I have quite a few books on submarine warfare in WW2 and remember reading in a few of them that when the DC was close an audible click would be heard just before the detonation. Depending on what you were reading at the time the click was attributed to either an arming mechanism or a sound wave. Anyway, I've had more than a few close calls but never heard a click. Is it just not modelled or has my hearing gone too?
