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Journal of the Acoustical Society of America

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Jan 1934

Volume 5, Issue 3, pp. 173-224

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The Influence of Phase on Tone Quality and Loudness; the Interference of Subjective Harmonics

E. K. Chapin and F. A. Firestone

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 173-180 (1934); (8 pages) | Cited 1 time

Online Publication Date: 13 Jun 2005

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A strong 108 cycle fundamental and one of its harmonics were impressed on one ear in various relative phases and sound pressures. The tone quality and the loudness of the combination were found to depend on the relative phase of the two components. In a certain phase relation the loudness of the combination was 3.5 db less than the loudness of the fundamental alone; varying the phase changed the loudness of the combination by about 10 db. The above observations may be explained by assuming that the ear mechanism distorts the pure components of a complex sound pressure, producing subjective harmonics which may either constructively or destructively interfere depending on the relative phases of the components. Some evidence was found in support of an assumption that the subjective harmonics due to a single low frequency pure tone actuating the ear, are in phase as cosine functions without epoch angles.

Supersonic Measurement of the Directional Characteristics of Horns

Stanford Goldman

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 181-195 (1934); (15 pages)

Online Publication Date: 13 Jun 2005

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Filtration of Elastic Waves in Solid Rods

R. B. Lindsay

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 196-201 (1934); (6 pages) | Cited 1 time

Online Publication Date: 13 Jun 2005

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The theoretical studies previously made on the filtration of compressional waves in solid rods by Lindsay and White have been extended to the case of torsional waves in a rod and of compressional waves in rods having solid rods for side branches. If an infinite cylindrical rod is loaded at equal intervals of length 2l with disks (having planes perpendicular to the rod) of mass m and moment of inertia I about the axis of the rod, the resulting structure is found to act as a low‐pass filter for torsional waves. The transmission bands are given by the condition +1 ≥ cos W ≥ −1, where
math
. Here k  =  ω/c  =  2πν/c, where ν is the frequency of the waves. The velocity of propagation c  =  (μ/ρ0)½, where μ = rigidity modulus and ρ0 is the mean density of the rod. The radius of the rod is a. For given I, increase in l decreases both the cut‐off frequency of the first transmission band as well as the upper limit of the first attenuation band. For given l, increase in I decreases the cut‐off frequency. There is next considered the case of an infinite cylindrical rod loaded at equal intervals of length 2l with perpendicular side rods of length ls. The approximate assumption is made that longitudinal compressional waves in the main rod set up transverse flexural waves in the side rods. Calculation indicates that if the side rods have free ends the structure acts as a low‐pass filter for compressional waves in the main rod. If on the other hand the side rods have rigidly clamped ends, the structure under suitable choice of dimensions (in particular l/ls≫1) can act as a high‐pass filter. Numerical illustrations are given.

Acoustic Filtration in Non‐Homogeneous Media

R. B. Lindsay, C. R. Lewis, and R. D. Albright

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 202-205 (1934); (4 pages) | Cited 1 time

Online Publication Date: 13 Jun 2005

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This paper considers theoretically the propagation of compressional waves in a structure consisting of an infinite series of alternating layers of two different media which may be either fluid or solid. It is shown that such a structure acts as a low‐pass acoustic filter. A number of special cases are computed and it is found that the cut‐off frequency depends essentially on the section length and the relative acoustic impedance of the media. The problem is shown to be mathematically quite analogous to that of the propagation of acoustic waves in air through an infinite tube containing alternate constrictions and expansions. Moreover the loaded solid filter considered in a previous paper by Lindsay and White proves to be a limiting case of the non‐homogeneous medium filter of the present article.

