International projectionist (Jan-Dec 1935)

16 INTERNATIONAL PROJECTIONIST January 1935 quantity — actually depends on all three. That there has not been a strict one-toone correspondence between loudness and intensity has been known for some time, but only recently has accurate quantitative data been obtained. Between pitch and frequency, on the other hand, it is generally thought that there is a strict one-to-one correspondence. Frequency is the number of vibrations per second made by the sound source, such as a tuning fork or a violin string. Most musical tones, however, are composed of a series of frequencies which are multiples of the lowest or fundamental. For such tones the frequency of the fundamental is considered as the frequency of the tone, while the number and magnitude of the harmonics produce the overtone structure that results in the perception ot a definite timbre. The intensity of the tone is the power content of the air vibrations at the position where the listener hears the tone. Among musicians loudness is roughly gauged in seven steps running from ppp (pianissimo) to fff (forte). Such a scale is entirely inadequate for scientific studies, both because the steps are too large and because there is no definitely established reference loudness. To provide a more suitable measuring scale, it has been the practice for some time in the Bell Laboratories to measure loudness in terms of the power intensity of a pure tone at a frequency of 1,000 cycles per second. Because of the wide range of intensities to which the ear responds, it has been convenient to use a logarithmic scale of values. The use of such a scale is further justified because the minimum change in intensity that the ear can detect seems to follow more nearly a logarithmic than an arithmetic law. Although no quantitative measurements have been made upon the timbre of a musical tone, we know that it depends not only upon the overtone structure but also upon the intensity. If a violin tone, for example, is reproduced at a very much higher intensity than that at which it is usually heard, it will be very evident that the timbre is changed. A scale for representing timbre is now being worked out and it will be interesting to see if some quantitative measurements similar to those reported under loudness and pitch can be made to describe the quality aspects of the tone. It is sufficient to say here that there is no doubt but that the results will show that timbre is dependent not only upon the overtone structure but also upon the intensity and the pitch of the tone. It is thus a safe conclusion that each of the three psychological characteristics of a tone is dependent on all three of the physical characteristics, although the influence of one is predominant in each case. FILMS, RADIO AND TELEVISION ASSAYED BY DR. GOLDSMITH SPjcAKiNG through a tiny microphone no larger than a matcnfcox, iastened to his coac lapel, a device he described as "permitting one man to be heard above a multitude", Dr. Alfred N. Goldsmith, noted scientist and consulting engineer of the RCA Manufacturing Company, described and demonstrated recently some late scientific developments from the leading radio research laboratories to more than 400 guests of the Cleveland Chamber of Commerce. The address was broadcast over a nationwide radio hookup. The lapel microphone worn by Dr. Goldsmith utilizes the "velocity" principle of operation in which reproduction is obtained by the varying impact, or velocity of the human voice on a sensitive metallic ribbon within the mechanism. With this device a public speaker can move about freely without impairing the quality of the sound. Pointing out that we already hear and will eventually see by radio, Dr. Goldsmith suggested that in the remote future radio might appeal to man's other senses, such as touch, taste and smell. For example, he said, there was the possibility of transmitting three-dimensional replicas of objects in the studio through "Teletactile Broadcasting", so that a solid representation which "might even be touched as well as viewed could be sent into the home." "Telegustatory Broadcasting", or the transmission of taste, might make it possible to "taste" a fine brand of coffee, for instance, by radio. The transmission of smells would perhaps be easier, he said, since the "Telolfactory" receiver need only spray into the air a duplicate of the odor transmitted. He emphasized, however, that these possibilities were now "only whimsical and remote imaginings". Sound Picture Progress To illustrate the remarkable progress which has been made in improving the quality of sound motion pictures, Dr. Goldsmith demonstrated for the first time in public a radically new system of high quality sound-on-film recording which, according to RCA engineers who developed it, will be the "motion picture sound of tomorrow", because it completely eliminates background hissing noises and, theoretically, makes possible the ultimate of realism in sound-on-film recording and reproduction. Using a special film recording of a musical performance in the Radio City Music Hall in New York, Dr. Goldsmith called attention to the ability of the new system to reproduce the full definitions and shadings of all the instruments in the orchestra over the complete audible range of sound, as well as to the complete absence of hiss during the quieter portions of the music. With the new recording method, the sound waves are halved into two separate but symmetrical sound tracks, one negative and the other positive, automatically eliminating the unused portions of the sound track which is a necessary part of all existing soundon-film systems. Speaking of the development of facsimile picture transmission, or the transmission of "still" pictures by radio, Dr. Goldsmith said that ultimately facsimile transmission will become a public broadcasting service of great popularity. Any printed or pictorial material will, sooner or later, be capable of speedy transmission instantaneously into a multitude of homes provided with simple automatically-functioning receiving equipment. While describing the steady and orderly development of television experimentally as amazing, Dr. Goldsmith felt it necessary to temper optimism with a note of restraint in discussing the future of television broadcasting. The problems of television extend beyond purely technical considerations of transmitter and receiver, he said. There is the tremendous economic problem of launching a nationwide television service, when the cost of connecting numerous broadcasting stations of only limited service range in a network is at present staggering. Then there is the question of supplying almost overnight a demand for talent which will be pleasing to the eye as well as the ear in such quantities as would drain the available supply in Hollywood, for instance, in a very short time. Then there is the important question of who will pay for the high cost of putting this talent on the air, for commercial sponsors would be called upon to pay a substantial portion of the cost of a feature-film production for an hour's broadcasting. That these problems will be solved in time Dr. Goldsmith did not doubt, but it is evident, he said, that much must yet be accomplished in the interim. A remarkable new device called an oscillograph was connected to a number of radio receivers to permit everyone to "see" the characteristics of the human voice or other sound in the form of fluctuating waves. A stream of electrons, otherwise known as a cathode ray, paints a continuous picture of the sound waves on a glowing, or "fluorescent" screen. The oscillograph, according to Dr. Gold