dBx Jargon Buster - Decibel

Welcome to the dBx Acoustics jargon buster! In this section, we list some common acoustic terms as well as standards and guidance you may be asked to comply with. If there’s something you need to know that we haven’t covered here, please let us know.


The decibel, written dB, is the unit by which sound levels are expressed. A level of 0dB is near total silence; a normal conversation may be around 60dB, a rock concert may be above 100dB.

Decibels often cause confusion as they add logarithmically -two noise sources of 40dB added together results in 43dB, not 80dB! As a rough guide, the smallest change in noise levels that humans can detect is typically around 3dB. Something which seems subjectively ‘twice as loud’ is likely to be around 10dB higher.

Acoustics – where 2+2 really does equal 5…!