bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Laminar Acoustical Materials
Authors: Watters Bill G. , Baruch Jordan J.
Published: September 2005

Recent developments in the lighting field, such as the use of large-area illumination, have made the incorporation of reverberation control in ceiling design extremely difficult. By applying established principles to the design of a thin absorbing material, it has been possible to produce a system having high translucency to light as well as a reasonable acoustical absorption coefficient. Since the material is actually resistive in nature and does not depend on diaphragmatic action, a great deal of freedom is permissible in mounting, and the absorption-frequency curve is broad rather than being sharply tuned. The basic material and several extensions and modifications of it show promise in the fields of functional absorbers, duct linings, large-area ceiling treatments, and wall treatments.
Identification of Stationary Parts of Speech Sounds
Authors: Muller Frank A.
Published: September 2005

An attempt has been made to identify vowel and fricative sounds experimentally with two parameters. These parameters are unique functions of a short-time power spectrum of the sound and vary continuously for any continuous variation of the spectrum. In this respect they differ from formant data. Such parameters can be derived in a multitude of ways. The parameters actually chosen should be comparatively insensitive to spectral differences that are found to be immaterial for aural identification. Weighted averages of the logarithm of the power spectrum turn out to have this property when the weighting functions are chosen adequately. A set of two parameters unite stationary speech sounds in a two-dimensional picture. The vowel part of it resembles the familiar vowel triangle, but in this picture the fricatives are added.
Analysis and Synthesis of Formants and Moments of Speech Spectra
Authors: Howard Calvin R. , Chang Sze-Hou , Carrabes Marcello J.
Published: September 2005

A system for the analysis and synthesis speech is described. In the analyzer, speech sounds are first classified into nonturbulent and turbulent groups. The first three formants of the former group and the first three moments of the latter group constitute six significant parameters of speech spectra. By measuring the zero-crossing densities and/or envelopes of automatically selected frequency bands, these parameters or their equivalents are extracted. To test the feasibility of using these parameters in a speech compression system, a synthesis procedure is carried out. The synthesized speech and its spectrograms are demonstrated. [The research in this paper has been made possible through support and sponsorship extended by the Electronics Research Directorate of the Air Force Cambridge Research Center, under Contract No. AF 19(604)-1039, Item I.]
Auditory Testing of a Formant-Coding Speech Compression System
Authors: Flanagan James L. , House Arthur S.
Published: September 2005

An evaluation of the intelligibility of speech transmitted by a formant-coding compression system is described. The compression system codes the input speech in terms of six electrical signals, representing the frequencies of the first three formants, the intensity of voicing and of friction, and the fundamental vocal frequency. These signals occupy a total band width of approximately 50 cps and require signal-to-noise ratios of approximately 30 db for their transmission. Natural monosyllabic utterances are transmitted through the compression system and are presented to listeners for identification. Vowel and consonant articulation scores are computed and sound-confusion matrices are constructed. The contribution to intelligibility of various components of the system and the inherent limitations of the system are examined and discussed. [This work was supported in part by the Air Force Cambridge Research Center under Contract No. AF 19(604)-626.]
Characteristics of Cornet Tones
Authors: Kent E. L. , Hall J. C.
Published: September 2005

Extensive tests were made to determine the characteristic differences between cornet tones judged by musicians to be acceptable or unacceptable. A research committee from the College Band Directors National Association collaborated in the evaluation tests with the cooperation of some of America's finest musicians. A valid group of judges was determined on the basis of repeatability and range of judgments. Musicians in the valid group were generally in close agreement. Where serious disagreement existed, a change in the quality of the tone during its production was usually found. Analysis of the tones used revealed the relationship between the subjective ratings and the following: the dynamics, the harmonic structure, and the formants. Other information was obtained as a by-product of the tests. Included were such things as: the relationship between the harmonic content and the musician's descriptive terms, such as, “bright” and “dark” tones; the difference between cornet and trumpet tones; and trends that may be expected in the tones produced by other wind instruments. Demonstrations will be used in presenting the paper.
Tone-Quality of Bowed-String Instruments and Its Variation by Violin-Making
Authors: Meinel H.
Published: September 2005

One problem of the investigation of musical instruments concerns the statement of physical characteristics of the tone quality. By musical experts' collaboration, old Italian violins and modern ones have been classified according to their tonal quality and physically examined by obtaining their response curves. The best old Italian master violins show physical particularities of tone quality which modern violins do not generally have. They affect the sound-color, transient phenomena, and “carrying power”—very important properties. Within a comparatively small range, conditioned by different musical taste, we can state an optimum response curve of violins. Curves of good and bad violas and violincellos have been taken, but are not sufficient for stating optimum curves. Furthermore, we must try to find fit measures of violin making, by means of which the optimal physical characteristics of tone quality can be attained. Methods must be found for building these optimum qualities into new violins. Such factors as shape, thickness of material, and varnish, seem quite important, while the bass bar, sound post, bridge, and strings are of less importance. Comparisons are given between a violin made on the basis of these researches and a Stradivarius instrument.
Factors Contributing to the Multiple Decrement of Piano Tone Envelope
Authors: Hundley T. Chase , Martin Daniel W. , Benioff Hugo
Published: September 2005

