Early morning commuters crossing King George Square may wonder why Mozart's melodies blare aggressively from speakers at the crack of dawn.

The Brisbane City Council introduced the classical music to the square in the heart of the CBD in 2012 but the practice was questioned this week.

A council spokeswoman said the move followed complaints about anti-social behaviour in the area.

But the homeless people who take shelter under the roofed section of the square have had to learn either to live with the racket or become fans of Bach and Beethoven.