In this context, noise refers to the mechanical vibrations or pressure waves of an elastic medium. The unit of measurement is decibel (dB). The pain threshold for humans is around 130 dB. The audible range of human hearing lies in the frequency range of 16-16000 Hz (below: infrasound / above: ultrasound).
Acoustic pressure is measured as a periodic change in air pressure caused by the sound wave.
These are vibrations caused by machines and transmitted to the body through the hands, feet or bottom (e.g. by lawn tractors).
This type of vibration is transmitted to the body from a hand-operated or walk-behind machine through hands and/or arms (e.g. trimmer, lawn mower, tiller, etc.).