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Dec 1966

Volume 40, Issue 6, pp. 1287-1567

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An Experiment in Bibliographical References

R. Bruce Lindsay

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1287-1287 (1966); (1 page)

Online Publication Date: 21 Jul 2005

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Some Deep‐Water Sound‐Transmission Paths South of Cyprus. Part II: Diffraction Effects

Lincoln Baxter, II and Robert Brockhurst

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1288-1299 (1966); (12 pages)

Online Publication Date: 21 Jul 2005

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Intensity and Fourier spectra of refracted and of bottom‐reflected acoustic arrivals in the Mediterranean Sea south of Cyprus at ranges between 16 and 20.4 NM (nautical miles) are presented, together with the most probable sound‐velocity profile and the near‐surface temperature structure. The arrival structure and relationship between pulse travel time and range indicate that most of the 100‐ to 800‐cps energy contributing to an arrival travels along paths similar to rays, but we find that, below 600 cps, there are frequency differences in the locations of these paths. The discovery of these frequency differences causes us to withdraw the postulate of scattering advanced in our first paper of this title and replace it with one of diffraction. According to Officer [Introduction to the Theory of Sound Transmission, McGraw‐Hill Book Co., Inc., New York, 1958), Chap. 2], such differences can be caused by diffraction occurring at depths where the absolute value ∣λ0(δc′/c)∣ of the ratio of the fractional change δc′, in the velocity gradient over a wavelength, to the velocity gradient c/λ0 is largest. Our results indicate that the diffraction is observable in the convergence zone if ∣λ0(δc′/c)∣ at such depths is approximately 5×10−4 or greater.

Near Field of a Dipole for Measurements in Shallow Lakes

Robert J. Bobber

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1300-1304 (1966); (5 pages)

Online Publication Date: 21 Jul 2005

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Acoustic measurements in shallow lakes are subject to interference caused by reflections from the lake surface and bottom. This interference is particularly serious at frequencies below about 2 kHz. If a dipole (two out‐of‐phase simple sources) is used as a projector, substantial sound‐pressure level is available in the near Field, regardless of the well‐known inefficiency of such a projector. At the same time, interference caused by lateral reflection is virtually eliminated by the farfield directivity characteristics of the dipole. The optimum relationships among dipole size, test distance, boundary geometry, and frequency are analyzed and verified by experiment.

Radiation Resistance, Cavitation Factor, and Beam Patterns for Steered, Closely Packed, Rectangular Arrays in a Rigid Plane

Norman T. Chin

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1305-1316 (1966); (12 pages)

Online Publication Date: 21 Jul 2005

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A large, closely packed, steered array is modeled by imposing a traveling wave along the surface of a rectangular radiator. The results in this paper are most pertinent to closely packed arrays made up of elements that are small as compared with a wavelength. For this type of array, it is shown that at large steering angles the cavitation‐limited power is greatly reduced below that achievable at broadside. The cavitation factor is generally less when the beam is steered along the longer side of an array than when the beam is steered across its shorter side. Integral solutions for the nearfield pressure and radiation resistance of a general steered array are presented. Numerical results show that the radiation resistance has a maximum value at a particular steering angle for a specific array, and the nearfield pressures pile up near the leading edge of the array as the beam is steered to a large angle. In the end‐fire case, approximate expressions for the radiation resistance and the nearfield pressure are derived for an infinitely long rectangular strip with beam steering across the width, and for a finite, slender, rectangular array with beam steering along the longer side.

Time Variability of Volume Scattering a Small Oceanic Area

Barry A. Gold and Peter Van Schuyler

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1317-1321 (1966); (5 pages)

Online Publication Date: 21 Jul 2005

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Volume‐scattering strengths are presented for both daytime and nighttime, measured at three different times, in the same oceanic area during a nine‐month period. The data are analyzed in ⅓‐oct bands covering the frequency region from 2.5 to 20.0 kHz. The maximum and minimum variation in scattering strengths over the nine‐month period range from 11 to 3 dB. Swimbladder volumes of fishes are determined from the acoustic characteristics of deep scattering layers. A volume of 0.72 cm3 is computed for fish residing at 950 m and 0.022 cm3 for fish at 610 m. Biological sampling of the deep‐scattering layers shows the presence of four families of fishes that possess swimbladders: Myctophidae, Gonostomatidae, Sternoptychidae, and Melamphaidae.