Acoustic Spectrum of an Elastic Body Submitted to a Shock

M. Biot

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 206-207 (1934); (2 pages)

Online Publication Date: 13 Jun 2005

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Resonance in Soft‐Walled Cylinders

Jack C. Cotton

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 208-212 (1934); (5 pages)

Online Publication Date: 13 Jun 2005

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Amplification of Small Bells

A. N. Curtiss and G. M. Giannini

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 213-217 (1934); (5 pages)

Online Publication Date: 13 Jun 2005

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Tenth Meeting of the Acoustical Society of America (A)

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 220-224 (1934); (5 pages)

Online Publication Date: 13 Jun 2005

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A Selective Microphone for Use in Acoustic Altimeters (A)

L. P. Delsasso

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 220-220 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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A modification of Bragg's amplitude meter is applied to a resonant diaphragm, associated with a parabolic horn, to provide a highly selective microphone. When used with an impulsive source of sound it makes possible the measurement of distances as low as 10 ft. while in the presence of sounds comparable to those in aircraft.
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Acoustics of a Board of Trade Room (A)

F. R. Watson

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 220-220 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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The acoustical problem of a board of trade room is quite different from that of an ordinary auditorium. Instead of a single speaker and a quiet audience, there is a group of perhaps 200 traders all yelling at the top of their voices, with attendant noises of a considerable number of telegraph instruments and loud calls for messenger boys. The acoustic problem is to ascertain the conditions which will promote the possibility of one trader being heard in the general uproar by other traders. Calculations are given for the loudness of one trader's voice compared with the loudness of the group, also the reenforcing effect of the ceiling and sidewalls. The conclusion is drawn that individual traders can be heard in much the same way that individual instruments are distinguished in an orchestra.
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Reverberation Measurements of Sound Absorption Coefficients (A)

Paul E. Sabine

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 220-220 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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A comparison is made of the results of the measurement of the absorption coefficients of twenty‐five commercial materials by the organ pipe and ear method with the results obtained by measuring the rates of decay by electrical means. A consistent variation in these results is shown, which can be explained by assuming a slight departure from linearity in the time versus logarithmic intensity relation.
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Reverberation Time and Absorption Measurements with the High Speed Level Recorder (A)

E. H. Bedell and K. D. Swartzel, Jr.

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 220-220 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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The high speed level recorder described by Messrs. Wente, Bedell and Swartzel may be used in many types of acoustical measurements. It is particularly well adapted to the measurement of reverberation time, however, because with a single interruption of the test tone a continuous curve of sound intensity during the decay period is obtained on a logarithmic scale. The level recorder has recently been modified so that measurements can be made through an intensity range as great as 90 db. This paper presents some data obtained with the level recorder on reverberation measurements in a sound chamber, and includes an investigation of the accuracy of the results as affected by the intensity range through which measurements are made, the use of rotating reflectors, warble tones, a number of loudspeaker and microphone positions, and a number of microphones simultaneously, placed at different locations in the chamber.
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Effect of Distribution and Location of Acoustical Material upon Its Sound Absorption (A)

V. L. Chrisler

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 220-220 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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Experimental data are presented showing that the absorption of an acoustical material depends upon the size of the surface of the acoustical panel as well as its location and the manner in which the panels are distributed around the room. This phenomenon depends to some extent on the frequency of the sound. Most of these measurements were taken in the laboratory but a few measurements have been taken on installations in various buildings. Measurements taken in the field agreed with those taken in the laboratory.
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The Absorption of Sound in Oxygen as Influenced by the Presence of Other Gases (A)

V. O. Knudsen and H. O. Kneser

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 221-221 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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The authors recently have described experiments which show that the absorption of audible sound in oxygen is strongly influenced by the presence of water vapor. [J. Acous. Soc. (Oct., 1933).] The present work describes the effects produced when other gases are mixed with oxygen, such as He, H2, CO, CO2, NH3, H2S, CCl4, C2H5OH, C2H2, C6H6, and other hydrocarbons. Of these gases, all except CO and CO2 produced effects similar to that produced by water vapor, that is, as the concentration of the foreign gas was increased from zero the absorption coefficient m increased to a maximum and then decreased. In every instance the maximal value of m coincided with that previously obtained for oxygen and water vapor (10×10−4 cm−1 at 3000 cycles and 20×10−4 cm−1 at 6000 cycles), but the concentration at which the maximal absorption occurred was very largely dependent upon the kind of foreign gas mixed with the oxygen. Thus, a trace of C2H5OH was sufficient to give the maximal absorption, whereas concentrations of the order of 10 to 50 percent were required for such gases as H2 and He. For all admixed gases, with the exception of water vapor, the concentration at which the absorption is a maximum is proportional directly to the frequency.
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The Place of the Acoustical Materials Industry in the Acoustical Society of America (A)

