ok, he must be talking about FR?
Yes. And since the in-room frequency response predicts perception at low frequencies, he is also talking about "how it sounds".
with bass trapping you manly target the decay of the modes.
Speakers + room = a "minimum phase system" at low frequencies. So when you correct the frequency response, you have simultaneously corrected the time-domain response, and vice-versa.
Bass trapping directly affects the time-domain behavior and therefore improves the in-room frequency response.
Multiple subs intelligently distributed directly affects the in-room frequency response and therefore improves the time-domain behavior.
To put it another way, it is the in-room frequency response peaks which take longer to decay into inaudibility. Smooth those peaks (whether by multiple subs or EQ or bass trapping or whatever), and those frequency regions no longer take more time to decay than the rest of the spectrum.
(Toole reports in his book that we perceive the frequency response peak, and not the ringing in and of itself, which implies that fixing the frequency response is fixing the problem. See post #493 above by
@NTK.)
getting the FR flat with treatment realy is something near impossible. you would have to be able to absorb ALL the energy of the mode.
Absorbing all the energy in the modes = anechoic conditions = not practical.
Matthew Poes is not the first person to conclude that a distributed multi-sub system is more effective than bass trapping at improving the in-room bass, but his extensive hands-on experience with both techniques qualifies him to comment from experience rather than from theory. I first learned the theoretical side from Earl Geddes in January of 2006.
Of course you can do both if space and resources allow, but most of the improvement will probably come from the distributed multisub system.
multi subs wont do anything for the decay
Multiple subs make the decay much more uniform across the spectrum and throughout the room, the "throughout the room" aspect being something that EQ of a single sub cannot accomplish for modal effects.
(Disclaimer: I have been manufacturing a distributed multi-sub system since 2006, so you are welcome to discount or dismiss my opinion since I am commercially involved.)