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Journal of the Acoustical Society of America

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Sep 1963

Volume 35, Issue 9, pp. 1321-1461

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Sounds of the Highland Bagpipe

Cyril M. Harris, Maurice Eisenstadt, and Mark R. Weiss

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1321-1327 (1963); (7 pages)

Online Publication Date: 20 Jul 2005

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An analysis has been made of the sounds of the Highland bagpipe. This instrument consists of a leather bag fitted with five pipes: the blowpipe through which the player fills the bag with air, the chanter that has eight open holes on which the melody is played, and two tenor drones and one bass drone, which produce harmonious steady tones. This study was made of the sounds produced by four individual pipers, each using his own instrument. Three of the pipers had considerable professional experience—the fourth was a young beginner. Spectral analyses were obtained for each drone and the chanter sounding separately under otherwise normal playing conditions. The harmonic structure of these sounds was investigated as a function of a number of parameters including blowing pressure, length of drone, and aging of the chanter reed. Transient as well as steady‐state conditions were studied.

Physical Measurements of Equally Speech‐Interfering Navy Noises

R. G. Klumpp and J. C. Webster

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1328-1338 (1963); (11 pages)

Online Publication Date: 20 Jul 2005

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The sound level of each of 16 diverse noises was adjusted so that loudspeaker‐reproduced rhyme words at a level of 78 dB (C) at one meter were reduced to 50% word intelligibility. Spectrum analyses (octave band and 20‐cps band), physical measurements (C, B, A, DIN 3 sound‐level meter weightings), calculations [Speech Interference Levels (SIL)], and peak fittings [to noise criteria (NC)‐type curves] were made to find which method came closest to agreeing that the noises were equally speech‐interfering.
SIL calculations that included the octave 300–600 cps predicted the speech‐interference aspects of the 16 noises best. The A and DIN 3 weighting networks, the conventional (600–4800 cps) SIL, and use of a restricted region (350–2800 cps) of NC‐type curves gave the next best prediction. The poorest predictors were the B or C frequency‐weighting networks and use of the NCA, NC, or ISO contours over their total frequency range.

Articulation Index and Average Curve‐Fitting Methods of Predicting Speech Interference

J. C. Webster and R. G. Klumpp

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1339-1344 (1963); (6 pages) | Cited 1 time

Online Publication Date: 20 Jul 2005

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Sixteen equally speech‐interfering noises were rated by using articulation index (AI) calculations and by using noise criteria (NC)‐type contours as averaging, not peak‐finding, devices. Articulation‐index scores based on 5 or 6 weighted octave‐band levels were equal to AI scores obtained by the 20‐band method and predicted very well that the noises were equally speech‐interfering. The use of NC‐type curves (from 500 to 2000 cps) to find an average, not a peak, noise level also gave good prediction. Equally speech‐interfering noises were not, however, equally “loud,” nor equally “noisy.” There was evidence to show that the frequency that divided noise‐masked speech into two equally intelligible frequency regions was 850 or 1000 cps, and was not 1700 or 1900 cps, which is the dividing frequency when the speech in quiet is progressively restricted in bandwidth by high‐ or low‐passed filtering.

Formant‐Frequency Extraction by the Method of Moment Calculations

Jouji Suzuki, Yasuo Kadokawa, and Kazuo Nakata

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1345-1353 (1963); (9 pages)

Online Publication Date: 20 Jul 2005

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The method of moment calculation was used for formant‐frequency extraction in computer processing from a digitalized spectrum pattern. Special attention was paid to the separation of frequency range for each formant. F̄, the first‐order moment of speech power spectrum, and F2e, the ratio of the second‐order moment to the first one of the spectrum, are used in this separation. Formants are calculated as first‐order moments within the separated portion of the spectrum. Analyses of errors of extracted formant frequencies due to the various factors such as the increase of pitch frequency, etc., were carried out by using the synthesized vowel‐type spectra simulated on the computer. This analysis and comparisons of extracted formant frequencies from the natural speech with the corresponding spectrograms have proven that the method gives acceptable results in actual speech analysis. The results can be regarded as first approximation of formant frequencies as bases of more detailed analysis such as “analysis‐by‐synthesis.”

