Motion Picture News (Oct-Dec 1929)

so Motion Picture News December 7, 1929 Acoustical Terms and the Usual Sources of Sound Troubles {Continued from page 44) or even by faulty recording. It produces that old situation where the actors' words are out of step with his actions. Another phenomenon that sometimes occurs is known as "flutter." As its name indicates, it describes a sort of tremolo or flutter in speech or music which quite ruins certain effects. This also is an apparatus defect, due to a variety of causes. Among these may be listed faulty adjustment of the film takeup, vibration of the exciting lamp, faulty speed control, etc. There is one case on record where such a tremolo was produced by two sets of concentrated reflections in the house itself, but this house was something of a freak. FINALLY, we ,come to what is probably the most frequent criticism leveled against the sound pictures, namely, distortion of sound quality. To the listener this distortion may evidence itself in a dozen different ways. He may characterize it as dullness or lifelessness, or he may comment on the predominance of low notes — what the radio broadcasters calls "going bass." If the above conditions exist the probability is that the upper frequencies have been wholly or partially destroyed. If, on the other hand, the effect is one of sharpness, shrillness or harshness, it is the low frequencies which must be reinforced. It should be noted that a similar type of frequency distortion may be produced by "selective" absorption of the materials used in the finish or furnishing of the theatre. Many of these materials are much more efficient sound absorbers for some frequencies than for others. In consequence, these frequencies are damped out more rapidly. In general, distortion from this type of absorption is much less aggravated than that first mentioned. There are other possible causes of this change in quality, but in general they are too technical to discuss here. Suffice it to say that wherever there is loss of naturalness, either in speech, in music or in sound effects, some sort of distortion in the apparatus is probably to blame. A great deal of progress has been made in the elimination of these various types of distortion, but it is nevertheless desirable to be able to recognize them when they occur. In regard to the solution of the various difficulties mentioned, certain generalizations may be made. Defects in recording, in synchronization, and in frequency range are rapidly being overcome in the laboratories. Some of these are much harder to overcome than others, and it will, no doubt, be a considerable length of time before anything approaching perfection is attained. The time will come, however, within the near future when further development of the talking picture will require a certain amount of skilled and experienced criticism on the part of the listener. At present many of the defects are quite obvious, but as time goes on and more improvements are effected, there will be a necessity for increasingly accurate and intelligent criticism. In the correction of difficulties inherent in the acoustics of the house itself a number of simple and efficient remedies are available. A half dozen or more large companies are engaged in the manufacture of materials for acoustical correction, and practically all of these companies maintain engineering departments which will perform theatre analysis. Research has developed the art to a point where theatre analysis can be made very complete. There are no acoustical faults which cannot at least be alleviated and few which cannot be completely Westinghouse Eng "Television for TELEVISION which can be viewed by a room full of spectators rather than by one or two was announced recently by Dr. Vladimir Zworykin, research engineer of the Westinghouse Electric and Manufacturing Company, to members of the Institute of Radio Engineers. The use of a cathode ray tube as a receiver gives this new type of television many advantages over the well known scanning disc method of visual broadcasting. The inventor is already in position to discuss the practical possibility of flashing the images on a motion picture screen so that large audiences can receive television broadcasts of important events immediately after a film of these is printed. These visual broadcasts would be synchronized with sound. The cathode ray television receiver has no moving parts, making it more easily usable by the rank and file of the radio audience. It is quiet in operation and synchronization of transmitter and receiver is accomplished easily, even when using a single radio channel. Another advantage is that, using a fluorescent screen, the persistence of the eye's vision is aided and it is possible to reduce the number of pictures shown each second without noticeable flickering. This in turn allows a greater number of scanning lines and results in the picture being produced in greater detail without in cured. In a large number of cases the solution lies simply in the installation of absorbent material in the correct quantity and in the correct areas. Excessive reverberation can be controlled by the use of sound absorbent materials and echoes and interfering reflections of all kinds may be to a large extent eliminated in the same manner. In cases where the remedy does not lie in the installation of acoustical material, minor changes in shape, etc., will generally effect a remedy. It is worthy of note that the development of acoustical materials has progressed within the past few years to a point where they are fully as attractive for their decorative possibilities as for their acoustical value. The acoustical engineer, architect and decorator, working side by side, have produced products that not only imitate the age-old decorative treatments, but actually offer new and practical decorative possibilities heretofore undiscovered. Correst acoustical materials can be so adapted to every size, shape or form of surface as to greet the eye with unlimited variety in color, tone value and structural effects. If unbroken surface and planes are desired, they can be obtained in any desired finish, stone textured, sanded, fabric applied, and imitation wood veneer, etc. Even a perfect background for the application of murals can be supplied. ineer Demonstrates a Room Full" creasing the width of the radio channel. The pictures formed by the cathode ray receiver are four by five inches in size. They can be made larger or brighter by increasing the voltage used in the receiver. The transmitter of this new television apparatus consists of a motion picture projector rebuilt so that the film to be broadcast passes downward at a constant speed. This film is scanned horizontally by a tiny beam of light which after passing through the film is focussed as a stationary spot on a photo-electric cell. The scanning motion of the beam is produced by a vibrating mirror which deflects the light from one side of the film to the other. Dr. Zworykin was forced to develop an entirely new type of cathode ray tube for his receiving apparatus which he calls a "kinescope." In this tube a pencil of electrons is bombarding a screen of fluorescent material. The pencil follows the movement of the scanning light beam in the transmitter while its intensity is regulated by the strength of the impulses received from the transmitter. The movement of the scanning beam, consequently of the cathode ray pencil are so rapid that the eye receives a perfect impression of a continuous miniature motion picture. A reflecting mirror mounted on the receiver permits the picture to be observed by a number of spectators.