Matthew J Poes
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- Oct 18, 2017
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I was trying to get some measurements that showed certain behaviors and my theater measured too well to use as an example. I decided to take some measurements of my living room setup which is just a basic older Pioneer receiver and mid-nineties Bose Acoustimas system. I already posted the speaker measurements, but the room acoustics differences were what surprised me most. I suppose it shouldn't have, the living room does measure normally, but part of me was really worried I would take these measurements and the living room would look great too.
There are a number of ways to assess a room's acoustics, so certainly this is just a basic snapshot of some of its properties. For a theater or listening room, the RT60 should really be flat more than anything, and below .5. A theater is preferably between .2 and .4, and a listening room can be anywhere from .2 to maybe as much as .5 and still be listenable.
Let me tell you how the living room sounds before I share anything with measurements. The livingroom is acoustically fine. It doesn't have terrible echo, no obvious flutter echo or slap echo problems. The room is pleasant to be in. It's a normal living room with wall to wall carpet and a modest pad. The wall behind the couch is a large window roughly 10'x6'. The window has light weight curtains which would provide a modest amount of absorption at mid and high frequencies. The couch is a synthetic leather (I think they call it vegan leather these days), otherwise there are no real acoustic treatments. A few paintings on the walls. Normal wall construction with 1/2" extra light weight drywall on 16" spaced study. The theater couldn't be more opposite. CLD walls with two layers of 5/8" high density drywall, acoustic panels everywhere, no windows, etc.
Here is the RT60 and Comparison:
RT60 Comparison. Theater is flat around 200ms, the Living room is not flat, ranging from 300ms at lower frequencies and midrange and 500ms at higher frequencies.
Measures of clarity aren't often used to assess a theater, but I think they have meaning. There are no standards for theater, basically higher the better, but what numbers sound good is unknown, and certainly at some point it could be too high. It is highly related to RT60, its a ratio of direct and later energy, so high Decay increases these values. I'd love to try and study this and find a way to correlate different clarity values with perceived clarity in the voices and music. None the less, here is a graph from each, you can see the theater is higher, as expected with the higher decay.
Living Room
Theater
You will see that the clarity values are clearly lower across the board for the livingroom, but its flatter to lower frequencies. That is because walls are great absorbers of bass, but not when they are thick and stiff, as in the theater. The CLD walls damp well, but it seems to only work at very low frequencies. In that 70hz to 150hz, its mostly reflective (but a normal wall would actually be somewhat absorptive).
And now for something to help see that, lets look at the Waterfalls:
Living Room: As you can see it doesn't look too bad. The response isn't as flat nor as extended. There isn't really much ringing from any modes, just one at 43hz. I haven't bothered to measure the room to see if that aligns with a mode, and oddly, the same kind of mode shows up in the theater. Since the house has a lot of rooms with common dimensions, it is possible that they have a common dimension that causes this.
Here is the theater, no EQ or Dirac is being used in this waterfall. As you can see, there are two modes. One is at 43hz and one is at 22hz. I do know that in this case those do happen to align with room modes. The 22hz mode doesn't respond to eq all that well and is a length mode in the room.
Overall I saw what I expected (mostly) but it isn't what I was hoping for
. The living room has better LF decay for not having any treatments, and given its construction, that makes sense. The treated theater has better decay overall with much smoother and flatter decay. It's better overall and does highlight the benefit of planned treatment. Especially in RT60 and Clarity.
I was hoping to see big ugly ringing, but alas, that wasn't to be.
There are a number of ways to assess a room's acoustics, so certainly this is just a basic snapshot of some of its properties. For a theater or listening room, the RT60 should really be flat more than anything, and below .5. A theater is preferably between .2 and .4, and a listening room can be anywhere from .2 to maybe as much as .5 and still be listenable.
Let me tell you how the living room sounds before I share anything with measurements. The livingroom is acoustically fine. It doesn't have terrible echo, no obvious flutter echo or slap echo problems. The room is pleasant to be in. It's a normal living room with wall to wall carpet and a modest pad. The wall behind the couch is a large window roughly 10'x6'. The window has light weight curtains which would provide a modest amount of absorption at mid and high frequencies. The couch is a synthetic leather (I think they call it vegan leather these days), otherwise there are no real acoustic treatments. A few paintings on the walls. Normal wall construction with 1/2" extra light weight drywall on 16" spaced study. The theater couldn't be more opposite. CLD walls with two layers of 5/8" high density drywall, acoustic panels everywhere, no windows, etc.
Here is the RT60 and Comparison:
RT60 Comparison. Theater is flat around 200ms, the Living room is not flat, ranging from 300ms at lower frequencies and midrange and 500ms at higher frequencies.
Measures of clarity aren't often used to assess a theater, but I think they have meaning. There are no standards for theater, basically higher the better, but what numbers sound good is unknown, and certainly at some point it could be too high. It is highly related to RT60, its a ratio of direct and later energy, so high Decay increases these values. I'd love to try and study this and find a way to correlate different clarity values with perceived clarity in the voices and music. None the less, here is a graph from each, you can see the theater is higher, as expected with the higher decay.
Living Room
Theater
You will see that the clarity values are clearly lower across the board for the livingroom, but its flatter to lower frequencies. That is because walls are great absorbers of bass, but not when they are thick and stiff, as in the theater. The CLD walls damp well, but it seems to only work at very low frequencies. In that 70hz to 150hz, its mostly reflective (but a normal wall would actually be somewhat absorptive).
And now for something to help see that, lets look at the Waterfalls:
Living Room: As you can see it doesn't look too bad. The response isn't as flat nor as extended. There isn't really much ringing from any modes, just one at 43hz. I haven't bothered to measure the room to see if that aligns with a mode, and oddly, the same kind of mode shows up in the theater. Since the house has a lot of rooms with common dimensions, it is possible that they have a common dimension that causes this.
Here is the theater, no EQ or Dirac is being used in this waterfall. As you can see, there are two modes. One is at 43hz and one is at 22hz. I do know that in this case those do happen to align with room modes. The 22hz mode doesn't respond to eq all that well and is a length mode in the room.
Overall I saw what I expected (mostly) but it isn't what I was hoping for
. The living room has better LF decay for not having any treatments, and given its construction, that makes sense. The treated theater has better decay overall with much smoother and flatter decay. It's better overall and does highlight the benefit of planned treatment. Especially in RT60 and Clarity.I was hoping to see big ugly ringing, but alas, that wasn't to be.