Electrostatic Microphones with Electret Foil

G. M. Sessler

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1354-1357 (1963); (4 pages) | Cited 13 times

Online Publication Date: 20 Jul 2005

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In this paper the operation of electrostatic microphones with foil electrets is studied theoretically. It is assumed that a foil electret has equal (free or bound) constant charges of opposite sign on its two surfaces. A formula is obtained which shows the generated output voltage of the microphone to be a function of the surface charges of the electret, the geometrical dimensions of the microphone, and the externally connected resistance. According to this formula, typical sensitivities of a few mV/μbar can be expected.
The electret microphone is also compared theoretically to a similar system with nonelectret foil. The calculations show that a surface charge of 10−8 C/cm2 on the surface of ½‐mil Mylar foil corresponds to a bias of about 45 V in the nonelectret reference system. It is pointed out in this connection that the measurement of surface charges of foil electrets by the induction method requires a correction formula.

Digital Computer Simulation of a Sampled‐Data Voice‐Excited Vocoder

Roger M. Golden

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1358-1366 (1963); (9 pages)

Online Publication Date: 20 Jul 2005

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A sampled‐data system representing a 10‐spectrum channel voice‐excited vocoder (VEV) has been simulated on an IBM 7090 digital computer. This type of simulation permits studying readily the effects of changes in major vocoder parameters, such as excitation, analyzing filter bandwidth, etc., without the lengthy waiting periods required for equipment changes. Programming for the simulation was accomplished by the use of a program compiler that allows specification of a sampled‐data system in functional‐block form. The system represented by the simulation was, in general, determined by finding sampled‐data equivalents (z transforms) of the filters and circuits used in an analog VEV. The derived z transforms were then used to realize functional‐block representations for the sampled‐data filters and circuits. However, to prove economically the feasibility of simulating an entire vocoder, the great number of bandpass filters needed were synthesized initially by using a unique and computation timesaving design. Speech processed by this simulated sampled‐data system is of excellent quality and often is better than that processed by some analog VEV's. The computer program requires about 172 sec to analyze and resynthesize 1 sec of recorded speech.

Design of Sonic Amplitude Transformers for High Magnification

Edward Eisner

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1367-1377 (1963); (11 pages) | Cited 7 times

Online Publication Date: 20 Jul 2005

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Using the design method described by Eisner and Seager, in which a suitable wavefunction is chosen and the corresponding profile is deduced, a new class of amplitude transformers is designed. The wavefunction used is a fourth‐order Fourier series. The resulting transformers give a useful compromise between the properties of the “stepped” and the “exponential” transformers. The output amplitude produced for a given maximum strain is somewhat lower than the amplitude given by the exponential transformer of the same magnification, but is much higher than that given by the corresponding stepped transformer. While the “Fourier” transformer is slightly less stiff in bending than the stepped, it is very much stiffer than the exponential.

Ultrasonic Atomization of Liquids

Richard L. Peskin and Roland J. Raco

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1378-1381 (1963); (4 pages) | Cited 1 time

Online Publication Date: 20 Jul 2005

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A theory of ultrasonic atomization of liquid films is presented. It is assumed that exponential growth of surface disturbances ultimately results in the formation of liquid drops, the diameters of which are proportional to the wavelength of the most rapidly growing initial disturbance. The hydrodynamic stability equations of the liquid film are examined, and the most rapidly growing initial disturbances are determined by numerical solution in the unstable region. A resultant correlation between drop size, transducer frequency, transducer amplitude, and liquid‐film thickness is obtained. Results are compared to previous theoretical and experimental conclusions.