Wallace Waterfall

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 221-221 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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Brief history of the connection between the acoustical materials industry and the formation of the Acoustical Society of America and a statement of the purposes for which the Acoustical Materials Association has recently been formed.
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History of the Use of Acoustical Materials (A)

Harold R. Berlin

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 221-221 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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A summary of the development and use of commercial sound absorbents and some problems in their manufacture and sale.
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Architectural Appraisal of Sound Absorbents (A)

M. A. Smith

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 221-221 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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This paper considers the various physical and architectural properties, other than that of mere sound absorbing efficiency, that affect the value of commercial absorbents, and attempts to present a rational basis for the appraisal of such materials by the architect.
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Writing Acoustic Specifications (A)

S. K. Wolf and G. V. T. Burgess

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 221-221 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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The writing of acoustic specifications is in such a chaotic and unformed state that it suffers enormously in comparison with the well‐ordered and fundamentally sound practices which have been built up in specifying the character of other parts of a building structure. This paper discusses the several phases of the existing problem, suggests methods of handling them, and reviews the work now being done to settle many of the questions which face the acoustic engineer. The objectives sought in the specification of acoustic material characteristics for noise reduction and for control of reverberation, and in the specification of sound insulative construction, and degrees of quiet in the operation of mechanical equipment are outlined. The sound frequency range to be considered, the method of measuring and checking the performance of specifications, the probable limits of accuracy of such measurements and the units and reference values to be used are discussed. The conclusion states the need of further work by acoustic material manufacturers, research engineers, and testing laboratories to provide the specification writer with all the information needed.
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Reverberation Measurements in Auditoriums (A)

G. T. Stanton, F. C. Schmid, and W. J. Brown, Jr.

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 221-221 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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The purpose of this paper is to present some of the results obtained in the measurement of reverberation in auditoriums. The methods used are described and certain limitations pointed out. Examples of decay curves obtained with a high speed level recorder under differing conditions are shown, and their relationship to reverberation time discussed. The results and their discussion are supplementary to other work in this field, and are offered at this time as an indication of present day opportunities for study of sound decay conditions.
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Phonetic Frequency Distribution in Formal American Pronunciation (A)

Chas. H. Voelker

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 222-222 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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The speech of radio announcers was chosen as approaching the norm for a formal type of general American Speech. 5946 radio announcements were studied. The announcer was identified through the mail after his program had been phonographically recorded through a vertical cut electrical recording head directly from the radio onto a wax record. These records were played and replayed until certainty as to just which sounds occurred could be ascertained. These records totalling 665,094 were recorded in phonetic notations (I.P.A.). The occurrence of each sound was counted and the data tabulated into frequency tables. The relative percentages of occurrence of each sound were determined and compared.
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Cavity‐Wall Influence in Cavity Resonance (A)

J. C. Cotton

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 222-222 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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Since the walls of the resonant cavities concerned in voice production are non‐rigid in character, a study of vocal resonance might well begin with an experimental investigation of various soft walled cavities. The apparatus being used in this study was described at the Ann Arbor meeting of the Society, November 29, 1932. Results of this investigation reveal a number of important differences in behavior from that predicted by the theory based on “perfectly rigid walls.” Among these differences are: a higher fundamental resonant frequency; a radical decrease in the amplification of the driving tone at a resonant frequency; a reduction or loss of resonant response at harmonics of the resonator's natural frequency.
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The Origin of the Threshold of Feeling in the Ear and Its Relation to Artificial Hearing Aids (A)

