Well with your edit, sound is basically meassured by the change in air pressure esecially with velocity, so the writer's whole purpose for using highly pressurized air was to show that manipulation of the air in general was meant to remove any sound vibration to cause the avalanche. I think looking too much into the science we forget the purpose of the explaination and that this of course is speculation on technology that may or may not exist in the near future.
VHD in general is very good with specific explinations of the science involved especially in fantasy.
I find most other fantasy lacks this degreee of specifics and realism, like flash relying on the speed force to get around stuff or superman straight breaking the laws with out explaination both of which are much better with it than all animes I have come across beside any vhd.
Pretty close to the same conclusion I came to, I went on a research binge after wondering for a bit lol, it was the only thing besides some confusing illustrations Amano did that derailed me a bit, thanks for the reply and have a great day, or night, depending on where you are. :)
Found something to put some inconsistency discomfort to rest, NASA is designing an aircraft that only produces a soft thump instead of a sonic boom when breaking the sound barrier. Far enough in the future I could see the boom maybe being nearly eliminated, just another two cents on it, it bothered me more than it should have lol