Growing up next to LHR in 50s and 60s one got very attuned to the many different engine sounds and could be very accurate about guessing the type from the noise . Even able to distinguish different type same engine, Comet /Caravelle for instance.
But that's along long time ago and cant be too fussy these days but having been in Czech rep last week the town i was in has a small but pool table flat grass field which I always check out when there. s i drove up this time Iwas treated toa gang of skydivers climbing aboard an AN2 . great cloud of blue smoke and rattling at start up and tremendous rumbling and clunking radial noise when taxying , so rare to hear any radial now.
They really a re quite amazing planes it was full of jumpers but was airborne in a tiny fraction of the runway length and 10 mins later up at dropping height , 8000ft?? maybe it had no apparent forward motion at all on a windy day . Lovely twenty minutes spent there..
i think it is often the sound that gets ones attention too and if it heralds something unusual even better, a few years back when I lived in Camberley I was out walking the dog and heard a very very unusual sound and a F4U Corsair hove into view, a real thrill. Also one still evening , again dog walking a most unusual clattering rumbling noise a long way off, luckily aclear sky and a clear view revealed a dark speck moving very slowly north to south and a good five minutes later it reveals itself a s its a JU52 , Never ever though i would see one , unbelievable slow and a wonderful sound (