Scott N. Reger

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 222-222 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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By means of a beat‐frequency audio‐oscillator, amplifier and a calibrated sound reproducer capable of high acoustic output levels it was found that 27 observers with complete bilateral hearing loss, due either to congenital defect or meningitic infection, but with normal tympanic membranes, possessed average value thresholds of feeling. This finding is interpreted to signify that the threshold of feeling is not causally related to stimulation of the acoustic portion of the eighth cranial nerve. The threshold of feeling in 33 ears lacking tympanic membranes because of the radical mastoid operation or prolonged otitis media was raised 20 db or more above the average values for normal ears, which suggests that the end organs responsible for the threshold of feeling are located within the tympanic membrane and epithelium lining the combined middle ear cavity and external auditory meatus. Individuals with pronounced hearing loss and intact tympanic membranes cannot tolerate high levels of sound amplification in a headphone to enable perception of speech sounds because of the pain elicited when high amplification stimulates the threshold of feeling. Individuals with equal hearing loss but lacking tympanic membranes can use sufficiently high levels of sound amplification to enable perception of speech sounds without arousing unpleasant sensations in the ear.
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Responses to Vibrations Received Through the Skin (A)

Louis D. Goodfellow

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 222-222 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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This paper presents some of the results of research on the senses of touch and vibration and the extent to which they can be used to interpret the vibrations of speech and music when the highly developed ear ceases to function. First, the author discusses the nature of the senses of touch and vibration—their neurological basis, the limits of frequency and intensity within which they function, and their capacity to discriminate subtle differences in pitch, intensity and quality. Other data on the senses of touch and vibration such as differences in sensitivity depending upon the part of the body used, and the individual observer, illusions of hearing due to vibratory stimulation, a comparison of auditory and tactual sensitivity, and the localization of the source of a vibrating body complete the description of the senses of touch and vibration. After a review of the research of Professor Robert H. Gault and his attempt to apply these data in developing a means of communicating with the deaf through these lower senses, the author presents available data on contemporary research in this field and a description of the Gault‐Teletactor, the apparatus used for transmitting the vibrations of speech and music to the finger tips of the deaf.
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Interpretations of Vibro‐Tactile Experiments (A)

Robert H. Gault

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 222-222 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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Touching is primitive “hearing.” The human ear is properly described as a highly developed organ of touch. In the course of evolutionary development leading to our ear, there appeared what is probably rightly called a “sense of vibration.” The author's current experiments involve a “sense of vibration.” This suggests the following question: Has the ear concentrated in itself all the “hearing” function that in early stages of phylogenesis was very widely distributed throughout the organism? Many thousands of observations in our wide variety of experimental situations, as well as the work of Dr. Katz in Rostock and Dr. v. Frisch in Munich, point to the negative of this question and support a phrase that was used by the late Dr. Victor Vaughn in his mention of some of our earlier work: “We hear not only with our ears but with our whole bodies.” There is no possibility of answering the question whether the practiced deaf in our experiments acquire the feeling that is the quality of hearing in normal subjects. It is at least plausible. From a psychologic angle the acquisition of the rudiments of spoken language and of the ability to interpret it in our procedure go along the same lines as in the usual normal situation.
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Synchronized X‐Ray and Oscillographic Speech Records (A)

G. Oscar Russell and Jose Palomo

J. Acoust. Soc. Am. Volume 5, Issue 3, pp. 223-223 (1934); (1 page)

Online Publication Date: 13 Jun 2005

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The synchronization of physiological and physical speech studies would seem to be the logical next step in analyses of their characteristics. Not only should a study be made of the physical characteristics as manifest in the oscillographic record, but the physiological position at any exact instant should also be known if a complete understanding is to be had. It is obvious that both records will have to be automatic. The x‐ray exposure time will have to be reduced to at least 1/120th of a second if a study of normal speech is to be made. Prolonged or sung vowels are not characteristic of normal speech. Consequently such x‐ray procedures have long since been discarded by careful investigators. Since motion picture x‐rays consisting of 1/120th of a second are not yet feasible, the instantaneous x‐ray exposure used in this study is chosen as the next best technique. Sound picture records likewise synchronized therewith serve as a check back on the final resultant.
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