Thought I'd add my two cents to the discussion.
There's no doubt in my mind that acoustical treatment can make a world of difference that both the ears and eyes can detect (from pre and post measurement graphs). Best start with some education I found. I have examples in my systems of reflective baffles, diffusion (QRD and Skylines) and absorption. Below are some of my learnings:
Measurements first: You can't manage what you can't measure plays a role here. At the very least measure frequency response (ideally a flat response is better) and reverb time (to avoid over dampening the room with things that absorb too much sound). I use Dayton Audio OmniMic which allows me to see the troubling frequencies so speaker placement and acoustic treatment placement experimentation can begin and note its affect. Often solving one problem frequency creates a new problem so it'll take patience to try and optimize speaker and acoustical treatment placement.
Treatment strategy: for most domestic sized rooms absorption of low frequencies and reflection and or diffusion of mid to high frequencies works well. This avoids over dampening. The transition frequency range for most home rooms where sound waves transition to "beams" due to smaller wavelengths is about 300-500Hz so you'll need bass traps to work below this range and diffusion to work above it.
Thickness matters: Too often manufacturers sell absorbers and diffusers that are too thin. And the reason you want them thick (at least 6") is so they don't act like a low-pass filter and only operate on some of the frequencies hitting it. You want the absorber or diffuser to work as broadband as possible so as not to skew the frequency range of its reflections and reflections of those reflections. For a diffuser, the depth of its slots or wells (for a QRD or Skyline type) determines its lowest frequency, so for example a 6.75" depth will work down to 500Hz as it is one-quarter of a 500Hz wavelength.
Sitting distance from treatments: Normally you can sit much closer to an absorber than a diffuser which needs more space for the scattering to occur so the sound coalesces by the time you hear it. If you need to be close to a diffuser - say on the ceiling or side walls which are near your listening position - then choose a 2-dimensional one (diffuses both horizontally and vertically) so that only about half of the reflections are coming your way.
There's no doubt in my mind that acoustical treatment can make a world of difference that both the ears and eyes can detect (from pre and post measurement graphs). Best start with some education I found. I have examples in my systems of reflective baffles, diffusion (QRD and Skylines) and absorption. Below are some of my learnings:
Measurements first: You can't manage what you can't measure plays a role here. At the very least measure frequency response (ideally a flat response is better) and reverb time (to avoid over dampening the room with things that absorb too much sound). I use Dayton Audio OmniMic which allows me to see the troubling frequencies so speaker placement and acoustic treatment placement experimentation can begin and note its affect. Often solving one problem frequency creates a new problem so it'll take patience to try and optimize speaker and acoustical treatment placement.
Treatment strategy: for most domestic sized rooms absorption of low frequencies and reflection and or diffusion of mid to high frequencies works well. This avoids over dampening. The transition frequency range for most home rooms where sound waves transition to "beams" due to smaller wavelengths is about 300-500Hz so you'll need bass traps to work below this range and diffusion to work above it.
Thickness matters: Too often manufacturers sell absorbers and diffusers that are too thin. And the reason you want them thick (at least 6") is so they don't act like a low-pass filter and only operate on some of the frequencies hitting it. You want the absorber or diffuser to work as broadband as possible so as not to skew the frequency range of its reflections and reflections of those reflections. For a diffuser, the depth of its slots or wells (for a QRD or Skyline type) determines its lowest frequency, so for example a 6.75" depth will work down to 500Hz as it is one-quarter of a 500Hz wavelength.
Sitting distance from treatments: Normally you can sit much closer to an absorber than a diffuser which needs more space for the scattering to occur so the sound coalesces by the time you hear it. If you need to be close to a diffuser - say on the ceiling or side walls which are near your listening position - then choose a 2-dimensional one (diffuses both horizontally and vertically) so that only about half of the reflections are coming your way.