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Journal of the Acoustical Society of America

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Jan 1962

Volume 34, Issue 1, pp. 1-132

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Spoken Digit Recognition Using Vowel‐Consonant Segmentation

P. N. Sholtz and R. Bakis

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 1-5 (1962); (5 pages)

Online Publication Date: 26 Jul 2005

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A procedure has been developed for recognition of spoken digits by means of digital computer simulation. Using power spectra computed at 10‐msec intervals, the words are segmented into vowels and consonants. Vowels are then classified into one of 11 categories by a multivariate statistical decision method operating on approximations of the measurements. Consonants are classified into one of three categories by means of an empirically derived decision tree. Recognition is then performed by means of a dictionary search. When tested on a sample of 493 words spoken by 50 speakers, and with the internal dictionary adjusted for optimum results, 97% of the words were identified correctly. It appears that this procedure is more tolerant of interspeaker variations than those previously reported.

Ultrasonic Atomization of Liquids

Robert J. Lang

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 6-8 (1962); (3 pages) | Cited 30 times

Online Publication Date: 26 Jul 2005

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An experimental study was made of the mechanism by which the ultrasonic vibration of liquid surfaces causes atomization.
At exciting frequencies in the range of 10 to 800 kc, uniform patterns of crossed capillary waves were found on the liquid surface when atomization occurred. The number‐median diameter of the particles produced was found to be a constant fraction, 0.34, of the capillary wavelength; the capillary wavelength is calculable by Kelvin's equation using the exciting frequency and properties of the fluid being atomized.
The evidence is strong that the mechanism of ultrasonic atomization involves the rupture of capillary surface waves and the subsequent ejection of the wave peaks from the surface as particles.

Propagation of Plane Sound Waves of Finite Amplitude in Nondissipative Fluids

David T. Blackstock

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 9-30 (1962); (22 pages) | Cited 10 times

Online Publication Date: 26 Jul 2005

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An extensive theoretical treatment is presented of the problem of plane progressive sound waves (simple waves) produced by continuous, high‐amplitude motion of a piston in a lossless, semi‐infinite tube. The fluid in the tube is assumed to be nondissipative; liquids as well as perfect gases are considered. The analysis is given in both Eulerian and Lagrangian coordinates. Earnshaw's exact solution in parametric form is first given for arbitrary piston motion. Special attention is then given to the case of sinusoidal piston motion. Approximate but explicit power‐ and Fourier‐series solutions for this case are derived from the exact solution. A low‐amplitude nonlinear theory of simple waves is proposed. In this theory nonlinear effects are considered in a simple yet general manner.
A brief analysis of shock formation is also given. It is shown that the generally accepted formula for the distance at which the shock forms when the piston motion is sinusoidal is rigorously correct only under very special circumstances.

Measurement of the Distortion of Finite Ultrasonic Waves in Liquids by a Pulse Method

R. P. Ryan, A. G. Lutsch, and R. T. Beyer

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 31-35 (1962); (5 pages) | Cited 2 times

Online Publication Date: 26 Jul 2005

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An rf pulse system is described for investigating progressive distortion of finite amplitude waves propagating in liquids. The system employs pulses short enough to avoid reflections but long enough to approach continuous wave conditions. A 25‐Mc quartz crystal backed by fused quartz serves as a nonresonant receiver for the first few harmonics of the 2.58‐Mc working frequency. Harmonic content is determined by Fourier analysis of waveform photographs, or by use of a heterodyne analyzer having bandwidth adequate to pass the pulse envelope. For an initially sinusoidal wave of 3.0 or 6.0 atm pressure amplitude in water, curves are shown tracing the decay of the fundamental and the growth and decay of harmonics through the fourth, to a propagation distance of 40 cm. Results are in good agreement with published theory within the region of convergence of the latter.

