Acoustic Panel Room Treatments : Built-in vs surface mount question

Hi Kirk,

Great question!
The one obvious consideration is flexibility of placement.  Due to room asymmetry (sometimes due to geometry, and/or construction materials used), it’s impossible to know exactly in advance where every treatment will go and how much is needed with certainty.  It comes down to a risk avoidance strategy.  What’s the cost of getting it wrong?  For example:

• SPEAKER TYPE - Front wall (behind the speakers) treatments are speaker-type dependent.  Personally, I have found that far fewer treatments are needed when using bi/dipole speakers than conventional box-type (ported or not).
• STRONG REFLECTIONS - Sidewall’s two 1^st order reflection points per wall can be treated or not and the treatment is usually a personal preference.  Want better imaging then use thick absorption, want a wider soundstage then don’t attenuate as much of the sidewall reflections via diffusion or reflection.  And to ensure a balanced timbre from the reflection (i.e. the reflection’s energy from an octave centered at 500Hz is within 4dB of an octave centered at 2kHz), a combination of products can be used at the 1^st reflection point with a diffuser placed in front of a thick absorber panel.
• DECAY TIMES – adding or removing absorption will impact your T30 decay times.  Do you have access to modeling tools to know in advance how much of it is needed, and if not then adding a few pieces at a time is less risky.

My advice is to build-in thick absorption at the 4 room corners and soffit areas of ceiling/walls that you know are needed in pretty much all scenarios, then use hung-on-the-walls pieces to treat the rest of the room.  And when doing this set up a temporary scaffold using long 10-12” wide boards supported by concrete building cinder blocks so that it’s about 2 feet above the floor to allow treatments to be moved laterally, pushed closer or pulled farther from the wall, and angled.  Even using REW you won’t get it optimized the first time so you’ll spend a good amount of time trying out different treatment combinations that measure well AND sound good to you.  If you need assistance deciphering early reflections, frequency response and decay time measurements, then I have a small business that can help you remotely.  Sounds like an awesome opportunity!

From what I've been told, acoustics depend on the frequencies you are trying to target. You can use various materials to break-up and skatter the sound like a wall of stacked firewood or rustic timbers. I did both for esthetics and acoustics. As far as ceiling panels goes,  flat will reflect and certain materials will absorb.  In my case I'll be getting  34"x34"x6" high hollow box clouds made from 1/2" thick felt and stuffing them with 6" Rockwool Safe and Sound acoustic insulation.  They will be suspended with a 4" gap and this gap + the height of the box creates 10" of absorption.  It sounds strange but apparently the distance of the underside of a panel that's suspended from the ceiling changes how the cloud behaves. And for me this 4" gap helps target some of the upper bass/lower mid frequencies and not just the high frequencies. They won't target deeper bass. 

I don't have room for acoustic wall treatments so I'm depending on these box clouds and an artistic 3D wood panel on the front wall to help improve conditions. It's far from perfect but it's something.  

I rendered these box clouds and that 3D wooden art panel into my existing room. Room esthetics is very important to me so I'm treating the room with this in mind. 

@kevinzoe thank you; that’s highly responsive to my question and raises a point i had not considered, which is the lack of flexibility for future adjustments that is inherent in built-in absorption.  Obviously, one would do a lot of professionally guided measuring and modeling before installation, but what happens if one changes speaker make or location (or maybe even furniture layout) later?  

All really useful stuff.  We’re no where close to embarking on another renovation, but I can see, when we are, there will be a lot of questions for a professional consultant and installer to think about and we will need to leave time for some trial and error before doing anything quasi-permanent.  

Given the room limitations in the next room on the renovation list (e.g. floor to ceiling windows on the east and south side and no wall at all on the west side), we may just have to live with some ceiling mounted treatments and work on finding the balance between maximum performance and minimum aesthetic harm.

@kirkwallace 

I had exactly the panels you described in my Family Room, until my unusually clumsy Sister-In-Law, destroyed three out of four.  I have since replaced all four panels with a 2” thick insulation foam (MUCH CHEAPER!) There is a small, but noticeable difference in the sound, but it gives my S-I-L more room to wobble through the room.  I also have a fully carpeted, padded floor, some cheap 2’x4’ foam panels that I’m playing with.  I have them on 7’ tall frames so I can move them around to see if I might want more absorption behind me. About half of my current room is open to other rooms, so there’s not much more I can really do for now.

My wife has been talking about moving, so doing much more would be a waste of time and money.

Only if she plans to let you come with her, @curiousjim 😂