Conversion of Electromagnetic to Acoustic Energy by Surface Heating

Luke S. Gournay

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1322-1330 (1966); (9 pages) | Cited 22 times

Online Publication Date: 21 Jul 2005

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The stresses that evolve in a thermally shocked liquid were examined. The magnitude and time duration of stress transients generated by a Q‐switched ruby laser were measured in the absence of a phase change and compared with results calculated from a simplified thermodynamic model. It is shown that the model agrees with experimental data over a wide range of incident electromagnetic intensity and for large variations of liquid properties. Results are also presented to show the effect of liquid vaporization on the stress transients and the parameters associated with formation of a gas phase.

Effect of Turbulence Nearfield on a Shielded Transducer

H. S. Heaps

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1331-1336 (1966); (6 pages)

Online Publication Date: 21 Jul 2005

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When a transducer of finite size is used to measure the spectral density of a turbulent sound field, the results are dependent on the size of the transducer. If the transducer is separated from the turbulence by a non‐turbulent medium, or by an elastic layer, then the recorded pressure is a function of both transducer size and layer thickness. Analysis of the effect of transducer size and separating layer is the purpose of this paper. The theory is developed for computation of attenuation of spectral density as a function of transducer size and distance from the turbulent layer.

Experiment on Sound Propagation in Shallow Water under Isovelocity Conditions

A. C. Kibblewhite and R. N. Denham

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1337-1344 (1966); (8 pages)

Online Publication Date: 21 Jul 2005

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An investigation into the long‐range propagation of sound in shallow, isovelocity water was carried out using an extensive area of the continental shelf off the west coast of New Zealand. The results obtained showed that a classic example of normal‐mode propagation in shallow water was involved. The values of attenuation obtained and the general behavior of the attenuation as a function of frequency are comparable with other shallow‐water areas. Other characteristics of the propagation mechanism can be explained in terms of depth variation and layering of the bottom.

Acoustic‐Impedance Measurements at High Hydrostatic Pressures

Gerald A. Sabin

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1345-1353 (1966); (9 pages) | Cited 2 times

Online Publication Date: 21 Jul 2005

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The theory, design, and operation of a system for the measurement of acoustic impedance at hydrostatic pressures to 10 000 psig are described. The system is a pulse tube featuring the use of coherent pulses. The acoustical characteristics of materials are determined from measurements made on small samples (2 in. diam × ∼ 6 in. long). Three different measurement methods are discussed.

Transduction of Boundary‐Layer Noise by a Rectangular Panel

Pritchard H. White

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1354-1362 (1966); (9 pages)

Online Publication Date: 21 Jul 2005

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The response and consequent sound radiation of a thin rectangular panel excited by convected boundary‐layer turbulence has been examined. By taking averages over a frequency band, and including many modes in this average, the detailed characteristics of the system are bypassed and only gross features such as panel modal density, ratio of radiation to total resistance, and the boundary‐layer characteristics are of interest. A large portion of the sound power is transmitted in the region of the hydrodynamic coincidence condition. The hydrodynamic coincidence frequency is the most important feature in determining the shape of the transmitted power spectrum, and the power law for the total power radiated. Good agreement between theory, and experiment serve to verify the basic assumptions of the theory.

Deformation and Motion Produced in Isolated Living Cells by Localized Ultrasonic Vibration

Walter L. Wilson, Floyd J. Wiercinski, Wesley L. Nyborg, R. M. Schnitzler, and F. J. Sichel

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1363-1370 (1966); (8 pages)

Online Publication Date: 21 Jul 2005

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Naturally‐isolated living cells were subjected to ultrasonic vibration by means of the tip of a steel needle applied directly to the cell surface or inserted into a drop of a suspension of cells in sea water. The needle was machined into the tip of a stainless‐steel cone, and the base of the cone was glued to one end of an electroded and polarized barium titanate hollow cylinder. This composite transducer was driven at its resonant frequency of approximately 85 000 cps. Ultrasound applier to the surfaces of egg cells of marine invertebrates produces rotation, translation, deformation, and fragmentation of the nucleoli; rotation and deformation of the nuclei; acoustic streaming of nucleoplasm and cytoplasm; and deformation of the cellular surface and fragmentation of the cell. Cells and intracellular bodies are often attracted to the sound source as a result of acoustic‐radiation pressure, and, especially for whole cells in suspension, this attractive tendency is typically superposed on a tendency of the body to take part in acoustic streaming of the surrounding medium. Some aspects of the motion can be accounted for in terms of presently available theory of nonlinear acoustics. Information on the physical properties of nucleolus, nucleoplasm, and cytoplasm is gained from use of this sonic technique.

