I’ve encountered a question in my study materials (Ballast 5.0 Practice Exam) that asks about the noise reduction in a room (a) that is separated from another room (B) by a sound partition. There is a noise producing source in room B.
The answer explanation states that “The thickness of a partition or other acoustical separation is irrelevant to the total noise reduction within a space.”
My question is, how is it possible that the thickness of a partition has nothing to do with noise reduction in adjacent space
@coachmarissayee @coachmikeparaszczak
Hi!
It sounds like the question is really about the difference between noise reduction (NRC) and sound transmission (STC).
- NRC measures how well surfaces inside a room absorb sound (reducing echo and reverberation). Think of acoustic treatments in a recording studio - these are porous, absorptive materials applied to the surfaces.
- STC, on the other hand, measures how well sound is blocked from traveling between rooms, which is where mass, air gaps, and thickness of assemblies come into play.
Since the question specifically asks about noise reduction, it’s focused on internal room acoustics, where adding wall thickness doesn’t help much. That kind of change would affect STC, not NRC.
On a real project, you’d likely consider both. But for the AREs, understanding what the question is really asking makes a big difference in getting to the right answer.
Hope that helps!
Thanks,
Mike
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Thank you for the explanation. NRC being focused on sound within a room vs. STC dealing with sound between rooms is a really helpful distinction to be mindful of.
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