United beat City, but what was the noise that Ronaldo heard?

Manchester United have today beaten local rivals Manchester City 1-0 at the City of Manchester Stadium, however the main talking point has to be Cristiano Ronaldo's red card. Wayne Rooney grabbed the only goal of the game to hand United all three points but it was Ronaldo who grabbed all the headlines.

The Portuguese winger was shown his second yellow mid-way through the second-half after he handled the ball inside the City box. Despite the United protests Ronaldo was given his marching orders by referee Howard Webb. Ronaldo jumped up for the header and for some strange reason he decided to put his hands over his face and handle the ball with both hands.

The 24-year old later claimed that he heard a noise as he jumped up for the header, but just what was that noise. As we all know any derby game in the Premier League is bound to be noisy and today's game was no exception. Personally, when I was watching the incident I didn't have a clue why he handled the ball. He wasn't pushed and the referee definitely didn't blow his whistle before he put his hands over his face.

There seemed to be a loud noise just as Ronaldo rose to head the ball, however the noise was clearly a horn from the crowd. So what else may he of heard?