Why Bigger Rooms Sound BetterDec 25, 2023
We often here that big rooms sound better, but why is that. Why can't we get a small bedroom to sound awesome. I mean, we see home studios that look awesome online all the time, so why do they have to be big to sound good?
This article will answer that question with the physics behind acoustics of small and large rooms and how this knowledge can help us understand and design our own studio builds.
1) A Quick Review Of Room Modes
Room modes require their own article, which I wrote here: Why Room Ratios Don't Work...Most of the time. But this article will focus on one aspect of room modes and room acoustics which is room volume. So, to quickly summarize, room modes are certain lower frequencies that create either peaks or nulls in your room. This means that when you walk around your room and play, say a 60hz tone, you will hear places in your room where the tone sounds louder, softer and miraculously even some places where you can't hear it all. I know freaky, but cool!
2) So what does this mean for small rooms?
This is a problem for your listening environment and your recording environment too. We want to sit where the space in the room is as flat as possible. To get a "good room" we can start with a room that has even spacing of room modes in the lower frequencies below 300 Hz. Notice I said even spacing. It turns out having more room modes more evenly spaced sounds better. Weird, I thought we didn't want room modes is what you are probably thinking. Nope, we do want them and we want them evenly spaced so that none of them really poke out and cause big dips or nulls when we walk around our room.
Here is a quote from the Master Handbook of Acoustics: " The short dimensions of a small room almost guarantee acoustical anomalies resulting from excessive spacing of room resonant frequencies." (Everest and Pohlmann, 436) Whoa, a lot to unpack there.
This means the smaller the room the more likely you will have uneven, blurry, muddy sound in the low end due to too much space between your room modes, aka "resonant frequencies."
3) What is so great about large rooms?
Here is another quote from the Master Handbook of Acoustics: "...large rooms have the inherent advantage of relatively more modes in the low-frequency region, and hence smoother low-frequency response"(Everest and Pohlmann, 436). The key word in this quote is smoother. The more modes means that the low frequency spectrum doesn't have big modal peaks followed by vast modal valleys where there aren't room modes. Remember, we want more room modes evenly spaced in the low-frequencies, 300 Hz and below.
Now let's visually look at this using the AMROC calculator. I am going to input three dimensions using the Sepmeyer room ratio. This ratio of 1: 1.28 : 1.54 will get us the best room sound given our different sizes. However, even with an acousticians room ratios we will quickly see the limitations of our smaller room.
First, here is the axial modes of a small studio with dimensions: 8ft ceiling, 10.24ft width and a 12.32ft length (2.44 m x 3.12m x 3.76m). The volume is 1,000 cubic feet.
Second, here is a mid sized studio: 12 ft ceiling height, 15.36 width, and 18.48ft length (3.66m x 4.68m x 5.63m) Volume = 3,400 cubic feet.
Third, let's look at a large studio: 16ft ceiling height, 20.48ft width, 24.64ft length (4.88m x 6.24m x 7.51m) Volume = 8,000 cubic feet.
Okay, so what does all of this mean? Each of those red blocks is an axial room mode. Axial modes are the most powerful and problematic types of modes so I am showing those. To compare, let's look at 100 Hz and below.
Small Room = 4 axial modes
Medium Room = 7 axial modes
Large Room = 9 axial modes
Remember, we want more modes in the low-frequency range to smooth out the room's response. Also, notice that the larger rooms go lower down in the frequency spectrum. This is also good because we want that "smooth" response as low as possible. Ideally to the threshold of hearing at 20 Hz.
Now you know why bigger rooms sound better. The larger the room the more room modes you get in the low-frequency spectrum leading to a smoother more even response in the room, which translates to a cleaner more accurate low end. The high end of a room is easy to fix with basic acoustic treatment. The low end is very difficult to fix. In fact, the Master Handbook of acoustics says that "...anomalies encountered in studios having volumes less than 1,500 cubic feet are sometimes severe enough to make small studio rooms impractical" (Everest and Pohlmann, 436).
Uggh! That totally bums us out right? What about your dreams of the bedroom studio or the small room in your basement. Great music is made everywhere, but know that for an accurate low end you will be always fighting an uphill battle in a small studio room. If you have the luxury of choosing a bigger and really higher ceilings then you should choose that room over the smaller room. This article was meant to give you some more tools in your arsenal of studio design, but not to discourage you altogether. I created amazing music in a very small room for many years and it did not stop me. Now, I create music in a bigger room and it has only made me better. You too can shoot for bigger and better rooms over time.
Everest, Frederick A., and Ken C. Pohlmann. “Modal Resonances.” Master Handbook of Acoustics, McGraw-Hill, New York, 2015.
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