Manchester United have asked an acoustic expert to investigate ways of making Old Trafford louder after fans complained that singing could not be heard properly, the Manchester Evening News has reported.
The club asked the specialist to write a report on the stadium, with the move coming after plans to set up a dedicated 'singing section' had been abandoned because of concerns over safety.
The specialist, who watched the game against Liverpool in January and will watch another before the end of the season, will present suggestions for steps that could improve the volume and atmosphere at the ground.
The Manchester Evening News said it was thought United had made the move after complaints from fans who sit in the famous Stretford End.
A United source told the paper: "There were supporters in the Stretford End who thought they had made a lot of noise - only for friends in different parts of the ground to say they couldn't hear them."
Meanwhile, United have shelved proposals to rehouse visiting fans after police said they were unhappy with the one-off relocation of Aston Villa supporters towards the end of last season.
Villa fans were moved from the East Stand to the top deck of the Sir Alex Ferguson stand, but Greater Manchester officers said there were safety concerns about putting large away supports in the steep, high structure.