the design and performance of miniaturized delay lines for operation in the temperature range of −30° to +70°C using ceramic transducers and low temperature coefficient of delay glass. The improvements have resulted in reductions in weight from 500 to 23 g and in size from 240 to 6 cm3. At the same time, the 3-db bandwidth of 15-Mc lines has been increased from 4.5 to 7.5 Mc with comparable attenuation.
Contralateral Threshold Shift and Reduction in Temporary Threshold Shift as Indices of Acoustic Reflex Action
Authors: Fletcher J. L. , Loeb M.
Published: September 2005

The purpose of the experiment was twofold: to compare the effectiveness of narrow band noise and a train of clicks in eliciting the middle ear acoustic reflex and to correlate two methods of estimating amount of reflex activation. One method involved measurement of increase in threshold in the contralateral ear; the other, measurement of reduction of TTS produced by a series of gun shots. Sixteen subjects were employed. Shifts produced by the clicks and noise were of the same order of magnitude (after correction for the direct masking effect by the clicks), but there was considerable reflex adaptation to the noise and none for the clicks. Correlations between contralateral threshold shift and reduction of TTS were small and not significant.
Statistics of Finite Ensembles of Periodic Waveforms
Authors: Fox H. L. , Starr E. A.
Published: September 2005

Measurements are presented of the probability density of finite sums of independent periodic waveforms. The variation in the probability density for sums of equal numbers of terms but different energy contributions from the independent members of the ensemble is illustrated. These data indicate the criteria to be applied in order to use a finite ensemble for the purpose of simulating a specific density function.
Mode Propagation in Ultrasonic Waveguides
Authors: Carome E. F. , Lastovka J. B.
Published: September 2005

Measurements of attenuation versus path length in liquid-filled ultrasonic waveguides indicate that the modes propagated are those characteristics of pressure-free boundary conditions, even when the liquid wets the walls of the guide. The possible explanation is that for a real liquid the appropriate boundary condition at the walls of the guide is one of vanishing tangential velocity. To study this effect, further measurements are being made with probe-type microphones. These various procedures are being used to determine the motion of the face of the source and to measure pressure profiles throughout waveguides of cylindrical and rectangular symmetry. Results of these studies will be compared with theoretical calculations. (This work was supported in part by the Office of Naval Research.)
Driving Point Impedances of Cylindrical Shells
Authors: Thompson W. , Rattayya J. V.
Published: September 2005

Explicit expressions for the driving point impedance of cylindrical shells subjected to concentrated fluctuating radial forces have been sorely lacking in the extensive literature on shell vibrations. This need was partly filled by a recent paper by P. A. Franken [J. Acoust. Soc. Am. 32, 473 (1960)], but his impedance expressions have been found to be valid only over a restricted frequency range. The purpose of the present paper is to supply convenient, more generally applicable expressions for cases of practical interest. The loads considered are sinusoidally varying, concentrated and locally distributed forces and moments. Impedance expressions are given for uniform shells, both infinite and finite. Impedance expressions are also given for the ring-stiffened shell of finite length. (This paper is based on work sponsored by the Office of Naval Research.)
The Reliability of Field Measurements of Sound Isolating Partitions
Authors: Hirtle Parker W.
Published: September 2005

Transmission loss measurements have been made on field installations of several partitions. Results of field measurements of the same components in several different installations are compared. Some comparisons are made with laboratory measurements of installations which attempt to duplicate field conditions and those which do not.
Sound Isolation of Conventional Doors in Field Installations
Authors: Farrell William R.
Published: September 2005

The presence of doors often seriously limits the achievable room-to-room sound isolation even when they do not occur in the common dividing partition. Room-to-room noise reduction measurements have been made of sound transmission paths through doors, including doors in the common dividing partition, doors separated by various lengths of corridor, and doors opening into larger spaces (secretarial pools, etc.). The noise reduction varies with the door construction, tightness of fit, spacing of the doors, size and absorption of the receiving room, and/or the intervening space. Measured data are presented and some preliminary conclusions drawn.
Intelligibility Study of the Hughes Digital Vocoder
Authors: Gerber Sanford E. , Morris William H.
Published: September 2005

