51¶¯Âþ

Place your hand in front of a working loudspeaker and you’ll feel a force
pulsing against your palm. The Technical University of Munich reckons you can
use that force to transport fragile objects. It suggests floating objects on a
cushion of high-frequency sound waves using a matrix of transducers like hi-fi
tweeters (WO 0061473/5/7). Laid out in a line, the tweeters fire sound waves
upwards. This provides the equivalent of an air cushion, while side-facing sound
generators push the object along.