bluuebunny/crossref_metadata_2025 huggingface dataset:
Some Variables in Audio Spectrometry
Authors: Benson R. W. , Hirsh Ira J.
Published: September 2005

Measurements of the long-time average spectrum of speech are reported with the purpose of pointing out the roles of several variables. Three different sampling times of three different types of speech material are analyzed with several band-width intervals. The speech of five young men and five young women contributes to the averaged results.

No significant differences are found among the three types of speech material nor among the three different sampling times of 30, 60, and 90 seconds. Octave, half-octave and equal-mel intervals appear to yield the same results. The only important difference between male and female speech appears in the octave 75–150 cps. The shape of the long time spectrum remains fairly constant from person to person while the over-all level contributes most to interpersonal variability. A discussion of the meaning of “over-all level” in this and previous reports is given.

A relatively simple system for obtaining these measurements is described.
Axially Symmetric Vibrations of a Finite Isotropic Disk. III
Authors: Aggarwal Ram Ratan
Published: September 2005

Graphically solving the frequency equation, the different real values of α for the same frequency have been obtained. When three such values of α exist, three independent boundary conditions have been made to satisfy at the curved surface of the disk. The resonant frequencies for which these conditions hold good have been evaluated, and the corresponding displacement curves for the vibrating faces of the disk have been compared with the experimentally obtained curves for the barium titanate disks. A test for the validity of this method has been provided by comparing the residual stresses at the curved surface with the compressional component of the stress at the center of the disk.
Surface and Volume Sources of Vorticity in Acoustic Fields
Authors: Medwin Herman , Rudnick Isadore
Published: September 2005

When a sound beam passes through a viscous fluid, vorticity is generated as a second-order effect and streaming results. The work of Eckart, which considers the vorticity generated in the medium, is extended to consider “surface sources” of vorticity which appear when the sound beam makes contact with a solid, restraining surface. As in the Eckart work, the dynamic shear viscosity coefficient μ is assumed to be independent of the density changes which accompany a sound wave. However, the effect of a density dependent bulk viscosity coefficient is investigated, and it is found that the sources of vorticity are unaffected. Previous work on streaming by other authors is discussed and reconciled, and it is shown that in many cases the predominant sources of vorticity are the “surface sources.”
Dependence of the Primary Pfeifenton (Pipe Tone) Frequency on Pipe-Orifice Geometry
Authors: Anderson A. B. C.
Published: September 2005

A derivation is presented of an expression relating the frequency of the primary Pfeifentöne, produced in a column of moving gas, to the geometry of the pipe-orifice combination which the Pfeifenton oscillations occur. The Pfeifentöne appear to be initiated in, and by the gas discharging continuously through the orifice. A comparison is made between the results obtained with this expression and experiment. Good agreement is shown between the values of the primary Pfeifenton frequencies predicted by the relation and the values obtained by experiment. These results apply for a thin orifice plate, and are expressed in nondimensional form.
On the Forces Due to Acoustic Wave Motion in a Viscous Medium and Their Use in the Measurement of Acoustic Intensity
Authors: Borgnis F. E.
Published: September 2005

The hydrodynamic flow associated with acoustic waves in viscous fluids is usually regarded as a disturbing effect in measuring acoustic intensities by radiation pressure. It is shown, however, by a simple application of the hydrodynamic momentum theorem, that the sum of the forces due to acoustic radiation and to the hydrodynamic flow, when a beam of plane waves is incident upon an absorber, is independent of the absorption in the medium and (within considerable limits) of the distance between the acoustic source and the absorber, if certain conditions are observed. This makes it possible to measure, in a simple way, the intensity of an acoustic beam at the source by measuring the total force due to radiation and flow without knowledge of the absorption coefficient of the fluid and without the use of thin screening films, which are commonly applied in order to eliminate the flow.
The Absorption of Ultrasonic Waves in Benzene Solutions of Methyl Metacrylate in Different Polymerization Stages
Authors: Wada Yasaku , Shimbo Sotoshi
Published: September 2005

Measurements of ultrasonic absorption are performed by a pulse method in benzene solutions of nine sorts of methyl metacrylate specimens of different intermediate polymerization stages, including the monomers and the final product of polymerization. In the case of the monomer, the absorption decreases rapidly with concentration. Solutions of the polymers without unreacted monomers show a similar absorption coefficient to that of benzene itself, in spite of the remarkably high viscosity. For the intermediate products the fraction of polymers is estimated from the absorption coefficient, assuming that only the unreacted monomers have influence on the absorption. For the solutions of the specimens in which the fraction of polymers is fairly large, the above assumption requires some modifications. In this case some parts of unreacted monomer molecules seem to be enclosed in the network structures of polymers and deprived of their influence upon the absorption.
Large Amplitude Vibrations of Rods and Tubes at Audio-Frequencies
Authors: Brennan J. N.
Published: September 2005

