Acoustic treatment for fireplace

[Trell]

Making guesswork and adding random panels is like throwing darts at the problem. It's hard to tell whether things got better or worse without measurements

And a large surface area has to be covered as well and if scatter/diffuser plates are not added to them you risk getting a “dead” room.

 

[Truett]

First reflections are not a negative as many speaker manufacturers take those first reflections into account when designing speakers and crossovers. Those are typically side wall reflections though. Floor reflections are usually avoided but if the hearth is only 20" deep, then again, the impact is not going to be that great. If the ceilings are already treated and the side walls have heavy curtains, the room likely has enough treatment already. A simple clap test can show if the room decay is too long.

The problem is that room acoustics are complex. A professional would take measurements throughout the room and address specific issues. Making guesswork and adding random panels is like throwing darts at the problem. It's hard to tell whether things got better or worse without measurements. There can be expectation bias that will lead one to think that there are improvements when in fact there was no real difference.

That makes total sense. The room Decay time is not long. And we have tested with REW. And the room sounds fantastic. Although you cannot see any of the absorption, and it really just looks like sheetrock until you look close to notice that it is fabric.

I guess we are just most interested to know that we treat this Center Channel situation, with this fireplace opening, as well as we can. Dialogue! At my age I am already a bit hard of hearing in one year, lol. So we just want to make sure that the dialogue is as clear as we can make it.

 

[basscleaner]

As for the fireplace, the main problem for sound here is concern, that cavern may be cause of resonance(s). It;s easy to illustrate by this sketch for the same issue for windows:

A window box with rectangular slopes generates two modes (vertical and horizontal directions). Decision is to make oblique slope surfaces. An ordinary angle 7 - 10 degrees (shown by red lines). Pehaps, your case is the same? If your furnace firebox has rectangular form, than it may produce resonances to be deleted from FR. You may do it by heavy iron grate inside or plate. If not (trapezoidal form), than you have nothing to worry about.