Well I know one thing for sure the Yak-18 is a very loud aircraft indeed taking into consideration its size.I don't know civil aircraft as as well as military but I was in the USAF and worked on the flight most everyday and I would still rank the Yak-18 as one of the louder planes I have seen er heard.Another really loud aircraft the old C-141s those things where much louder than any other cargo aircraft in the USAF you where supposed to wear ear plugs and ear phones and still the C-141 seemed loud to me.
Strange how you get to know engine sounds in my career the bases I was at I was either around A-10s or heavy cargo planes both of which use turbofans and they all do have their distinctive sounds the older KC-135s for example sound different than the newer R(the Rs have different engines) model ones and C-17s sound different than C-5s.I got to where I could know that something different was coming by hearing it before I saw it.Like the Bone(If you dont know what that is you dont need to know but you better fear it
) I heard one coming down the taxiway before I saw it and knew it was not a cargo plane it had some sort of electrical trouble and landed at our base.Another time I heard two German MiG-29s the sound they make is very different from western turbines.Ever heard a P-51 or a Spitfire with the same Merlin engine?Very unique sound.I will always miss the visceral experience of a military flight line never the same day twice.We used to say "I love the smell of JP-8 in the morning." as joke on Apocalypse Now.