It plays an important role in relaxing those we serve. Not only is there this soft background music, but soft colors, plants, and the legal library somewhere else. Experiment for yourself and see if your experience is any different. Monkey see, monkey do. This fashion in direct opposition to using verbal persuasion or reasoning to effect certain behavior.
Parents unconsciously model for their children and wind up with, to some extent, behavioral clones.
Ever notice how much alike families are. They tend to talk alike, walk alike, react alike, make similar preference, etc. This information is also used in therapy. If you establish rapport, they will follow your lead. For example, in order to gain rapport with an agitated client, it is very useful to rise up to the level of their agitation including their posture, movements and breathing.