Which of the following describes ultrasound?

Ultrasound refers to sound waves that are above 20 kHz. This frequency range is not audible to the human ear, which typically can detect sounds between 20 Hz and 20 kHz. Ultrasound technology is widely used in various fields, including medical imaging and treatment, as well as in industrial applications for cleaning and non-destructive testing.

The critical aspect of ultrasound is its high frequency, which enables it to produce images in medical diagnostics (like ultrasound scans) due to its ability to penetrate soft tissues and reflect off structures within the body. This ability makes it distinct from lower frequency sounds, which have very different properties and applications.