So, what are the requirements for soundproofing?
The term ‘soundproofing’ is rather misleading, because in most real-world situations, you can cut down on leakage but you can’t get rid of it altogether. Sound isolation is a more accurate term. The simplest way to attenuate sound is to put a solid wall in its way — the more solid, the better the isolation you’ll get. As a rule, if you double the mass of a wall, you halve the amount of sound transmitted through it. Unfortunately, sound isolation tends to fall with frequency, so even though you may be able to get the mids and highs under control, the chances are that you’ll still be able to hear the bass drum and bass guitar thumping away from outside. That’s why when you walk past a club, all you can hear from outside is bass. To give you some examples of what to expect, a single brick wall might have a quoted Sound Reduction Index (SRI) of 45dB (this is averaged over a range of frequencies, so the bass-end isolation will be rather worse than this figure) while a domestic panel door m
