Is the baryonic acoustic oscillation a sound wave?

I was told by a friend that a baryon acoustic oscillations are sound waves with a wavelength so large that they can travel through a vacuum. Is there any truth to this? I read what Wikipedia has to say about BAOs but I couldn't really understand the concept. Is a BAO a sound wave? Can it travel through a vacuum?

BAOs occur across a very large range of scales, all of which are by human standards "big". The most important scale is that corresponding to a wave which had time to complete $\frac{1}{4}$ of a cycle by the time of "recombination", which is $\sim 150\,{\rm Mpc}$ ($\sim 490\,{\rm Mly}$) in today's Universe. This scale is "visible" and a distance at which galaxies are more likely to be separated than other distances.