I don't care what the rankings say, it's just not that loud at Lambeau. I've been to three games, including playoffs and have always been underwhelmed by the noise.
I don't necessarily feel it's a reflection of support or anything like that. Maybe it's the geriatrics. Maybe fans just like to enjoy watching the game rather than screaming. Maybe they're not drunk enough. I don't really know or care. Lambeau and Packer fans are many great things, being loud just doesn't happen to be one of them.