A new apparatus for investigation of sound propagation constants for large amplitude audio-frequency vibrations in metals is described. One novel feature of the apparatus is the use of tuned resonant supports that are tilted with respect to the specimen. The tilting minimizes the tendency to chatter due to the Poisson effect. Because the supports are driven at their resonant frequency, large amplitudes may be achieved without the occurrence of an energy loss due to slipping at the contact surfaces between supports and test specimen. The error caused by energy dissipation due to the internal friction of the support is, in most cases, negligible. In those cases where it is not negligible, it can be closely estimated and corrected for. Auxiliary equipment permits determination of the resonant frequency of the specimen to better than 1/1000. The total error in the determination of the logarithmic decrement varies between 2 percent and 5 percent.
Acoustical Vibrations of Rings
Authors: Kaiser Elmer R.
Published: September 2005

The frequencies of tones when metal rings are struck in radial and axial directions have been investigated in a variety of steel and bell-metal rings.

The classical formulas relating frequency with ring dimensions and physical properties of the materials compare closely with actual measurements except for thick rings. The fundamental tone is predominant in the smaller rings but the fundamental fades and the overtones predominate as the rings increase in diameter and decrease in width and thickness.

Comments are given on musical properties of rings which may be promising but which have not been fully explored.
Effect of Losses on Transmittivity of Plates
Authors: Fay R. D.
Published: September 2005

The theory of the transmittivity of immersed plates is extended to include the effects of losses associated with shear waves. The loss is computed for the transmission maxima which occur for five modes of vibration and is compared with observations made at a fixed frequency of 112 megacycles. The general agreement is is good but not within the experimental error for all of the five modes. The value of the loss factor, which was determined to give agreement in a simple case, is difficult to appraise without data at other frequencies.
Piezoelectric Well Hydrophones
Authors: Vogel C. B.
Published: September 2005

Information about the velocity of sound in the earth is normally obtained by shooting dynamite at the surface and measuring traveltime to a detector suspended by cable within a deep well. In such measurements errors are sometimes introduced by noise transmitted down the cable. A piezoelectric hydrophone for use in deep wells was constructed and has been useful in discriminating against such noise. Hydrophones are also well suited for tandem use in wells to measure interval velocities. Their substantially aperiodic response facilitates resolution of shear waves, and their relatively constant coupling to the earth makes possible measurement of attenuation. Several types of hydrophone are described and the results of some field experiments are discussed.
A Compact, Versatile Filter-Type Sound Analyzer
Authors: Scott H. H. , von Recklinghausen D.
Published: September 2005

Availability of a pocket-sized miniature sound level meter meeting all ASA standards has created demand for a small, equally portable sound analyzer as a companion instrument. The analyzer described surpasses all applicable ASA standards. The separate high and low cut-off filters may be adjusted independently, and the noise pass band may be locked in any band width which is an integral multiple of 12 octave, from 12 octave through the standard 1 octave band, etc. The range of the filters extends one octave lower and one octave higher than the ASA standards. These features permit considerable added precision and flexibility of analysis.

For protection and ease of carrying, the instrument is housed in a leather case similar to those used for amateur motion picture cameras. The case is equipped with a shoulder strap which allows the analyzer to be carried about easily while in use. It can also be used as a general purpose adjustable filter or as a wide-range amplifier.
On the Band Width of Vowel Formants
Authors: Bogert B. P.
Published: September 2005

Measurements were made on a sample of vowel utterances, by male talkers, of the band widths of the first three formants. It was found that the band width was essentially constant and independent of the particular vowel. The mean values for bars 1, 2, and 3 were 130, 100, and 185 cps. respectively. Ten percent of the 300 band widths measured were less than 90 cps and ten percent greater than 260 cps.
The Mechanism of Generation of Infrasound by the Ocean Waves
Authors: Daniels Fred B.
Published: September 2005

A detailed explanation is given of a mechanism by means of which the ocean waves may generate sound waves.
Acoustic Birefringence of Liquid Polystyrene
Authors: Bennett G. S. , Hall D. A.
Published: September 2005

Preliminary data of an extended program on acoustic birefringence are presented, showing the existence of such birefringence in poly-alpha-methyl-styrene at a frequency of 1000 kc/sec, and that a linear relation exists between the magnitude of birefringence and transducer current.
High-Frequency Auditory Response of a Bottlenosed Porpoise, Tursiops truncatus (Montagu)
Authors: Schevill William E. , Lawrence Barbara
Published: September 2005

Conditioned responses of a bottlenosed porpoise (Tursiops truncatus) showed its upper frequency limit of auditory response to be about 120 kc. The analogy of human bone-conduction ultrasonic “hearing” is considered. Some aspects of phonation and echo-location are commented on.
Transformer Couplings for Equivalent Network Synthesis
Authors: Bauer Benjamin B.
Published: September 2005

