That's good stuff.
Not so sure I believe there is no fall off with distance, but good nonetheless.
He didn't say there was no attenuation with distance, just that it didn't follow the basic inverse square law.
The inverse square law is trivially easy to derive for a point source of energy radiating in all directions uniformly, even when in a perfectly conductive medium. Parallel sources behave rather differently in this regard. The sound will be attenuated, just with a different dependence on distance.