bluuebunny/crossref_metadata_2025_split huggingface dataset:
Acoustical Properties of the Salt Lake Tabernacle
Authors: Hales Wayne B. 
Published: September 2005

Prof. Wallace Sabine's method of determining reverberation periods was used. Organ pipes in the tabernacle organ served as the source of sound. By opening and closing doors and windows the absorbing power of the building was found to be 630 open window units. The period of reverberation increased from 1.63 seconds for a note of 16 v.p.s. to a maximum of 5.21 seconds for 348 v.p.s. thence decreasing to 0.97 seconds for 8368 v.p.s. The constant of decay of sound, the mean free path, the paramoter k, and the volume of the building were determined by observing the variations produced in the reverberation by variations in the intensity of the sound.
The intensity of the sound was determined throughout the building and expressed in terms of the intensity meter from the source. It was found to vary from 100 per cent at near stations to 4.2 per cent at remote distances.
Articulation tests showed the percentage of syllables accurately received varied from 39 per cent for normal conversation voice to 59 per cent for preaching voice, to 80 per cent for electrically amplified voice. When the reverberation was reduced from 5 seconds for the empty building to 2.3 seconds when 3100 people were present good hearing increased from 52 per cent to 59 per cent for preaching voice in spite of presence of additional noises caused by audience.
Effects of Distortion Upon the Recognition of Speech Sounds
Authors: Steinberg John C. 
Published: September 2005

Physical studies of speech waves in conjunction with articulation tests have shown that in normal speech, the fundamental sounds are distributed in intensity and frequency. For example, the vowels are some 20 to 30 db greater in intensity than the fricative consonants, and require the range of frequencies, from a recognition standpoint, from 500 to 2500 cycles as compared with the range from 1500 to 8000 cycles for the fricatives. Some sounds, such as the vowels, tend to approach a “steady state” condition; others, such as the stop consonants, are of relatively short duration and almost “transient” in character. In both cases, however, recognition appears to depend considerably upon the initial period of growth and the final period of decay.
With these facts in mind, the primary effects of distortion may be readily understood. Distortion which tends to increase the intensity spread between sounds, or which effectively lowers the received speech level, decreases the articulation of the less intense sounds. Distortion which suppresses a portion of the frequency range, decreases the articulation of the sounds that are characteristic of that range. Systems which overload for the intense sounds tend to decrease the intensity spread, and may therefore increase the articulation of the faint sounds while decreasing the articulation of the intense sounds. Reverberation affects the various sounds differently, the greatest impairment occurring for the nasal and stop consonants. In no case did an increase in reverberation time cause an increase in articulation.
An Audiometric Method for Measuring Sound-Insulation
Authors: Waterfall Wallace 
Published: September 2005

The audiometric method of measuring the sensation level of sounds can be readily adapted to sound insulation measurements. The equipment consists of an electrical oscillator and amplifier which, by an automatic switch, is connected alternately to a loud speaker and to an attenuator and telephone receiver. The loud speaker is placed on one side of the partition to be measured and, by varying the attenuator a loudness match is made between the sound from the loud speaker and from the telephone on each side of the partition. The attenuator is graduated in decibels so the difference in the readings gives the reduction factor of the partition. Tones of 256, 512, 1024 and 2048 cycles are used. For field work, the audiometric method has the advantage that noises usually encountered do not seriously interfere with measurements.
As a check on the audiometric method, eight adjoining rooms, each an eight foot cube, have been constructed. Walls of different types separate adjoining rooms. Measurements on these partitions by the audiometric and an instrumental method show good agreement. They also agree well with measurements by the reverberation method on an identical partition tested by Paul E. Sabine at Riverbank Laboratories.
Music as a Humanizing Agent
Authors: Lomb Henry C. 
Published: September 2005

Among the many possible applications of acoustics, the practical application of music to the humanizing or betterment of all elements of our populations stands in the front rank.
Such application presupposes an influence of music on human behavior. Of this influence we find daily corroboration in the playing of martial and sacred music and in the melodies and harmonies of song and symphony.
The cause of this effect has until recently baffled scientific investigation. But the tremendous potency of music is doubtless largely due to its appeal to all classes of humanity. As the sole universal language of mankind, far transcending speech in range and power, it should be possible to employ it as a great humanizing force for the benefit of mankind.
The effectiveness of music is not limited here by its character of a language of feelings, since all mental and physical activities are determined greatly, even though unconsciously, by our emotions.
Research, particularly in the psychology of music, to bring about larger actual and personal participation in musical activities, not merely passive contemplation thereof, is here indicated.
Sound Concentrator for Microphones
Authors: Olson Harry F. , Wolff Irving 
Published: September 2005