It may be shown that regardless of the type of analogy chosen (“impedance” versus “mobility”), disconformity will be encountered in synthesizing the equivalent network of a mechano-acoustic array. A method is described employing transformer couplings for getting around this difficulty. As a result, it becomes possible to construct equivalent circuits of mechanical arrays in a simple and straightforward manner by the method of impedance analogy. Similar benefits are achieved for the method of mobility analogy in the synthesis of equivalent circuits of acoustic arrays. Equivalent networks for certain mechano-acoustic arrays which cannot be conventionally synthesized become feasible through this method.
Equivalent Network Representations for Solid and Mercury Delay Lines
Authors: Dairiki S. , Lawrence T. E. , Mapleton R. A.
Published: September 2005

An equivalent network representation is derived for mercury and solid delay lines. A transfer function that relates output voltage to input voltage is the quantity selected to represent the delay line, and this transfer function is derivable from a matrix equation. Mercury and solid delay lines are compared in terms of the gain band width product of the delay line. The comparison extended to include factors not present in the circuit representation. Other topics discussed are third-time-around signals, acoustic transformers, glued crystals, input impedance, wave propagation, and diffraction. The final selection between solid and mercury delay lines is determined by the specific application.
Acoustic Impedance of Rectangular Tubes
Authors: Wood John K. , Thurston George B.
Published: September 2005

An expression for the acoustic impedance of a section of infinite parallel planes is derived. Measured values of the impedance of long narrow rectangular tubes show good agreement with this theory when an appropriate end correction is used. The theory compares favorably with impedance measurements on short rectangular tubes or slits even when the effective length of the slit is 3.7 times the geometric length.
End Corrections for a Concentric Circular Orifice in a Circular Tube
Authors: Thurston George B. , Wood John K.
Published: September 2005

The results of an experimental investigation of the end corrections for acoustic resistance and acoustic inertance for a concentric circular opening in a partition in a circular tube are presented. The end corrections are taken to be that length which must be added to the geometrical length of the orifice when introduced into an expression for the acoustic impedance. This expression can be derived on consideration of a tube of infinite length failed with a viscous, incompressible fluid. Used in this manner, the two end corrections are found to take on the same values, these values agreeing with those derived for inertance on the basis of the mass contribution due to higher order waves in the tube, treating the orifice as a plane piston source. Graphical criteria for the onset of measurable nonlinearity are presented.
Barium Titanate Admittance-Temperature Characteristics
Authors: Lane A. L.
Published: September 2005

There is a large amount of data in the literature describing the temperature effects on the dielectric and piezoelectric constants of barium titanate. This paper, however, describes the temperature effects on the admittance of barium titanate transducers operating near resonance. Both “pure” and leaded ceramic mixtures are compared over the 0–20°C temperature range. Some results of calcium additives are also given. Despite extreme fluctuations of the dielectric and piezoelectric constants over this temperature range, it is possible at certain frequencies near resonance for the transducer conductance and susceptance to vary very little with temperature. Water admittance circle diagrams and power-frequency curves—all plotted at different temperatures—are presented and analyzed from an equivalent circuit point of view. One of the significant conclusions derived from this experiment is that the radiated power of even a pure ceramic transmitting transducer, properly matched to its source at this optimum frequency, will remain maximized regardless of the temperature variation. While the barium titanate temperature effects were studied for given underwater transducers, the information outlined is of value to anyone encountering temperature variations in a resonant barium titanate ceramic.
Optimum Directivity Patterns for Linear Point Arrays
Authors: Pritchard R. L.
Published: September 2005

The sharpest major lobe of a directivity pattern due to a linear array of equally-spaced point elements is achieved when the elements are excited in such a manner that all minor lobes in the pattern have the same relative amplitude. Methods of producing such equal-minor-lobe patterns originally given in the radio literature by C. L. Dolph and by H. J. Riblet are summarized briefly in this paper. In particular, the synthesis method indicated by Riblet is described in general terms, and the effect of the element spacing is discussed in detail. Included in this discussion is the subject of super-directivity. Results of numerical calculations based on these methods are presented as families of curves showing the relationships existing among angular width of the major lobe, relative amplitude of the equal minor lobes, directivity index, and number and spacing of the elements in the array for 5–13 odd numbers of elements. In addition, the synthesis methods are extended to compensated, or steered, arrays.
The Concept of Radiation Scattering and Its Application to Reinforced Cylindrical Shells
Authors: Junger Miguel C.
Published: September 2005

This paper presents an approach which permits the analysis of elastic scatterers embodying complicated structural characteristics. Such problems cannot be investigated by means of the methods previously applied to the study of the scattering action of simple elastic bodies.

