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Journal of the Acoustical Society of America

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Jul 1983

Volume 74, Issue 1, pp. 1-389

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Stimulus characteristics and relative ear advantages: A new look at old data

Judith L. Lauter

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 1-17 (1983); (17 pages)

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A recent report of a series of dichotic listening experiments [Lauter, J. Acoust. Soc. Am. 71, 701–707 (1982)] showed that although individual listeners differ in the ‘‘absolute ear advantage’’ shown for a given sound, there are patterns of ‘‘relative ear advantages’’ that are consistent across listeners. It was suggested that these patterns might provide a means of studying which features of test sounds are important in determining ear advantages. A survey of 12 earlier experiments, including a brief synopsis of procedures, results, and conclusions, followed by reanalysis of individual scores, shows that patterns of relative ear advantages were also present in earlier results, though obscured by an analysis that focused on the average listener. Examination of these patterns and the characteristics of sounds tested reveals a few acoustical features of sounds (e.g., event timing, bandwidth, number of dimensions changing with time) that seem to affect ear differences in a consistent way, from listener to listener and under a variety of experimental procedures. It is suggested that with attention to systematic manipulation of characteristics of test sounds, patterns of relative ear advantages may prove helpful in telling us more about the perception of complex sounds.
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43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.66.Rq Dichotic listening

Measurement of the acoustic internal source impedance of an internal combustion engine

David F. Ross and Malcolm J. Crocker

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 18-27 (1983); (10 pages) | Cited 2 times

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The standing wave tube technique has been adapted to measure the acoustic internal source impedance of an internal combustion engine. In order to implement this technique an extensive experimental facility was designed and constructed and simple test cases were evaluated for validity. In addition an adaptation of the standing wave tube method incorporating a random signal as the external driver sound source and digital data analysis techniques were introduced to reduce the experimental difficulty and time consumption. Normalized specific acoustic impedance data at a constant engine speed of 2200 rpm show little change with varying engine load conditions. Similar data at a constant engine load condition of 254‐mm Hg exhibit more significant dependence on engine speed.
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43.58.Bh Acoustic impedance measurement
43.20.Ks Standing waves, resonance, normal modes
43.40.At Experimental and theoretical studies of vibrating systems

Parameters influencing the sonic velocity in compact calcified tissues of various species

S. Lees, J. M. Ahern, and M. Leonard

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 28-33 (1983); (6 pages) | Cited 6 times

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Compact calcified tissues from a wide variety of species were used in a study of the dependence of sonic plesio‐velocity on physical parameters. A linear dependence of velocity on wet density has been found for each of three categories of wet mineralized tissue: compact long bone measured in the axial direction, compact long bone measured in the radial direction, and hyperpycnotic mineralized tissues. A similar linear dependency was found for dry calcified tissue using the dry density. In addition to these three parameters (density, orientation, and water content) two other factors were identified. The bone fibers in long bone matrix are ordered with respect to the bone axis and the anisotropy of long bone matches that of its matrix. There is no corresponding order to the fibers in hyperpycnotic tissue matrix. The fifth parameter is believed to be the porosity. Fish bone is much more porous than other compact bone from long bone and the sonic velocity in fish bone is much lower than for other bone. These parameters are not independent.
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43.80.Cs Acoustical characteristics of biological media: molecular species, cellular level tissues
43.35.Cg Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in solids; elastic constants
43.58.Dj Sound velocity

Evaluation of a tactile vocoder for word recognition

P. L. Brooks and B. J. Frost

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 34-39 (1983); (6 pages) | Cited 2 times

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Normal subjects learned to identify words through a tactile vocoder. The vocoder employed 16 filter channels, each with a bandwidth of 1/3 octave, with center frequencies ranging from 200–8000 Hz. The output of each filter was detected and after logarithmic amplification the resulting outputs were transmitted to a 16‐channel solenoid array placed on the subject’s ventromedial forearm. Words, spoken ‘‘live voice,’’ were used as stimuli; the subject was able to feel both the vocalizations of the reader and herself and, most importantly, extensive training was provided. In 40.5 h one subject learned 70 words and a second subject reached criterion on 150 words in the comparatively short time of 55 h. Words that were poorly identified initially were identified more readily with increased experience. Phonetic identification tests showed that the features of voicing, nasality, and frication were reliably recognized, indicating the tactile vocoder will be useful in providing information to complement lipreading. Finally, subjects learned rapidly to generalize word‐learning to unfamiliar readers.
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43.70.Dn Disordered speech
43.66.Ts Auditory prostheses, hearing aids
43.66.Wv Vibration and tactile senses
43.70.Jt Instrumentation and methodology for speech production research

