Objects suspended by near-field acoustic levitation. https://www.bjultrasonic.com/ We are professional ultrasonic cleaning solution and ultrasonic cleaner parts manufacturer and supplier, including ultrasonic generator, ultrasonic transducers & piezoelectric ceramics.
The frequencies of the ultrasonic sound waves used by ultrasonic cleaners to clean objects are very high, above 20 kHz. That is beyond the level of frequency that human ears can detect. Therefore, even though ultrasonic frequencies are very high, they cannot damage our ears. What you should be concerned about are the undertone frequencies.