The decrease in decrement of piano tone envelope with tone duration has been reported previously. Possible causes of the rate change have now been investigated, including the following: different rates for different groups of vibration modes; nonlinearity of transformation of mechanical energy to acoustical energy; storage of mechanical energy for subsequent acoustical radiation; transfer of energy between string modes perpendicular and parallel to the bridge; interference between strings which are almost exactly in tune; and change in rate of energy transfer from the multiple-string source, before and after transition from an initial in-phase condition to a later out-of-phase condition. The suggestion of the last factor and its theoretical basis was the specific contribution of Dr. Benioff. The last two factors, which are closely related, were found to control the rate change in most cases.
Some Basic Aspects of an Informational Theory of Music
Authors: Moles André
Published: September 2005

In the revolution of musical doctrine under the impact of electroacoustical techniques, informational theory brings some concepts for building a new theoretical system which is now conspicuously lacking. Music is one of the messages of our environment, and the human channel, as a consequence of psychophysical uncertainty principles, determines basically the repertories of sound symbols. According to the point of view of the receiver, various repertories appear as “semantic” (intelligible) and “aesthetic” (for a large part sensorial) messages intricately involved in the sound sequences. It is possible to separate experimentally informational contents related to the various repertories, which can be distinguished according to the time scale of perception. The system of values thus obtained gives a metrical pattern of the musical signal. Taking into account the variations of informational rates which a particular individual can grasp, it is possible to reach some general rules governing the musical signal, especially in the simple cases of the work of arrangers of light music, which is more clearly defined after the capacity of the listener. These rules appear particularly useful in the new field of experimental music which makes a wide use of electronic and acoustical means.
Absolute Judgments of Musical Tonality
Authors: Corso John F.
Published: September 2005

The purpose of the present study was to determine the accuracy of discrimination of trained musicians in judgments of equally-tempered tonalities. In Part I, 27 subjects made absolute judgments of the tonality (key signature and mode) of three series of tape-recorded piano tones presented through a loudspeaker at an 80-db intensity level. The stimuli consisted of three randomly-ordered presentations of 12 major and 12 minor keys within each test series. Series A consisted of eight-tone ascending diatonic scales; Series B, eight-tone randomized diatonic “scales”; and Series C, four-chord progressions (tonic, subdominant, dominant seventh, and tonic). For each tonality within each series, the stimulus duration was approximately 4 sec with 6 sec between stimuli. All 216 judgments (72 for each series) were made in a single hour. The results of Part I showed that the average amount of information transmitted (4.58 bits presented) was 1.02 bits for Series A, 0.37 bits for Series B, and 0.77 bits for Series C. An analysis of major-minor discriminations showed that the average amount of information transmitted (one bit presented) was 0.47 bits for Series A, 0.03 bits for Series B, and 0.37 bits for Series C. In Part II, seven subjects were retested on the same stimulus materials but made only major-minor judgments. Under this condition, the average amount of information transmitted was approximately twice that obtained in the major-minor analysis of Part I. It is suggested that judgments of musical tonality are probably multidimensional and influenced by set.
Report on an Investigation of 300 Historic Church Bells
Authors: Thienhaus Erich
Published: September 2005

During the last war and in the years immediately thereafter, extensive measurements of partials (frequency, amplitude, damping, and range of vibrations) were carried out on over 300 bells in the Hamburg bell depository. In addition, the strike tone and the rib form (meridian section) of the bells was determined. The author describes the measurement procedures, reports statistical results with regard to the damping of partials, and discusses the questions of beats between the partials and of the strike tone. Finally, results concerning the Brinnel hardness and the metallographic structure of the bell metal are presented.
Measurements with Ordinary Sound and Ultrasonics Carried Out in the Physical Laboratory of the University of Louvain
Authors: Van Itterbeek A.
Published: September 2005

