Often music is background noise or used to cover other sounds. Music can be a good way of masking the sounds of what a Dom is doing as he gets things prepped for the scene to evolve. That way the sub does not know what to anticipate; of course this assumes the sub’s vision was impaired.
My favorite song this year to have queued for when a sub is getting pushed psychically or mentally in a scene is “Walls” featuring Quilla from Sultan and Ned Shepard