Extensional Waves in Fluid‐Saturated Porous Cylinders

G. H. F. Gardner

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 36-40 (1962); (5 pages) | Cited 14 times

Online Publication Date: 26 Jul 2005

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Pochhammer's method of analysis for waves in circular cylinders is extended to Biot's theory for an elastic porous solid saturated with a compressible viscous fluid. Attention is given mainly to slender rods vibrating at low frequencies. The boundary condition of zero stresses on the curved cylindrical surface is used to derive the frequency equation from which phase velocity and attenuation may be obtained. In general, two types of extensional waves exist, just as there are two types of dilatational waves. The attenuation per unit length of the first kind of wave is proportional to the square of the frequency at low frequencies except when the wavelength of dilatational waves of the second kind is about half the perimeter of the cylinder. In the neighborhood of this frequency the attenuation may show a maximum. Waves of the second kind behave like a diffusion phenomenon, except in the same neighborhood.

Response of Internally Damped Beams on Vibrating Supports

F. Edward Ehlers

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 40-53 (1962); (14 pages)

Online Publication Date: 26 Jul 2005

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The classical Euler beam equation is modified by introducing a hysteresis damping term which is proportional to the strain but which is in phase with the strain velocity. General solutions are obtained for the cantilever, clamped, and pin‐supported beams whose supports are moved by a prescribed function of time. For sinusoidal vibration of the support, the analysis of a cantilever beam is compared with experiment and with the corresponding solution in which the damping is proportional to the rate of strain as formulated by Sezawa. The hysteresis type damping gives results closer to the experimental values than Sezawa's method. The shear stress and displacement in a cantilever beam whose support falls on an elastic platform are investigated. The analysis is applicable to clamped and pin‐supported beams by substituting the appropriate resonant frequencies and eigenfunctions. Simple formulas for dynamic load factors at the resonant frequencies are found by comparing the maximum displacement or shear stress of the beam under sinusoidal vibration of its supports with the corresponding displacement or shear stress for a static loading under a centrifugal acceleration of the same amplitude as the sinusoidal acceleration. Rice's theory of random noise is applied to the response of the beam on a support vibrating in a random manner.

Isolation from Vibration with a Mounting Utilizing Low‐ and High‐Damping Rubberlike Materials

J. C. Snowdon

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 54-61 (1962); (8 pages)

Online Publication Date: 26 Jul 2005

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The dynamic mechanical properties of rubberlike materials have been briefly reviewed. The value of a mounting composed of a low‐ and a high‐damping rubber in parallel is in this way made apparent. Expressions have been derived from which the ability of the so‐called parallel mounting to isolate vibration from any nonrigid foundation may be determined, if the mechanical impedance of the foundation is known.
One‐ and two‐stage mounting systems have been considered. To compare their performance, the mechanical impedance of a damped beam has been employed to simulate the behavior of a nonrigid foundation. It is shown that the parallel mounting suppresses resonant motion at the natural frequencies of the foundation and the mounting systems with similar effectiveness to the high‐damping rubber, yet provides the greater isolation at other frequencies. The isolation afforded by the mounting is, in fact, often comparable to that which the low‐damping rubber affords.

Long‐Range Shallow‐Water Bottom Reverberation

K. V. Mackenzie

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 62-66 (1962); (5 pages) | Cited 6 times

Online Publication Date: 26 Jul 2005

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A theory is presented which enables the computation to be made of 200‐ to 3000‐cps bottom reverberation returning from very great ranges in shallow water. Typical computed curves are presented for reverberation level vs range/water depth. Computed curves are presented for scattering strength vs range/water depth. These later curves are presented for both the isospeed and negative sound‐speed gradient cases.

Long‐Range Shallow‐Water Signal‐Level Fluctuations and Frequency Spreading

K. V. Mackenzie

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 67-75 (1962); (9 pages)

Online Publication Date: 26 Jul 2005

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The fluctuation of the received sound for frequencies of 350, 700, 1200, and 2400 cps was studied for transmission over flat 60‐fathom sand and 50‐fathom sandstone bottoms out to ranges of 15 miles. The received sound fluctuated over a range of 50 db. In general, the amplitude distribution was neither Gaussian nor Rayleigh. No significant correlation was found between the outputs of the receiving hydrophones which were separated vertically by 90 or more feet. The frequency was spread due to transmission and the relative power P is related to the half‐width of the spectra ∣f − f0∣ from 350 to 2400 cps by
math
, where b  =  (7.7±0.8)×10−6 (cps)2 for the sand bottom and (3.9±2.7)×10−6 (cps)2 for the sandstone bottom. Special measurements indicated no significant asymmetry between the spectra above f0 from that below f0.

