I haven't seen this movie since, probably, about 1971. I remember the big room full of women, listening intently to the slowed-down sounds and trying to work out the code. At the time I didn't question why it was all women, but it seemed like a cool idea.
"The truth 24 times a second."
I haven't seen this film, but I think I can answer the question.
The screenwriter Leo Marks was a genuine cryptographer during the Second World War, and at that time large numbers of women were drafted into the armed forces. One of the tasks they were put to was decoding and deciphering messages received from agents in occupied Europe.
Part of Leo Marks's job was to train and motivate these female teams, so that they became more than passive note-takers. You can read about this in his fascinating memoir "Between Silk and Cyanide"
how interesting. I vaguely thought the film was reminiscent of the goings on at Bletchley park etc, now. I know why.