Bed (music bed / underscore)
Low-level continuous music running under narration: there to hold the energy, not to be noticed.
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What it is
A bed is continuous music sitting well under narration, there to carry energy and hide edits, not to be listened to. Radio and podcasting say 'bed', film and TV say 'underscore', and both mean the same job: keep the room alive while someone talks.
Good beds are boring on purpose. Loop-friendly, no vocals, no melody that competes with the sentence, no drop that steals the moment. Typical level is roughly 15dB to 20dB below the voice, and it usually sits behind a ducking setup so it dips automatically when the narrator speaks. Cut the bed's midrange around 1kHz to 3kHz and the voice gets its own lane without you turning the music down further.
The classic mistake is picking the track you love rather than the track that disappears. If you catch yourself humming it back, it is fighting your script. Second trap: beds need an ending. Loop it to the last word, then let it resolve or fade over two to three seconds, because a bed that stops dead sounds like a broken file.
Ask AI for it
Compose a 90 second instrumental music bed for a product explainer voiceover: warm, mid-tempo, no vocals, no strong melody in the 1kHz to 3kHz vocal range, minimal percussion, a light 8 bar loop that can be trimmed anywhere, and a clean 3 second resolve at the end. Mix it to sit about 18dB under a spoken voice track.