I ran across it again today while reading a reviewer's evaluation of some speakers in that other audio magazine, and, as usual it produced the raised eyebrow and the little smile. The statement, a rough equivalent of which comes up from time to time in speaker reviews everywhere, was, "The bass extends to just a bit below 40Hz, but....they create the illusion of going even lower than that." The speakers create that illusion, do they? How very clever of them. How do you suppose they do it?
Clearly, there is some measurement reference involved in the review in question. How else do you support the flat statement about actual bass extension? Beyond that, though, the reviewer attributes to those particular speakers the capacity to create the specific illusion of greater bass extension - presumably only when is appropriate. Tough task, I think, for a little box of transducers and crossovers even if you accept that the whole job of a speaker is to create the illusion that musicians are playing in the room.
I suggest such illusions are created in the mind of the listener. I'm doing it right now with a pair of Shure E3c's driven by a Headroom Total Bithead playing lossless files from an iPod. The full range of the music is there for me, but, much as I think that set-up is OK for iPod listening, I don't credit those little in-ear phones for creating all of the bass that I'm "hearing". Then again, I'm not a professional reviewer.