On Frequency Response Curves in Rooms. Comparison of Experimental, Theoretical, and Monte Carlo Results for the Average Frequency Spacing between Maxima

M. R. Schroeder and K. H. Kuttruff

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 76-80 (1962); (5 pages) | Cited 16 times

Online Publication Date: 26 Jul 2005

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The average frequency spacing 〈Δfmax〉 between adjacent maxima of the frequency response curve between two points in a room is determined by experiment, theory, and Monte Carlo computation. In earlier papers it had been shown that, above a certain critical frequency, 〈Δfmax〉 is reciprocally related to reverberation time and not dependent on other room characteristics—disproving a belief that 〈Δfmax〉 is a useful measure of the acoustical quality of rooms. Theory predicts 〈Δfmax〉  =  3.91/T60, where T60 is the reverberation time. Monte Carlo computation gives 3.90/T60. Measurements in two very different rooms using a vacuum tube voltmeter for reading the sound pressure are in good agreement with these predictions. Measurements with a logarithmic level recorder give, as in earlier investigations, much larger values. The discrepancy cannot be explained by the level recorder′s 0.5‐db quantization. This paper shows that: (1) The Monte Carlo method is a useful tool for solving complex problems in room acoustics. (2) Level recorder measurements of frequency (or space) irregularities of rooms must be taken with several grains of salt.

Optimum Acoustic Criteria of Concert Halls for the Performance of Classical Music

Fritz W. Winckel

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 81-86 (1962); (6 pages) | Cited 1 time

Online Publication Date: 26 Jul 2005

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The known criteria of room acoustics are not sufficient to characterize the quality of concert halls. To obtain more specific information on the acoustic qualities of concert halls, the author went on tour with the Cleveland Orchestra, making measurements in 15 concert halls. These measurements revealed that the dynamic range of performed music and also the tempo are different in the several halls. The dynamic range depends on the noise level of the room and the state of sound diffusion. The tempo of music is at a maximum in concert halls which have optimum reverberation time and diffusion.

A Mapping of Binaural Click Lateralizations

Newman Guttman

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 87-91 (1962); (5 pages)

Online Publication Date: 26 Jul 2005

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This experiment principally attempted to map the movements of lateralized auditory images associated with 1‐pps unfiltered clicks heard at two intensity levels and over a wide range of interaural time and intensity differences. With sensation level at 16 db in both ears, lateralization effects were heard for interaural time differences as large as ±15 msec. With 16 db SL in one ear, the minimum level in the other ear producing effects was −6 db, the effect usually being a “bulge” of the image in the audible ear occurring within ±2 msec interaural time difference. Approximately the same time‐difference limits were found, respectively, for 36 db in both ears and 36 db in one ear paired with the minimally effectual −2 db in the other ear. The time‐difference limits within which fusion was “complete” (only one image heard) ranged from 3–7 msec, louder ear leading, to 3 msec, louder ear lagging. It is suggested that the results set a bound on the contribution of direct binaural correlation to the precedence‐effect phenomenon.

Magnitude Estimations of Pitch

Jacob Beck and William A. Shaw

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 92-98 (1962); (7 pages)

Online Publication Date: 26 Jul 2005

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Using the method of magnitude estimation, the experiments reported investigated the effect of the frequency of the standard upon the pitch functions for piano tones and randomly chosen pure tones. The pitch functions obtained are found to agree in an important respect with each other and with the function previously reported for pure tones chosen to correspond to notes on the musical scale. When the frequency of the standard was the lowest tone presented, the magnitude estimations yielded a function similar to the revised mel scale, and when the standard was a frequency nearer the middle of the series, the magnitude estimations yielded a steeper function closer to the original mel scale. Data are also presented showing that the numerical value of the standard can affect the magnitude estimation function. These results indicate that response biases relating to the frequency and numerical value of the standard may be expected to influence the pitch function determined by magnitude estimations. The nature and effect of these biases are discussed. It is concluded that care is required in viewing magnitude estimation judgments as reflecting a simple correspondence between frequency and the sensation of pitch.

