/ ʌltrəsaʊnd /
Množina reči ultrasound je ultrasounds.
echography · sonography · ultrasonography
Pressure waves similar in nature to sound waves but occurring at frequencies above 20,000 Hz (cycles per second), the approximate upper limit of human hearing (15–16 Hz is the lower limit).
Ultrasonics is concerned with the study and practical application of these phenomena.
The earliest practical application was to detect submarines during World War I, but recently the field of ultrasonics has greatly expanded. Frequencies above 80,000 Hz have been used to produce echoes as a means of measuring the depth of the sea or to detect flaws in metal, and in medicine, high-frequency pressure waves are used to investigate various body organs. High-power ultrasound has been used with focusing arrangements to destroy deep-lying tissue in the body, and extremely high frequencies of 1,000 MHz (megahertz) or more are used in ultrasonic microscopes.