A discussion is presented of the method and procedure of intelligibility testing employing artificial speech. Several experiments are described in which the vocoder was tested under various conditions. Since the Hughes vocoder is a digital system, the bit rate employed is of considerable interest in terms of its effect upon received intelligibility. Word intelligibility studies were performed using three different bit rates, and the results of these studies are discussed. Moreover, studies were made of various conditions of filtering within the vocoder, and these results are presented. Finally, future studies and applications of the digital vocoder are forecast.
Dynamics of Stable Cavities during Acoustic Cavitation
Authors: Flynn H. G.
Published: September 2005

Stable cavities in a field of acoustic cavitation are small gas-filled cavities that have a lifetime which is long compared with the period of the sound field. The oscillations of such cavities in liquids under the influence of a sinusoidal pressure field have been studied to gain insight into mechanisms important in phenomena associated with acoustic cavitation, such as erosion and chemical reactions. A nonlinear differential equation for the motion of the interface of a stable cavity has been solved numerically on a digital computer and analytically by an iterative method. Stable cavities, which may pulsate through many periods of the sound field, may be contrasted with transient cavities whose lifetimes are short compared with the period of the sound field. A transient cavity is a small gas-filled bubble that on expansion to some maximum size contracts violently; during most of the collapse phase a transient cavity acts as though it contained only vapor. The transformation of stable cavities into transient cavities as a function of frequency and pressure will be discussed. (This research is supported by the Office of Naval Research.)
Acoustics of Four Large Viennese Halls
Authors: Skudrzyk E. J. , Hirschwehr E.
Published: September 2005

At the Acoustical Society meeting in the fall of 1955, a paper was presented on the development of several types of room sound absorbers. These absorbers, which were tuned to a frequency of about 200 cps, had an absorption coefficient of more than 80% between 200 and 1500 cps. These absorbers have been used in the acoustical design and construction of four large Viennese halls. The largest hall, which is 100 yd long, 120 yd wide, and about 20 yd high, has a reverberation time of four seconds—exactly as planned. As a result of the nearly optimum shape of the hall, the intelligibility for random syllables spoken at the center of the hall is 96% at the remotest seats. This is equivalent to being adjacent to the speaker. Loudspeakers must be used, however, to overcome the noise produced by the audience. The second largest hall is 60 yd long, 30 yd wide, and 20 yd high. The side walls, which are made of glass arranged in a zigzag pattern, do not produce the slightest echo. The end walls are constructed of tuned brick absorbers. From an acoustic standpoint, the skating hall is probably the most impressive. This hall, which is heavily damped particularly at the low frequencies, conveys the impression of a hall in a luxuriant hotel. The only noise that reaches the occupants is the soft scraping of the skates on the ice. This paper presents details of the acoustical construction of these buildings and the results obtained.
The Discrimination Limen for Loudness under Varying Rates of Intensity Change
Authors: Wolsk David
Published: September 2005

Two studies have been conducted on the influence of the rate of auditory intensity change upon a subject's ability to discriminate that change. In experiment I the stimulus intensity changed gradually through time. Complete psychophysical functions were obtained for four subjects at five rates of change between 2 and 150 db/min. To control for possible differential auditory fatigue effects, a stable level of fatigue was maintained throughout the trials. The slowest rate of change was the only one which produced results significantly different from the other rates and this was so for only two of the four subjects. In experiment II a warbling type of intensity variation was used with four warble rates between 0.3 and 3.0 beats/sec. The rate of change of the warble amplitude was adjusted for each warble rate to serve as a compensation for the fewer number of warble cycles presented in a given observation time with the slower warble rates. This control has apparently not been used before in two previous similar studies whose results indicated a very definite decrement in discrimination as the warble rate decreased. The results from this experiment showed no significant effects on the DL from varying the warble rate. The results will be discussed in terms of individual differences and changing discriminative criteria as they relate to temporal factors.