Temporary Threshold Shifts in Hearing from Exposure to Combined Impact/Steady‐State Noise Conditions

Alexander Cohen, Bengt Kylin, and Paul J. LaBenz

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1371-1380 (1966); (10 pages)

Online Publication Date: 21 Jul 2005

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Temporary threshold shifts (ITS) in pure tone hearing acuity are reported for 15 subjects exposed in separate 15‐min periods to taped impact sounds [played back at 124‐ to 127 dB peak sound‐pressure level (SPL)], to three levels of filtered (75‐ tn 1200 cps) steady‐state noise (90, 100, 110 dB SPL), and to combinations of the recorded impact sounds with each level of the steady‐state noise. TTS's from all such exposures were typically small, with the largest shifts occurring in the 1000‐ to 3000 cps frequency range. When combined with 90‐ and 100 dB steady‐state noise, the impacts caused less threshold shift than when presented alone. Such TTS reductions were believed due to the relatively greater ability of the steady‐state noise to arouse and sustain the acoustic reflex with its consequent sound‐attenuation effect. The addition of the 110 dB steady‐state noise did not induce a similar result quite possibly because this exposure, by itself, caused threshold shifts equal to or exceeding those of the impact sounds. More‐effective stimulation of the acoustic reflex was believed responsible for findings showing less TTS for combined impact/steady state noise than from exposure to just the steady‐state component of the combination. Indirect measures of acoustic‐reflex response [contralateral remote masking (CRM)] generally indicated that those ears with a strong reflex response show less noise‐induced shift. Correlations between TTS from impact and from steady‐state noise for the subject group indicated some degree of positive correspondence limited to frequencies of of 2000 cps and below and strongest for those subjects with a poor reflex response as shown by their CRM data.

On the Generation of Odd‐Fractional Subharmonics

Peter J. Dallos

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1381-1391 (1966); (11 pages)

Online Publication Date: 21 Jul 2005

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In chinchilla ears, between 1000 and 3000 Hz, the common one‐half frequency subharmonic is not present. Instead, pairs of odd‐fractional subharmonics are seen. These distortion components appear at threshold only in specific frequency relations with the fundamental. Above threshold, both the frequency and the magnitude of the subharmonic depend on the stimulus intensity. With direct mechanical stapes stimulation and with various probe‐tone experiments, it was shown that the odd‐fractional subharmonics originate in the inner ear. The phenomenon of subharmonic squelch effect was described.

On the Application of the EC Model to Interaural jnd's

N. I. Durlach

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1392-1397 (1966); (6 pages)

Online Publication Date: 21 Jul 2005

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This paper reports some preliminary results of an attempt to apply the equalization and cancellation (EC) model of binaural unmasking to data on interaural just‐noticeable differences (jnd's). The interaural dimensions that are considered are time, amplitude, frequency, and decorrelation.

Membrane Resistance in Endolymphatic Walls of the First Turn of the Guinea‐Pig Cochlea

B. M. Johnstone, J. R. Johnstone, and I. D. Pugsley

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1398-1404 (1966); (7 pages) | Cited 1 time

Online Publication Date: 21 Jul 2005

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Microelectrodes were inserted into the three scalae of the first turn, and resistance measurements were fitted to a model having six pathways. The six pathways with average resistance values are (1) blood vessels inside the cochlea to the outside of the bulla—1.6 kΩ, (2) blood vessels inside the cochlea to scala tympani—0.6 kΩ, (3) blood vessels inside the cochlea to scala vestibuli—0.8 kΩ, (4) blood vessels inside the cochlea via the stria vascularis to scala media—13 kΩ, (5) scala media direct to scala tympani (organ of Corti)—24 kΩ, (6) scala media direct to scala vestibuli (Reissner's membrane) 46 kΩ. There was no indication of a need to include a direct pathway from scala tympani to scala vestibuli. The “length constant” of scala media in the first turn is about 2.0 mm. The resistance changes due to moderate sound were found to be small, but measurable. Changes of resistance with anoxia showed first a decrease and then an increase in the resistance from scala media to ground.

Origin of Summating Potential

J. R. Johnstone and B. M. Johnstone

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1405-1413 (1966); (9 pages) | Cited 2 times

Online Publication Date: 21 Jul 2005

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The relationship between sound and cochlear potentials is considered in the light of von Békésy's observations of movement of the cochlear partition and Davis' variable‐resistance theory of hair‐cell function. An equation is derived relating hair angle to basilar‐membrane movement. The equation is ϕ  =  arcot (Yα+cotϕ0) where ϕ is the hair angle and α is proportional to basilar‐membrane movement. ϕ0 is the resting hair angle. Y is the ratio of the distance between basilar membrane and hair cell apex to the distance between tectorial membrane and hair‐cell apex. It is shown that the sigmoidal shape of this function leads to a linear dependence of microphonics on sound intensity, generation of harmonics, and production of positive and negative summating potentials by inner and outer hair cells, respectively. The behavior of the cochlear potentials, including the effect of sound pressure in reversing summating potential polarity, effect of cochlear pressure changes, and reversal of summating potential polarity with anoxia, is also accounted for. A mechanical model of the organ of Corti, used to illustrate our theory, is described, together with results obtained from the model.

