STCs

Understanding sound from outside the rabbit hole.

(Or, procrastinating while trying to build a booth)

STC  is the US measurement of sound transmission. Basically, it offers a reading of sound on one side of wall, compared to sound on the other (the source of the sound.) The higher the reading, the better the problem has been dealt with. But…

The PROBLEM with a basic reading is that it is not attentive to the range of frequencies that penetrate the wall. 

Most often the lower frequencies do the most damage – invading your recording space with rumbles form trucks on the road outside, planes and domestic appliances. (Equally, your guitar, bass and drums could penetrate the wall from the studio side to annoy people at home inside the house).

So, STC is problematic because it doesn’t offer an honest reading from below the 125Hz range – that low end.

Soundproofing company.com suggests that you CAN look around for materials that won’t cost as much as the branded “Mass-loaded vinyl, resilient channel, “soundproof drywall,” “sound board,” “soundproof insulation type products.  Instead, they say, stick to the inexpensive basics:

  • Essential Decoupling
  • Mass added from inexpensive 5/8” drywall
  • A competent Damping Compound

If you need to see what they mean by this, have a look at their illustrations here. They have a range of walls that measure 52 STC, 67 STC and 73STC.

Water-filled booths won’t be the answer: apparently, sound travels through water five times faster than it does through air!

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