The scattered wave pressure produced by elastic scatterers may be expressed as the sum of two terms, one representing “rigid body scattering,” i.e., the scattering which would exist if the scatterer were rigid and immobile, the other representing “radiation scattering,” which is associated with the sound radiated by the scatterer vibrating under the effect of the incident wave pressure. These two terms are derived here for three important cases.

The problem is now reduced to one in elasticity, specifically to the problem of solving the equations of motion of the elastic system for its forced response. The scattering pattern can then be computed. This procedure is applied to a scatterer in the form of a cylindrical shell reinforced with regularly spaced septa.
Acoustic Streaming Equations: Laws of Rotational Motion for Fluid Elements
Authors: Nyborg Wesley L.
Published: September 2005

It is shown that the third-order differential equations commonly used in connection with acoustic streaming are special approximations to the law of rotational motion for a fluid element. An expression is derived for the torque exerted by stresses on a spherical element of fluid, about its center of gravity. The average torque in a steady-state sound field consists partly of (1) a sonic torque, exerted by the sound field and partly of (2) a viscous torque due to the induced steady flow. Expressions are also derived for the instantaneous rate of increase of moment of momentum of a spherical fluid element, due to angular acceleration, expansion and shearing. Interpretation is given to individual terms in various streaming equations. In general, any field consisting of superposed elementary waves will give rise to a nonzero distribution of sonic torque. In the special case of a directional source the distribution is similar to that of the gradient of the magnitude of radiation pressure.
A Study of the Building Blocks in Speech
Authors: Harris Cyril M.
Published: September 2005

Identification of the information-bearing elements of speech is important in applying recent thinking on information theory to speech communication. One way to study this problem is to select groups of building blocks and use them to form standardized speech which then may be evaluated; a method having the advantage of simplicity is described. Individual recordings of the building blocks were made on magnetic tape and then various pieces of tape were joined together to form words. Experiments indicated that speech based upon one building block for each vowel and consonant not only sounds unnatural but is mostly unintelligible because the influences on vowel and consonants are missing which ordinarily occur between adjacent speech sounds. To synthesize speech with reasonable naturalness, the influence factor should be included. Here these influences can be approximated by employing more than one building block to represent each linguistic element and by selecting these blocks properly, taking into account the spectral characteristics of adjacent sounds so as to approximate the time pattern of the formant structure occurring in ordinary speech. There is no a priori method of determining how many building blocks are required to produce intelligible standardized speech. This can only be determined from experiments involving listening tests. Such tests are described.
A Probe Tube Method for the Transfer of Threshold Standards between Audiometer Earphones
Authors: Corliss Edith L. R. , Burkhard Mahlon D.
Published: September 2005

To establish threshold standards for various types of earphones, from a set of threshold standards that has been determined for one particular type of earphone by a hearing survey, an empirical relationship must be found giving the sound pressures in the calibrating coupler corresponding to equal sound pressures in the ear. This has previously been accomplished by means of loudness balancing between earphones. The method described in this paper makes use of a direct probe measurement of the sound pressure developed by an earphone at the entrance to the ear canal. The experimental process is described and the results of tests to establish the equivalence of the probe method and loudness-balancing are given. In addition, several of the conditions under which loudness-balancing is carried out were investigated by the probe method. Equal loudness sensation was found to correspond to equal sound pressures at the ear, within the limits of experimental error.
Note on Thermal Relaxation of CO2 in Presence of H2O and D2O Molecules
Authors: Sette D. , Hubbard J. C.
Published: September 2005

The large effect of water vapor on the thermal relaxation of carbon dioxide has not yet been satisfactorily explained. In order to have more information on the characteristics of the phenomena involved, we have tried to compare the effects produced by H2O and D2O molecules on the relaxation of carbon dioxide by determining the changes in the dispersion curve. Commercial CO2 was used. The shape of the dispersion curve shows a departure from the single relaxation time theoretical curve, which increases with the H2O and D2O content. If this result is confirmed by others, it would indicate that these impurities strongly affect the mechanism of energy transfer among CO2 molecules. The objection, however, can be made that we have assumed that during the experiments the water absorbed on the walls of the interferometric system did not vary. In any case the comparison between the effects of H2O and D2O can be made. We find the values 1.86 and 2.50 for the respective ratios of the transition probabilities in the collision H2O-CO2 and D2O-CO2, the two values being determined from two different sets of mixtures. An approximate theoretical calculation of the ratio of the transition probabilities considering only the mass change of the added impurity, gives a value 1.25. The same ratio would instead be less than unity if the important process were the energy exchange between rotation of H2O or D2O molecules and vibration of CO2 molecules. The latter mechanism does not seem therefore to be responsible for the large decrease of relaxation time when water vapor is added to carbon dioxide.
The Near Field of a Helmholtz Resonator Exposed to a Plane Wave
Authors: Ingard Uno
Published: September 2005

