The frequency of ultrasound is therefore greater than 20,000 hertz. Ultrasound, like audible sounds, is transmitted by means of longitudinal waves. Ultrasound is used in medicine to break up ...

Don't get confused with this quantity frequency ... All the electromagnetic waves travel at 300,000,000 metres per second (\(3\times 10^{8}\,m\,s^{-1}\)). Sound travels at about 340 metres ...