Michel,
Toole makes a clear distinction between trained and untrained listeners. Toole has noted the differences, as other researchers, such as yourself, have. Ando has even
quantified those differences, at least in the case of musicians versus ordinary listeners.
To me, the box on pp. 119 of
Sound Reproduction sums it up nicely. I will quote a portion of it, just to give a taste
:
(Emphasis is mine.) (I also noticed that I had penciled a note in the margin on pp. 119 that says, "Possibly the most important section in this book."
)
It is our responsibility to understand the science of acoustics. However, understanding the science is only the first step. It is much more important to be able to use that scientific understanding to create a room that sounds good to the listener. Therein lies the art of acoustics.
I hope you don't mind—and I'm not trying to nitpick—but I'm going to use the background noise criteria you cited as an example:
What sense would there be to setting an NC-15 criteria for background noise for a listening room that will have, because of circumstances beyond the acoustician's control, an HVAC system that can only meet NC-25? Is it really responsible to dictate thousands of dollars worth of changes to the HVAC system when NC-25 is probably going to be perfectly acceptable for the listener? In the grand scheme of things, spending boatloads of money for what amounts to ~10 dB more S/N is probably a poor use of precious listening room funds. (IMHO it is anyway.) The listener is fully capable of enjoying the room whether they have 45 or 55 dB of S/N.
That's not to say that the listener with deep pockets shouldn't have the best possible room. I have designed listening rooms for those types of folks. Background noise barely measurable with my Type 1 instrumentation; "ruler-flat" frequency response down to 32 Hz; laboratory quality isolation; ultra-low T
60; early reflections at least 15 dB down; etc. Those are certainly fun rooms to work on. To me, they sounded phenomenal and I consider them some of my best work.
However, for quite a few of those designs, I noticed that some of my colleagues—many of them ordinary listeners—would comment that it sounds
good. No "WOW!" No blown away. Just "good." Like "what's-all-the-fuss-about?" good. To me, this is an important thing to keep in mind.
To put it another way, is the room going to be used by an audiophile that claims she can hear flies fart, or is it going to be used by a family of four to experience
The Wizard of Oz on the "big screen" for the first time since giving up the 19" TV in the family room, or is it going to be used by someone who just enjoys listening to good Mozart recordings in stereo? I don't believe the widely varying design needs of these listening rooms (et al) can be addressed by standards. (But that's not to say we shouldn't try!
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