Susceptibility to intraspeech spread of masking in listeners with sensorineural hearing loss

Maureen Hannley and Michael F. Dorman

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 40-51 (1983); (12 pages) | Cited 4 times

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Previous research with speechlike signals has suggested that upward spread of masking from the first formant (F1) may interfere with the identification of place of articulation information signaled by changes in the upper formants. This suggestion was tested by presenting two‐formant stop consonant–vowel syllables varying along a /ba/–/da/–/ga/ continuum to hearing‐impaired listeners grouped according to etiological basis of the disorder. The syllables were presented monaurally at 80 and 100 dB SPL when formant amplitudes were equal and when F1 amplitude was reduced by 6, 12, and 18 dB. Noise‐on‐tone masking patterns were also generated using narrow bands of noise at 80 and 100 dB SPL to assess the extent of upward spread of masking. Upward spread of masking could be demonstrated in both speech and nonspeech tasks, irrespective of the subject’s age, audiometric configuration, or etiology of hearing impairment. Attenuation of F1 had different effects on phonetic identification in different subject groups: While listeners with noise‐induced hearing loss showed substantial improvement in identifying place of articulation, upward spread of masking did not consistently account for poor place identification in other types of sensorineural hearing impairment.
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43.70.Dn Disordered speech
43.66.Dc Masking
43.66.Sr Deafness, audiometry, aging effects

Spectro‐Temporal Modulation Transfer Function (STMTF) for various types of temporal modulation and a peak distance of 200 Hz

G. A. van Zanten and C. J. J. Senten

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 52-62 (1983); (11 pages) | Cited 2 times

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For noise which is spectrally modulated (ripple noise) as well as temporally modulated (the ripples move), the Spectro‐Temporal Modulation Transfer Function (STMTF) is defined as the curve relating modulation threshold to temporal modulation frequency with ripple spacing as a parameter. A white noise stimulus was spectro‐temporally modulated in the 0.2‐ to 1.0‐kHz region with a spectral modulation frequency (peak distance) of 0.2 kHz. Three types of temporal modulation were applied: the ripples rolled upward, downward, or the peaks and troughs interchanged periodically. It is shown that the STMTFs for these types are equal. So, for a ripple spacing of 0.2 kHz the spectro‐temporal modulation thresholds are independent of the type of temporal modulation. These STMTFs appeared to be low‐pass functions, no minimum was found. Their plateaus were at the same modulation depth as the modulation thresholds found by previous investigators who employed stationary ripple noise.
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43.66.Dc Masking
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Ba Models and theories of auditory processes

Level and phase of the (2f1–f2)‐cancellation tone expressed in vector diagrams

Eberhard Zwicker

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 63-66 (1983); (4 pages)

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Sets of level and phase data of the (2f1–f2)‐cancellation tone were measured with the same fit of the earphone. The results obtained were transferred into vector diagrams as x‐y representations. Characteristic rules for the development of the cancellation tone can be extracted from a detailed analysis of such diagrams.
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43.66.Ki Subjective tones
43.66.Ba Models and theories of auditory processes

Temporal gap detection in noise as a function of frequency, bandwidth, and level

Peter J. Fitzgibbons

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 67-72 (1983); (6 pages) | Cited 13 times

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Temporal gap resolution is measured with Békésy tracking procedure and filtered noise stimuli in the frequency range below 6000 Hz. Stimulus parameters include high‐pass and low‐pass cutoff frequency, band center frequency, bandwidth in a 2‐oct range, and signal level in the low‐to‐moderate intensity range. The pattern of results indicates that gap resolution improves with an increase in stimulus frequency in a manner that can be described by a linear function with a slope of about 2 ms/oct. This relationship applies to signal levels greater than 25–30 dB SL. A linear trend also describes gap threshold as a function of the empirical critical bandwidth within the same frequency range. Implications of the results for simple functional models of temporal processing are examined.
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43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.66.Ba Models and theories of auditory processes

