The 1883 explosive eruption of Krakatoa volcano made the loudest sound in history
By Lithograph: Parker & Coward, Britain; - Image published as Plate 1 in The eruption of Krakatoa, and subsequent phenomena. Report of the Krakatoa Committee of the Royal Society (London, Trubner & Co., 1888)., Public Domain, Link
The final fourth explosion of the 1883 eruption generated a sound estimated to have a volume of 310 dB [1]. If something is ten times louder than something it is 10 dB greater on the logarithmic scale. The Krakatoa explosion was so loud that it ruptured sailors' eardrums 64 km away and it could be heard clearly 5000 km away.
In comparison, a fighter jet takeoff about 25 metres away equals about 150 dB (enough to cause eardrums to rupture). A difference of 160 dB translates a difference of 16 orders of magnitude, that is a number with 16 zeros in it.
Wikipedia on the 1883 eruption of Krakatoa [1]
Comparative noise examples [2]