It's good to know where the audible thresholds are. However, it is just as good, if not better, within reason, to design to minimize them in the first place. Just what are the sources of group delay, and how can they be designed out? If they were to be essentially eliminated, or reduced within reason, the anguish about whether they are audible or not could become moot.
Pooge - I agree completely.
The sources that I know of almost all have to do with diffraction. To me all sources of this must be minimized. This can come from the speakers, horns, even the room itself (nearby objects etc.). The audibility of the actual delay goes up with delay and then falls again. Once the GD has exceeded 5-10 ms then its just another room reflection. But very early GD in the .2 - 2.0 ms region mess with our imaging perception. These early sources of GD must be kept to a minimum and I don't really think that there is a "threshold" below which they are not a problem. That's because the audibility increases with SPL so even very small audibility at 80 dB may be quite noticeable at 110 dB. Maybe 110 dB is beyond the level that you listen at, but maybe you don't listen at 110 dB because the GD gets disturbing. 110 dB at a concert is quite common, but it doesn't bother most of us.
I can take the 110 dB at most theaters because the sound is simply annoying. I have a suspicion that GD is more annoying to older listeners, but that is just a guess based on what I find annoying now versus what I could tolerate years ago. Maybe it's age, but maybe its just that I got used to not having it and now I can't stand it.
The sources that I know of almost all have to do with diffraction. To me all sources of this must be minimized. This can come from the speakers, horns, even the room itself (nearby objects etc.). The audibility of the actual delay goes up with delay and then falls again. Once the GD has exceeded 5-10 ms then its just another room reflection. But very early GD in the .2 - 2.0 ms region mess with our imaging perception. These early sources of GD must be kept to a minimum and I don't really think that there is a "threshold" below which they are not a problem. That's because the audibility increases with SPL so even very small audibility at 80 dB may be quite noticeable at 110 dB. Maybe 110 dB is beyond the level that you listen at, but maybe you don't listen at 110 dB because the GD gets disturbing. 110 dB at a concert is quite common, but it doesn't bother most of us.
I can take the 110 dB at most theaters because the sound is simply annoying. I have a suspicion that GD is more annoying to older listeners, but that is just a guess based on what I find annoying now versus what I could tolerate years ago. Maybe it's age, but maybe its just that I got used to not having it and now I can't stand it.
I have a guess that the content, and compression schemes used to raise average levels in movies have far more to do with why they sound bad in theaters than GD. The trailers are particularly bad, my ears are shot before the movie starts if I forget to wear plugs during the trailers.
Seriously, take a typical modern movie soundtrack (especially "action" movies) and play it over your Summas at 110 dB and report back if it does not sound annoying.
As far as age and annoyance vs. level, even in large rooms at 57 years old I find over 100 dBA annoying, small rooms about 90- dBA is topping out my tolerance level, though when younger 115 dBA was tolerable (if clean) in a large room.
Seriously - I only watch movies at home because I can't stand the sound at theaters. Now it is true that they seem louder, but I seem to be able to hit comparable levels in my theater without it sounding as bad as it does at the commercial theaters. I've measured the levels in my room at 110 dB so I know that's not a problem, but I have not measured the levels in a commercial theater.
Basically I don't think that it is the sound track, but it could be bad sound setups in the commercial theaters. That could be a myriad of problems I suppose.
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