The Joseph Pompei quoted in the article is Holosonics' founder. He's been working on this a long time; twenty years ago his demos knocked my socks off (1) at the Media Lab

(1) metaphorical sock-knocking only, no diplomats were harmed by his demos

Do you have any thoughts on why this hasn't seen mass-market adoption? Any major downsides? I have never ever heard of this technology or seen it integrated into the speakers of the big companies in this space. But looking at it just makes me go WOW.

Perhaps it's the lack of bass? For string music and spoken word ultrasound directional audio is fine, but for most music it's not really appropriate.

Imperial War Museum in London seems to employ something like those in their exhibitions. They have black rectangular plates affixed in various places with very localized sound fields underneath them.

An old KickStarter-backed project that does the same thing is currently available at http://www.soundlazer.com/ . The physics behind it are explained at http://www.soundlazer.com/what-is-a-parametric-speaker/ .

I have one of the soundlazers. Hardly use it because it's particularly punishing on the ears even at low volumes.

Was fun bringing into the office and reflecting sounds off the roof into other cubicals...

What about walls? And how would you target only one room in a hotel? Multiple intersecting beams?

This not possible with sound waves. EM yes because they work in magic extra-dimensional ether that no one has explained yet. But sound needs an uninterupted physical medium to propagate.

No ether, no magic, no extra dimensions, just radiation. Check out http://www.physlink.com/Education/AskExperts/ae175.cfm for an explanation of how it can pass through walls and https://en.wikipedia.org/wiki/Luminiferous_aether if you want to know why we know there isn't an aether/ether and how things work without it.