• Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 

Journal of the Acoustical Society of America

BROWSE VOLUMES

Year Range: 
Search Issue | RSS Feeds RSS
Previous Issue Next Issue

Apr 1985

Volume 77, Issue 4, pp. 1295-1636

Page 1 of 5 Pages Next Page | Jump to Page

Chairman’s introduction: Harry F. Olson Memorial Session

Harry B. Miller

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1295-1295 (1985); (1 page)

Full Text: | Download PDF

Show Abstract
The reason for choosing the papers and the speakers is first given. Then, a brief introduction to each speaker’s paper is given.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.38.+n Transduction; acoustical devices for the generation and reproduction of sound
43.55.-n Architectural acoustics
43.75.-z Music and musical instruments

Some personal recollections of early experiences on the new frontier of electroacoustics during the late 1920s and early 1930s

Frank Massa

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1296-1302 (1985); (7 pages)

Full Text: | Download PDF

Show Abstract
During this brief presentation, time will be turned back a half‐century to permit some personal recollections of early experiences as we explored the new frontiers in electroacoustics. The availability of the vacuum tube for the amplification of weak signals made possible the practical application of a variety of wide‐range, low‐sensitivity transduction techniques for the generation and reproduction of sound. Our training in electrical engineering provided an understanding of electrical measurements and design techniques that we could adapt for new specialized uses during our early stages of acoustic measurements and electroacoustic research. The demands of the new talking picture industry for improved electrical recording and reproduction of sound helped finance the costs of electroacoustic research, which resulted in rapid progress in the sound reproduction and recording industry during the early 1930s. In less than a decade the reproduction of sound was transformed from the primitive limited frequency range of the mechanical phonograph to the high quality electrical recording and reproduction made possible by the rapid advances in electroacoustic engineering.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.58.+z Acoustical measurements and instrumentation
43.38.+n Transduction; acoustical devices for the generation and reproduction of sound
01.60.+q Biographies, tributes, personal notes, and obituaries

Theory, ingenuity, and wishful wizardry in loudspeaker design—A half‐century of progress?

George L. Augspurger

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1303-1308 (1985); (6 pages)

Full Text: | Download PDF

Show Abstract
During the past 50 years the course of professional loudspeaker design has been well documented. The history of high fidelity consumer products is less familiar and more erratic. Loudspeaker designers seem to have embodied three archetypes in varying proportions: the elegant theoretician, the inspired tinkerer, and the wishful wizard. A brief examination of some of their enduring successes, ephemeral favorites, and resounding failures is presented.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.38.Ja Loudspeakers and horns, practical sound sources
43.38.Tj Public address systems, sound-reinforcement systems

Some remarks on electro‐mechano‐acoustical circuits

Leo L. Beranek

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1309-1313 (1985); (5 pages)

Full Text: | Download PDF

Show Abstract
The advanced development of electro‐mechano‐acoustical circuits dates in the US from Wente (1917), Firestone (1933), Mason (1941), Olson (1943), LeCorbeillier and Yueng (1952), Bauer (1953), Beranek (1954), and Hunt (1954). Earlier significant use of electrical (radio) analogies was made by Darrieus (France, 1929) and Haehnle (Germany, 1932). This paper treats the period in which Olson’s work was centered and cites some examples of the use of the electro‐mechano‐acoustical circuits in microphones, loudspeakers, and rotational devices.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.58.Wc Electrical and mechanical oscillators
43.38.Ja Loudspeakers and horns, practical sound sources
01.65.+g History of science

Origins of magnetic recording concepts

Marvin Camras

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1314-1319 (1985); (6 pages)

Full Text: | Download PDF

Show Abstract
Many brand new ideas in modern magnetic recording are quite ancient. Case histories in basic foundations of this art are good examples. Metal particle tape was proposed 95 years ago. High‐frequency bias has its roots in the Marconi wireless detector of 1902. Digital recording goes back at least to Morse’s telegraph of 1838. The rotating‐head principle used for video recorders dates back about two decades before it became practical. Sendust used in the latest recording heads was invented in 1936. Magnetic disks, the important memory of computers, were demonstrated in 1903. Soundstriping for motion picture film was advertised in 1917. Personal experiences in nearly a half‐century of magnetic recording are related.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.38.Qg Magnetic and electrostatic recording and reproducing systems
01.60.+q Biographies, tributes, personal notes, and obituaries
01.65.+g History of science

