"My neighbour has been blasting out music since six o'clock," one resident complained of the concert taking place several miles away in Oberhausen, police said in a statement.
Germany has strict rules on respecting "Ruhe", or silence, and dozens called after a 10 p.m. noise deadline to complain. Not everyone was unhappy, the police statement said. When told about the concert, one angry caller said: "If that's the case, I'll sit on my balcony and listen."