The art of sound pictures (1930)

SOUND TECHNIQUE 227 operator. After that, every one on the entire sound stage must keep absolutely silent, since every sound that is made will be recorded on the sound film along with the dialogue or music which is being shot. The lights on motion picture sets are, of course, intensely bright and very hot. Swarms of flies collect, as if by magic, around these lights. The buzzing of these flies in the microphone makes a record which later sounds like the rasping of steel files. Before the sound and picture apparatus are interlocked, therefore, an assistant director carefully sprays the entire set with a fly poison which at least reduces the number of insects, so that their buzzing becomes less noticeable and finally inaudible. Rubber or felt-soled shoes must be worn by the director and all his assistants. The actors themselves usually wear shoes especially prepared for sound picture taking. The squeaking of a new shoe records very easily in the microphone and when reproduced in a projection room sometimes sounds like the snapping of firecrackers or the crackle of twigs in a forest. If a sound stage is not completely insulated from all outside sounds, an aeroplane passing high over the studio may drown out the sound record of an entire scene. Stray cats mewing or scratching about the set have sometimes cost the company thousands of dollars in destruction of sound records. The sound of the motor and gears in a picture camera was found to be so loud that it badly marred the sound records. This difficulty was first overcome by building sound-proof booths with thick plate glass windows like the portholes of a steamship, through which pictures might be taken. The camera and the operator were placed inside the booth before the sound and picture recording