Mike... many thanks... got an ear-to-ear grin out of this...
You have described testing quite similar to what I was thinking, BUT, I had absolutely no idea what to expect, how to deal with it, or how I could even explain it. I was just going to post graphs so others could tell me what I needed to understand. You just covered that really well, gave me a framework, and helped me tremendously. What you said was very clear.
There is an effect I don't know any word for - best description is hearing slices of the reverberent field. My musician buddy and I learned to "hear" individual acoustic treatments by having one person sit in the prime listening position, while the other carried various panels around and focused the panels effect on the listener.The "effect" is, we perceive acoustic panels like they are chunks of the sound field, that we can move and manipulate using the position and construction of the panel. Over the last 2 years we have worked to assemble these sound field chunks into a fairly smoothe and balanced auditory envelope. And now we can't perceive which subtle changes are improvements. .. all depends on what we are listening to. So here I am... learning about REW and targeted parametric equalization, so that we can refine our efforts.
Following forum advice on materials, methods, and priorities I have been slowly building an array of 23 freestanding, rectangular wall panels (17 @ 6" x 48", 6 @ 24" x 48" for first reflections) , 2 floor-to-ceiling, freestanding front corners (actually 4 half-height stackable units), 31 small dome-shaped ceiling panels (to improve diffusion), and a couple of ovals (for front and rear wall). Sounds like a lot, however, I intentionally built many on a "very" small scale, to provide a more even acoustic distribution. An acoustic engineer told me he had great luck with lots of smaller panels (6' x 48 "), distributed all the way around the room. We found he was right and I am using the small scale idea to "assemble" the sound field, with carefully placed treatments, on every surface, but the carpeted floor (where Im playing with chairs, foot rests, and tables to manipulate effect).
This fits in quite well to acheive your suggestion of controlling the reflections to generate a smoothe Haas field and tune the frequency effects - if I can figure out where to place the panels to grab the unwanted reflections, and aim the desirable ones. Another nice thing is we were unknowingly practicing exactly the kind of manipulations you suggest for creating the dense field. Ahh Hah !!... theres the word for my "effect" in your post... "specular" sound field. My "chunks" of sound are the specular effects of the panels, and our "auditory envelope" is the Haas field... woo hoo!!!... if Im not misunderstanding? Sure do wish I had a great memory, because I'll bet I have read a lot of this, but forgot or didn't understand at the time.
Lastly, I was also concerned about killing the room with to much absorption. So I used soft plastic sheeting, duct tape, fabrics, and wood framing to replace some of the absorption surface, with diffusion. By building and covering the thinner, rounded profiles with reflective materials I feel I have tuned the panels to stay lively, while controlling much of the bass response. Since everything is either freestanding or simply moved, I can very easily rearrange the treatments, to sculpte the sound field. Also, I have been sure to build a few extra panels/treatments, so I know I have enough building blocks to finish the job... and can quickly add and subtract effect as needed.
A quick question... Do you enjoy this sort of "long" post with a student... or have you done it so much its sort of boring? I'd like to know so I can tailor my posts.
I have already scheduled to get together with my audio cohort, in a week, so we can assemble and try out the equipment. He has a bit of experience from years ago, and we tend to get more done together, than seperately. I read instructions on graph resolutions and info transfer, and I hope to have some "real" work done in a couple of weeks.
With great appreciation
, and lots of loud hoots and excited hollers
... Bye... Don...