Fifty years of stereo phonograph pickups: A capsule history

C. Roger Anderson

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1320-1326 (1985); (7 pages)

Full Text: | Download PDF

Show Abstract
From the 45° disk recording system shown in the 1933 benchmark stereo work of Blumlein to the present‐day generations of pickups with ultrasonic capabilities is a long evolution of analytic and engineering effort. This paper is a recognition of advances along the way, such as the theory of tracing distortion, stylus contours, transducer principles, light and stiff moving systems, tracking requirements, and the design insight that led to contemporary pickups which perform superbly at 1‐g stylus force.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.38.Vk Stereophonic reproduction
01.65.+g History of science

Engineering highlights of the LP record

Daniel W. Gravereaux

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1327-1331 (1985); (5 pages)

Full Text: | Download PDF

Show Abstract
For 35 years, the long playing microgroove 33‐1/3 rpm disk record has brought to the consumer the highest fidelity programming of any mass media. This is due to the valued efforts of many engineers, scientists, and technicians in the development and implementation of microgroove mastering techniques, cutting and playing transducers, electroplating, stamping techniques, lacquer blanks, cutting styli, mastering lathes, presses, and vinyl formulation. This paper presents those developments which greatly augmented the information capacity of the record. It emphasizes a few of the highlights in the engineering of the most standardized sound medium in the world—the LP.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.38.Md Sound recording and reproducing systems, general concepts
01.65.+g History of science

Reminiscing—The stereophonic record

H. E. Roys

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1332-1334 (1985); (3 pages)

Full Text: | Download PDF

Show Abstract
The author became active in the sound recording field in the early 1930s and remained active in that field until retirement in 1967. When, in 1957, two slightly different systems of recording stereophonic records were introduced for standardization he was a member of the engineering committee of the Record Industry Association of America and Chairman of the Phonograph Committee of the Electronic Industries Association. The situation was unique in that stereophonic recorders and pickups were not readily available and the choice for standardization had to be based largely upon theoretical considerations. The difference between the two was slight. The V‐L system recorded one channel vertically and the other laterally. The 45–45 system recorded both channels vertically, but at a 45° angle with respect to the surface of the disk. Record engineers in Europe gathered and decided in favor of the 45–45 system. Engineers in this country did likewise. Thus for the first time in the history of records a common agreement with respect to standardization was reached prior to mass production.
Show PACS
43.10.Ln Surveys and tutorial papers relating to acoustics research; tutorial papers on applied acoustics
43.38.Vk Stereophonic reproduction
01.60.+q Biographies, tributes, personal notes, and obituaries
01.65.+g History of science

Analysis of elastic wave signals from an extended source in a plate

Chung Chang and Wolfgang Sachse

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1335-1341 (1985); (7 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
This paper considers the forward and inverse problems of an extended, finite source of elastic waves in a thick plate. The signals received at a point in the nearfield of a source are computed by a superposition of the signals found with a generalized ray algorithm from point sources of variable strength arranged along a straight line. Synthetic waveforms corresponding to several source types and spatial distributions on the surface and in the interior of the plate are shown. A processing algorithm is also developed which utilizes the signals detected at just one receiver point to obtain the solution to the inverse source problem. Examples are shown in which the time dependence and the spatial distribution of a source are recovered from synthetic waveforms.
Show PACS
43.20.Bi Mathematical theory of wave propagation
43.40.Dx Vibrations of membranes and plates
43.20.Ks Standing waves, resonance, normal modes

Limited aperture effects on ultrasonic image reconstruction

Vladimir G. Kogan and James H. Rose

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1342-1351 (1985); (10 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
In the inverse Born approximation the shape of a weak scatterer can be determined from a knowledge of the backscattered ultrasonic amplitude for all directions of incidence and all frequencies. Two questions are considered. First, what information on the scatterer shape is preserved and what is degraded if the scattering data are available only within a limited set of incident directions (limited aperture)? This problem is addressed for a spherical weakly scattering uniform flaw. It is shown that the problem of a general uniform ellipsoidal flaw can be reduced to the spherical case by a scale transformation; however, the apertures in these two cases must be related by the same transformation. Second, limited aperture and finite bandwidth Born inversions were performed for strongly scattering flaws (voids and cracks) using numerically generated scattering amplitudes. These inversions were then compared with the weak scattering analytic results, which show many common features.
Show PACS
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation
43.60.Gk Space-time signal processing, other than matched field processing