During the last two years new measurements were started on the following subjects: 1. Measurements on the velocity of sound in gaseous mixtures in connection with thermal diffusion at ordinary pressures and high pressures. The velocity of sound is measured to determine the concentration of the gas mixtures. These measurements are carried out in connection with the theory of Clark, Jones, and Furry. From this theory it is possible to separate the ordinary diffusion coefficient from the thermal diffusion coefficient. 2. Development of an acoustical thermometer. As the velocity of sound, is proportional to the square root of the absolute temperature, a very accurate acoustical interferometer has been developed to measure the temperature of liquified gases (liquid helium, hydrogen, or oxygen). The same apparatus has also been used in another application: the determination of the conversion of normal hydrogen into para. 3. Measurements on the relaxation for the rotational energy in hydrogen gas. New measurements are carried out in normal-and parahydrogen at liquid oxygen temperatures. The velocity is measured as a function of pressure down to low pressures. 4. Debye-Sears-Lucas method is used for liquid helium. The diffraction pictures are analyzed by means of a microphotometer. The theory of Brillouin is discussed.
Modulation Method for Measurements of Ultrasonic Dispersion
Authors: Zverev V. A.
Published: September 2005

A new method for measurements of the dispersion of waves is described. The experiment gives directly the value of D = d2k/dω2(k, wave number; ω, angular frequency). The measurements of D is based on the transformation of phase modulation in amplitude modulation and vice versa, when a modulated sine wave travels through a dispersive medium. The sensitivity of the method depends only on the noise level in the receiver and it is independent of the unavoidable small random variations of the sound velocity in the medium under test. The results of experiments on ultrasonic waves in thin wires (longitudinal waves where used) and in water at 1 Me/sec (modulation frequency: 100 kc/sec) are given. The experiments were undertaken for determining the possibilities of the method in acoustics. In the case of longitudinal waves in a thin wire the dispersion can be calculated from the theory of elasticity. The value of D obtained experimentally is in a good agreement with the calculated one. The relative change of the phase velocity corresponding to the frequency interval of 100 kc/sec was about 10−4 In water, no dispersion was observed that agrees with the theory. A variation of velocity of 1 cm/sec in a frequency interval of 100 kc/sec was detectable when the receiver band was about 1 kc/sec. In order to prevent reflected waves an optical indicator of ultrasonic waves was used.
Ultrasonic Propagation Measurements in Sea Water up to 400 kc
Authors: Hashimoto Tomiju , Kikuchi Yoshimitsu
Published: September 2005

The propagation characteristics of ultrasound in sea-water and its ultrasonic reflection loss on the sea-bottom or on fish-schools must be studied for both the design and the practical operation of echo-sounders, fish-finders, and SONARs. This paper shows a practical method for the above-mentioned study, together with the results of measured propagation characteristics in both vertical and horizontal directions, as well as the ultrasonic reflection loss on the sea-bottom and on fish-schools, using 10, 14.5, 28, 50, 200, 300, and 400 kc. The propagation attenuation in a direction vertical to the sea-surface is due mainly to spherical divergence, but the attenuation in a horizontal direction is partly caused by absorption as well. This absorption becomes larger at higher frequencies: in fact, the results of experiments show that the absorption is 10–20 db/km at 28 kc, 31–50 db/km at 200 kc, and about 120 db/km at 400 kc. The reflection loss of the ultrasound at a fish-school decreases as frequency increases. On the contrary, the reflection loss of the sea-bottom increases as frequency increases. At 200 kc, therefore, the echoes from ground-fishes sometimes become stronger than that from the sea-bottom.
Velocity of Sound in Pure Liquids and Liquid Mixtures
Authors: Koodriavtsev B. B.
Published: September 2005

The velocity of sound was expressed in terms of internal energy and some physical constants, and an equation was derived to calculate the velocity of sound in pure liquids and liquid mixtures. Acoustical velocities were calculated for a number of binary mixtures of organic liquids and compared with experimental data. The observed variation of sound velocities with concentration was explained. The agreement between the theory and the experiment is quite satisfactory. The sound velocity equation was used to calculate the velocity of sound in aqueous solutions of electrolytes. The values predicted by theory are in good agreement with the experimental data. These values were used to determine the adiabatic compressibility for aqueous solutions of various alkali halides. Some conclusions were drawn concerning the acoustical properties of electrolyte solutions and the possibilities of applying acoustic measurements to calculation of various physico-chemical data.
Determination of the Normal Hearing Reference Level
Authors: Glorig Aram , Grings William , Wheeler Douglas E. , Quiggle Robert R.
Published: September 2005

The auditory thresholds of two groups of “fairgoers” were examined at the Wisconsin State Fair in 1954 and 1955. Each group was tested with pure tones with a view to determining the reference level of normal hearing. The first group consisted of 3500 persons between 10 and 79 years of age. They were tested by the method of limits in 5 db steps with a standard, commercially available audiometer. The normal threshold data were derived from 202 males and females between 18 and 24 years of age. The second group consisted of 122 males and females between 18 and 24 years of age. This group was rigidly screened for otologically significant history and physical findings. They were tested several times by the method of limits in 212-db steps with a modified standard audiometer. These data were then compared in various ways to determine the effects of attenuator step-interval, repetition of tests, method of analysis, differences in earphones and couplers, etc., on the determination of the reference level for normal hearing.
Effects of Noises on the Neuromuscular Activity
Authors: Bugard P. , Romani J. D.
Published: September 2005