A sound concentrator is described having the shape of a parabolic horn, with a microphone at the focus and an associated acoustic network for equalizing the response. Amplification is obtained at low frequencies due to action as commonly attributed to horns and at high frequencies due to the reflections of sound from the walls to the focus. The theory for the parabolic horn attached to a microphone is developed and compared with the experiment.
In order to determine the frequency at which the reflection from the walls becomes of importance, a comparison of the parabolic horn with a double conical horn of approximately the same size is made. Experimental results on these two horns show that reflection from the walls begins at 1500 cycles and increases in importance with frequency. The directional pick-up properties of this parabolic horn have been investigated and determined as a function of the frequency of the impinging sound. The characteristic peaks of the short parabolic horn are reduced to an optimum value by means of Helmholtz resonators loosely coupled to the horn at the receiver end.
Audible Frequency Ranges of Music, Speech and Noise
Authors: Snow W. B. 
Published: September 2005

This paper describes the use of an electro-acoustic system, transmitting the audible frequency range almost uniformly, in determining by ear the frequency ranges required for faithful reproduction of music, speech, and certain noises.
Sounds were reproduced alternately with and without filters limiting the frequency range transmitted by the electrical circuit. The filter cut-offs producing just noticeable changes in the reproduction were deduced from judgments of listeners as to the presence or absence of filters. It was found that for absolute fidelity all musical instruments except the piano require reproduction of the lowest fundamentals. The frequencies above 5,000 cycles were shown to be important, some instruments and particularly noises requiring reproduction to the upper audible limits.
Tests were made in which experienced listeners judged the degradation of “quality” produced by a series of filters. The judgments showed definitely that the quality continues to improve as the frequency range is extended down to 80 or up to 8,000 cycles. Although somewhat indefinite on cut-offs outside these limits, they indicated that reproduction of the full audible range was considered most perfect.
Reduction of Noise in Subways
Authors: Watson F. R. 
Published: September 2005

A new consideration in the reduction of the disturbances of noisy machines recently occurred to the author. The matter arose in connection with a study of subway noises, in which it appears that the sources of disturbance are traceable to the following sources—the impact between car wheels and the rails that causes both of these elements to vibrate; the grinding of the gears that communicate the power from the motor to the car axles, together with the vibration of the gear wheels; and finally the vibration and rattle of the loose parts of the car.
A simple experiment showed that the rail vibrations could be deadened effectively by clamping pads of felt on the web of the rail. In actual use, however, the use of such deadened rails produced no noticeable effect—an apparent paradox. Consideration of the action of the ear gives a simple explanation of the paradox. Suppose that each of the five sources of noise mentioned has approximately one billion units of threshold intensity, the total intensity thus being 5,000,000,000 threshold units, with a loudness of 97 decibels. If now the rail noise is completely eliminated, the intensity is reduced to 4,000,000,000 threshold units, but the loudness is reduced only one unit to 96 decibels, and therefore would not be detected by the ear. By the same reasoning it is apparent that to reduce the noise appreciably, say to 50 decibels it is necessary to reduce all the disturbing elements to at least 100,000 threshold units. If only one remains with an intensity of 1,000,000,000 threshold units, the loudness still has the high value of 90 decibels. In other words, it is waste of effort to quiet any one element of a noisey machine; it is necessary to reduce the vibrations of all the disturbing elements, assuming them to be of about the same intensity.
A Device for Direct Measurement of Sound Absorption Coefficients
Authors: Sabine Paul E. 
Published: September 2005

This paper describes a small scale device for direct comparison of the intensity of sound reflected from a surface of unknown coefficients with that reflected under identical conditions from surfaces whose coefficients have been determined by reverberation methods. It consists of means for producing sound of fixed intensity and frequency at an angle of incidence of 30°, and measuring the energy reflected at this same angle. Calibration is effected by measuring the intensity at the “pickup” of sound reflected from a highly polished marble surface, and from surfaces of known coefficients, and finally when no reflecting surface is interposed in the path of the incident sound. These measurements show a strictly linear relation between the intensity of the reflected sound and the reflection coefficient of the reflecting surface. The intercept of this line on the coefficient axis shows the percentage of the stray energy directly from the source to pickup. This percentage is very constant as the intensity in the incident beam is varied.
Coefficients obtained by this method show excellent agreement with reverberation coefficients obtained by measurement on identical samples.
A Critical Study of the Precision of Measurement of Absorption Coefficients by Reverberation Methods
Authors: Sabine Paul E. 
Published: September 2005