Effect of Lack of Parallelism of Sample Faces on the Measurement of Ultrasonic Attenuation

Rohn Truell and William Oates

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1382-1386 (1963); (5 pages) | Cited 11 times

Online Publication Date: 20 Jul 2005

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The measurement of ultrasonic attenuation and velocity at megacycle frequencies demands that the sample faces be parallel within limits that require extreme care. The importance of maintaining the tolerances in question is shown in terms of the echo patterns for various cases in which the tolerances are held and in which they are not. In order to measure attenuation of crystalline quartz to within about 10% at 1000 Mc/sec, the required wedge angle θ should be about 5×10−8 rad or less. This turns out to be just barely possible. under rather special conditions. At the highest frequencies attained thus far (i.e., about 25 000 Mc/sec) with ultrasonic stress waves, the limits on parallelism are so severe that there are at present no instruments capable of making the necessary measurements to control the sample parallelism.

Theory of Bubble Pulsation and Cavitation

Gerald Houghton

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1387-1393 (1963); (7 pages) | Cited 3 times

Online Publication Date: 20 Jul 2005

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First‐ and second‐order perturbation methods for small amplitudes have been used to obtain periodic solutions to the modified Rayleigh equation that are applicable to the adiabatic pulsation of bubbles in liquids. It is demonstrated theoretically that bubble pulsation is a damped oscillation whose fundamental frequency is a function not only of hydrostatic pressure and surface tension, but also of liquid viscosity, and that integral overtones of the fundamental may exist at large amplitudes. A theory of vibration‐induced cavitation is presented in which the Rayleigh equation is transformed into an equivalent Mathieu equation for small radial motions. The onset of cavitation at small pressure amplitudes is found to be a sharp function of frequency, bubble radius, and hydrostatic pressure, and it is shown that there is a frequency and bubble size above and below which, respectively, cavitation will not occur. Applications of bubble pulsation and cavitation phenomena to pumping and mass transfer operations are discussed.

Acoustical Properties of Water‐Filled Sands

A. W. Nolle, W. A. Hoyer, J. F. Mifsud, W. R. Runyan, and M. B. Ward

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1394-1408 (1963); (15 pages) | Cited 10 times

Online Publication Date: 20 Jul 2005

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Experimental studies were made of the propagation of longitudinal waves in several mixtures of water with quartz sands fractionated as to particle size. The most probable particle size in the several samples ranges from 0.01 to 0.07 cm. The experimental frequencies were approximately 400 to 1000 kc/sec. Additional measurements in the same frequency range cover the reflection and scattering of underwater sound from essentially plane surfaces of these aggregates. The velocity and attenuation data are related satisfactorily to a well‐known analysis for a porous acoustical material having a pliable skeleton. The reflected signal, as a function of angle of incidence, behaves approximately as expected from the conditions for continuity at the plane surface, when the appropriate complex index of refraction is used. The scattering data are compared with the analysis based on a random distribution of scattering amplitude per unit volume, with autocorrelation distance proportional to the particle size. The analysis predicts the limiting behavior of scattering coefficient with respect to particle size and frequency, but predicts a more rapid fall of scattering amplitude beyond the critical angle than was observed. The magnitude and autocorrelation properties of the fluctuations in scattered signal as the apparatus was translated to scan the sand surface were observed, and found to correspond approximately to a model based on a Gaussian distribution of local scattering amplitude.

Effect of the Nearfield on the Cavitation Limit of Transducers

Charles H. Sherman

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1409-1412 (1963); (4 pages)

Online Publication Date: 20 Jul 2005

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The cavitation‐limited acoustic power of a transducer depends on its nearfield structure. Cavitation begins when the pressure amplitude reaches a certain value, but the pressure distribution is usually not uniform, and only the pressure component in phase with the velocity contributes to radiated power. In estimating cavitation limits, these near field effects must be considered as well as those effects that depend on the properties and condition of the medium. An analysis of cavitation‐limited power that clearly separates the nearfield effects from other effects is presented here. A parameter γ that determines the nearfield effect on the cavitation limit is defined, and γ is calculated for circular pistons, hemispherical pistons, flexural plates, and multipole spheres. The values of γ are usually in the range 0.25–1.0, where unity corresponds to no near‐field effect, and a value less than unity means that the cavitation‐limited power per unit area is reduced by that factor.

