(1) Silent in flight, they came to ground with a great susurration.
Susurrus
Definition:
(n.) The act of whispering; a whisper; a murmur.
Example Sentences:
(1) From this distance – approximately 900 metres – the susurrus of slowly turning blades sounds like a distant country road, minus the intermittent heavy rumble of semitrailers that are a fixture in less isolated rural areas.