Bleed Through

Magnetic tape or film stores audio information via metal particles applied to one side of the tape or film. A record head applies a magnetic flux to those particles, which then orient themselves to represent the audio information. A playback head reads the magnetic flux stored on the tape to reproduce the sound.

Tape and film is stored wound on reels with the recording medium wrapped around itself repeatedly to the end of the reel. Bleed through, also known as print through, occurs when the magnetic flux stored on one wrap of tape transfers to the tape wrapped above or below it in the reel. Over time the magnetic flux, especially the strong flux typical of a loud audio event, can influence the metal particles on several adjacent wraps of tape. This will create an “echo,” (sometimes numerous “echoes”), before and/or after the original audio event.

The terms print through and bleed through are sometimes used to refer to another anomaly known as crosstalk, though their defining characteristics are different.

The bleed through in this clip occurs after the initial line of dialog has been delivered.