It read 111 decibles in the room.
With live acoustic drums plus the speakers, if you only got 111 dB I suspect that you measured on "A" weighting. You should measure on "C" weighting for loud sounds. "A" is for quiet sounds. A typical drummer can put out 115 dBC all by himself without breaking a sweat, and closer to 120 if he tries hard. Add in the speakers with the backing track, and I'd say that you were close to 120 dBC in there. Next time you measure, do make sure that your meter is set to "C" and "Slow". Also, check that it is calibrated, if you have access to a calibrator.
But anyway... "
Upstairs in my house the loudest reading I got was 82 decibels". So you got about 29 dB of isolation. That's very typical of ordinary house walls and ceilings, so not surprising.
So you have answered one of the two key questions here: "How loud are you?". The other question that you still need to put a number to is "How quiet do you need to be?" You can estimate that using your meter, by measuring the ambient levels in the target location you mentioned, late at night when it is very quiet, and there's no noise going on anywhere. Measure in the same places as you did here, to get that lowest level, then subtract that from the higher levels, and the difference is how much isolation you need.
The rest of the inside was around 50-56.
Still pretty high. Very audible, and probably annoying. Most people judge that something like 35 dBC is acceptably inaudible, or maybe 40 or even 45 dB if the ambient level is a bit higher. So your levels are 15 to 20 dB higher, which makes them "not very quiet".
Outside of my neighbors house 130 ft across the street was 75 on their front steps
Also pretty loud! Drums at 75 dB would not be something I'd want to hear from my neighbors, and I'd be very tempted to have a chat with the cops about that, if it happened regularly!
My goal is to get it down to where they can't hear anything inside their house and hopefully not much inside mine.
So very roughly, you would need an additional 40 dB of isolation, above and beyond what you already have, to achieve that goal. You already have 20-something, so we are looking at a total upwards of 65 dB isolation. That's do-able, but not easy, and not cheap. The practical limit for home studios is around 70 dB: getting more than that is VERY hard to do. Most home studios get around 50 dB isolation, maybe 60. That would be realistic.
You didn't mention budget, but that's an important issue. The higher you go in isolation numbers, the higher and HIGHER you go in cost. Exponentially. The reason is not hard to understand: The decibel scale is already logarithmic: each time you go up ten points on the scale you are MULTIPLYING the energy levels by ten. To put that in perspective, to get from 30 dB of isolation to 40 dB, you need to block ten times more energy. To get from 30 dB to 50 dB, that's two "steps of ten", so you need to block 10 x 10 = one hundred times more. To get from 30 dB to 60 dB, you need to block 10x10x10 = one thousand times more energy. And from 30 to 70 dB you would need to block ten thousand times more energy. That's scary, when you look at it from pure math numbers. And it pans out in real life, not just on paper. Fortunately, there are some things you can do to increase isolation without going to extreme expense, but for high levels, it gets expensive.
Not trying to scare you! Just pointing out reality.
I have 11 rolls of mass loaded vinyl that was given to me that I could incorporate into this if it makes since.
If you have it, then you might as well use it. Especially if you got it for free. But it's not something that studio designers and acousticians normally recommend for home studios. It works, yes, because it has mass, and mass is what stops sound. But MLV is very expensive mass, and sound waves really don't care what the price tag was for the mass. They just react to the mass, not the price. So it makes sense to get the least expensive mass that will do the job, and usually that is plain old 5/8" drywall. Now, 11 rolls won't go very far, so I would save that for the toughest spots, and just use ordinary dyrwall, MDF, OSB, plywood, and similar products for most of your mass.
Also I was planning on using 2 mini-split system for the HVAC, do you see a downside to that instead of duct system?
You still need ducts! You need to get fresh air into the room and remove the stale air, so you have to have ducts and silencers and fans. That's a given for studios. So there's not a lot of difference between using a ducted mini-split or a non-ducted mini-split. The only thing that changes, is where you mount it. T There are pros and cons both ways, but for the majority of studios that I design, I put a ducted mini-split outside the isolated area of the studio, and that feeds into a duct system, into the rooms. I do this to keep all the noise outside, and also for other reasons, such as simple access for cleaning, maintenance, repairs, replacement. But sometimes I do non-ducted or "ductless" mini-splits inside the room, when there's no other easy options. Both can work.
- Stuart -