Ultrasonic Sensor Thingies

[Clyd3]

All educated (and not) peoples answer me!
It's about those Ultrasonic sensors.
Why are they called that. The stuff professionally called ultrasonic doesnt normally pass through air does it? I mean when examining metal parts for aircraft and stuff, and when examining body parts, they have to use gels and stuff for that purpose. I know for other purposes as well, but YOU DONT want air in the way...
So is it just a friendly way of saying higher pitched sound or something, like bat's radar and stuff?

 

[Dr.EM]

I believe it is yes, just high frequency, inaudible to humans, sound. Ultrasonic sensor alarms generally use 40khz region sound, which is twice as high as what a good pair of human ears can hear

 

[Clyd3]

thanks

 

[Laplink]

Ultrasonic is greater frequency than humans can hear.

Subsonic is lower frequency than humans can hear.

Subsonic can also mean a speed slower than the speed of sound.

therefore:-

Supersonic is a speed greater than the speed of sound.