ultrasound
(ˈʌltrəsaʊnd)
[f. ultra- 2 c + sound n.3]
Sound waves or vibrations with frequencies greater than those audible to the human ear, or greater than 20,000 Hz; also, ultrasonic techniques.
| 1923 Proc. & Trans. R. Soc. Canada XVII. iii. 143 When the electrical exciting sources were alternating in potential, the tonic trains of ultra-sound so produced—120 pulses per second—could be heard in the stethoscope. 1936 Jrnl. R. Aeronaut. Soc. XL. 25 Ultra-sound waves are generated by a quartz oscillator arc propagated through a surrounding liquid medium. 1953 J. Y. Cousteau Silent World 104 Are porpoises equipped with sonic or ultra-sound apparatus by which their squeaks give them the feel of unseen bottom topography? 1958 Oxford Mail 30 June 4/4 Some firms now use ultrasound to detect flaws in metal. 1968 New Scientist 16 May 347/1 The moth's sensitivity to ultrasound may have other uses. 1984 Times 16 Nov. 12/4 Any woman who is worried about malformations would be subject to a detailed ultrasound scan. |