Psychophysical studies evaluating the feasibility of a speech processing strategy for a multiple‐channel cochlear implant

Y. C. Tong, P. J. Blamey, R. C. Dowell, and G. M. Clark

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 73-80 (1983); (8 pages) | Cited 18 times

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This paper reports further psychophysical studies on a multiple‐channel cochlear implant patient evaluating the feasibility of a speech processing strategy which converts the acoustic fundamental frequency to electric repetition rate, the second‐formant frequency to electrode position, and the acoustic amplitude to current level. The first four studies evaluated the use of a special pulse pattern to minimize the loudness variation with electric repetition rate. The chosen pulse pattern consisted of multiple pulses occurring in the first half of each repetitive period (MPP) in contrast to the more conventional pattern with a single pulse per period (SPP). The results showed that MPP approximately equalized the loudness variation with repetition rate. The dynamic range of current, the pitch variation with repetition rate, and the difference limens for repetition rate were found to be similar for MPP and SPP. Two other studies investigated interaction between electrode position and repetition rate (RR). The first of these showed that the patient could make use of information provided by rising or falling RR trajectories superimposed on individual electrodes or electrode trajectories as an indicator of the direction of intonation variation. The second of these studies showed that the dissimilarities amongst the hearing sensations produced by steady‐state stimuli differing in electrode position and repetition rate were characterized by two perceptual components, relating to the two electric parameters, respectively.
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43.66.Ts Auditory prostheses, hearing aids
43.66.Mk Temporal and sequential aspects of hearing; auditory grouping in relation to music
43.71.Gv Measures of speech perception (intelligibility and quality)

Influence of physiological noise and the occlusion effect on the measurement of real‐ear attenuation at threshold

E. H. Berger and J. E. Kerivan

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 81-94 (1983); (14 pages) | Cited 9 times

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The most commonly alleged experimental artifact associated with real‐ear attenuation at threshold (REAT) measurements of hearing protection devices (HPDs) was examined: Masking of the protected thresholds due to physiological noise amplified by the occlusion effect. An ear canal mounted subminiature microphone was used to obtain objective measures of physiological noise in occluded and unoccluded test conditions and of the insertion loss (IL) of insert, semi‐aural, supra‐aural, and circumaural HPDs when exposed to broadband noise with a sound pressure level of 93 dB. Measurements spanned 1/3 octave bands from 125 Hz to 2 kHz. Attenuation was also measured via a subjective REAT procedure and the magnitude of the occlusion effect was examined via bone conduction audiometry. The IL data confirmed the accuracy of the REAT results except at the lowest frequencies tested, where the degree to which the REAT values were spuriously inflated was quantified and found to be device related. Furthermore, the magnitude of the error (which never exceeded 5 dB) could be predicted by measuring the physiological noise in the occluded ear and calculating how much this would mask the occluded threshold. It was noted that no evidence was found in the data to suggest a dependency of HPD attenuation on sound level.
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43.66.Vt Hearing protection
43.66.Yw Instruments and methods related to hearing and its measurement
43.64.Ha Acoustical properties of the outer ear; middle-ear mechanics and reflex

Multiple scale analysis of the spirally coiled cochlea

Chee Hoong Loh

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 95-103 (1983); (9 pages) | Cited 3 times

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The method of multiple scales is applied to the analysis of a curved box model of the spirally coiled cochlea. The fluid motion is fully three‐dimensional and the basilar membrane movement is represented by a single mode of deflection. Coiling parameters for the human cochlea are determined from the experimental data of von Békésy [Experiments in Hearing (McGraw‐Hill, New York, 1960)]. The approximate solution is numerically calculated to yield comparisons with the uncoiled case. It is found that the coiling effects are long‐wave in character and the results do not differ significantly from the corresponding straight box model.
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43.64.Bt Models and theories of the auditory system
43.64.Dw Anatomy of the cochlea and auditory nerve

Dependence of noise‐induced hearing loss upon perilymph magnesium concentration

Z. Joachims, W. Babisch, H. Ising, T. Günther, and M. Handrock

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 104-108 (1983); (5 pages) | Cited 1 time

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Noise‐induced hearing loss (NIHL) is significantly greater in rats fed a magnesium‐deficient diet than in rats on a magnesium‐rich diet. The hearing loss was found to be negatively correlated with the magnesium concentration of the perilymph. It is suggested that also in man, the magnesium concentration in the perilymph may be of importance in determining susceptibility to NIHL.
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43.64.Gz Biochemistry and pharmacology of the auditory system
43.66.Sr Deafness, audiometry, aging effects
43.64.Tk Physiology of sound generation and detection by animals

Acoustic‐reflex activity and behavioral thresholds following exposure to noise

Kenneth J. Gerhardt and Ernest L. Hepler, Jr.

