All about decibels
There is no physical difference between a sound produced by speech, music and noise. Sound becomes noise when it produces a hearing sensation considered as unpleasant, annoying or dangerous for the health. Thus, everyone has their own perception of noise that depends on many components related to context as well as personal and cultural history.
Noise or sound?
According to its definition in the dictionary, “noise is sound perceived as non-harmonious, as opposed to music.”
Decibel scale
Sound intensity is expressed in decibels on a scale going from 0 dB(A), the threshold of human hearing, to 120 dB(A), the upper limit of common noises in our environment. However, as of 85 dB(A), be careful, it becomes dangerous!
Sound perception
The human ear can hear noise levels going from very low to very loud, from whispering to a supersonic plane flying over, in a range of frequencies going from 20 hertz (very low-pitched) to 20,000 hertz (very high-pitched).
Addition of decibels
Decibels do not add up in an arithmetic way but according to a logarithmic progression. Thus, when two noise sources of the same intensity add up, the noise level increases by 3 decibels.