system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why do most DVD’s and Blu Rays have the action and background noise much louder than the actor’s voices?
gpt
Dvd's and Blu-rays have the audio mastered in surround sound. Voices are typically sent through the center channel, while background noises and action come through all of the other speakers (typically, 4).

When played through a stereo, headphones, or a TV, all of those channels of audio are played through only 2 speakers.

Depending on how the engineers master the audio, and how your device decodes the signal, you sometimes wind up with those 4 channels of other noise overpowering the one channel of voice.