We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
SOUND TRANSLATION 467
verts the light modulation produced by the movements of the film pasl the light beam into electrical currents. The associated amplifier amplifies the currents to a level suited to the loudspeaker which, in turn, radiates sound directly to the ears of the audience viewing the film.
Sound Transport. Sound transport systems vary widely in design and in performance. Theoretically, the objective of the design is to transport the film past the sound light beam in a fixed plane with constant velocity. Practically, however, all transport systems deviate from this ideal, having spurious speed variations introduced by mechanical and other irregularities and eccentricities that modulate the theoretically constant film velocity. To some degree, all systems have an in-and-outof-focus effect that arises from the shift of the film from the theoretical fixed plane. In the former case, the speed modulation causes a like modulation of the signal derived from the film. This spurious signal modulation is called flutter. In the latter case, the in-and-out-of-focus effect that arises from the shifting of the actual plane that the film takes as it moves past the sound-scanning beam produces the equivalent of a flutter modulation of the effective width of the scanning beam slit. This latter effect is quite pronounced in several makes of 16-mm sound projectors, but there has been no attempt made so far to measure it separately in order to determine its magnitude, or to set limits for acceptable performance.
Flutter in Transport Systems. The human ear is quite sensitive to frequency modulation of a sine-wave, 3000-cps tone. The sensitivity depends not only upon the amplitude of the variation, but also upon its frequency. Since 3000 cps is a frequency to which the human ear is particularly sensitive to both amplitude and pitch variations, it was chosen as the frequency for flutter testing with test films. The film is recorded at constant amplitude on a machine that has but a small fraction of the flutter to be expected in the best machine to be tested with the film. The American Standard 3000-cycle, Flutter Test Film Z22.43, obtainable from the Society of Motion Picture Engineers, meets this requirement. A flutter bridge for measuring flutter is manufactured by RCA and others; the RCA flutter bridge is widely used. Different flutter-measuring instruments such as the ERP* or the Altec provide different readings for the same phenomenon. The instrument used and the method of test should always be specified when the results of flutter tests are reported.
*EKP division of Western Electric Company.