ultrasonic
adj.describing sound waves that are too high for humans to hear. You often hear about this in medicine or when talking about how animals like bats communicate.
adj.relating to sound waves with a frequency above the upper limit of human hearing, typically exceeding 20 kilohertz. Often describes diagnostic imaging or industrial cleaning processes.
“The doctor uses an ultrasonic scanner to see the baby.”
“Bats navigate through the dark forest by emitting ultrasonic pulses and listening for the echoes.”
“Engineers employed ultrasonic testing to detect microscopic cracks in the aircraft's fuselage that were invisible to the naked eye.”
Typically used attributively before a noun.
Usage ultrasonic inspections
“This technique has been especially powerful in realms where humans cannot stay for long, or for species that emit infrasonic or ultrasonic sounds beyond human hearing range (20- 20,000 Hz).”
“The SMACs were stable in air and survived being bathed in a highly acidic solution for hours under harsh ultrasonic vibrations without breaking.”
From ultra- + sonic.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.