Ultrasound

Professional Definition

Ultrasound – sound whose spectrum is contained in the frequency range above 16kHz.

In acoustic engineering, this boundary is often taken conventionally. Although the theoretical upper limit of hearing for a young, healthy person is around 20 kHz, in technical standards and literature, the value of 16 kHz is often encountered as the threshold above which we begin to talk about the ultrasonic range. These waves are characterized by very short wavelengths, which allows for their precise focusing and use in defectoscopy and imaging (e.g., ultrasound).

Acoustics in Simple Words

Imagine that sound is light. Audible sounds are the colors you see every day – from deep red (low bass) to purple (high tones). Ultrasonics are the acoustic equivalent of ultraviolet (UV). They are there, carrying energy and information, but your "eyes" (ears) are not built to perceive them. Similar to a dog whistle, which produces a sound audible to the four-legged friend, but for us is silence – it is a classic example of utilizing the boundary between audible sound and ultrasound.

Summary

Ultrasound refers to acoustic waves with frequencies exceeding the threshold of human hearing (usually >16-20 kHz). Due to their short wavelength, they have a wide range of applications in technology, medicine, and navigation, even though they remain beyond the reach of our direct perception.