Resonances of plates and cylinders: Guided waves

G. Maze, J. L. Izbicki, and J. Ripoche

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1352-1357 (1985); (6 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
The study of the normal diffusion of an ultrasonic plane wave by cylinders and plates imbedded in the water shows resonances which are the natural modes of vibration. When a natural mode of an elastic target is excited, the energy which is stored during the forced excitation is emitted after the end of the forced excitation. The observation of backscattered spectra obtained by the Resonance Isolation and Identification Method (RIIM) from an aluminum cylinder shows supplementary resonances. The directivity pattern of the transducer is the cause of these supplementary resonances. The behavior of these resonances is analogous to the resonances of the plate. This leads us to study the natural modes of the cylinder. All the resonances which are experimentally detected may be considered as normal modes of the target. The results obtained on plates and cylinders have a common point: the generation of a guided wave by the excitation of a resonance.
Show PACS
43.20.Fn Scattering of acoustic waves
43.40.Dx Vibrations of membranes and plates
43.20.Bi Mathematical theory of wave propagation
43.20.Ks Standing waves, resonance, normal modes

Volume scattering: Echo peak PDF

T. K. Stanton

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1358-1366 (1985); (9 pages) | Cited 3 times

Full Text: | Download PDF

Show Abstract
The statistical properties of the backscattered acoustic echo from clouds of scatterers are examined. These clouds could be plankton, nekton, bubbles, etc., or a combination. The clouds of interest are sufficiently dense so that echoes from the individual scatterers overlap. The scatterers are assumed to be randomly distributed in space so that, at high enough acoustic frequencies, the individual echoes are not correlated (random phase). The probability density function (PDF) of the maximum echo value achieved in a depth gate has been analytically derived, computer simulated, and measured in the field. It is shown to be quite different than the Rayleigh PDF of the envelope, even for gate durations smaller than one transmission ping duration. An approximate analytical expression for the echo peak PDF is derived by first modeling the echo as a discrete ‘‘stepped’’ waveform where the ‘‘steps’’ are statistically independent of each other. The problem is then solved by straightforward extremal statistics. There is excellent agreement between the theoretical PDF, computer simulations, and field data. While we are concerned with gate durations several times one ping duration, the analytical expression for the PDF is shown to accurately describe the PDF over ranges of the gate duration less than the ping duration to much greater than the ping duration. From the echo peak PDF one can (1) estimate the abundance of occasional large scatterers that are within the clouds (for example large fish feeding on plankton) since their occurrence is differentiable from the rest of the cloud in the PDF, and (2) clearly differentiate between conditions where the echoes overlap and do not overlap. Once it is determined whether or not they overlap, lower or upper bounds in scatterer density (number per unit volume) may be calculated. Both of these applications can be performed in situ.
Show PACS
43.20.Fn Scattering of acoustic waves
43.60.Cg Statistical properties of signals and noise

Sea surface scattering: Echo peak PDF

T. K. Stanton

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1367-1369 (1985); (3 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
We examine the statistical nature of the backscattered acoustic echo from the sea surface. In particular, the probability density function (PDF) of the maximum value of the echo achieved in a time gate is studied. We compare data from a 70‐kHz sonar at near grazing angles to a recently developed statistical model that was employed in the context of (biological) volume backscattering [T. K. Stanton, J. Acoust. Soc. Am. 77, xxx–xxx (1985)]. The model fits the data quite well which implies that, like with volume scatterers in the ocean, the backscattered signal from the sea surface is effectively composed of many scatterers that each produce random phase, random amplitude echoes. The results can be applied to sidescan sonars where ‘‘clutter’’ from the sea surface may interfere with the detection of near surface biological organisms. From the theoretical model a probability of false alarm may be derived to aid in the detection.
Show PACS
43.20.Fn Scattering of acoustic waves
43.30.Hw Rough interface scattering

Computation of velocity and density profiles of acoustic media with vertical inhomogeneities using the method of characteristics applied to the slant stacked data

Philip M. Carrion

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1370-1376 (1985); (7 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
An algorithm which is based on a discrete version of the method of characteristics is presented. The procedure consists of the transformation of the measured data into the slant stack domain (the domain of intercept time τ and horizontal slowness p) following application of the one‐dimensional inverse method of characteristics to an arbitrary pair of traces in the (τ‐p) domain. The result of the inversion is a pair of acoustic impedance functions which are used for separate computation of the velocity and density profiles in the acoustic medium. Advantages of the method are that (1) it can be directly applied to the data in the time domain, (2) it appears to be efficient in terms of computations, and (3) it does not require the acoustic impedance to be smoooth. A synthetic example illustrates the accuracy of the method.
Show PACS
43.20.Hq Velocity and attenuation of acoustic waves
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Bi Mathematical theory of wave propagation