This paper is the result of a careful comparative study of the coefficients obtained by various methods used for the measurement of absorption coefficients employing the equations of the reverberation theory. Both organ pipes and an electro-dynamic loud speaker were used as sources of sound. With the latter, both steady tones and flutter tones were employed. Absorbing power was measured by determining the rate of decay from measurements of the reverberation time for known relative values of the steady state intensity, using the loud speaker source. The results indicate that a loud speaker operated at a fixed value of the input current sets up a steady state intensity that is constant, independently of the absorbing power of the room. The measurements with the organ pipes confirmed the assumption that the latter acts as a source of constant acoustical power output, setting up a steady state intensity that is inversely proportional to the total absorbing power of the room.
Comparison of the results using steady and flutter tones shows that with a frequency range of a semitone above and below the mean frequency the measured values agree within the limits of experimental error. As between the organ pipe and the loud speaker, the former shows consistently higher values on four materials tested at the tone 512 vibrations per second, although the difference is only slightly greater than the experimental error. At other frequencies there is no consistent difference.
The experiments showed that although total absorbing power scan be measured with a precision of the order of 2% or 3% yet errors of this magnitude, if cumulative, may result in variations of about 10% in the value of the absorption coefficient, computed from the difference in absorbing powers of the reverberation chamber with and without the test sample present.
Comparison of results with result on identical samples tested in other laboratories show that at the frequency 512, the agreement between different laboratories is within the limits of accuracy of the methods so far developed.
Acoustic Adjustment of Curved Walls in Auditoriums
Authors: Watson F. R. 
Published: September 2005

The modern trend among architects to use curved walls in auditoriums brings into considertion the adjustments that are helpful in reducing the resultant echoes and concentrations. Coffering these curved surfaces breaks up the reflected sound somewhat, but usually leaves more or less concentrated echoes. The application of absorbing material in a checkerboard pattern, with bare wall between the absorbing pads is promising. The pads absorb sound and change the phase of the reflected waves which interfere with the waves from the bare spaces, so that this arrangement appears more effective than coffering.
A more drastic treatment is to make the entire surface of grill work, whereby the incident sound passes through without reflection to a space behind the wall which may be used as the plenum chamber of the ventilation system. The appearance of the wall can be made satisfactory if the holes in the grills are not large, and if the surface is suitably decorated. This plan was tried in a New York auditorium with successful results, so that it now appears possible to use such curved walls, and allow architects freedom in the design of auditoriums with curved interiors.
The Muscial Scale and Its Tuning
Authors: White William Braid 
Published: September 2005

The accepted system of tuning divides the octave into a succession of twelve tones, of which the frequency relations are such that if n be any tone n : n + 1 = 1 : 2112 from which also it follows that n : n + 12 = 1 : 2
This system, however, is purely artificial and was adopted in the eighteenth century in order to effect a practical compromise between the growing demand for freedom of tonal combination, and the limitations of a keyboard which had fastened itself upon practical musical performance. The paper discusses the nature of the musical scale and the anomalies which arise when an attempt is made to evoke intervals and chords in accurate relations of frequency with only twelve separate tones available in each octave. Some of the acoustical defects of equal temperament are pointed out especially in relation to music as heard. A thorough reconsideration of the subject is suggested for the general benefit of the reproducing arts and of the future of Music as a living form of expression.
Measurement and Frequency Analysis of Sound from Large Reduction Gear Units
Authors: Abbott E. J. 
Published: September 2005

In order to determine noise specifications in absolute units for a certain type of large reduction gear measurements were made of the sounds produced by ten machines in operation at a large central generating station. An average weighted total intensity, and a frequency analysis were made of the noise of each machine. It appears that these data are suitable and sufficient for absolute noise specifications on this type of machine.
It was found that 1 db. represents an important difference in loudness in these machines which places quite rigorous requirements on the apparatus and the methods of measurement in order to eliminate errors due to wave patterns, location, load, speed, etc. Data on these points are given.
A very close check was obtained between the observed frequencies of the various notes, and the movements of certain parts of the machine. By a comparison of the frequency analyses of the different machines it was possible to locate which part of the machine was responsible for the noise, and something of the nature of the defect producing the noise.
The Salient Features of the Functioning of the Cochlea, with Demonstration of a Transparent Hydraulic Model
Authors: Meyer Max F. 
Published: September 2005

