NASA Sound Suppression Water System
The earth shaking sounds of a rocket launch produce acoustic energy that could cause damage to instruments on any rocket launch, but the space shuttle orbiter was more exposed because the payload sat much closer to the launch pad than payloads atop standard rocket launch vehicles. To counter the effects of this energy for the shuttle program, a sound suppression system was used consisting of water in different forms.
At the base of the launch vehicle's solid rockets, high pressure and high volume water sprays in excess of 300,000 gallons per minute. The high pressure spray is complimented by large red nylon bags filled with water. VTI manufactures these bags. The system of water spray and sound suppressing bags act as hydraulic baffles reducing acoustical levels within the orbiter payload bay to about 142 decibels, below the design requirement of 145 decibels. The billowing white clouds you were used to seeing during the shuttle launches is actually not smoke, but steam from the water boiling off the launch pad.