(1) The sound produced by an electric bell (100 to 125 db) induces in the guinea pig an increase of the excitability of the sciatic nerve, as measured by the electronic rheotome of Pluven and Guiot. This excitability seems due more to a central stimulation than to a peripheral one. The diffusion of responses seems to imply a sensitive motor reflex rather than a mere hyperexcitability of the motor fibers. (2) Any sound can induce a hyperexcitability provided it is definitely above the level of the usual sound environment of the animal. The effect of an experimental sound can thus only be estimated by referring to the mean level of noise before the experiment; this implies taking certain precautions during the breeding or manipulation of animals. (3) In animals submitted to ether anesthesia the excitability is not noticeably altered. The fact that the action of sound under anesthesia does not induce any new alteration may be the result of two causes: (a) either anesthesia prevents the psychological stress, or (b) anesthesia exerts an influence on the transmission of the nervous impulse through the via auditoria and the cerebral circuits. This would not be true of ultrasonics of low frequency and high level (160 to 165 db): anesthesia does not seem to reduce the destructive effect of intense airborne ultrasonics on the skin, the underlying tissue and the nervous centers.
Low-Frequency Attenuation of Cover-Type Ear Defenders in Relation to the Flesh Impedance
Authors: Shaw E. A. G. , Thiessen G. J.
Published: September 2005

The lumped constant theory given earlier [J. Acoust. Sec. Am. 26, 947(A) (1954)] has been extended to take into account the finite area of contact between cushion and head. The modified theory is based on the premise that the cushion and flesh have infinite bulk modulus, and leads to the conclusion that there is an effective cover area which is equal to a linear combination of the “inner” and “outer” areas. The physical methods of attenuation measurement described earlier have been further developed to permit the determination of both the amplitude ratio and the phase shift in transmission. Such measurements make it possible to calculate the impedance of the flesh under the cushion at frequencies between 30 and 500 cps. The preliminary values of stiffness and resistance (8 × 107 dyne-cm−1 and 3 × 105 dyne-sec cm−1) are, respectively, less by a factor of 6 and greater by a factor of 10 than the magnitudes of the corresponding mastoid parameters recently determined by Corliss et al. and Dadson et al. This suggests that the low-frequency impedance presented by the head to a circumaural ear defender cushion is mainly determined by the viscous and highly compliant flesh rather than the comparatively rigid skull.
Impedance at the Eardrum
Authors: Zwislocki Josef J.
Published: September 2005

Measurements of acoustic impedance at the eardrum are of scientific as well as of practical interest. On the one hand, they permit us to draw conclusions concerning the mechanism of the middle ear and indirectly of the inner ear. On the other hand, the impedance at the eardrum affects the sound attenuation provided by earplugs and semi-inserts as well as the performance of miniature earphones. The diagnostic value of impedance measurements of the ear for middle ear diseases remains doubtful. Earlier impedance measurements at the eardrum are not in good agreement. It is difficult, therefore, to decide which data to use. With the exception of one experiment, in which approximately thirty normal ears were investigated, these measurements concern individual ears. In the group experiment the measurements were limited to four sound frequencies. In order to gain additional data we undertook to measure the acoustic impedance at the eardrum with methods sufficiently simple to permit investigation of a considerable number of ears at ten or more sound frequencies. So far our results do not differ considerably from the previous group experiment.
Distribution of Sound Intensities and Path Time Difference of Reflections in Halls
Authors: Schodder Georg R.
Published: September 2005

In several broadcasting studios, concert halls, theaters, and a church, the time succession of sound reflections has been recorded at a large number of positions. The oscillograms obtained have been analyzed with respect to path time differences and intensities of the reflections, the levels of which are no more than 10 db below the level of the primary sound. The reported results include the individual numbers of registered reflections falling at different seats for one hall, and for some halls the corresponding mean numbers per seat, the distributions of the path time differences of the registered reflections, and the distributions of their intensities. Also, the general influence of the position of the sound source on the reflections has been investigated, as well as the successions of the sound reflections which would be received by the one-channel transmission systems. These measurements will form a basis for an investigation on the subjective effects of sound reflections.
Use of the General Radio Type 1556-A Impact Noise Analyzer to Measure Reverberation Time
Authors: Anderson C. D. , Lane R. N.
Published: September 2005

