The Four Building Blocks of Acoustics

Over time I have found that there is a general lack of understanding of acoustics. Even among some sound professionals, it is viewed as a sort of black art. Those who understand it might be viewed as people who have sold their afterlife to some malevolent deity in return for understanding The Secrets.

Tain’t so.

So what I want to do is provide articles that demystify acoustics, dispel myths, and even provide tips and things that you can use to improve the sound in the rooms where you work, record and listen to music, and watch movies. Don’t worry about the math – there won’t be any unless you really want it. But you’ll have to ask.

The Four Building Blocks of Acoustics –
In acoustics, there are four primary elements used to control what happens sonically in a room. They are absorption, diffusion, barrier, and vibration isolation.

Absorption is the best known and the most misused, usually by going to the local home center and buying a bunch of fluffy fiberglass to “soundproof” a room. Technically, there is no such thing as “soundproofing”, and the fluffy stuff wouldn’t do it even if there were.

Diffusion takes what are called specular or hard reflections (“angle of incidence equals angle of reflection”), and spreads the sonic energy in different directions.

Barrier is used to contain sound and prevent it from intruding into other spaces. This is the element that allows multiple adjacent rooms to exhibit movies at a multiplex, assuming the builders used it.

The last element is vibration isolation. This keeps sonic energy, particularly powerful low frequency sound, from getting into a building’s structure and using that as a path to intrude into other rooms where the sound may not be welcome.

Once you understand these elements, what they are and how to use them, you’ll have the knowledge to make your edit room, studio, or home theater a really nice listening space. So watch for the next blog, where I’ll discuss the first element, Absorption.