I've read that due to the TU-95's thirty two blades rotating at supersonic speeds, the Bears are so loud that they could be heard by submerged submarines and SOSUS sonar devices on the sea bed !
The loudest I've personally heard is Harrier. Even taxing past it made my ears protest.
Tornado GR4 seems variable noise constant speed. It was a shock moving from Kinloss to Lossiemouth. The locals at Cold Lake AFB Canada, told me "they knew when we were there on det by the noise".