Found something intriguing. Turns out, an explosive water dump was used to launch the shuttle, intended to dampen the sound vibrations from the engines. A million liters of water turn into a massive waterfall a few seconds before launch and last only 20 seconds. It’s reported to reduce up to 20dB and it’s worth it: used for all subsequent launches. There’s a video in the link.
I can’t find a word about it in the Russian internet. Maybe I’m not searching right.
https://metinmediamath.wordpress.com/2013/12/01/space-shuttle-launch-and-sound-suppression/
Hi, I'm Rauf Aliev. 