The near field of a spherical Helmholtz resonator exposed to a plane wave is computed and shown to be in good agreement with measurements. Comparison is made with the near field of a resonator terminating a cylindrical tube. A discussion of the calculation of the dissipation in the resonators is included.
Scattering of Underwater Plane Ultrasonic Waves by Liquid Cylindrical Obstacles
Authors: Bezuszka Stanley J.
Published: September 2005

This paper is a report of a theoretical investigation of sound scattering from liquid cylindrical obstacles immersed in water following closely the conditions prevailing in the previous experimental work of Tamarkin, Bauer, and others. An incident plane wave being assumed, series solution was found for the total scattered wave. Numerical calculations were carried out using parameters approximating those of Tamarkin's experiments (radius of obstacle, 0.635 cm; sound frequency, 1.145 mc/sec; wavelength, 0.13 cm). A series of scattering patterns, confined principally to the forward direction for an angular spread of about 14° (with the obstacle at the vertex) were calculated for eight liquids, chosen to give a spread of kia values (ki the wave parameter inside the liquid and a the radius) between 26.0 and 41.0. The results of this theoretical investigation confirm the experimental findings that for the liquids examined the scattering is diffractive and lies in the zone between the geometrical region and the region of Rayleigh scattering. Quantitative comparisons are made between the theoretical and experimentally plotted results with special emphasis on the experimental resonance curve and its theoretically computed counterpart.
The Measurement of the Velocity of Sound in Liquids
Authors: Graham G. M.
Published: September 2005

A new technique for the measurement of sound velocity in liquids has been developed, which is especially suited to frequencies in the range from 0.5 to 5 mc. It employs an approximation to the boundary conditions in Guptill's closed form solution for the radiation field between two infinite walls with a piston source in one wall.

Measurements have been made in distilled water at 0.6 and 7.6 mc with an error of less than 0.2 percent in the low-frequency measurements. No dispersion is indicated to the order of the experimental error, in the temperature range from 10 to 20°C.

A description of the apparatus is given.
Distortion in Phonograph Reproduction
Authors: Roys H. E.
Published: September 2005

Three distortion methods, the harmonic, the SMPE intermodulation, and the CCIF (a difference frequency), have been studied, mainly on a theoretical basis, as a means of analyzing distortion encountered in phonograph reproduction. The harmonic method is somewhat difficult to apply and some of the harmonics may be beyond the range of the system. The IM has been used in the past with considerable success, and appears to be a good method of analyzing tracing distortion. The difference frequency methods appears to be somewhat insensitive to tracing distortion but offers theoretical advantages in that the analysis may be made right up to the cut-off frequency of the system, practically it is somewhat difficult to apply.
Electro-Optic Sound-on-Film Modulator
Authors: Carpenter Robert O'B.
Published: September 2005

The electro-optic effect in the crystal ammonium dihydrogen phosphate provides a high-speed light valve with ruggedness, long life, and ease of handling not possessed by the similar Kerr effect in liquids. In this paper the design of a practical sound reproduction unit for making variable density 35-mm tracks will be described. Frequency response of the light valve is flat to over 20 000 cycles, the over-all system being limited to about 10 000 by the slit-width film speed effect. Tests of distortion and sound quality in the sound tracks obtained are described.
A Practical Noise Reduction Treatment for Diesel Engines
Authors: Ancell James E.
Published: September 2005

A noise reduction treatment for Diesel engines is described, which, though not the ideal approach to the problem, is practical, economical, and applicable to both new engines and those already in service in the field. This treatment was designed making use of the results of a survey of the relative importance of the various noise sources on the Diesel engine. The treatment consisted of a set of sheet metal covers, lined internally with acoustical absorbing material, which were mounted directly over the noisy areas of the engine by means of built-in vibration isolation. Noise reductions for the direct sound were at least 8 to 12 db, which were observed at a distance of one foot from the engine. The total loudness of the engine noise at six feet was reduced from 320 to 220 sones. This is a substantial improvement with regard to voice communication in the immediate vicinity of the engine. The speech interference level of the engine noise at six feet was reduced from 87 to 82 db.
A New Integral Ratio Chromatic Scale
Authors: Simonton Theodore E.
Published: September 2005

