The locals used to get real upset with 81s doing slow coal drags up Como Bank in the day .
Actually I remember residents arcing up over the compressors starting up on 86s in Loftus Up refuge overnight .
It isn't a trivial issue and is the reason why more current units are fairly quiet eg GT46ACEs 93s NRs .
Cars and trucks are a lot quieter than they used to be , why not locomotives . Not everyone gets a solid drawbar over train noises .
BDA, what many do not understand in all of the noise issue is that its not about hearing a luvly yum yum coming up the hill for some sort of loco sound ecstatic experience, rather about those people who live alongside the rail lines and end up with all kinds of new train types over the years, and the overall pitch of the PM's as well as other factors.
The 81's are a good example, for the crews a nice quiet cab only bettered by the 47cl, a bit cramped in seating though, but the big thing with them was the way they sounded and felt at ground level. When they first came to Werris Creek in numbers I was sitting in Pangela loop and went to get water at the signal box and felt a vibration in the ground thought the start of an earthquake or something, when I commented to the signalman he simply said an 81cl at the front of the down train. The closer it got the greater the vibration and it was felt before you heard it. It was very much a rumbling vibration and very much something you felt through the legs.
When the residents at Tighes Hill and around Waratah station complained about the rumbling and the PM pitches on stationary trains, the issue was found to be that many of the drivers failed to center the reverser and the high idle pitch shook windows of the old homes. Reasons why sound barriers were erected in many areas.
Other areas of noise can be found not on the loco's but with many of the wagons these days that have a lot more harsh crashing with the couplers as the train is going, not always in the same spot either so hard to blame a track specific issue, it is very much heard up here on the CC with the loco's in full power.
One thing for sure is that I am glad I do not live close to a railway line. The worst I have ever heard though was at Yeronga around 4 years ago when a QR diesel with a GM motor approached the station heading north. Cannot remember the class/type but from the first hearing of it I thought it must have been close but it took around 5 minutes before it appeared, the sound was incredibly loud, and worse than a 42cl. It was a low nosed type hood type.