In the 1950s, a jet fighter had a great top speed, but lousy acceleration. On the other hand, piston-propeller fighters had great acceleration, but lousy top speed.

Maybe, they thought, if you put a propeller on the front of jet fighter, you could get both acceleration and top speed. So the engineers heavily modified a Republic F-84 Thunderjet.

[...]

There was another problem with the XF-84H. Even at idle, the outer tips of the small propeller were traveling faster than the speed of sound, so they made a horrendous racket. It was the loudest plane ever built. There was no chance of secret testing.

The Thunderjet was so loud that it could be easily heard about 35 kilometres away. On one occasion, they powered up the engines of the XF-84H on a runway, while what they thought was an empty C-47 transport plane was parked on a nearby runway. This C-47 was side-on to the propeller of the XF-84H, where the noise was loudest. When they shut down the engine, they heard banging noises from the C-47. An engineer had been doing maintenance inside, and the incredibly loud banshee-like noise had thrown him into an epileptic fit. The banging noise was the flailing of his limbs. And yes, he did recover after a few days.

Yes, this was surely the loudest plane ever built. Maybe that's why they called the modified Thunderjet, the Thunderscreech. It was never fast enough to break the Sound Barrier, but it did break the Noise Barrier.