Although this question has already been answered briefly, let’s explore this idea a little further by asking ourselves a few questions.
Some examples of everyday functional music include: music for film and tv, music for advertisements, music for educational purposes, and programed electronic sounds in some commercial appliances (like a dishwasher that plays a short melody when the cycle is complete).
In some instances music is specifically written to be background music. In fact, the term Muzak has been synonymous with background music in America for nearly a century. In other cases, popular music is repurposed to be background music either by other musicians or by companies simply playing music softly in their stores.
There are many excellent examples of music being repurposed by Hollywood to serve a functional purpose. Stanley Kubrick used the music of famous composers like Richard Strauss and Gyögy Ligeti in his movie 2001: A Space Odyssey. It’s safe to say that in this use the music is functional, but not in a way originally intended by the composers.