An investigation was made using the Defense Research Laboratory reverberation chamber to determine the feasibility and practicability of using the General Radio type 1556-A impact noise analyzer to measure reverberation time. Calibration curves are plotted giving reverberation time vs db difference between the peak and average levels read from the GR1556-A impact noise analyzer for reverberation times from a fraction of a second to several seconds using both condenser discharges and bands of white noise as the source. These data are compared with data from the theoretical analysis of the circuit.
Effect of Splayed Walls of a Room on the Steady-State Sound Transmission Characteristics
Authors: Nimura Tadamoto , Shibayama Kimio
Published: September 2005

The steady-state sound transmission characteristics of a fan-shaped room, taken as an example of a splayed room, were analyzed mathematically. The wave-type factors “en,” developed by Morse and others, and the distribution of the normal modes of such a room were compared with those of a rectangular room. The fan-shaped room with ρ0≃1.2∼1.4 has good characteristics in the low-frequency region, where ρ0 is the ratio of the outer and inner radius of the room. And such a fan-shaped room corresponds to a splayed room with l/a≃0.09∼0.17 where a is the mean length of the parallel walls and 2l is the difference between them. The transmission characteristics in model rooms of various shapes were measured. The shape of the model was varied from the rectangle to trapezoid and to quadrangle with nonparallel walls, while keeping the interior volume of the room constant. The experimental results, obtained on the decrease of the frequency irregularity in the transmission characteristics of a trapezoid room, showed a good agreement with the theoretical results and our experiences.
Practical Production and Use of Multitones
Authors: Raes Auguste C.
Published: September 2005

This paper discusses undesirable features of warble tones and random noise for measurements in architectural acoustics; multitone sources are offered as a better alternative. The advantages and disadvantages of recorded signals are considered, for two methods: (1) tape recorder and single oscillator (multiple recording of a series of selected frequencies); and (2) tape recorder and number of oscillators (single recording of the common output from multiple oscillators). Tests have been made to determine the smallest number of single tones which a multitone should contain to give satisfactory decay curves; only two components have been found to be necessary. The paper describes a “duotone” generator which provides a very simple and stable source, continuously adjustable over a single range which covers all standard frequencies used in architectural acoustics.
Acoustical Problems of the Stratford (Ontario) Permanent Shakespearean Theater
Authors: Tanner Robert H.
Published: September 2005

After three very successful years, the authorities of the Stratford (Ontario) Shakespearean Festival are planning to replace the unique theater tent with a permanent structure. The Festival's original home is an interesting mixture of Greek amphitheatre, Elizabethan stage, and present-day circus tent, and the new building will retain nearly all of these features, including a seating capacity of around 2000. With no proscenium arch, an “acting angle” of over 180°, circular banks of seats centered on the middle of the stage, and a small gallery, the new design presents a number of interesting and unusual acoustical problems, such as ensuring high intelligibility in sections of the audience on which an actor has turned his back. The location of an orchestra of reasonable size so that it will not interfere with the pageantry of the productions is also a matter of some difficulty. This paper details the solutions proposed for the building which is scheduled for completion before the 1957 Festival Season. It is hoped that a later paper may discuss the results achieved.
Wall Pressure Fluctuations in a Turbulent Boundary Layer
Authors: Willmarth W. W.
Published: September 2005

In the flow of air past a solid surface, a turbulent boundary layer is produced. The turbulence is ordinarily thought of as velocity fluctuation but in addition pressure, temperature and density fluctuations also occur. The turbulent boundary layer causes a sound field to be set up in the free stream and also induces fluctuating normal loads on the boundary. If the boundary is elastic, its motion will set the air on each side into motion. Thus, additional sound radiation is to be expected. In an initial investigation of this problem some of the properties of the wall pressure fluctuations in a turbulent boundary layer have been measured. The equipment used in the investigation includes: a specially designed low noise and turbulence level wind tunnel, a small barium titanate microphone for frequencies up to 50 kc and the necessary electronic equipment. The quantities measured were the root-mean-square pressure at the wall and the power spectrum of the wall pressure. It was found that the root-mean-square wall pressure was a constant portion (0.0035) of the free stream dynamic pressure for 0.2 <M <1 and 106 <R <13 × 106. [Supported by the National Advisory Committee for Aeronautics.]
Acoustic Radiation from a Stationary Cylinder in a Fluid Stream
Authors: Etkin B. , Korbacher G. K. , Keefe R. T.
Published: September 2005

Theory. Lighthill's theory of aerodynamically generated sound is applied to the flow past a stationary circular cylinder with a fluctuating wake, a phenomenon related to “Aeolian Tones.” The main predictions of the theory are as follows: (a) A tone is produced having the same frequency as the wake. Its directionality is that of a line dipole with axis normal to the stream. This sound is associated with the fluctuating lift force acting on the cylinder. (b) A tone is produced having double the wake frequency. Its directionality is that of a line dipole with axis parallel to the stream. It is associated with the fluctuating drag force. (c) The intensity of both tones at points of the midplane in the far field varies approximately as U6, where U is the stream velocity. (d) The acoustic power varies as Un, n lying between 5 and 6. Experiments. Measurements were made in the subsonic wind tunnel laboratory of the Institute of Aerophysics. Circular cylinders of various diameters were mounted in the tunnel test section, and sound pressures were measured at points inside and outside the tunnel over a range of speeds. Graphs are presented showing over-all sound pressure levels, sound spectra, and equal level contours. The results obtained are in general agreement with the predictions of the theory.
Acoustics of an Irrotationally Moving Perfect Gas
Authors: Oestreicher Hans L.
Published: September 2005