The IRC scale presented herein is neither a Pythagorean scale, nor a just scale, nor an equally tempered scale, as those terms are defined in Acoustical Terminology, but it is shown to possess the major advantages of all three. In a D-D octave, all of the notes are interconnected by a perfectly symmetrical arrangement of just fourths, and the note frequencies of the octave containing C4=256 cps are 144, 153, 162, 171, 180, 192, 204, 216, 228, 240, 256, 272, 288. A distinguishing characteristic of the IRC scale is that four ascending octaves commencing with a C embrace exactly four successive just fifths (C-G-D-A-E) immediately followed by four successive just fourths (E-A-D-G-C). The IRC scale, like the conventional just scale, is based on alternately conjunct and disjunct just tetrachords, but the IRC tetrachord intervals are the smoothly decreasing ones of 9:8, 10:9, 16:15, instead of the just scale irregularly arranged intervals of 16:15, 9:8, 10:9. The major and minor tones of the IRC scale are divided by the known superparticular proportion, giving, in addition to the just semitone 16:15, semitone ratios of 17:16, 18:17, 19:18, and 20:19. These five semitones are located in smoothly progressing order, forming three perfect harmonic series embracing a just major third, fourth, and minor third. The IRC scale is shown to be superior to the just and Pythagorean scales and to excel the equally tempered scale in modulation. If, as the author believes, Helmholtz was correct in his thesis that just intervals are musically better than equal tempered intervals, then the IRC scale is also superior to the equally tempered scale, possessing, among many other advantages, greater ease of tuning pianos and organs, and the ability to tune pianos, violins, and cellos exactly alike and play them in the same temperament.
Masking of Speech by Bands of Noise
Authors: Hirsh I. J. , Bowman W. D.
Published: September 2005

The threshold of intelligibility for two-syllable (spondee) words was measured in the presence of different levels of masking noise. Twelve different bands were used, one (20 to 6600 cps) approximating a white noise and each of the other eleven containing a band of frequencies corresponding to a pitch interval of 250 mels. The absolute thresholds for these bands were also measured to permit transformation of the noise level from an absolute scale to a scale of sensation level.

The results show linear relations between the masked threshold and noise level for white noise and for bands of noise between 394 and 1420 cps. For noise bands above 1420 cps this masking function is accelerated, while the two bands below 394 cps yield sigmoid masking functions. Of the bands used, the most effective contained frequencies between 670 and 1000 cps. The signal-to-noise ratio at threshold for this band was about −25 db while for bands above or below it became gradually smaller than −25 db, reaching a minimum of −60 db for the highest and lowest bands. White noise was more effective than any band, giving a threshold S/N ratio of −15 db.
Acoustic Trauma in the Guinea Pig
Authors: Davis Hallowell
Published: September 2005

The ears of anesthetized guinea pigs were exposed to intense tones of 135, 545, 2000, or 8000 cps at sound pressures (at the eardrum) from 138 to 148 db re 0.0002 microbar. The electrical output was recorded by differential intracochlear electrodes before, during, and after the exposures.

The injury caused by 8000 cps centers in the basal turn, by 2000 cps in the second turn, by 500 and 185 cps in the third and fourth turns of the cochlea. No single tone, at the intensities and durations employed, injured all of the cochlea.

The “threshold” and also the maximum voltage of the cochlear microphonic are valid indices of the anatomical injury seen under the microscope if the proper test frequencies and positions of electrodes are used.

The destructiveness of a tone does not depend on its frequency. Equally severe (probably permanent) injuries were produced by a one-minute exposure at all four frequencies tested when the intensity level was about 144 db at the eardrum.
Observation of a Further Tartini Pitch Resulting from a Physical Sinusoid Added to a Tartini Pitch
Authors: Meyer Max F.
Published: September 2005

The sinusoidal air waves 9+6+2, shaking the skull, produce not only the commonly expected Tartini pitch 3 but also the rather surprising pitch 1, but none other. However, these occur only within a total range that barely encompasses the human voice. For this restriction a plausible evolutionary hypothesis suggested. The mathematical theory for the pitches 3 and 1 is furnished on the basis of a strictly hydraulic, i.e., nonvibratory, function of the cochlear phragma.
Acoustic Spectrum Terminology
Authors: Heindsmann T. E.
Published: September 2005

Terminology used to describe line spectra is discussed. It is proposed that “discrete component” be used to describe the individual elements comprising a line spectrum and that “tonal component” be used to describe its auditory equivalent.

Editor's Note: The kind of confusion mentioned in this letter may result from failure to distinguish between cause and effect. See note in Sec. 6 of the American Standard Acoustical Terminology Z24.1–1951, in regard to such words as tone, which “are used to refer both to the production of sound waves and to the nature of the associated sensation. There is often not complete correspondence between the two; which of the two meanings is desired must be made clear from the context or units of measurement.” It may be remarked, also, that in acoustics it is the sound pressure which is commonly measured directly—only very rarely the sound intensity.

