I commented on this 200 days ago.[1]  I pointed out that you could build a demo version with off the shelf components. 4000  piezoelectric transducers in a 1 meter square frame, with enough separate drivers that you could form and steer a beam, ought to do it.  It would take several kilowatts of power to get the claimed sound power level.  Audio in that power range is used for ultrasonic welding of plastics. It&#x27;s attenuated with distance, of course, so a few meters out, you&#x27;re not getting much power.<p>[1] <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10420539" rel="nofollow">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=10420539</a>