Posted by 1939 on June 17, 2002 at 12:21:08:
In Reply to: Hi-Pitch / Lo-Pitch / A440 - When?? posted by Marty Neilan on June 17, 2002 at 12:17:25:
Grolier says:
"An international standard adopted in 1939 places a' (A above middle C) at 440 double vibrations per second."