If there’s an award for feeling like a failure and an idiot all at the same time, I’d like to toss my hat in the ring for the nomination.
I recently attended a workshop on acoustics as it relates to office construction. I arrived early and introduced myself to the presenter, thinking that might be a great opportunity to get the inside scoop on how to solve the acoustical puzzle office environments present.
So I dove in and started talking, but when I heard the words coming out of my mouth I realized all those voices in my head were trying to speak at once. The presenter looked me straight in the eye and in a flat-footed voice said, “Give everyone a set of earplugs.” I slithered off to a seat in the back row as far from the podium — and everyone else — as I could.
After an hour of technical jargon vis-a-vis different materials, methods of construction, STC’s, NRC’s and CAC’s, each of us was handed a clipboard. Attached to it was a sheet with several technical questions relating to acoustical treatments. We were then invited to visit four sound labs and rate them.
I stared at the questions. Is this a trick? I wondered. How am I supposed to know whether there’s insulation in the walls, perimeter enhancements around the electrical boxes, or whether the ceiling tiles are acoustical?
I vowed to do my finest acoustical Sherlock -ing and went about ticking off the Yes/No boxes as best I could.
And you know what? I failed miserably.
Which wasn’t so bad, really. It got me thinking about the chasm between the physics of acoustics and how we as human beings experience acoustics.
What follows is my visceral experience of those four sound labs.
Sound Lab #1
Echo, echo, echo …
The visual equivalent of the acoustics in this room would be mirrors on all four walls so that no matter what direction you looked in you’d see your own image replicated forever and ever and ever. Technically speaking, this room could have done with a higher NRC (Noise Reduction Coefficient), but I had no way of determining its STC (Sound Transmission Class) or CAC (Ceiling Attenuation Class). Both of those have to do with how much outside noise is getting into the room, and how much of the noise I’m making is getting out. I had no way of experiencing the latter because the echo from my own voice was driving me nuts. I can’t stay here any longer, I decided.
Sound Lab #2
Can anybody hear me? This room felt like what I imagine it would feel like to be buried alive. Let’s call it “acoustical claustrophobia.” The room suffered from too high an NRC rating, which on the surface might sound like a good idea but it created a mind-numbing experience. Ever talked to someone when you’re wearing headphones or earplugs? You can hear them and you know your lips are moving but you can’t hear yourself? This experience was like that — isolating.
Sound Lab #3
The walls held up the ceiling but that was about it — they hardly kept outside sound from coming in and I expect the walls were equally bad at keeping sounds created by me from leaking out. Light seeped in around the door and the ceiling tiles were poorly fitted. Think cheap hotels, where the walls only serve to keep you from seeing what you’re hearing from your neighbors in the next room.
Sound Lab #4
This was the most acoustically comfortable one of the lot. The word I’d use is private. I could hear myself speak and, while external voices could be heard, they were not comprehensible. My guess was that this room struck the right balance between NRC, STC and CAC ratings.
So much for my gut experience. I still got several answers wrong.
So here’s my takeaway on NRC’s, STC’s, CAC’s & YOU
- There aren’t any hard and fast rules about combining these acoustical values. The acoustical quality of a space cannot be predetermined by considering these ratings alone.
- The internal and external environments have to be considered holistically. For example, what is the frequency of the sound you’re trying to keep in, or out? If the guy next door likes to play the ukulele while tiptoeing through the tulips, you’ve got bigger problems.
Finally, do what you need to do to make the environment work for you. As the sage presenter suggested, should all else fail, shove in the old earplugs and get back to work.