Ultrasound

Professional Definition

Noise containing sounds from 10 kHz to 40 kHz.

This definition includes the upper range of the audible spectrum (high tones from 10 kHz to 20 kHz) and low ultrasound (above 20 kHz). Ultrasound noise is characterized by a very short wavelength, making it highly directional and quickly attenuated in air over greater distances. Sources of this type of noise are often ultrasonic cleaners, plastic welders, compressors, and some pneumatic tools.

Acoustics in Simple Words

This can be compared to a dog whistle, which is inaudible to humans but irritating to animals. In the case of ultrasound noise (particularly in the lower range of 10-20 kHz), some people (especially the young) hear it as an unbearable, high-pitched squeal. For others, it is inaudible, but it acts on the body like “invisible radiation” – exhausting the nervous system, even though the ears do not register a specific sound. It's like being in a room with a flickering fluorescent light at a very high frequency – the eyes do not see it, but the brain gets tired.

Summary

Ultrasound noise is an acoustic emission in the range of 10 kHz – 40 kHz, often generated by industrial devices. Although its audibility is limited (especially in older individuals), it can have negative vegetative effects and requires the use of specialized hearing protection.