"The need for standardized tonal characteristics was recognized from the early days of
sound-on-film, and the first attempt to codify the system was made by the Motion Picture Research
Council (reporting to the Academy of Motion Picture Arts and Sciences) in 1937. A panel listened to
a wide variety of material over typical theatre loudspeakers and determined the optimum
high-frequency attenuation"
http://www.hps4000.com/pages/special/Do ... -Curve.pdf
one of my favorite part :
-"(One interesting side note is that the 1948 booklet has a recommended power amplifier
wattage table, based on the number of seats. Fifteen watts was considered acceptable for a theatre
with up to 700 seats—at 4,500 seats, the recommended power amplifier capacity was 100 W"