It's weird to think of some asteroids as being not much more than free-floating bags of gravel, but the Universe is under no obligation to adhere to our expectations.
To a walker practised in such places a difference between impact on maiden herbage, and on the crippled stalks of a slight footway, is perceptible through the thickest boot or shoe.
So you kind of have to get that gravelly thing in your scream while you're pinching your vocal folds and tightening your diaphragm just to get out enough air.