Analysis of higher‐order mode effects in the circular expansion chamber with mean flow

Jeong‐Guon Ih and Byung‐Ho Lee

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1377-1388 (1985); (12 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
The effects of higher‐order acoustic modes produced by the areal discontinuities of the simple expansion chamber with mean flow on the acoustic performance are studied. The chamber is modeled as a piston‐driven circular rigid tube with no losses and, by using the Fourier–Bessel expansion, a general expression of the output pressure to the given input uniform volume velocity is obtained for a whole chamber. Quantitative estimation for the transmission loss can be performed using the derived four‐pole parameters, whereas the characteristics of the chamber, as a result of the interactions between the plane wave and the transverse waves, can be easily investigated with respect to the relative locations of the inlet/outlet, the chamber length, and the mean flow. The expression as a form of C in four‐pole parameters is adopted to describe the chamber characteristics for computational convenience. All the parameters involved in the experimental works by Eriksson [L. J. Eriksson, J. Acoust. Soc. Am. 72, 1208–1211 (1982)] are taken in the examples. Using the derived four‐pole parameters, the transmission losses for both the concentric and offset inlet/outlet configurations are predicted and compared with the experimental results. The theoretical results of the present study are in good agreement with the experiments of the authors and the previous works.
Show PACS
43.20.Mv Waveguides, wave propagation in tubes and ducts
43.20.Ks Standing waves, resonance, normal modes
43.20.Bi Mathematical theory of wave propagation

Asymptotic fluid–structure interaction theories for acoustic radiation prediction

H. Huang and Y. F. Wang

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1389-1394 (1985); (6 pages)

Full Text: | Download PDF

Show Abstract
It is well known that at extremely high or low frequencies, the fluid–structure interaction effects can be represented asymptotically by simple equations. Thus, it appears that an optimum computation scheme for predicting acoustic pressure field radiated from a submerged elastic structure could be a combination of various asymptotic theories and the exact formulation. This paper explores the ranges of applicability of some asymptotic theories, using the problem of radiation from a spherical elastic shell as the bench mark. It is found that the ‘‘added mass’’ and ‘‘plane‐wave’’ approximations are quite adequate, respectively, for ka<1.0 and ka>5, where ka is the ratio of the circumference of the spherical shell to the acoustic wavelength. For the intermediate frequency range, a theory termed second‐order Doubly Asymptotic Approximation (DAA2) is suitable. At intermediate frequencies near resonances, however, the exact formulation is needed.
Show PACS
43.20.Rz Steady-state radiation from sources, impedance, radiation patterns, boundary element methods
43.20.Bi Mathematical theory of wave propagation
43.20.Fn Scattering of acoustic waves

Close range scintillations in anisotropic scattering media

Shimshon Frankenthal

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1395-1402 (1985); (8 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Using the Rytov approximation, an expression is derived for the log‐amplitude correlation function of weak fluctuations induced in a plane wave propagating in a forward‐scattering medium. The expression is valid at any range where weak fluctuations exist, including ranges which are shorter than the correlation length. For ranges well in excess of the correlation length, we derive a general expression for the scintillation index, which applies also in nonisotropic media, for moderate and high frequencies. The behavior of the scintillation index at very short ranges in isotropic media characterized by one or two scales is examined, and its dependence on frequency (k) and range (z) is listed for several regimes. Propagation is also studied in a nonisotropic medium, where the refractivity fluctuations are governed by the Garrett–Munk internal‐wave spectrum. Here, the frequency–range dependence of the scintillation index changes from k3/2z5/2 at near ranges to kz2 at more distant ones.
Show PACS
43.30.Ft Volume scattering
43.20.Fn Scattering of acoustic waves
43.20.Bi Mathematical theory of wave propagation

The azimuthal dependence of bistatic surface scattering: A comparison between theory and experiment