Low‐Frequency Sound Attenuation in the Deep Ocean

R. J. Urick

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1413-1422 (1963); (10 pages)

Online Publication Date: 20 Jul 2005

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Signals received from Sofar bombs dropped from an aircraft eastward from Bermuda have been studied quantitatively. The energy density of the signals received at Bermuda, measured in various bands between 20 and 1600 cps, can be accounted for by cylindrical spreading beyond a “transition range” predicted approximately by simple considerations, plus an attenuation coefficient in dB per megayard given by the linear expression 1.5+8.2 f, where f is the frequency in kc/sec. At frequencies below 1 kc/sec, this attenuation is far in excess of that which would be produced by absorption alone. At very low frequencies the excess attenuation is postulated to be due to the failure of the Sofar sound channel to act as an acoustic trap. At frequencies from about 50 to 500 cps, quantitative evidence is presented to indicate that the dominant attenuation process is scattering by index‐of‐refraction inhomogeneities deep in the sea. Other characteristics of Sofar‐transmitted signals are described.

Radiation Impedance of Membranes and Plates: Their Acoustic Coupling with the Propagating Medium

S. Lowenthal and P. Tournois

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1423-1428 (1963); (6 pages)

Online Publication Date: 20 Jul 2005

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The radiation impedance of membranes and plates of finite width, carrying traveling wave, is calculated. The method used leads to a relatively simple analytic expression. The problem of acoustic coupling of these strips with the fluid propagating medium is then examined.

Analysis of Reflection Patterns in Auditoria

J. P. A. Lochner and P. Meffert

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1429-1431 (1963); (3 pages)

Online Publication Date: 20 Jul 2005

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Recent investigations in this laboratory made it possible to compute the intelligibility of speech from reflection patterns in auditoria. The present paper describes how standard laboratory equipment could be used for analyzing the reflection patterns into a form suitable for computation.

Sensory Thresholds and Response Bias

Donald A. Norman

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1432-1441 (1963); (10 pages)

Online Publication Date: 20 Jul 2005

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Sensory differential thresholds are studied by two models: a discrete model, the neural quantum theory, and a continuous model, signal detectability theory. A comprehensive series of auditory experiments is reported that was designed to obtain measures of both the detection and decision processes of the observers when the signal consists of a brief increment in the amplitude of a pure 1000‐cps tone. The analyses performed on these experiments support the existence of a low differential threshold in hearing. These analyses include the location of the isosensitivity functions and the characteristics of the psychometric functions. The experiments do not, however, provide sufficient evidence to permit a definite conclusion about the validity of the neutral quantum theory, except that it is clear that the decision model applied to the quantum theory is incorrect for “high”‐amplitude signals.

Application of a “Relative” Procedure to a Problem in Binaural‐Beat Perception

Jerry V. Tobias

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1442-1447 (1963); (6 pages) | Cited 1 time

Online Publication Date: 20 Jul 2005

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The existence of binaural beats has long been considered an indication of binaural interaction for timing and for periodicity information. In the past, bilaterally matched sound‐pressure or sensation levels have been used in the investigation of these beats, and the measuring technique was one that may be termed “absolute.” However, the present study, in investigating with a “relative” technique the limits of dichotic intensity which permit binaural beats, shows that listeners respond to the presence of beats whenever the tones to both ears are above threshold. It is suggested that this new result fits more neatly into current theoretical formulations. The frequencies investigated ranged from 100 to 2000 cps. As other authors have previously reported, the best performance occurred in the 400‐ to 600‐cps range. The present findings strengthen the case for an auditory nervous system with timing channels independent of other transmission lines and, thereby, also have implications for pitch theory.

