Decibel Definition - What is a Decibel?
A decibel is the unit of measurement for the objective volume of sound. Decibels measure how much air pressure is displaced by the sound. The louder a sound is, the more air it will displace (which is what causes it to sound loud, as the higher pressure air hits our eardrums). The amount of air pressure created by a sound can be quantified, and that number is represented in decibels.