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 109-114 (1983); (6 pages)

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The relationships between properties of the acoustic reflex and temporary threshold shift (TTS) were examined in eight subjects exposed to a 95 dB SPL, 1.0‐kHz octave‐band noise for 4 h. The specific pattern of TTS obtained from this exposure was consistent with the expected sensitivity changes along the cochlear partition. Maximum decrease in behavioral thresholds was noted at 1.4 kHz with significant TTS also occurring at 2.0 and 4.0 kHz. Behavioral threshold at 0.5 kHz, one octave below the center frequency of exposure, was not affected. Significant reflex threshold shift (RTS) occurred at 1.4 and 2.0 kHz. In addition, RTS was noted at 0.5 kHz in the absence of any change in behavioral sensitivity at that frequency. Magnitude of the acoustic reflex was examined from threshold to 10‐dB sensation level. A systematic reduction in magnitude was noted during the noise exposure for 1.4 and 2.0 kHz. The same pattern did not emerge for 0.5 kHz. Magnitude of the acoustic reflex pre‐exposure was significantly correlated to TTS at 1.4 kHz. Changes in acoustic reflex thresholds and magnitudes followed the same time course as changes in behavioral thresholds during the growth and recovery periods.
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43.64.Ha Acoustical properties of the outer ear; middle-ear mechanics and reflex
43.66.Ed Auditory fatigue, temporary threshold shift
43.50.Qp Effects of noise on man and society

Effects of crossed‐olivocochlear‐bundle stimulation on cat auditory nerve fiber responses to tones

Margaret L. Gifford and John J. Guinan, Jr.

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 115-123 (1983); (9 pages) | Cited 7 times

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Phase, synchronization index, and average firing rate were calculated from period histograms of tone burst responses obtained from sound level series with and without electrical stimulation of the cross‐olivocochlear‐bundle (COCB). For most fibers, at low sound levels, COCB stimulation shifted the rate and synochronization index level functions up in sound level but did not shift the phase‐level function in the same way. These effects can be accounted for if the stage at which the COCB acts precedes the stage at which analog signals are changed into neural firing patterns with a given rate and synchronization index, but does not precede the stage at which the level dependence of phase is introduced. Some level series show an abrupt phase change and ‘‘dips’’ in rate and synchronization‐index level functions at high sound levels. COCB stimulation shifted these abrupt phase changes and dips down in sound level and usually had little effect at sound levels above these abrupt phase changes and dips. The following explanatory hypothesis is developed: excitation of an auditory‐nerve fiber is the result of two factors which are out of phase and have different growth functions. The two factors cancel when they are equal in amplitude producing the dips and phase changes. COCB stimulation reduces the more sensitive factor but does not change the other factor so the two factors cancel at a lower sound level with COCB stimulation.
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43.64.Pg Electrophysiology of the auditory nerve

A technique for improving detection and estimation of signals contaminated by under ice noise

Roger F. Dwyer

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 124-130 (1983); (7 pages)

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Recent analyses of FRAM II arctic data have shown that under ice ambient noise can be at times highly impulsive and non‐Gaussian. The analyses included time domain statistical measurements which were consistent with previously reported results of experiments made within the Canadian Arctic Archipelago. New findings in the frequency domain based on skew, kurtosis, and cumulative distribution function estimates, also indicate the existence of strong non‐Gaussian noise. It is known that the ability to detect and estimate signals contaminated with non‐Gaussian noise using conventional processing is degraded compared with optimum techniques which utilize knowledge of the noise statistics. Results comparing the performance of conventional and nearly optimum signal processing methods are presented using the FRAM II data.
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43.60.Cg Statistical properties of signals and noise
43.60.Gk Space-time signal processing, other than matched field processing
43.30.Nb Noise in water; generation mechanisms and characteristics of the field

