Originally Posted by bpape
As to whether or not subwoofer range ringing is detrimental, I don't know that a single paper that you cited is enough to get me to ignore 2 second decay times fom 80Hz down.
I should explain more carefully the experiments done in this paper. The authors distinguished between two types of modal EQ. There is the precise parametric inverse filter method, where you have to match and cancel the center frequency, Q, and gain. There is also a non-parametric, less critical method where all you do is equalize the magnitude response to reduce the mode amplitude without trying to match its exact characteristics. You are not going to clean up the modal decay with such a cruder method, because you are not matching and precisely cancelling the resonance.
In the experiments, a synthetic room mode was added, and the the second type of EQ was done on it. At most frequencies, subjects could readily discriminate the EQed synthetic room mode vs. no added mode when the modal decay time was only 0.2 to 0.3 seconds. Sound reasonable? There was no amplitude peak at the modal frequency because it was EQed down, but the pesky decay tail remained. Although softer, this could still be heard.
But several modal frequencies were used, and an interesting thing happened at very low frequencies. To quote the authors:
"Below 100 Hz the value [discrimination threshold] exploded so that at 50 Hz in these listening conditions the subjects could not notice systematically any difference within the given samples even for a synthetic mode decay time of almost two seconds."
More experiments are planned, as these listening tests were done with just single room modes and 8 subjects listening to only four types of sound (speech, bandpass noise, drum hits, and rock music) at a single listening level of 75-80 dB.
I encourage anybody interested in the science of acoustics to read the original literature. Don't take my word for it. Read any paper carefully, and judge for yourself!