I don't think there's much in that to be honest.
If you take the individual readings from both rounds of games then 3 of the 5 'quietest' out of all 19 (Villa/So'ton yet to play) were Swansea vs Arsenal, QPR vs Man City and Palace vs Us, which all had really good atmospheres, but being small stadiums were unlikely to match Old Trafford or the Emirates.
It seems it was only individual journalists using smart phone apps recording the single loudest sound rather than taking the average over 90 mins or accounting for the size of the crowd, and presumably sitting in the media sections of the various main stands away from the loudest parts of the stadiums.
http://www.independent.co.uk/sport/football/premier-league/manchester-united-named-premier-leagues-loudest-fans-despite-late-push-by-chelsea-according-to-smart-meter-app-9878952.htmlIn saying that, I'm surprised Can's goal (assuming it was the loudest moment during the game) didn't put us higher:
84 - Old Trafford, Man Utd vs Palace
83 - Emirates, Arsenal vs Man Utd
83 - Stamford Bridge, Chelsea vs West Brom
83 - KC Stadium, Hull vs Spurs
83 - Britannia, Stoke vs Bunley
81 - Etihad, Man City vs Swansea
80 - St James', Newcastle vs QPR
78 - Goodison, Everton vs West Ham
78 - King Power, Leicester vs Sunderland
78 - White Hart Lane, Spurs vs Stoke
78 - Hawthorns, West Brom vs Newcastle
78 - Stadium of Light, Sunderland vs Everton
78 - St Marys, Southamption vs Leicester
77 - Anfield, Liverpool vs Chelsea
76 - Loftus Road, QPR vs Man City
76 - Liberty, Swansea vs Arsenal
76 - Selhurst Park, Palace vs Liverpool
74 - Upton Park, West Ham vs Villa