Optimum and sub‐optimum source localization with sensors subject to random motion

Peter M. Schultheiss, Erramilli Ashok, and John P. Ianniello

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 131-142 (1983); (12 pages)

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When an array is used to estimate source location, random motion of the receiving sensors can seriously limit performance. This paper models sensor motion as a flat, bandlimited Gaussian process independent from sensor to sensor. Cramer–Rao bounds on errors in time delay estimates are derived and these are converted to bounds on range and bearing errors. The validity of the bandlimited model is examined, and the performance of conventional and optimal processors compared. It is shown that conventional processors can achieve near‐optimal performance if the post processing signal‐to‐noise ratio is sufficiently large and the motion of the sensors sufficiently slow. For short observation times T, the optimum and conventional processors have the same errors due to sensor motion; for longer observation times the incremental errors decrease as T−1.
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43.60.Gk Space-time signal processing, other than matched field processing
43.30.Vh Active sonar systems

A method for treating statistically dependent inputs to an OR‐ing device

William A. Struzinski

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 143-145 (1983); (3 pages)

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A technique is presented to compute the OR‐ing loss for statistically dependent inputs to an OR‐ing device. An example is given, and it is concluded that the OR‐ing loss decreases with an increase in the correlation coefficient.
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43.60.Gk Space-time signal processing, other than matched field processing

Asymmetric light diffraction by pulsed ultrasonic waves

Thomas H. Neighbors, III and Walter G. Mayer

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 146-152 (1983); (7 pages) | Cited 1 time

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Low‐MHz, continuous ultrasonic waves traveling in a transparent medium cause light to be diffracted into discrete diffraction orders when light and sound propagation directions are normal to each other. When pulsed ultrasonic waves are used the diffraction orders split into secondary orders which are asymmetric with respect to the central diffraction order. This splitting is derived and a general expression provided for the intensity as a function of the ultrasonic pulse Fourier spectra. Examples are provided which demonstrate the degree of asymmetry for an exponential driving pulse and the convergence to the classic Raman–Nath results when the pulse approaches a continuous wave.
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43.35.Sx Acoustooptical effects, optoacoustics, acoustical visualization, acoustical microscopy, and acoustical holography
43.20.Bi Mathematical theory of wave propagation

An intrinsically irreversible thermoacoustic heat engine

John Wheatley, T. Hofler, G. W. Swift, and A. Migliori

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 153-170 (1983); (18 pages) | Cited 21 times

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Certain thermoacoustic effects are described which form the basis for a heat engine that is intrinsically irreversible in the sense that it requires thermal lags for its operation. After discussing several acoustical heating and cooling effects, including the behavior of a new structure called a ‘‘thermoacoustic couple,’’ we discuss structures that can be placed in acoustically resonant tubes to produce both substantial heat pumping effects and, for restricted heat inputs, large temperature differences. The results are analyzed quantitatively using a second‐order thermoacoustic theory based on the work of Rott. The qualities of the acoustic engine are generalized to describe a class of intrinsically irreversible heat engines of which the present acoustic engine is a special case. Finally the results of analysis of several idealized intrinsically irreversible engines are presented. These suggest that the efficiency of such engines may be determined primarily by geometry or configuration rather than by temperature.
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43.35.Ty Other physical effects of sound
44.90.+c Other topics in heat transfer (restricted to new topics in section 44)
43.28.Kt Aerothermoacoustics and combustion acoustics

Convergence zone positions via ray‐mode theory

A. Beilis

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 171-180 (1983); (10 pages)

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Ray‐mode theory is used to predict the location of convergence zones. The WKB formulation of ray‐mode theory is extended to account for sound speed depth variations that are more rapid than allowed by the WKB approximation. The location of the zones based on these two formulations are compared to numerically calculated values. The agreement between the numerically calculated locations and the locations based on ray‐mode theory is good. A range variation of the environment is included into the ray‐mode formulation. The range variation is taken slow enough that mode identity is preserved (adiabatic mode theory). This analytical calculation shows how the positions of convergence zones change in a range‐dependent environment.
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43.30.Bp Normal mode propagation of sound in water
43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance
43.20.Dk Ray acoustics
43.20.Bi Mathematical theory of wave propagation

Effect of source‐motion‐induced transmission fluctuations in intersensor correlation

J. H. Doles, III

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 181-187 (1983); (7 pages)

