How Does Sound-Damping Tape Work?

Here is more information on 3M Vibration Damping Tape 434. There is a technical data sheet [PDF] on the page, but the way they link to it causes most browsers to download the file with the stupid name “multimedia.pdf” rather than display it within the browser.

I used to work with a guy in the 1970s who later moved on to a company packaging minicomputer systems for office environments. One challenge was racket that contemporary line printers made, which made them unwelcome in the cubicle farm. They discovered the main problem was not the printer mechanism itself, but rather the steel panels of the cabinet acting as a sounding board/drum head which was efficiently coupling the sound to the air and transmitting it everywhere. They discovered that bonding thin lead sheets to the inside of the cabinet panels with silicone RTV caulk caused the sound to be damped the instant the panel was excited by air vibration, and worked dramatically better than the sound-absorbing foam often used to deal with the problem. Heaven knows how much trouble that would get you into today in Safetyland, but the “leaded” line printer, running flat out at 300 lines per minute, only made about as much noise as an IBM Selectric typewriter.