Room Treatment

 To me, an acoustic panel can diffuse, absorb or reflect.  It's a generic term for any treatment.  Of course I could be wrong....

+1 winoguy -- "acoustic panel" is not specific about whether it diffuses or absorbs.

IME, Acoustic panels are primarily designed to absorb sound waves to reduce room echoes and reverberation, while acoustic diffusers scatter sound waves to create a more balanced and natural-sounding acoustic environment. Check out some of the very best rooms in Audiogon Virtual systems to have better understanding and placement of these two very critical but different acoustic treatments. 

@lalitk It's hard to get clear on this for a lot of folks. If you go to Acoustimac's website, it aligns "acoustic panel" with absorption. If you go to GIK, the first things displayed are diffusers but they also have absorption on the page.

Viz. https://www.gikacoustics.com/product-category/acoustic-panels/

I see GIK and other sites like it have panels for absorption, and Decware has diffusers which look like window slats or turning vanes, and they recommend one for each wall. I was looking to see if anyone has experience with both, and what application works best for a standard 15x15 listening room with gypsum wallboard walls.

A "panel" is a generic term. 

Panels can be absorbers, diffusors or a combination.  There are also bass traps which are a type of absorber that is especially effective in the bass region. 

GIK makes some panels which are a combination with absorption materials behind a diffusion grid.  This allows for high frequency diffusion along wiht mid range absorption.

“what application works best for a standard 15x15 listening room with gypsum wallboard walls.”

I recommend you seek consultation from GIK, they provide free consultation. Whatever they recommend, I suggest you treat each area in steps. This will allow you to understand the impact of acoustic panels/diffusors and further evaluate the need to treat your room. It’s easy to overdo absorption and kill the liveliness of a space, especially in a smaller room; hence my recommendation for doing it in steps. Not knowing your room, we are just shooting in dark here. Let’s say you have a conventional room with four walls + ceiling which gives you five areas to address,

Front, Back, Sides, Ceiling and Corners.

Starting with the first reflection points (side walls and ceiling) usually gives the biggest improvement in clarity, while bass traps in corners help smooth out low-frequency response. The back wall can be tricky—some rooms benefit from absorption, while others need diffusion to maintain spaciousness.

Hope this helps!

https://www.amazon.com/Master-Handbook-Acoustics-Seventh-Everest/dp/1260473597

Acoustic panels absorb while diffusers reflect signal (scatter)

Acoustic panels absorb sound waves to reduce echo and reverberation, making a room quieter and more controlled. They’re usually made of foam or fabric-covered insulation and placed on walls or ceilings.

Diffusers, on the other hand, scatter sound waves to create a more natural and balanced sound without making the space feel "dead." They’re typically made of wood or plastic with uneven surfaces.

If you want a controlled sound, go with panels; if you want to keep the room lively while preventing echoes, use diffusers, or better yet, a mix of both.

A lot of good info already provided. The part mentioned about over doing it with absorbers is of the most importance as it happened to me. Bottom line, a combo of bass traps, absorbers, absorbers/diffusers and diffusers in the right combination will get you the optimum results. What that combination is will be specific to your room. It's basically like equipment, cables, fuses, etc... There is not one for all fit. The best I can help anyone with is to take a look at my house of stereo acoustic setup under my details, system. 

I worked for a company that did commercial acoustical treatment. Panels are sound absorption material that mount against a wall (i.e. one surface covered). Baffles are suspended and all sides ave active in sound absorption. Diffuser are to spread in the listening environment.

@lalitk 

I have every square inch of my walls covered with 5” of rock wool, and every square inch of my ceiling covered with 14” of rock wool. The floors mostly covered either Moroccan cotton rugs  

I have a very dead, semi-anechoic room. It works perfectly. You can hear the difference when you walk in, before any music is played. 

So I am wondering what you mean by overdoing it? 

So I am wondering what you mean by overdoing it? 

@unreceivedogma signs a room is overtreated...the room feels emotionally uncomfortable as our brains expect reflections...you start removing absorption and find improvement...the room feels overly warm due to a scarcity of high frequency wavelengths...the room sounds smaller than it actually is.    

An over dampened, deadend, etc room results in a test chamber is not generally an optimal listening environment. The best results are with a combination of treatments that allow life into the music so it  sounds more natural to the space it was recorded in.

Thus, there might not be a perfect way to do this as music is recorded in quite a wide range of places, studios, live venues outdoors, concert halls, etc.

If you take the time to study the subject then use the minimal amount of bass traps, diffusers and absorbers to get to the place where it sounds the best to you for your tastes in the variety of music you listen to then that is perfect, for you.

Rick

@unreceivedogma

Yes, it is possible to over-treat a room. Over-treatment typically refers to,

- Excessive absorption of mid and high frequencies while leaving the low end untreated. This creates an unnatural, muffled sound with no liveliness or air.

- Lack of appropriate diffusion, which can make the room feel claustrophobic and sterile by removing natural spatial cues.

However, in a semi-anechoic room like yours, the goal is to minimize reflections almost entirely, creating an ultra-clean, controlled soundstage. In such rooms, the “liveliness” and spaciousness should come from the recording itself, not from the room reflections. If you’re thrilled with the sound of your system, you’ve probably nailed it.

@lalitk

@seanheis1

@raam

I am THRILLED with the sound.

yes: all the dimensionality and atmospherics is coming from the groove almost entirely.

The room is not dead, I am getting full spectrum.

And, the sound is somehow holographic: on some recordings, sounds seem to originate from either side or behind me. I suspect this has something to do with the woofer placement, which is behind me.

To be clear: I am not arguing that you cannot kill a room with over-damping. I am arguing that most experienced audiophiles would look at my room and say: this has to sound terrible.

But it is the opposite.

My architect went to Harvard to get his masters. A good friend of his from back in those days was an acoustical engineer who now holds a number of patents. When my architect told him about my restoration of an historic home to its original aesthetic, while also making it near-passive house in energy performance, he also told him btw the client is also an audiophile. That is when he hit on the idea (based on some of his ongoing theoretical work) of the room treatment. Allegedly, until me, no one had done it yet.

I’m always up for experimentation and as it was a gut reno of a building that was distressed and abandoned for 21 years, it cost me nothing to frame it out and put the rock wool insulation in as I was going to do anyway for thermal barrier and fire resistance reasons, install the audio, crank it up, settle back and let it rip. If it worked, cover it with fire resistant burlap. If it didn’t work, up goes the sheet rock.

I covered it with burlap: his friend nailed it. No need to spend $$$$$s on expensive traps, diffusers, absorbers etc, all of which are ugly aesthetically. All for the cost of what I was doing anyway: basically, the acoustic insulation is a freebie piggy-backing on the thermal barrier.

I figured that I could always ADD harder surfaces (framed posters, eg) if it was too muddy but that has been unnecessary.

The Mastering Lab shelving on the Altecs is set to neutral on both the midrange and the highs most of the time, and when I do adjust it, it’s at most by 10 to 20%

As for “emotional distress” caused by a dead room: guests feel the opposite. They volunteer that it feels serene, peaceful, meditatively zen-like.

I've always found clapping to give me general sense of liveliness/damping of room, I've been on both side of equation. I've accumulated many types of acoustic treatments over the years since changes in system may require change of treatments. I mostly rely on items like carpet and tapestries when I need absorption, acoustic panels like Skylines and Synergistic HFT for diffusion. Just a few strategically may be all one needs, easy to overdo it with treatments.