You're descending at a relatively high speed in calm air, and since there was no forecast for nor little chance of turbulence, you let the airspeed climb into the yellow arc, but fail to keep your attention focused on the airspeed indicator. Then you hear this buzzing noise. What might that mean?
When traveling at the speed of sound at sea level (assuming we use a "standard" atmosphere at 15 degrees C), the dynamic pressure (the same pressure sensed by a pitot tube) is very roughly equivalent to...