Tchaikovsky's 1880 work 1812 Overture, which is scored for artillery and has passages marked as ffff (in a score, "fortississimo" (fff) instructs the musicians to play the marked passage extremely loudly and is normally the loudest volume specified; "fortissississimo" (ffff), which means to play louder than fortississimo, is sometimes used) has been described as the loudest classical piece. The piece has been played with FH70 155 mm (6.1 in) howitzers and Type 74 Main Battle Tanks included in the orchestra instrumentation (a typical 155mm howitzer generates about 180 dB at the source, sufficient to sometimes cause immediate and permanent hearing damage (artillery crews are issued hearing protection)). The piece is usually performed outdoors or with simulated or recorded cannons, but an indoor performance with live cannon at the Royal Albert Hall has been cited as having been particularly loud.
[0] https://en.m.wikipedia.org/wiki/Mohs_scale_of_mineral_hardne...