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An asymptotic mode representation of the signal field radiated by a narrow‐band source executing slow horizontal motion has been developed. An approximation to this representation has been used to estimate the amount of coherent correlation between the signals received at two sensors after an appropriate adjustment has been made to account for time delay and Doppler difference. A calculation of intersensor coherent correlations for a specific scenario indicates that there can be significant coherent correlation degradation when the signal received at one (or both) of the sensors has faded. This degradation is due to amplitude and phase fluctuations caused by interference between modes.
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43.30.Bp Normal mode propagation of sound in water
43.60.Gk Space-time signal processing, other than matched field processing
43.30.Cq Ray propagation of sound in water

A coupled mode solution for acoustic propagation in a waveguide with stepwise depth variations of a penetrable bottom

R. B. Evans

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 188-195 (1983); (8 pages) | Cited 35 times

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See Also: Erratum

Show Abstract
A coupled mode solution is formulated for the problem of acoustic propagation in a cylindrically symmetric ocean divided, in range, into a finite number of adjoining Pekeris waveguides of differing water depths. Attenuation is included in the bottom and the problem is discretized by assigning a pressure release boundary condition at a depth which is sufficiently far removed to prevent significant energy from returning to the water. This formulation includes backscatter from the depth variations of the water column and full coupling between a finite number of modes propagating in the water column and in the bottom. Numerical results based on an implementation of this solution are presented.
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43.30.Bp Normal mode propagation of sound in water
43.30.Dr Hybrid and asymptotic propagation theories, related experiments
43.20.Mv Waveguides, wave propagation in tubes and ducts

Acoustic dispersion in a deep ocean channel

Albert A. Gerlach, Kenneth D. Flowers, and Robert B. Johnson, Jr.

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 196-203 (1983); (8 pages)

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Acoustic dispersion in a deep ocean channel is characterized by the dependence of sound propagation speed on signal frequency along the axial propagation path. A model normal‐mode solution of the wave equation is employed to compute the acoustic field for sinusoidal signals as a function of both axial range and frequency. A virtual propagation time is defined which reflects the range‐dependent phase of the acoustic field. When signals of different frequency are transmitted, the remotely observed frequency ratio (for a given range rate) will fluctuate about the true frequency ratio of the transmitted signals. The magnitude of the fluctuation is directly proportional to the true frequency ratio. A measure of the spectral dispersion is defined as the difference between the observed and true frequency ratios. The dependence of this measure on range and signal frequencies (for a given frequency ratio) is determined to be relatively insignificant. It is concluded that acoustic dispersion in a deep ocean channel is microscopic in its measure, but it can be significant for applications involving the phase correlation of broadband (or spectrally separated) signals over long time intervals.
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43.30.Bp Normal mode propagation of sound in water
92.10.Vz Underwater sound
43.30.Cq Ray propagation of sound in water

Model validation of the geometric dispersion of acoustic signals propagated in a deep ocean channel

K. D. Flowers and A. A. Gerlach

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 204-209 (1983); (6 pages)

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In this paper we report the results of an experiment designed to measure the effects of geometric dispersion on acoustic cw signals propagated to long ranges in a deep ocean channel. The experimental results are shown to compare favorably with model calculations using a standard normal mode model. It is concluded that the effects of dispersion can be successfully simulated for a wide range of frequencies, frequency ratios, and signal‐to‐noise ratios.
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43.30.Bp Normal mode propagation of sound in water
92.10.Vz Underwater sound
43.60.Gk Space-time signal processing, other than matched field processing

Slope propagation: Mechanisms and parameter sensitivities

Robert A. Koch, Steven R. Rutherford, and Susan G. Payne

J. Acoust. Soc. Am. Volume 74, Issue 1, pp. 210-218 (1983); (9 pages) | Cited 1 time

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An adiabatic normal mode analysis is used to identify cylindrical spreading, renormalization, bottom attenuation, differential mode excitation and reception, and mode cutoff as major physical mechanisms influencing underwater acoustic propagation over slopes. Propagation is sensitive to the shallow water sediment attenuation but not to the slope angle.
Show PACS
43.30.Bp Normal mode propagation of sound in water
43.30.Jx Radiation from objects vibrating under water, acoustic and mechanical impedance
92.10.Vz Underwater sound
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