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WallDamp Walls in Action

Published On: June 12, 2020Tags:

Don’t Let Your Walls Turn Into Uninvited Drummers

We all know listening to and mixing music can be fun, and can even be enjoyed with multiple people. But even John Bonham was not invited to every party. This week’s quick lesson will show you how to make sure you only hear the drumming you want to.

Sound Pressure is Relatively Low

Many of you are familiar with the idea of “100 dB,” but you may not know the physics involved. SPL (sound pressure level) as we use it is a decibel (dB) scale relative to a baseline value of 20 micropascals. That is a ridiculously tiny amount of pressure. For comparison, 94 dB SPL represents 1 Pascal of pressure, which is 1 Newton per square meter. For those of you not intimately familiar with the metric system, this is the weight of about one average apple spread out over a square yard. Again, very small!

Very Loud Sounds

So when does sound pressure reach a meaningful level? How about 120 dB, the threshold of pain? Well, now we are up to 20 apples spread out over a square yard. A healthy middle schooler could carry that bucket. We all know the risk of working around jet engines that generate in excess of 140 dB. Now we are up to 200 Pascals which is equivalent to a mere half ounce per square inch…and our hearing is wrecked!

Why Does This Matter?

If these sound pressures are so small, then why are we worried about the walls being shaken? Well, the high amplitude subwoofer waves literally shake the structure of the room. And the physics works both ways: a wall that generates 20 Pascals of pressure because it is shaking is generating, you guessed it: 120 dB SPL. We definitely do not want 2,3,or 6 extra sound sources in our audio room generating 120 dB after a big bass note!

Un-damped Wall

(play through real speakers for best results)

Notice the sloppy, booming sound that seems to add tone as it develops? That will smear your bass and destroy accuracy.

Damped Wall

(play through real speakers for best results)

Notice the tight, snappy, resonance-free sound? That is the way all your walls should sound.

Keep those uninvited drummers at bay!

A Fist Thump

The preceding audio files demonstrated the audible result of thumping the butt of a fist against the wall. Recalling the lesson above, you will realize this is a much higher physical pressure than any music you play will exert on the face of your wall. But do not underestimate the resonance effects of 20 Hz bass notes on your building’s structure. Those vibrations will travel through the framing members and surfaces.

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