The propagation and radiation of sound in a stationary flow of a perfect gas is formulated as initial-boundary value problem of a hyperbolic differential equation with space dependent coefficients. This equation and a corresponding equation for sinusoidal vibrations of the source, together with a proper radiation condition, are the basis for the generalization of most fundamental theorems of conventional acoustics as, theorem of reciprocity, Helmholtz formula, energy balance, etc. The sound fields of specific sources and estimates of the influence of small regions of rotational flow (boundary layer) are discussed.
Propagation of Sound in a Swirling Fluid
Authors: Mawardi Osman K.
Published: September 2005

The propagation of a sound wave in a swirling fluid has been examined. The fluid motion is contained in a cylindrical conduit. The influence of the mean motion on the normal modes of the conduit has been studied under the assumption that the motion of the mean is governed by the equations of an incompressible fluid. [This work has been supported in part under Contract No. 33(616)-3307 with Wright Air Development Center.]
Some New Aspects of the Acoustical Behavior of Animals
Authors: Busnel René-Guy
Published: September 2005

The recent progress of acoustical techniques have made it possible for biologists to study the sounds produced by animals. These are of special interest since they can be correlated with specific forms of behavior. But parallel with these studies of what one might term “pseudo-language” and the establishment of the “animal vocabulary,” an equally interesting aspect of the question is the study of the reactions of animals to sounds produced by man. My studies and those of my collaborators have led me to propose the terms “phonokinesis” and “phonotaxis” in order to classify, at least provisionally, the reactions of animals. These reactions which of course can appear with natural signals from the same animal species, are at times called forth by signals of another species. By an analytic procedure and for certain zoological groups such as the invertebrates and the lower vertebrates, we have succeeded in defining certain of the physical properties of sounds which provoke these reactions, permitting for example to attract or to drive away animals at a distance. The detailed study of different noises, used at times empirically for millenia by peoples close to nature, is extremely interesting and shows that certain types of hunting or fishing gear are actually generátors of acoustical signals to which certain species react. The forms of behavior in response to sound have more than theoretical interest; their deeper understanding may, a few years hence, lead to important applications in the protection of cultures.
Sonic Resonances of Mammalian Red Blood Cells
Authors: Ackerman Eugene
Published: September 2005

Studies of the breakdown rate of mammalian red blood cells in cavitating fields generated by 50 kc to 1 mc vibrations show three types of frequency effects. The focused sonic fields used are monitored by a pressure sensitive probe as well as by the tranducer current readings. At certain frequencies, the breakdown rate increases many-fold for fixed acoustic pressures in the exposure chamber. Also at these frequencies the apparent threshold for cellular disruption is lowered. This type of frequency effect is associated purely with the nature of the sonic field employed. A second type of effect occurs at other frequencies where the relative breakdown rates of erythrocytes of different species varies appreciably from their normal values. Since all the cells are exposed to the same sonic field, this variation appears to be caused by the particular cell type. A third effect is the variation of the relative threshold for cellular disruption of erythrocytes of different species. The relation of the two species dependent phenomona to surface resonance modes of the cells will be discussed. [This research was supported in part by Grant H-1769 from the National Heart Institute, National Institutes of Health, Public Health Service.]
Measurements of Viscoelastic Properties of Animal Tissues
Authors: Fitzgerald Edwin R. , Ackerman Eugene , Fitzgerald James W.
Published: September 2005

During the past few years increasing interest in dynamical mechanical properties has led to the development of many methods for dynamic measurements on rubber-like solids. One of these, the Fitzgerald apparatus, is based on complex impedance measurement of an electrodynamic transducer driving a sample in shear. The complex mechanical shear modulus and related properties can be determined over a continuous wide range in frequency, rigidity, and temperature. This paper presents preliminary measurements of complex dynamical mechanical properties of animal tissues made with equipment of this type. Samples (approximately 12 in. diam × 116 in. thick) of muscle were taken from a freshly killed cow. Measurements of the complex shear modulus were made on the tissue as a function of time, frequency, and strain.
Absorption of Intense Ultrasound in Live Animal Tissues
Authors: Hueter Theodor F.
Published: September 2005

