It is widely recognized that the tone of a 12 fret Martin is, in general, superior to the tone of a 14 fret, but the reason for the superiority is the location of the bridge on the soundboard.

On a 12 fret the bridge is placed closer to the center of the soundboard than is the case with a 14-fret and the supposition is that this leads to better sound transmission. Makes sense, if you think about it.

Murray