By Simon Cambers

NEW YORK (Reuters) - Andy Murray said on Thursday the noise created by the U.S. Open's new retractable roof over Arthur Ashe Stadium is a distraction to players and makes it difficult to react to opponents' shots.

But the British second seed managed to shut out the noise and Spain's Marcel Granollers during a 6-4 6-1 6-4 second-round victory played while rain beat down on the closed roof and crowd noise reverberated inside.

The Wimbledon and Olympic champion ground down the world number 45 in a match involving numerous lung-busting rallies and played under a cacophony of sound with the $150 million roof closed from the start.

"It's because we use our ears when we play,” Murray said, explaining the difficulty. "It's not just the eyes. It helps us pick up the speed of the ball, the spin that's on the ball, how hard someone's hitting it.

"If we played with our ears covered or with headphones on, it would be a big advantage if your opponent wasn't wearing them."

At times, the players could barely hear the ball off their strings and the rain hammering on the roof was almost deafening but Murray kept calm to clinch a convincing victory.

"At first we didn’t know if there was just more people come in at the change of ends, but then we quickly realized it was the rain," Murray said.

But the Scot, chasing his fourth grand slam title, said players will cope with the extra noise.

"As an athlete, that's what you do. We adjust to conditions, different conditions every week," said Murray.

"I'm sure if the feedback is that the TV or the spectators aren't enjoying the match as much then they will look into it and try and change it.

"But if it's fine on TV, which from what I have heard it is, I don't know what the fans have said about it yet, but the players will adjust."

Murray led 5-2 in the first set only for Granollers to hit back but the Scot won a game lasting more than 10 minutes to break and clinch it on his seventh set point.

After breaking for 3-1 in the second set, Murray pulled away to double his lead and he broke in the ninth game of the third to earn victory.

Murray, the champion in 2012 and chasing a fourth grand slam title, will now play either 30th seed Gilles Simon or unseeded Italian Paolo Lorenzi.

(Editing by Frank Pingue)