Masking‐Level Differences with Continuous and with Burst Masking Noise

Dennis McFadden

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1414-1419 (1966); (6 pages) | Cited 15 times

Online Publication Date: 21 Jul 2005

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Psychometric functions were obtained for several interaural phase combinations with both continuous and burst masking noise. In the burst conditions, the signal (400 cps, 125 msec) and the wide‐band masker (45 dB/cycle) were gated simultaneously; in the continuous conditions, only the signal was gated. Performance on burst N0‐S0 was only about 0.5 dB worse than that on continuous N0‐S0, but the masking‐level differences (MLD's) for N0‐Sπ Nπ‐S0, N0‐Sm, and Nπ‐Sm were 4–6 dB smaller with burst than with continuous noise. In an additional experiment, the noise burst (N0) was gated 0, 75, 150, 250, 400, 600, and 1000 msec before the onset of the signal (Sπ). These MLD's increased gradually between 0 and 600 msec and then leveled off at approximately the value obtained with a continuous masker. A single‐interval YES‐NO procedure was used in these experiments. When two‐alternative forced choice was used, the difference between continuous and burst noise was considerably diminished.

Measurement of Stapedial‐Footplate Displacements during Transmission of Sound through the Middle Ear

M. Rubinstein, B. Feldman, H. Fischler, E. H. Frei, and D. Spira

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1420-1426 (1966); (7 pages) | Cited 3 times

Online Publication Date: 21 Jul 2005

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The frequency response of stapedial‐footplate vibration during sound conduction was measured on fresh cadaver specimens. Specially designed and adapted instruments made these measurements possible at sound levels lower than those causing discomfort to living subjects (84 114 dB), and with a continuous frequency sweep between 100 cps and 10 kcps. The results show a similarity with the curves of subjective ear sensitivity, suggesting a dependence of the over‐all sensitivity of the ear on the middle‐ear frequency response. Linear increase of vibration amplitude with sound level was found to exist up to around 104 dB; above this sound level, there is a gradual limiting of the stapedial excursions. Speculations on energy transfer from the middle to the inner ear showed nearly optimal matching between them. The influence of the aging process of the specimens is discussed.

Efferent Inhibition of Auditory‐Nerve Responses: Dependence on Acoustic‐Stimulus Parameters

Michael L. Wiederhold and William T. Peake

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1427-1430 (1966); (4 pages) | Cited 1 time

Online Publication Date: 21 Jul 2005

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Electrical stimulation of the crossed olivocochlear bundle in anesthetized cats reduces auditory‐nerve responses (N1) if the acoustic stimuli are at low sound‐pressure levels but does not produce detectable changes in neural responses for click stimuli more than 60 to 70 dB above visual‐detection level for N1. When the sound‐pressure levels of high‐frequency (10 000‐Hz) and low frequency (400‐Hz) transient acoustic stimuli were matched according to a physiological criterion, the neural response to the high‐ frequency stimulus was reduced more by olivocochlear bundle stimulation than the response to the low‐frequency stimulus. These result, suggest certain characteristics for the mechanisms which influence the activity of single auditory‐nerve fibers.

Measurement of Specific Acoustic Impedance

Joseph Wood Rogers

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1431-1432 (1966); (2 pages)

Online Publication Date: 21 Jul 2005

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The theory of an experimental procedure that can be used to measure specific acoustic impedance is presented in this paper. No moving parts are required. Only two measurements need be made. A sequence of simple calculations is presented for reduction of these data.