Most data in ultrasonic absorption in tissues have been obtained in fresh excised tissue samples a few hours after death of the animal. Advanced techniques now allow one to make measurements in live tissues under physiological conditions. In these experiments such important factors as temperature, blood flow, muscle tonus may be controlled to a certain extent, and their influence on sound propagation can be studied. From the point of view of the basic mechanisms that may be involved both in the extraction of energy from a wave propagated through tissue and in the production of more or less reversible biological changes in tissue, absorption measurements over a wide range of acoustic intensities, up to 103 watts/cm2, are of interest. There is evidence that in some types of tissues the susceptibility of different tissue components to ultrasonic damage is related to the observed differences in the magnitude of the absorption coefficient. The significance of these studies will be illustrated by some preliminary results obtained in the use of focused ultrasound for neurosurgery. [Work sponsored in part by Air Force Contract AF 33(616)-2976.]
Technical Demands of Ultrasonic Dental Instruments
Authors: Balamuth Lewis , Kleesattel Claus
Published: September 2005

Before it was possible to produce an instrument which the dentist could safely use in his office, a number of physical and biological conditions had to be met. This paper presents a succinct account of the salient features of this development against the industrial background of precision ultrasonic machining from which it sprang. The physical performance of the ultrasonic drill itself will be discussed in the light of the demands of dentistry in removing tooth structure. From the biological point of view the effect of the drill on the human organism is paramount. A brief resumé will be given of the status of this important topic and its relation to the technical design problems encountered. A comparison of the ranges of frequency encountered in medical therapy and dentistry will be included.
Early Cancer Diagnosis through Ultrasonics
Authors: Kikuchi Yoshimitsu , Uchida Rokuro , Tanaka Kenji , Wagai Toshio , Hayashi Shuichi
Published: September 2005

We succeeded in obtaining ultrasonic echoes from human intracranial ventricles and brain tumors, not only through the dura mater during surgical operation, but also through the skull at preoperative and postoperative examinations. In these experiments, we used 1–5 megacycle ultrasound and A-Scope presentation. We found, among other things, that an echo from the ventricle wall pulsates slowly and rhythmically with synchronization to each heartbeat. Furthermore, we succeeded in detecting echoes from various abdominal organs and tumors through the skin, and found that the echoes reflected from the bowel move in correlation to bowel peristalsis. As the echoes are so clearly perceptible, we are now engaged in developing an “ultrasono-tomography” for a horizontal section of the human head or abdomen by plan-position indication; such a tomograph cannot be obtained by any other penetration-method including x-ray. In thoracic examination also, we have made achievements not only in ultrasonic diagnosis of breast tumor but also in the detection of fluctuating echoes from the heart which are considered valuable for studies on heart function. We also obtained echoes from lung tumors and from pneumonia-infected lungs. Another important finding is the decrease of ultrasonic attenuation in narcotized tissue. This finding will introduce a future possibility in quantitative measurement of the degree of anesthesia.
Filters and Matching Layers for Ultrasound
Authors: Tartakovsky B. D.
Published: September 2005

Methods of acoustical matching on the boundaries of different media by means of matching layers are studied theoretically and experimentally. Conditions are found giving the least transmission loss in a wide frequency band for a given number of layers. One- and two-layered elements made of different materials were tested experimentally. The resulting matching of ultrasonic lenses and prisms in the water increased the transmission coefficient to the value of 98–99%. The transmission coefficient of a steel plate covered with matching layers reaches 90%. Interference filter composed from three layers exert a wide-band filtering action on inclined rays and correct the form of the wave front.
Control of Noise (Especially Subaudible Noise) in a 2250-kva Diesel-Engine Power Plant
Authors: Fukushima Koki , Nimura Tadamoto , Kido Ken'iti
Published: September 2005

Many complaints were raised when a Diesel-engine power plant went into operation, because subaudible noises from the plant violently rattled doors and windows of houses located about 70 meters away. The plant had two 1100 hp diesel engines; the second engine was remodeled after the preventive measures were taken. Field measurements were carried out with only one engine in operation. The components of 28 and 8 cps of the noise were about 50 and 2 watts, respectively; the rattles were mainly caused by sound pressure of 28 cps which was near 95 db at the houses in question. The vibration through the earth was negligibly small. In the first step of the preventive measure, an exhaust silencer was remodeled and the component of 28 cps was reduced to below 75 db and the rattles disappeared. Then a new intake silencer was attached, since it was anticipated that the residual component of 8 cps (from the scavenging pump) would become harmful when three engines were operated in parallel. Audible noise was decreased by about 20 db. The sound pressure at various points inside of both silencers was recorded and frequency-analyzed to make clear the silencer action.
Sound Propagation and Thermodynamics of Irreversible Processes
Authors: Meixner Josef
Published: September 2005