Summating Potential of the Cochlea in the Guinea Pig

Teruzo Konishi and Tomohiro Yasuno

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1448-1452 (1963); (5 pages)

Online Publication Date: 20 Jul 2005

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The cochlear microphonics and the summating potential were recorded simultaneously by means of a superfine micropipette which was introduced into scala media through the round window. A sudden jump in dc resting potential from negative to positive occurred as the tip of the electrode penetrated the reticular lamina. At this instant a reversal in polarity of the summating potential and the cochlear microphonics was observed. The polarity and amplitude of the summating potential to long‐lasting pure tones were dependent not only on intensity and frequency of stimuli but also upon the position of the recording electrode along the cochlea. A dc polarizing current was applied between scala vestibuli and scala tympani in the basal turn. Although both the positive and negative summating potentials were usually enhanced by dc current traveling from scala vestibuli to scala tympani and depressed by the dc current in the opposite direction, there were several exceptions. This fact suggests that the hair‐bearing surface of the hair cells becomes unstable when the intracellular potential is changed markedly. Inconsistency of the summating potential with respect to both magnitude and polarity may be due to the instability of the hair cells that are exposed to a high potassium environment and a continuous anodal polarization in the form of the endocochlear potential.
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Comments on Impact‐Noise Measurement

T. Mariner

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1453-1453 (1963); (1 page)

Online Publication Date: 20 Jul 2005

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The ISO tapping machine does not rank‐order floors according to the relative noisiness of the underlying room when the floors are subjected to hard‐heeled, female foot traffic. Therefore, the criteria outlined in the recently released FHA Bulletin #750, based on the ISO tapping machine, should not be accepted as a de facto national standard.

Frequency‐Dividing Networks

Lawrence Fleming

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1454-1454 (1963); (1 page)

Online Publication Date: 20 Jul 2005

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Where two complementary filters (crossover networks) are used for frequency‐band division in sound reproduction, the sum of the outputs usually contains considerable phase distortion. Subtractive arrangements using a single filter can be made free from such distortion, but have been complicated to realize in practice. A subtractive filter is described which is simple and cheap.

Origin of Mechanical Bias for Transducers

Harry B. Miller

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1455-1455 (1963); (1 page) | Cited 1 time

Online Publication Date: 20 Jul 2005

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The people who were familiar with the birth of this invention have agreed to speak for the inventor before the origin gets hopelessly forgotten.

Effect of Cutoff Configuration on Pure Tones Generated by Small Centrifugal Blowers

L. A. Lyons and S. Platter

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1455-1456 (1963); (2 pages)

Online Publication Date: 20 Jul 2005

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Two methods for reducing the blade‐passage tone of a centrifugal blower are presented, and their effectiveness is described.

On Transonic Pressure Fluctuations

Peter A. Franken

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1456-1457 (1963); (2 pages)

Online Publication Date: 20 Jul 2005

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Data on transonic pressure fluctuations are related qualitatively to the corresponding local flow conditions.

Reflection and Transmission Coefficients for Stress Waves in Bars

R. Plunkett and R. B. Doolen

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1457-1458 (1963); (2 pages)

Online Publication Date: 20 Jul 2005

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Previous experimental work has raised a question about the validity of one‐dimensional wave theory for predicting the reflection of compression pulses in elastic bars. The measurements reported here are in much better agreement with these predictions than those previously reported.

Comment on “Nonstationary Response of Continuous Structures to Random Loading”

J. L. Bogdanoff and J. E. Goldberg

J. Acoust. Soc. Am. Volume 35, Issue 9, pp. 1458-1458 (1963); (1 page)

Online Publication Date: 20 Jul 2005

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