Clllankk! (with extra emphasis on the 'k'!): the commanding hue and din of a Pentax 67 firing.
I looked like the very odd man out last week on a viewing platform over a waterfall then everybody stepped well back after the camera fired. What did they expect, a Chinese firecracker??
My Zero Image pinhole has no shutter sound at all with a 'sliding shutter'. Great for spying!