SMPTE RP 90:2004

Abtract:

(1.1) This practice specifies a type U audio frequency test film to be used for adjusting the mechanical and electrical parameters of 16-mm motion-picture magnetic audio reproducers operating at 24 frames per second. — NOTE – The film velocity of 16-mm film is also commonly stated as 7.2 inches per second or 183 millimeters per second, and historically stated as 36 feet or 11 meters per minute. (1.2) The International Organization for Standardization recognizes two reference levels for test films — type U with a reference level of 185 nWb/m and type E with a reference level of 320 nWb/m — in order to account for differing meter types in common use in the United States and Europe.