Foil‐Electret Microphones

G. M. Sessler and J. E. West

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1433-1440 (1966); (8 pages) | Cited 5 times

Online Publication Date: 21 Jul 2005

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Electrostatic microphones with foil electrets are described. Foil electrets are solid dielectric materials, such as fluorocarbon, prepolarized in an electrostatic field at an elevated temperature. The use of electrets eliminates the need for an external dc bias. The sensitivity of these microphones depends largely on the surface charge of the electret and is typically between −50 and −60 dBV for a sound‐pressure level of 1 μbar. The sensitivity of fluorocarbon electret microphones does not decay over periods of the order of years at room temperature. Extrapolation tn room temperature of results obtained at elevated temperatures indicates the time constant of the sensitivity of fluorocarbon microphones to be between 30 and 103 years, depending on the preconditioning (temperature cycling) of the systems. The relative humidity is of little influence on the time constant. Even at 80°C and high relative humidity, the time constant is still of the order of 100 days. The capacitance per unit area of electret microphones (about 60 pF/cm2) is three times greater than that of air‐gap systems. Because resonance frequency and sensitivity do not depend on the diameter of the system, a capacitance much higher than that of air‐gap systems can be achieved for a given bandwidth. The free‐field frequency response is within ±1.5 dB from 50 to 14 000 Hz when the microphone is terminated by a few megohms.

Effects of Stimulus Content and Duration on Talker Identification

Peter D. Bricker and Sandra Pruzansky

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1441-1449 (1966); (9 pages) | Cited 1 time

Online Publication Date: 21 Jul 2005

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Sixteen listeners attempted to identify the talker when listening to speech samples of varying duration and content. The samples, recorded by 10 different talkers, were of five types: excerpted vowels, excerpted consonant‐vowel (CV) sequences, monosyllabic words, disyllabic nonsense words, and sentences. Identification accuracy improved directly with the number of phonemes in the sample even when duration was controlled. Stimulus‐response matrices differed substantially between the two vowels ([a] and [i]) used in the vowel and CV samples: relative identifiability of the talkers, response preference, and error patterns were all found to depend on vowel type. Confusion matrices for a given vowel exhibit definite asymmetries. In a limited additional study, subsets of listeners made identifying responses with the tapes reversed; performance deteriorated on even the briefest excerpts. The results pose some difficulties for a model of talker‐identification behavior based on attributes of voice quality.

Speech Intelligibility for Space Vehicles, Using Nitrogen or Helium as the Inert Gas

Julian P. Cooke and Sarah E. Beard

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1450-1453 (1966); (4 pages)

Online Publication Date: 21 Jul 2005

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A laboratory investigation was carried out to help evaluate verbal‐communication intelligibility in a man‐rated altitude simulator when either helium or nitrogen was added to the oxygen atmosphere. Some eight operators and 37 male subjects were tested with a total of 16 500 random word events at pressures of 5 psia (pounds pressure per square inch, absolute), using 70:30 mixture of O2:He or O2:N2 mixtures and also 100% oxygen at 3.5 psia. An increased lack of intelligibility has been known to occur as gas densities have been reduced. Differences in test scores following the substitution of helium in place of nitrogen at the pressures and mixtures employed resulted in no increased loss of intelligibility other than that associated with the reduced gas density, although some modification of speech can be detected by listeners.

Perception of Segments of English‐Spoken Consonant‐Vowel Syllables

William A. Grimm

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1454-1461 (1966); (8 pages) | Cited 1 time

Online Publication Date: 21 Jul 2005

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This study was undertaken to determine the effect upon perception of deleting different numbers of 10 msec segments from the initial part of each of a set of consonant‐vowel syllables. The scores that were analyzed were proportions of correct identifications of the residual elements by panels of listeners. The outcome was expressed in terms of correct identifications at each duration of the stimuli. Both the correct and error responses were studied to determine the relationship of voicing, manner of release (plosiveness and fricativeness) and place of articulation, to the identification of the stimuli. The results of the experiment indicate that the present procedure is feasible for studying the intelligibility of syllables and their constituent phonemes, and that the voicing manner of release, and place of articulation of the consonant remain evident when the syllable is truncated at the initial end to commence 50 msec before the peak intensity of the vowel of the syllable. The listeners were able to detect correct place of articulation more accurately than either voicing or manner of release as greater amounts of the initial part of a syllable were removed. The responses were related to the threshold of detectability.

Intense Ruby‐Laser‐Induced Acoustic Impulses in Liquids

E. F. Carome, C. E. Moeller, and N. A. Clark

J. Acoust. Soc. Am. Volume 40, Issue 6, pp. 1462-1466 (1966); (5 pages) | Cited 8 times

Online Publication Date: 21 Jul 2005

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An experimental study has been made of the acoustic signals induced in liquids by the focused beam from a Q‐spoiled ruby laser. Very intense acoustic impulses have been produced with laser pulses of less than 0.05 J total energy. These appear to be generated by dielectric breakdown and not associated with the hypersonic waves that may be produced simultaneously by stimulated Brillouin scattering. The observed impulses have peak pressures of approximately 500 atm and frequency components in excess of 2400 Mc/sec.
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