SOUND PICTURES

Greymouth Evening Star, 10 December 1929, Page 4

SOUND PICTURES

TWO DIFFERENT PROCESSES Hollywood has gone “talkie”; the ■silent drama has. gone “talkie.” To what extent Hollywood has been influenced by dialogue pictures that have revolutionised ' the industry can be judged by the production schedules at Hollywood studios. Where a year or two years ago talkies were an experiment, to-day more than 85 per cent, of the pictures being made at the film centre are sound or dialogue pictures. Few would have dreamed that the industry would have had such development since the first public presentation by Warner Brothers in New York City in August, 1926. Much interest has been aroused among the general public as to the details of the talking motion picture system. How is sound recorded in conjunction with the film? How is the sound reproduced ■ in the theatre! Where does the sound come from? Behind the screen, at the,side of the s tage, or in the ceiling of the theatre! These are questions which motion picture patrons are interested in having answered.

To begin with, the telephone is the source from which sound pictures have grown. Engineers in America, who had been studying transmissions of sound for years, were the first to develop amplifying units which would build up tone from an infinitely small volume' to the clear resonance that is heard in the leading talking picture theatres to-day. Amplifiers in the theatre work on the same principle that telephone amplifying devices manufactured by the Western Electric Company build up the tone at various points in long-distance telephone circuit. It is because of the long experience of this company in sound that they were first in the field of talking motion pictures. For that reason their equipment has been adopted by the leading producers and exhibitors as the standard.

Two different methods of recording and reproducing the sound are employed. In. t'he first, known as the disc method, the sound is recorded on and reproduced from a wax disc operated in synchronisation with the film. This is the method used by Warner Brothers for their vitaphone productions and by First National Pictures, who make their productions under the name of Vitaphone. In the second, the film method, the sound is photographed by means of light variations on the side of the film itself. This is the method used by Fox and their Movietone releases. It is also the method that Metro-Goldwyn-Mayer and United Artists employ, and for their productions they will likewise use the Movietone.

THE DISC METHOD. With the disc method the first step In photographing and recording a scene is taken in a motion picture studio equipped with special facilities. These include one or more microphones placed about the studio, out of range of the sound of orchestra, speaker, or vocalist. Sound-proof booths house the camera, so that no. extianeous noises may interfere with the recording. When a scene is to be recorded the camera photographs it, while the microphones pick up the desired sounds. These sounds, striking the diaphragm of the microphone, cause it to vibrate, and these vibrations are translated into a fluctuating cFctric current that tows through wires to a control room. There the current passes through an amplifier system on to a recording device, where the fluctuations of the current are changed into mechanical vibrations, which are recorded on a disc of soft wax. To ensure that the picture and sound aie perfectly synchronised, the motors which run the cameras and the turntable carrying the disc are made to run at uniform speed and in synchronism. These motors are started and reach full speed together, and continue to run together. When picture and sound recorded by this method are reproduced in a theatre othei’ equipment, made by the Western Electric Company, and known as the Western Electric Sound Projector System, is employed. A standard motion picture projector is used for the film, while a turntable is added for the sound record. Both are operated by the same motor, and means are provided to control the speed automatically. An adaptation of the familiar Western Electric public address system makes it possible to pick up electrical vibrations from the reproducer, amplify them, and, by means of loud-speaking telephones located in the theatre, transform them into sound. For the average theatre two large horns, placed behind the motion picture screen, are sufficient. The motion picture film and the needle for playing the record are set in place, as indicated by marks, prior to running of the sound picture. The motor is then started, and the film and the record are mechanically operated in synchronism. The mechanical vibrations of the needle are transformed into sound vibrations, which pass through the horns behind the screen.

SOUND ON FILM. When a production is made- by the film method quite a different process from that outlined above is employed. In this latter method both the motion picture and its sound accompaniment are recorded on the same film. This process in photographing vibrations in light intensity on the film. The sounds to be recorded are picked up by microphones which have the property of changing sound vibrations into electrical vibrations. These are amplified and in turn vary the intensity of a recording light. This light is contained in a tube that is inserted in the back of a motion picture camera in such a way that the variations in light intensity fall directly upon a narrow ledge of the negative film on which the motion picture is also simultaneously being recorded. Apart from the fact that the motion picture camera is motor-driven, and is connected by wire with the telephone apparatus, there is little difference between the recording of picture and voice by this method and the ordinary picture recording in a motion picture studio. The presentation of one of these sound films to an audience is, in effect, a reversal of this process. The standard film containing both picture and sound in a photographic record, is run through a standard moving picture projection machine to which has been attached a sound reproducing unit. This unit includes a light that is reflected on to the sound record of the film. As the sound record on the film passes the light it interrupts the light shining through it, and sets up

light variations corresponding to those photographed. These variations then fall on a photo-electric cell which changes the light variations back to electrical variations.. The latter variations, being too delicate to be heard directly, are amplified, and carried by wire from the projection booth to the horns placed at the back of the motion, picture screen, from which the sound emerges.