Wayne A. Kinney and John G. Zornig

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1403-1408 (1985); (6 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Scattering strength values computed using a time‐domain version of the facet‐ensemble method [W. A. Kinney and C. S. Clay (to be published)] are compared with some values measured by J. G. Zornig [J. Acoust. Soc. Am. 63, 758–767 (1978)] in an experiment on the azimuthal dependence of bistatic surface scattering. Results are presented for a waterborne 1.3‐MHz pulse impinging on a wind‐generated surface at a 30° grazing angle. In the experiment, the surface wavelets were mostly long‐crested within the ensonified region. Their direction of propagation varied and they were slightly crescent shaped. The wavelets scattered strongly in all azimuthal directions. Agreement between theoretical and experimental data was achieved by approximating the scattered response from a portion of a wavelet by the response of an ensemble of facets oriented tangentially to the portion. Surface scattering experiments that involve complex surface features of large roughness require a complete deterministic description of the surface to help in explaining results.
Show PACS
43.30.Cq Ray propagation of sound in water
43.30.Hw Rough interface scattering
43.20.Fn Scattering of acoustic waves

Measurement of sound absorption in low salinity water of the Baltic Sea

Hans G. Schneider, Rolf Thiele, and Peter C. Wille

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1409-1412 (1985); (4 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
Shallow water propagation measurements in the thermocline–halocline refractive sound channel of the Baltic Sea are utilized to estimate the absorption coefficient in low salinity water of 8 ppt (8.0 pH, 4 °C) for 0.5–10 kHz. The lower margin of the present data which are derived from transmission loss by subtraction of cylindrical spreading can be represented by the Francois and Garrison formula of 1982. However, measurements of the boron relaxation frequency indicate that this agreement does not necessarily support the assumed salinity dependence of the relaxation frequency but might be produced by appropriate scattering loss of the refractive channel.
Show PACS
43.30.Es Velocity, attenuation, refraction, and diffraction in water, Doppler effect
43.35.Bf Ultrasonic velocity, dispersion, scattering, diffraction, and attenuation in liquids, liquid crystals, suspensions, and emulsions
92.10.Vz Underwater sound
93.30.Rp Regional seas

Source depth estimation in waveguides

E. C. Shang

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1413-1418 (1985); (6 pages) | Cited 10 times

Full Text: | Download PDF

Show Abstract
In the present paper an approach to source depth estimation in a waveguide is proposed. The method is based on the mode filtering technique. By using a mode filter, the field sampling data of a vertical array are transformed to a vector which consists of two parts: (1) the eigenfunction of each mode and (2) the modal phase corresponding to the source range. The latter part can be compensated by means of range information extraction proposed in our previous paper [Shang et al., J. Acoust. Soc. Am. Suppl. 1 74, S78 (1983)]. The data vector consisting of a finite number of mode eigenfunctions then becomes ‘‘almost orthogonal’’ and can be used to construct a source depth power estimator. It is well known that the ‘‘closure’’ is a property of a complete, orthonormal set of functions, and because the mathematical expression of ‘‘closure’’ is a correlation type, a correlation operator is a reasonable one for identifying source depth. The resolution is the magnitude of −(H/M), where H is the water depth and M is the effective mode number. Some numerical examples and scale model experimental results are shown.
Show PACS
43.30.Bp Normal mode propagation of sound in water
43.20.Mv Waveguides, wave propagation in tubes and ducts

Measurement of number and size distributions of reflecting objects by pulsed ultrasound

Andrej A. Stravs and Urs von Stockar

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1419-1424 (1985); (6 pages)

Full Text: | Download PDF

Show Abstract
The echoes of different types of reflectors, which appear alternately but in a random way in certain positions in the sound beam of an ultrasonic probe, may be registered and classified according to their amplitude heights. If the response profiles (echoes versus position) are known and differ from each other, the number distribution of the reflectors can be deduced based on geometrical considerations and by using the acquired histogram of echo amplitudes. The principle has been demonstrated with steel balls of different sizes rolling on a central axis perpendicular to a round piezo, yielding the distribution of relative sizes.
Show PACS
43.30.Ft Volume scattering

Diffraction of Rayleigh waves in a half‐space. I. Normal edge crack

Bien Q. Vu and Vikram K. Kinra

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1425-1430 (1985); (6 pages) | Cited 5 times

