I have heard of this idea about 2 years ago, when Copenhagen City Council, the police, and the employees at the Copenhagen Grand Central Station were being fed up and annoyed by some drug addicts, alcoholcs, prostitues and homeless people hung around at one specific side of the Grand Central Station, and a street right next to the station. Although they were quiet and not violent, some people got nervous when passing by these folks to catch the train.
To tell them politely that these folks should go somewhere else, they installed speakers in that specific area of the central station playing all sorts of classical music. - And it worked!