Watch this video and note the audio after the two parts where Hitchcock overloads the mic.
Notice that slight echo? What do you think that is? Well I’ll tell ya…
I believe it’s audio printing or bleeding. When this was captured, audio was stored on magnetic tape as a series of, yes, magnetic fields. And the tape was wound up in a reel. Louder sounds equated to stronger magnetic fields, and when a loud sound was recorded and then reeled up with the rest of the tape, some of the magnetic field might have bled onto the tape just above and/or below it.
Hitchcock likes to emphasize the word “all,” and he does so twice in this clip. Listen for a little echo of “all” after he says it. Notice that it happens about two seconds later. That’s not because he’s in a large room and the sound is reflecting off of the back wall.
But if my theory is correct, the strong magnetic field would bleed through to the next adjacent layer of tape in both directions, so we should really hear the echo before he says it as well as after he says it. Let’s listen again.
Yep. You can hear the “all” of “…and it’s all nonproductive…” not only after he says it, but before he says it. He says “all” at 39 seconds and you can hear images of it at 37 seconds and 41 seconds. He says “all” again in “…but when all these are removed…” at 1:06 and you can hear the bleed-through at 1:04 and 1:08.
Magnetic printing confirmed.
Also it’s a good clip. Shout out to my old film school peep Kirk Sullivan for retweeting it.