The decibel is a unit of measurement that relates the ratio of a physical value to another value and is expressed on a logarithmic scale. The common symbol for decibel is dB. The decibel is used as a measure for many parameters in science and engineering such as acoustics (sound), electronics (power levels) and control theory.
The decibel originates from methods used to express performance and loss in telegraph and telephone circuits. The term ‘bel’ was coined in honor of Alexander Graham Bell, and the decibel, being 1/10th of a bel was established.
For most of us, the decibel is the familiar term relating to how loud a sound is.
With sound, the sound pressure is typically what is measured and is the local pressure deviation from the base or equilibrium atmospheric pressure, caused by a sound wave. In air, the sound pressure can be measured by a standard microphone, and is measured in pascals (Pa.)
To get to the common decibel reading we are familiar with, a little mathematics comes into play.
- where Lp is the Sound Level in dB, prms is the measured sound pressure, and pref is the standard sound reference pressure of 20 micropascals.
- The prms is what is measured by a microphone
Below are some representative sounds and the decibel rating – Note that sounds that are above 85 dB can cause hearing issues, and proper protection should be taken.
Some other interesting blogs about sound for you take a look at-
If you would like to talk about sound or any of the EXAIR Intelligent Compressed Air® Products, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.