摘要:

The reason for choosing the papers and the speakers is first given. Then, a brief introduction to each speaker’s paper is given.

ISSN:0001-4966    

DOI:10.1121/1.392068

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392069

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392070

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392071

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392019

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392020

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392021

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392022

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392023

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0001-4966    

DOI:10.1121/1.392024

出版商:Acoustical Society of America    

年代:1985

数据来源: AIP