Why do some Airbus jetliners at full thrust sound like turboprops? When riding an A3xx I always noticed the unique &quot;turboprop&quot; like sound when close to full throttle. Why is that so?
I'm assuming you mean that buzzing/growly/deep humming sound.
That is the tips of the fan blades in the first stage fan disc approaching the speed of sound, and getting close to forming shock waves. Their noise generation becomes strong at that point.