Yeah, that's the actual question and probably a reason why it's not an established technique

Also, low-frequency waves naturally are lower energy. Why not bury the output and increase the frequency?

It would have the added benefit of supposedly keeping away ground-dwelling pests; supposedly.

I recall reading an article about thermoacoustic cooling years ago, but couldn't find anything more current than this old wired article [1]. More recent articles about Ben and Jerry's refrigerators have been about changing refrigerants, so I suspect the research didn't work out.

Also, sort of sound and heat related, piezo fans seem to be a niche way to move air around without a spinning blade.

[1] https://www.wired.com/2003/01/hear-that-the-fridge-is-chilli...