Properties of the Eighth Nerve Action Potential

R. J. Ruben, U. Fisch, and W. Hudson

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 99-101 (1962); (3 pages)

Online Publication Date: 26 Jul 2005

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The eighth nerve action potential in the cat was recorded from the round window and from the eighth nerve. The conduction velocity, measured directly and computed from the fiber diameter, was found to be approximately 25 m/sec. Comparison of the onset of the action potential at the round window and its appearance in the eighth nerve showed a delay of 0.3 msec, based upon the theoretical time of transmission according to the conduction velocity. As the stimulus intensity was increased, a decrease in the latency of the action potential of the eighth nerve was noted.

Inner Ear Response to High‐Level Sounds

Merle Lawrence, David Wolsk, and Pieter Schmidt

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 102-107 (1962); (6 pages)

Online Publication Date: 26 Jul 2005

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The cochlear ac potentials in response to a stimulating tone of rapidly increasing intensity undergo a rapid reduction in amplitude after reaching a certain maximum. The record seen on the cathode ray screen is indistinguishable from that reported for middle ear muscle action, yet the response described here occurs in the absence of muscles or of the entire middle ear. This effect is described as a “clamp,” but it is found to be the result of overloading in the inner ear. Within the limits of these experiments it is shown that the rate of rise of a tone makes no difference in the form of the cochlear ac response. This finding, if carried to extremes, would suggest that the inner ear behaves the same in the presence of impact noise as it does in the presence of steady‐state or slowly rising tones.

On the Width of Critical Bands

John A. Swets, David M. Green, and Wilson P. Tanner, Jr.

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 108-113 (1962); (6 pages) | Cited 6 times

Online Publication Date: 26 Jul 2005

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A different technique of analysis is applied to the experiment suggested by Harvey Fletcher for measuring the width of the critical band. This experiment determines the ability of noise bands of different widths to mask a pure tone centered in the band. The analysis considers two filters in series, one outside and one inside the observer. The width of the second filter (the critical band) can be estimated from measurements of the reduction in the noise power at the detector which is effected by the pair of filters. The width of the critical band is estimated under four different assumptions about the shape of the band. The results provide a context for discussing the reasons that may underlie the widely varying estimates of the critical bandwidth which have been obtained in previous studies.

Minimum Phase Responses for the Basilar Membrane

James L. Flanagan and Carol M. Bird

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 114-121 (1962); (8 pages)

Online Publication Date: 26 Jul 2005

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Appreciable experimental data exist for the amplitude of basilar membrane displacement as a function of sound frequency. Data on the phase of displacement vs frequency are relatively meager. At low frequencies the latter do not relate well to the phase predicted by recent mathematical models for membrane displacement. To examine the difference, we programmed a digital computer to calculate: (1) minimum phase functions corresponding to the experimental amplitude vs frequency responses; (2) inverse Fourier transforms of the experimental amplitude and phase data; and (3) inverse transforms of the experimental amplitude and calculated minimum phase data. The results were: (1) At low frequencies the calculated phase differs from the experimental phase by about ½π radians or more, with the membrane displacement leading that of the stapes. Constant delay (i.e., linear phase) does not account for the difference; (2) inverse transforms of the experimental data yield nonrealizable impulse responses, i.e., responses which are nonzero for negative times; and (3) inverse transforms of the experimental amplitude and calculated phase yield proper impulse responses. At low frequencies, therefore, the experimental amplitude and phase data do not seem completely compatible. For several reasons, the phase data seem more likely to include a small imprecision than do the amplitude data.

