Background music serves several psychological and structural functions in a podcast interview:
Music acts as an audio "marker" or bumper, signaling to the audience that a topic is shifting or a segment is ending. Best Practices for Mixing Talk Audio
Music should remain subtle, generally mixed at -20 to -30 decibels (or roughly 5% to 15% of the voice volume) to avoid competing with the host or guest.
Instrumental versions are preferred over lyrical tracks because they provide ambiance without vocal frequencies clashing with the conversation.
Use fades (2-5 seconds for intros, 3-7 seconds for exits) to prevent jarring starts or stops. Navigating No-Copyright and Royalty-Free Standards