No from what I saw before it adds a marginal amount to one existing fan. I saw a formula on it once but I cant find it and the numbers were different so I cant just hand you their answer anyway. I think if your fans noise is measured in db and not dbA then its simply +3 decibels for every time you add another fan of the same type. If its measured in dbA I don't think its that simple but still wouldn't literally just add up.