Brooklyn is a quiet suburb generally. The trains can be heard but are infrequent and not a major issue. Depending on location in Brooklyn the road noise can be heard at low levels. Having said that in most places close to a major road get distant noise of some level.
As a resident I would say. A terrible place don't even consider unless your looking for an affordable town with good transport ,community, schools and restaurants and club and a pub . And only 50 mins form CBDs surrounded by bush and water who would want to live here.
Please don't tell anyone it's a great place we like our secluded hamlet!