Originally Posted by amirm
Now, let's see if you are afraid to answer your own questions.
To begin, I think addressing the issue of personal preference is deceptively difficult. I started a thread about just this topic, here
. dragon and local weren't so receptive to the idea that personal preference might actually be something difficult to define on a personal level. I'm not convinced.
In any case, one potential solution is to let an expert design your room and trust he knows his stuff. You have done that for your showroom. Not exactly in the DIY spirit of course. Another possibility is to just pick one expert that you believe should know his stuff, and follow their advice. That seems to also be your suggestion, choosing Toole as the expert. Sounds reasonable. I can't fault that logic, just that when following it to the natural conclusion we arrive somewhere you seem unwilling to go.
You see, Toole partially throws the problem back in your face, as has been pointed out multiple times in this thread, by specifically pointing out absorbed lateral reflections might provide a more intimate, precise, accurate listening experience which some listeners may prefer. Here's a quote from this thread on my own take on this...
Originally Posted by bigus
My take or summarization or interpretation of his work in this area is that for the average person, in the average residential room, with the average or typical program material (for most people this is TV/movies with speech and non-critical music listening), lateral reflections from untreated walls are unlikely to be destructive and may even sometimes prove beneficial.... The point is, there are many such possible conditional criteria that Toole's work can't speak to directly. He even gives explicit leeway for such preference, as Sanjay has tried so eloquently to highlight. And if in the end I want to know whether the reflections contained in my room, with my speakers, using my preferred source material improve or detract from the experience to my ears, how am I to find out...?
So we have one fly in the ointment; what is our individual preference, do we care to find out or just follow a graph of "the average", and if we care to find out... how?
Suppose we take the "I'm average" route you suggest, following Toole who provides averaged results of listener tests that, if you stick your fingers in your ears ever so gently and ignore questions about listener training/experience, program material, etc., might persuade you to buy into the "tastes better" mantra and just forego absorption. Thus, requiring only his treatment frameworks and frequency response measurements, right?
Simple enough, right? But then, as you and Toole mention, perhaps a room can be overly reflective. Ah, well there's another fly in the ointment. What rooms are overly reflective? Can you tell by looking? Can you tell by listening
if, as you point out here and numerous times in the past, our hearing/perceptions are fallible under biased sighted conditions? I'm thinking, perhaps you need measurements
. But what measurements then? Can a frequency response tell me in the specular region how lively a room is? I think not. Perhaps you have in mind a simplistic measure like RT60, but that is useful (and defined) only for large acoustical spaces that have well developed statistically defined reverberation. If you try and use it in a small space, in your home, as many people have, you might get a result that leads you in the right direction... or you may not. Step a couple of feet to the left with your mic, into a region of high gain specular reflection, and you may get a different result pointing you in a different direction. But let's be especially generous and assume that your suggestion of a single 500Hz RT60 measurement is adequate for ascertaining the general "liveliness" of a room, and that the range suggested by Toole at that frequency will lead to a good result. We measure our room and it is too lively (being designed as a dedicated HT, and lacking lots of furniture). We need to apply some treatments, but where?
There are tools which have been developed specifically for this purpose. But you have to decide what to with the information gathered. Well, Toole says lateral reflections are good. So we don't want to kill those. Past research starting with the Haas interval and continuing to the present is available to help define reflections that may be harmful to precise localization, intelligibility, whatever. Toole suggests strong reflections coming from the front or back walls may be especially bad. So you start looking for specific reflections that are too early or late or too strong in gain that might cause a "too lively, overly reflective" room you and Toole mention (or, if you used your two ears and biased brain first, suspected you had, somehow). Ah, we identify a couple of likely candidates... now what to do with them? We want to preserve lateral reflections according to Toole, and we want to avoid altering the frequency response of the specular reflections according to Toole, so we apply broadband absorption (or diffusion, choose what is practical) to as small an area as possible that will reduce the gain of the reflection such that it now falls within the limits literature suggests will be benign, or according to Toole, good.
We listen. We measure, in both time and frequency domains. Repeat based on preference and measurements. All is well. Perhaps we even achieve better results than possible by willy nilly placing furniture and/or treatments around the room that will likely result in lower than optimum lateral reflections and higher than necessary front and back wall reflections.
Now examine the above closely. What we accomplished was surgical treatment of high gain specular reflections with as small as possible broadband absorption. We did exactly as Toole suggested at every step. We also did EXACTLY
as local and dragon have suggested, nay, screamed, at every step. Never did we deviate from Toole's gospel.
Now, if we wanted more accurate imaging, or wished to use modern processing to provide laterally arriving diffuse sound, or for whatever reason we wished to go further than his "average" we would simply use our same time domain measuring tools to go further down the path of surgical absorption or diffusion, treating more reflections in order of gain and time criteria, as measured, arriving at various points along the path at many of the room models you have lambasted until it suited our taste, just as Toole says is OK. The only real difference that Toole has staked out from many of the prior models is that he suggests preserving the maximum possible lateral energy, and other have advocated preserving the maximum possible late arriving lateral energy. Whoa! But in either case, following Toole's "average" listener path, or following his nod down the more precise imaging path, there is a place for time domain measurements.
That is my answer, and I believe Toole's, local's, and dragon's too.