American Standard Acoustical Terminology Z24.1–1951 is about to be revised. Suggestions for the improved wording of these definitions are welcomed. They may be addressed to the Chairman of Writing Group Z24-W-5, R. W. Young, U.S. Navy Electronics Laboratory, San Diego 52, California.
A Physical Approach to the Generalized Loudspeaker Problem
Authors: Mawardi Osman K.
Published: September 2005

Most analyses of loudspeaker performances are based primarily on the consideration of details of the electromechanical coupling. This approach has proved too inadequate to handle loudspeaker radiation problems. An attempt has been made to set up a general expression relating the free field sound pressure at a remote point to the electrical signal applied to the loudspeaker terminals. This relation in the form of an integral equation is solved exactly for a loudspeaker of circular shape. By means of the solution of the integral equation it appears possible to apply to this problem methods analogous to circuit analysis techniques which represent the transfer function of the system in terms of its characteristic points in the complex frequency plane.
The Effects of Viscosity and Heat Conductivity on the Transmission of Plane Sound Pulses
Authors: Knudsen John R.
Published: September 2005

The dissipative effects of viscosity and heat conductivity are studied here in connection with the flow of a compressible fluid in a parallel channel or tube. Two kinds of waves or pulses are considered and the distortion from the customary square wave calculated. An observer at a fixed point on the channel and two traveling with the wave are seen to give information as to the order of decay or dissipation of the wave with increasing time.
Attenuation of Repeated Shock Waves in Tubes
Authors: Werth Glenn C. , Delsasso Leo P.
Published: September 2005

As very intense sound waves propagate, the wave-shape changes into one of saw-tooth form producing abrupt rises in pressure called shock fronts. This waveform distortion into so-called repeated shock waves is caused by the nonlinearity of the medium. The objective of this study has been to obtain experimental facts relative to the propagation of repeated shock waves in tubes and to compare these with existing theory. An intense sound source was constructed and appropriately coupled to a series of measuring tubes. Observations were made on the velocity and attenuation of fully developed shock waves for a variety of gases, for pressure amplitudes as great as 0.25 atmosphere, and for a fundamental frequency range of from 400 to 1200 cycles per second.

The data were compared with previous theoretical work, particularly that of Professor Rudnick. Agreement was found in the general aspects of the theory; the exact magnitude of the effect remains to be explained. This discrepancy between theory and experiment may be resolved by considering in greater detail the absorptive processes involved.
Velocity of Sound in Glycerol
Authors: Fergusson F. A. A. , Guptill E. W. , MacDonald A. D.
Published: September 2005

A method of measuring the velocity of sound in liquids by determining the critical angle for the sample and a known liquid is described. The method has been used to measure the velocity of sound in glycerol. The velocity at 7.5 mc and 25°C is 1964±10 m/sec. The velocity for glycerol-water mixtures is also reported.
A Technique and a Scale for Loudness Measurement
Authors: Garner W. R.
Published: September 2005

A method of loudness scaling is presented for obtaining a true ratio scale of loudness. Two separate loudness functions are required, one based on equisection judgments and the other based on fractionation judgments. Interrelation of these two scales allows determination of all constants necessary for a ratio scale. The method provides validation of the assumptions underlying its use. Experimental data are also presented which show that (1) the method is valid for individual observers; (2) differences between loudness scales of different observers are considerably reduced with the method; and (3) the loudness function obtained with this method is much flatter than the standard scale now used. It is then shown that this new loudness scale is in better agreement with other data on equal loudness intervals than the standard scale. It is also shown that this scale is in agreement with monaural-binaural loudness data and data on loudness of multicomponent tones.
A Cortical Test of Auditory Function in Experimentally Deafened Cats
Authors: Hind Joseph E. , Schuknecht Harold F.
Published: September 2005

This investigation was designed to study the correlation between behavioral audiograms and recordings of cortical potentials in experimentally deafened cats. Cortical thresholds were defined as the minimum intensity of tone pulses capable of eliciting strychnine potentials. Curves expressing threshold elevation with respect to normal animals were prepared for both the behavioral and cortical responses; these graphs were proportioned in accordance with the anatomical frequency scale and displayed above charts of cochlear histopathology. A mean value of 3.0-db greater loss for the behavioral test was obtained when the differences between corresponding pairs of behavioral and cortical threshold elevations at all frequencies in all animals were averaged algebraically. The standard deviation of this collection of threshold differences was 17.4 db. Hypotheses advanced to explain the discrepancies include the effects of: (1) uncontrolled physiological variance in the cortical recording procedure; (2) the fact that the absolute cortical threshold exceeds the absolute behavioral threshold by 30 to 40 db; (3) the use of an abrupt onset for the cortical tone pulse. It is concluded that the cortical test is the most practical and descriptive electrophysiological indicator of threshold cochlear function presently available although it cannot be considered a precise substitute for behavioral threshold determinations.
Characteristics of Radiating Variable Resonant Frequency Crystal Systems
Authors: Welkowitz Walter , Fry William J.
Published: September 2005

Calculations based on the usual one-dimensional theory of piezoelectric crystal systems have been carried out for several particular variable resonant frequency crystal systems radiating into water. Curves are presented showing the (1) power output as a function of frequency for operation both on and off resonance, (2) resonant frequency shift as a function of backing length, and (3) relative band width as a function of frequency. The validity of certain approximations is checked so that the operating characteristics of systems made up of different materials can be quickly estimated. The curves indicate that a variable resonant frequency system of crystals all of equal free-free resonant frequency operating with an allowable power variation for fixed applied field strength of 2:1 can have a continuous variation of resonant frequency of about 2.3:1. A system half the crystals of which have twice the free-free resonant frequency of the others for the same allowable field strength variation can operate over a frequency range of about 5.3:1.
Self-Maintained Oscillations of the Jet in a Jet-Edge System. I
Authors: Nyborg Wesley L.
Published: September 2005