A short survey of the general ideas of thermodynamics of irreversible processes is given. It yields a powerful and straightforward method for treating relaxation phenomena of many kinds. To the much more complicated kinetic theories it leaves only the task of determining numerical values for certain properties, such as relaxation times, of the considered material. An important application is the theory of absorption and dispersion in the propagation of sound. It gives a very simple and reliable approach to many results of interest and permits the unambiguous treatment, for instance, of the superposition of losses due to different causes such as internal transformations and transport phenomena. As an illustration the sound absorption in a dissociating gas is discussed. Some aspects arising with sound propagation in solid materials (including viscoelastic ones) are briefly mentioned.
Experimental Investigation of Relaxation Processes Arising When Ultrasonic Waves Pass through Liquids
Authors: Nozdrev V. F. , Sobolev V. D. , Sultanov A. M. , Bormosov U. N.
Published: September 2005

The article describes relaxation processes in acetates and formiates found experimentally. The investigation was carried on by impulse and optical methods at frequencies 1–30 Mc. In the interval of temperatures from −40°C to +30°C in methyl acetate, athyl acetate, methyl formiate, and athyl formiate, two complete regions of relaxation are found in every substance. In athyl acetate an investigation of ultrasonic waves absorption along the line of saturation was carried on, including critical and supercritical regions: one in the interval of temperatures 160°–210°C, the other in the critical region of the liquid phase of athyl acetate. For every relaxation region the time of relaxation and frequencies corresponding to the centre of relaxation were determined and volumetric viscosity of thermal capacity, relating to internal and external degrees of freedom and heats of activation were calculated. In conclusion, possible mechanisms of experimentally established relaxation processes are discussed.
Vibration Treatment of Metals
Authors: Seemann H. J.
Published: September 2005

In the treatment of solid and liquid metals with ultrasound, the electrodynamic method offers the advantage that the treated material itself constitutes the sound transducer; as a result, transducer components otherwise necessary are eliminated. In the treatment of melts, one is faced with a compound vibration system consisting of the crucible and the melt itself. Theoretical relationships for the maximum efficiencies attainable with the electrodynamic method are reported, and conclusions are drawn regarding optimum design. In addition to the damping factor of the melt, the damping factor of the crucible material has an important influence on the efficiency which can be attained. Investigations in the area constitute, therefore, an important pre-condition for the further development of the electrodynamic method. For this purpose an installation has been developed that makes it possible (for suitably shaped resonators) to measure the resonance frequency and the damping factor as a function of temperature and amplitude. The excitation of the test samples is accomplished electrodynamically; amplitude measurements are carried out by a capacitative method. Experimental results with a variety of metalic materials at temperatures up to 1000°C are reported. The installation can also be used at the same time for vibration treatment of the test samples. In conclusion, mention is made of other equipment developed in accordance with a similar principle, particularly suited for exact measurements of damping over a broad range of frequency, amplitude, and temperature.
About the Penetration of Ultrasonic Energy through Thin Air Lines
Authors: Tarnóczy Thomas H.
Published: September 2005

One of the basic phenomena of the ultrasonic defectoscopy is the reflection of ultrasonic energy from air enclosures which may be penetrated by ultrasonic waves only if the air layer is exceedingly thin. According to a well-known formula derived by Rayleigh which is adopted and referred to by all well-known handbooks, an ultrasonic beam of, e.g., 2.5 Mcps frequency traveling in glass should be reflected nearly completely by an air layer of thickness of 10−5 mm or more. This is not, however, in conformity with experimental results to be given below. Experiments were carried out with high-polished glass plates. The thickness of the air layer between the glass plates was determined by optical means with interference fringes. It has been found that the ultrasonic beam of 2.5 Mcps frequency penetrated without energy loss through an air layer even of 4 × 10−4 mm thickness. The investigations at several frequencies and with different thicknesses displayed a difference of two orders of magnitude between the penetrating thresholds found experimentally and those computed from the Rayleigh formula. Air layers of about 10−4 mm thickness between glass plates reflect no ultrasonic energy in the frequency range of 0.5 to 2.5 Mcps.
Exact Solution of Wave Scattering by Irregular Surfaces
Authors: Marsh H. W.
Published: September 2005

The problem which Lord Rayleigh considered (reflection from a corrugated surface) and which several have treated approximately in recent years, is developed in a general form. An exact solution is obtained by extensive use of Wiener's generalized harmonic analysis. This solution is readily extended to include electromagnetic waves, general elastic waves, and nonplanar nonharmonic sources. Numerical evaluation of the formulas is considered by means of an operational representation, from which various types of successive approximations can be constructed. Applications can be of special interest in scatter communications and in underwater sound transmission and reverberation. Experimental evidence from the latter area indicates that a rather detailed theory is necessary for an adequate account of the situation.