Sound and Noise – Understanding the Difference
Sound
Sound is created by pressure changes in a medium, usually air, caused by vibration or turbulence. These pressure changes travel as waves moving outward from the vibrating or turbulent source.
Noise
Noise is simply unwanted sound. It is one of the most common occupational health hazards and is often a by-product of various industrial processes.
Note: A short video by Dan Clark provides a quick overview of the nature of sound and noise, as well as strategies to prevent hearing loss in the workplace.
How Sound is Measured
Sound is measured using two key metrics: decibels and frequency.
- Decibels (dB): Measure the sound pressure or intensity.
- Frequency: Refers to the pitch of the sound and is measured in hertz (Hz), or cycles per second. The pitch—how high or low a sound appears—is determined by its frequency. Higher-frequency sounds are generally more irritating and can be more damaging to hearing than lower-frequency sounds.
The human ear is most sensitive to frequencies between 3,000 and 4,000 Hz. Damage in this range often makes it difficult to understand higher-pitched voices and other sounds within these frequencies.