A theory is presented for the self-maintained transverse oscillations which arise in a low-velocity jet as it plays upon an obstacle, thus generating edge tones. It is assumed that transverse forces act on each particle of the jet as it travels toward an obstacle, and that this force is due to “sources” of hydrodynamic origin localized near the obstacle. The law of motion is set up in the form of an integral equation involving unknown functions for the force field. It is shown that a number of important properties of jet-edge systems, and of the edge tones they produce, can be deduced from the equation, even for highly simplifying trial assumptions about the unknown functions.
On the Dissipative Viscoelastic Constants of Higher Order
Authors: Knopoff Leon
Published: September 2005

The limitations imposed upon the usual elastic and viscoelastic constants are reinvestigated. Defining viscoelastic properties of a higher order, it is found that methods which have been used for the first-order quantities are insufficient to determine relationships between the higher-order constants. Necessary but non-sufficient criteria are arrived at by means of arguments involving energies in dissipative processes.
On the Theory of Sound Reflection in an Open-Ended Cylindrical Tube
Authors: Levine Harold
Published: September 2005

The propagation of dominant mode plane sound waves within a cylindrical tube having arbitrary cross section and extending indefinitely from an open end is studied theoretically. A quantity of special interest is the end correction, which characterizes the reflection coefficient at wave lengths large compared to the transverse tube dimensions. The reflection coefficient and end correction fit naturally into a boundary value formulation of the wave propagation problem, whose solution hinges on that of one or more integral equations. Since the integral equations do not in general admit of exact solution, practical techniques for approximately determining the physical quantities are important. Among these are the stationary or variational principles, which can be cast into a variety of independent forms, corresponding to the different nature of boundary distributions. Another technique is based on initial modification of an integral equation so as to utilize the possibility of explicit and rigorous solution. Approximate forms of the reflection coefficient and end correction are obtained in this manner, with the distinction of yielding exact results when the tube cross section is circular. A brief comparison of the different procedures is included.
Laboratory Evaluation of Field Measurements of the Loudness of Truck Exhaust Noise
Authors: Callaway D. B. , Hall H. H.
Published: September 2005

Simple loudness judgment tests were performed by a jury of 15 observers on the recorded noises of approximately 100 highway trucks. The loudness of the noises calculated by a modification of the equivalent tone method proposed by Beranek and co-workers ranges from about 20 to 200 sones. Observers were instructed to rank the noises in six loudness classes and were allowed to listen to a sample of class 1 and class 6 after each 20 recordings. The calculated loudnesses were then divided into six classes with class limits set by a 40 percent loudness increase per class. Although the subjective tests were conducted with no elaborate controls, a correlation coefficient of 0.94 was found between the average judgment of the group and the calculated loudness class. The correlation coefficient between average judgment and total sound pressure level was 0.78, whereas the correlation coefficient between the average judgment and the level on the A-network of the sound level meter was 0.83. Experimental techniques and the capabilities and limitations of the loudness-calculation methods are discussed.
An Anechoic Tank for Underwater Sound Measurements under High Hydrostatic Pressures
Authors: Darner Charles L.
Published: September 2005

The new USRL tank for making acoustic measurements under hydrostatic pressures up to 1000 psig and controlled temperatures from near freezing to near boiling is described. The internal treatment of the tank with wedges of Insulkrete, a sound absorbing material composed of pine sawdust and Portland cement, is pictured. Oscillograms of the pulsed signal show the reduction in reverberation level effected by Insulkrete. The conversion by Insulkrete of high-frequency sound energy into heat is illustrated by schlieren photographs.
The Study of a Sound Field by Means of Optical Refraction Effects
Authors: Kolb J. , Loeber A. P.
Published: September 2005

An optical effect of an ultrasonic field discovered by R. Lucas and P. Biquard, namely the broadening of a slit image, can be computed in a simple way which is based on a method by Wiener. It is useful in the frequency range below 1 Mc/sec for the point by point study of the pressure distribution in a stationary sound wave. Photographic records of this distribution were made. A simple method of measuring the wavelength is described.
A Windscreen for the Ear
Authors: Hayes J. R. M. , Cudworth A. L.
Published: September 2005

Whenever human beings must hear faint sounds in windy places, the masking effect of the noise caused by air turbulence in the ear canal can be a serious problem. We have measured this masking effect at several frequencies, wind velocities, and wind directions. We have also measured to what extent this masking is reduced by a windscreen for the ear.