Four Tools of Acoustical Design - Part 3: Barrier
In our last two articles (November 2018 and January 2019), we looked at absorption and diffusion. These acoustical tools work on the sonic environment within a room; we use them to make a room acoustically accurate and the listening experience pleasant. The next tool we’ll look at has less to do with what we hear, and more to do with what other people hear.
This tool is used to isolate a room, keeping inside sound in, and outside sound out. I call it barrier, and its job is to minimize sound transmission through it. Unlike the first two tools, this one keeps outside sound from contaminating your recordings or disturbing you, and your sound from disturbing other people.
This is traditionally referred to as soundproofing, which is really a misnomer. It’s important to understand that in terms of completely blocking sound, there is no such thing as soundproofing. Trying to block sound is like a leaky faucet—you can tighten the spigot, but it ends up taking more and more effort to get less and less effect. You can reduce it to where you may not be able to hear it, but there’s still some there. Depending upon what you do in the room, this may or may not be important.
Many times I’ve also heard sound-proofing used to refer to anything that has to do with acoustical treatment—this is even more inaccurate and imprecise. Gluing a bunch of absorption on the wall will not keep sound from intruding into (or from) the next room!