I'm huddling inside Main Street station waiting for a Carlton streetcar when the sound of violins wafts up from the subway. Unless there's a full orchestra busking down there, it's a recording. And then I realize it's playing over the station's internal speakers. But why?

The answer is nefarious youths. In 1998, a community safety audit conducted after a fatal stabbing at Kennedy station suggested piping in Bach, Sibelius, Schumann, and others would repel gangs. New lights, CCTV, and additional security patrols were also ordered.

7-Eleven convenience stores and Vancouver's SkyTrain had used the same musical tactic with mixed results. The thinking, according to the Toronto Star when the Kennedy pilot project began, was that youths would rather move than listen to "highbrow" music. Some kids in B.C. just shouted over the classics.

The London Underground also uses orchestral music for the same reason in some of its stations.

According to TTC spokesman Brad Ross, the idea has since been expanded over the last 16 years to Warden, Victoria Park, Main Street, Bathurst, Dundas West, Runnymede, Finch, and Greenwood stations, stops close to high schools or colleges.

Classical music, in fact any music the listener finds repellant, suppresses dopamine production in the brain, "souring their mood and making them avoid the music," according to a Seattle Times story on the concept.

The music isn't coming from an internal DJ, says the TTC's Danny Nicholson. A company called Stingray360 in Montreal that specializes in "sensorial marketing solutions" provides the music feed and covers the licensing requirements for about $14,500 a year.

"A lot of dentists pay for it," he says. "If you're in a dentist's office you often hear recorded music that comes from the same sort of thing."