In constructing a model for demonstration of the function of the cochlea two assumptions are what we ought to keep clearly out of our mind: (1) that the living cochlea might contain dead building material of such physical properties as vulcanized rubber or tensile metal, (2) that the cochlea might contain contractile tissue, muscle tissue, that is, building material, which, in itself or in the supports in which it is inserted, could, from time to time at least, actively produce any stresses.
A mechanical theory must recognize four salient features: (1) that any sound pervades the cochlea no matter whether the window flexibility is considered in theorizing or put down as negligible in theorizing or is actually (pathologically) impaired—just as any sound pervades any building with all its rooms and partititions, and that such a primitive function is almost certain to have at least a weak and otherwise limited stimulating effect; (2) that the main and more adequate (but not exclusive) stimulating effect in mammalian animals (having an elongated cochlea tube) is likely to result from displacements of the phragma due to pressure differences between the windows, which are unsymmetrical to the meatus; (3) that the bulge formed by the displaced phragma can not travel, but can only lengthen itself, as is demonstrated by inspection of the hydraulic model; (4) that the formation of a bulge on either side of the average location of the phragma is succeeded by the development of stress in the phragma, as is demonstrated by inspection of the hydraulic model.
Plane Sound Waves of Finite Amplitude
Authors: Fay R. D. 
Published: September 2005

The principal object of the analysis is to find the change in type of periodic plane waves of sound of finite amplitude propagated in free air.
A solution of the exact equation of motion is obtained as a Fourier series. Due to the nonlinear relation between pressure and specific volume there is found to be a gradual transfer of energy from components of lower frequency to those of higher frequency. Since the effect of viscosity is to attenuate the higher frequency components more than the lower, there is always a wave form having the harmonic components in a stable relation such that the decrease in relative magnitude of any component due to viscosity is compensated by the relative increase due to non-linearity. The conditions for stability vary with intensity. There is therefore no permanent wave form, but the stable wave will change its form more gradually than any other wave of the same intensity and wave length. The change in type of any wave is toward this stable form. There is a marked departure from the sinusoidal in the stable type even for waves of very moderate amplitude.
The Determination of Absorption Coefficients for Frequencies up to 8000 Cycles
Authors: Hopper F. L. 
Published: September 2005

The necessity for the determination of coefficients of sound absorption for frequencies up to 8000 cycles has been brought about by the improvements being effected in increasing the range of recorded and reproduced frequencies in sound pictures and broadcasting. Naturalness and intelligibility are enhanced by the addition of these higher frequencies which further increases the effect of realism. Consequently, with the development of apparatus capable of handling a wider frequency band, a knowledge of acoustical conditions over an equally wide band of frequencies is required.
From a knowledge of absorption coefficients at the lower frequencies it appears to be impracticable to predict coefficients at the higher frequencies, consequently a resort to measurements is the only satisfactory solution. The apparatus and technique for the determination of coefficients of absorption for frequencies up to 8000 cycles by the chamber reverberation method are discussed. Factors affecting these measurements, such as sound absorption in air, size and methods of mounting the test samples, and so on, are described. The absorption coefficients for a number of commercial materials for these higher frequencies are shown. Since materials having different types of frequency absorption characteristics, as well as absolute absorption, are required for such work as: the reduction of noise, the acoustical treatment of theatres and auditoriums, and the treatment of rooms or stages used for the electrical recording of speech or music, such information is necessary in order to intelligently design such acoustical treatment.
Control of Pitch in Wind Instruments
Authors: Taylor John Bellamy 
Published: September 2005

A statement often heard or read as coming from some prominent musician is to the effect that of all the orchestral instruments only the violins (including the larger members of violin family) and the slide trombones can play in perfect intonation. The absence of frets on the finger-board permit performer to nicely determine vibrating length of string and sliding tubes of trombone give similar opportunity for precise determination of air column length. Coupled with the claimed pitch superiority of violins and trombones there is also an implication that a better “ear” is required for acceptable playing of these instruments than is needed for playing other orchestral instruments, viz., flutes, oboes, clarinets, bassoons, horns, and trumpets.
While the wind instruments do have a limited tuning range, it is misleading to speak of them as of “fixed pitch,” and erroneous to assume that uncovering the proper vents, or depressing the proper pistons assures a tone of definite pitch. This is because the air column of instrument is, through mouthpiece or reed, sufficiently coupled to lips and oral cavity of player to give him an appreciable control of the air column time of vibration. This allows sounding the tone either definitely “out of tune” or, within reasonable limits, raised or lowered in pitch to come in close accord with the tones from other instruments. To exercise this pitch control musically and artistically the wind instrument player is as dependent on a good “ear” as is the performer on the strings.
Some of the Factors which Affect the Measurement of Sound Absorption
Authors: Chrisler V. L. , Snyder W. F. , Miller Catherine E. 
Published: September 2005

Curves have been drawn showing the effect of water vapor and temperature on the total absorption of a reverberation room. At 4096 cycles changes in barometric pressure seem to have an appreciable effect.
When highly absorbent materials are placed in the reverberation room, the rate of decay is not uniform.