Why in some older media (television, VHS and cassette tapes) do you hear music/dialogue very softly before it actually happens?

Question

I worked as a projectionist for a few years so in learning how sound is read off the film itself, I always assumed this is a phenomenon related to the fact that film is stored in rolls (same for VHS and cassette tapes), but what exactly is happening? Does sound from another part of the reel transfer due to the fact that the film touches? Maybe I’m way off, but I can’t for the life of me ask the right question to get an answer anywhere.

In: 13

Answer 1

You guessed it.

The tape uses magnetic patterns to store audio. Sometimes if it sits long enough, stuff from the layers above/below “leaks” onto other parts of the tape.