Even then there was probably a tiny droning noise in the sky, but nobody who had watched the takeoff from nearby could possibly hear it.

It blurred into the old droning noise, which even now was only faintly audible.

That ugly mechanical droning noise in the sky still reverberated in Gundersen's mind, shattering his new-found peace.

On the other side, Robin heard a droning noise.

There was a faint droning noise in the east.

He heard a droning noise and looked up.

The droning noise grew louder.

After the group had been resting for a half hour, they were disturbed by a distant droning noise that rapidly escalated.

There was a harsh droning noise.

The droning noise was like thunder.