Exactly. 2.5 khz at a low level is much more audible than the same level of, say, a 10k whine.
But if a measurement is given in db(A), the measurement itself is weighted for the threshold of hearing. So values given in dbA are usually a reasonable representation of perceived volume.
http://en.wikipedia.org/wiki/Equal-loudness_contour
http://en.wikipedia.org/wiki/DB%28A%29