Well, G-SPOT, parked my kite next to a 1-11 in September 2011...in Ouagadougou / Burkina Faso (DFFD). They sadly did not depart before us, so couldnīt hear the noise. But I remembers BA 1-11s sound very well...although I think you rather feel the noise than hear it.
The Beechjet 400 has a real nasty noise btw.