Loudest Sound Ever?

The explosion of the French munitions ship SS Mont Blanc in Halifax, Nova Scotia on Dec. 6, 1917. Over 2000 dead and 9000 injured. Blast equivalent to 2..9 kilo tons of TNT. This was the largest man-made explosion at that time!

The Who
Carter Finley Stadium 1989

Lumen Field (Centurylink Field), Seahawks home games: sustained SPLs 125+ dB. 
I’ll watch at home thank you. 
Once in my youth I fired a 357 Magnum, having forgotten to put on ear protection - took two days to hear correctly, and likely did some long-term damage. 

1969. South Vietnam. B52 strike about a mile too close to a F0 I happened to be occupying. "Shook me all night loooooong. "  Diz

The guitar solo during Comfortably Numb on the Roger Waters The Wall tour. At the Boston Garden.