Voice under
A voice over that turns out to be too quiet. Particularly relevant to a translated voice over that is quieter than the dialogue being translated.
What? What's he saying? Man, shoot the sound engineer, he turned out a voice under.
Voice under
When the music is so loud in a commercial you can't understand the announcer.
"That restaurant looked good, did you get the address?" "Naw, sorry, it was a total Voice under."