Temporary Threshold Shift with Changing Duty Cycle

Weldon Selters and W. Dixon Ward

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 122-123 (1962); (2 pages)

Online Publication Date: 26 Jul 2005

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The empirical rule that interrupted noise having an on‐fraction R produces R times the TTS that the same noise would produce if on continuously (the on‐fraction rule) was tested for R≈0.5 and for various duty cycles from 1 min to 16 min. The TTS from the 1‐min and 2‐min duty cycles agreed with the value predicted by the rule, but the 4‐min, 8‐min, and 16‐min duty cycles gave respectively 1.07, 1.21, and 1.29 times the R‐based values. This result indicates that the on‐fraction rule breaks down when on‐off times exceed about 1 min, but that the rule may be extended for periodic or nearly periodic noises by incorporating correction factor based on the length of the period.
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Comments on the Measurement of the Relative Size of dc Potentials and Microphonics in the Cochlea

G. v. Békésy

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 124-124 (1962); (1 page)

Online Publication Date: 26 Jul 2005

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Role of Time Integration in the Discrimination of Frequency Response Patterns

F. V. Hunt

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 125-125 (1962); (1 page)

Online Publication Date: 26 Jul 2005

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The hypothesis is advanced that a time‐invariant pattern of frequency response can be discriminated in the presence of a variable pattern of frequency‐response irregularity only when the listening interval is of sufficient duration to allow the variable part of the total response pattern to be averaged out. Qualitative evidence seems to support the hypothesis, but quantitative evaluation of the needed integration times is still wanting. If the effect is real, however, it may have an important bearing on the interpretation of the conventional A ‐ B tests used for the assessment of sound reproducing systems.

Average Responses to Clicks Recorded from the Human Scalp

C. Daniel Geisler and Walter A. Rosenblith

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 125-127 (1962); (3 pages)

Online Publication Date: 26 Jul 2005

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The use of a method of electronic averaging in the detection of electrical responses from human subjects is briefly described. The correlation of such data with psychophysical data from the same subject is discussed.

Lateral Line in Fish—Possible Mode of Action

E. E. Suckling

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 127-127 (1962); (1 page)

Online Publication Date: 26 Jul 2005

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The proposal is made that fish detect low‐frequency sounds as “internal vibrations” rather than as direct oscillations of the water.

Helmholtz's Aversion to Tempered Tuning Experimentally Shown to be a Neurological Problem

Max F. Meyer

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 127-128 (1962); (2 pages)

Online Publication Date: 26 Jul 2005

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Experiments show that the brain of people of ordinary musical endowment, when unsophisticated, enables them to esthetically appreciate melodies that are even more mistuned than the equally tempered scale.

Comment on “Aid to Music Composition Employing a Random Probability System”

J. Murray Barbour

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 128-129 (1962); (2 pages)

Online Publication Date: 26 Jul 2005

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A recently published article states that “a composing machine employing a random probability system based upon Stephen Foster songs may be developed ….” Later the authors make the categorical statement: “The resulting music [i.e., produced by the machine], while new, sounds like Stephen Foster music.” However, because of many errors in notes and rhythms and a failure to comprehend musical design, the output of the machine bears no resemblance whatever to the songs of Stephen Foster. A possible alternative method of mechanically simulating Foster's style is suggested.

Ultrasonic Dispersion in Dissociating Dinitrogen Tetroxide

Harvey Blend

J. Acoust. Soc. Am. Volume 34, Issue 1, pp. 129-130 (1962); (2 pages) | Cited 2 times

Online Publication Date: 26 Jul 2005

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The velocity of sound was measured in dissociating dinitrogen tetroxide. These measurements were made over a frequency range of 20 to 800 kc and pressure range of 1 to 70 cm Hg giving a frequency/pressure range of 0.0217 to 60.8 Mc/atm. The temperature range covered was from 0° to 50°C. At 20°C and 10 cm Hg the velocity change was 4% over the frequency range stated and the relaxation time was 1.72 μsec.
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