Full Text: | Download PDF

Show Abstract
This paper is concerned with the diffraction of Rayleigh surface waves by an edge‐crack normal to the free surface of a half‐space. An experimental technique was developed to yield accurate and reproducible measurements of the scattered field on the free surface both in the vicinity of the crack and far away from it. The results show that the nearfield scattered field is very sensitive to the crack length and possesses many characteristic features which are shown to be potentially useful in the area of nondestructive testing and evaluation. The farfield transmission and reflection coefficients AT and AR were measured under both the steady time‐harmonic motion and the transient motion of the half‐space. In the short‐wavelength limit (l/λR≥2), both AR and AT achieve the crack‐length‐independent values, namely AR=0.41 and AT=0.06; the former agrees with the reflection coefficient of a quarter‐space and the latter agrees with the combined transmission coefficient through the leading corner, the tip, and the trailing corner of the crack. For l/λR≤2, AR and AT were found to agree very well with a recent theoretical solution of Achenbach and his co‐workers [D. A. Mendelson et al., Wave Motion 2, 277–292 (1980); Y. C. Angel and J. D. Achenbach, J. Acoust. Soc. Am. 75, 313–319 (1984)].
Show PACS
43.35.Pt Surface waves in solids and liquids
43.20.Fn Scattering of acoustic waves

Excitation conditions of flexural traveling waves for a reversible ultrasonic linear motor

Minoru Kuribayashi, Sadayuki Ueha, and Eiji Mori

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1431-1435 (1985); (5 pages) | Cited 6 times

Full Text: | Download PDF

Show Abstract
This paper presents a theory and experiments on a reversible ultrasonic linear motor, consisting of a thin beam, two ultrasonic transducers, and a slider. The slider rides upon the crests of transverse traveling flexure waves propagating down the beam from one transducer to the other.
Show PACS
43.35.Yb Ultrasonic instrumentation and measurement techniques
43.35.Ty Other physical effects of sound

Relations among different frequency rating procedures for traffic noise

Daniel R. Flynn and Simone L. Yaniv

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1436-1446 (1985); (11 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
A series of calculations was performed to ascertain how well one frequency‐weighted rating, such as weighted sound level, loudness level, or perceived noise level, may be predicted from another such rating. A total of 103 average sound level spectra, measured at several distances from different types of highways, was used in these calculations. It was found that knowing a single noise rating, such as the A‐weighted sound level, enables one to predict other outdoor ratings in this set of 103 spectra with a standard deviation of the order of 1–2 dB. If, in addition, traffic speed and mix and the distance to the highway are taken into account, these standard deviations can be reduced to 0.5–1 dB, depending upon the particular noise rating of interest. Equations are given for predicting one rating from another; the associated standard deviations are presented as a measure of how well any given rating can be predicted from a single measured, or otherwise known, noise rating. It is concluded that it is not critical which frequency‐weighting procedure is used in conjunction with highway noise criteria since one descriptor can be predicted from another with small statistical uncertainty. Thus, if human response criteria, or stimulus‐response relationships, have been developed in terms of one frequency‐weighting procedure, these may be translated into equivalent criteria expressed in terms of a metric that is easier to measure or predict.
Show PACS
43.50.Ba Noisiness: rating methods and criteria
43.50.Lj Transportation noise sources: air, road, rail, and marine vehicles

Reverberation time in enclosures: The surface reflection law and the dependence of the absorption coefficient on the angle of incidence

Giuliana Benedetto and Renato Spagnolo

J. Acoust. Soc. Am. Volume 77, Issue 4, pp. 1447-1451 (1985); (5 pages) | Cited 1 time

Full Text: | Download PDF

Show Abstract
The sound decay and reverberation time of enclosures depend on the amount of randomization achieved during the decay. The randomization is determined by the degree of surface roughness and absorptivity and is also related to the shape of the enclosure. Many authors showed that, even in the hypothesis of a memoryless reflection law, the reverberation time largely varies when the absorptivity is nonuniformly distributed on the surfaces, for a fixed value of the sound absorption coefficient. In this paper, applying a ray‐tracing simulation procedure to a simple two‐dimensional enclosure, the effect is shown to be still stronger when a certain fraction of specular reflection is taken into account. In this case, it is also proved that one cannot neglect the effects connected to the dependence of the sound absorption coefficient on the incidence angle, which seems to introduce additional sound randomization.
Show PACS
43.55.Br Room acoustics: theory and experiment; reverberation, normal modes, diffusion, transient and steady-state response
43.55.Dt Sound absorption in enclosures: theory and measurement; use of absorption in offices, commercial and domestic spaces
43.55.Ka Computer simulation of acoustics in enclosures, modeling
Page 1 of 5 Pages Next Page | Jump to Page
Close

Home Publications Meetings Contact ASA Site Map Back to Top

Copyright © Acoustical Society of America

close