Building a Recording Studio — Part 6
Back in part 3 of this series, I performed 3 tests to get a baseline on how much sound escaped the garage before we did any sound proofing. Since then, I’ve done two updated versions of the tests as the studio has progressed and the results are impressive! Let’s take a look at the results.
I performed 3 tests, the Ambient Sound Test, Pink Noise Test and Tom Sawyer Test. In all cases, I took measurements from several spots
- 3 feet in front of the speakers
- At the back of the room in what will be the storage area
- Just outside of the studio behind the speakers
- Just outside of the studio about 1/2 way along the long wall
- Just outside of the studio door opposite the speakers
Test 1: Baseline Test
In the baseline test, there was framing, but nothing else so sound could easily escape the room. Also, there was a window right behind the speakers and we had that removed since more drywall will always be better than some glass
Test 2: Outer layers of drywall
For the second test, we had the first two layers of drywall on the outside walls but nothing on the interior walls. The windows had been filled in and the top ceiling was in place, but there was no insulation yet.
Test 3: Insulated walls and ceilings, no doors
The third test took place when all of the drywall and insulation were complete but not yet taped and there were no doors in yet. Some of the tests, as you will see, are pretty complete and had great results but the lack of doors gives an opportunity for a lot of sound to escape.
Test 4: Everything except door handles
For the most recent test, it is starting to look like a real room. We have doors, some lights and the corner bass traps are being built. The only real gap is that most of the doors have a big hole in them where the handles or deadbolts go since I don’t want to install those until they’re painted but otherwise the room is sealed. If you turn off those lights, it gets DARK.
OK, so here are the results of the pink noise test in all four of those tests at each of those 5 locations.
The outcome is excellent. As you’d expect, just having the outer layer of drywall helped only on the outside where there was no other gap openings but the sound was still very clear. Adding the insulation and the second layer of walls made a huge difference and sound was pretty much undetectable on the side of the studio. Adding the double doors, though, really seals the deal. With the noise cranked even higher than before inside (let’s dime those little monitors!) we tried hard to hear anything outside and we could not hear any hint of the maelstrom happening inside except for when we were near the open holes in the doors. Since some of the doors don’t have latches yet, their seals don’t close completely so we should get even better results as soon as they’re all fully closable.
When I was testing with the sound meter at the Outside Front position where there are 2 doors, each with a hole from a lock-to-be, the sound level about a foot to the right of the hole was the measured 47.1db but if you stuck the mic right in the hole, it would jump to just over 70db. You could also really feel the sound coming through that hole. Adding some pretty massive locks and levers should block that noise completely.
The Tom Sawyer test sees similar results. The main point of that test is to looks for signs of thumping bass or any sense of music playing. In the latest test, except for right outside of the front next to the doors with knobs on them, you can’t hear anything but the chirping of the birds.
Finally, a note on the limitations of my sound level meter. The lowest level I’ve been able to record on it is 36.7 and that’s inside the studio with nothing on. The levels I’m getting outside in the rear and side of the studio at this point are completely unrelated to the sound in the studio, they are the ambient sound of the breeze and the birds in the neighborhood.
One more test to go
I’ll do the test one more time, once everything is finished and the acoustic treatments I wrote about in part 5 are installed. That part is running a bit behind schedule since the folks at GIK Acoustics are swamped with orders (I guess everyone is building a studio now?). I don’t expect the numbers to change a lot since we’re pretty much at the limit of my testing device, except that I have ordered some new studio monitors which are much larger than the ones I’ve been using for these tests. The tests have been on a pair of M-Audio BX5a Deluxe monitors but my new speakers will be a pair of Focal Trio6 Be monitors which are significantly more powerful and have more bass so the final test will be important to see if we still need to drop the volume when we drop the bass.