Yes, it's understood that at audio frequencies the small portion of the wave energy which penetrates into the conductor penetrates entirely into conductors of the typical sizes used in audio, but what was being referred to was the energy remaining outside the conductor which actually reaches the speaker. One source which was cited here before is the excellent series by Dr. Lesurf which was originally prepared as introductory material for his students in electronics and physics at St. Andrews. See
sections 6.2 and 6.3 for an explanation of energy transmission along wires. In addition, see Issue No.24 of The Audio Critic for the "Hip Boots" article beginning at
p.75 , especially the explanation of the professor at pp. 76 and 81.
