# The Decibel: An Important Term in Lab Safety We talk a lot about noise in this blog, for very good reason: A quieter lab is a safer lab. Lab safety requires being able to easily hear and understand your fellow lab workers, so we engineer our dedicated lab furniture to make your lab quieter.

In order to talk about sound and noise, however, you need the proper terminology. The decibel, often abbreviated as dB, is a frequent term in posts where we talk about noise safety in the lab. Let’s take a closer look at the humble decibel—where it came from, what it means, and why it’s so ubiquitous in discussions about noise and lab safety.

## History of the Term ‘Decibel’

Where does the term “decibel” comes from? Modern efforts to measure sound volume originated in the need to quantify signal loss over telephone lines and telegraph cables. Early terms included MSC (for miles of standard cable) and TU (for transmission unit).

Eventually, the Bell System renamed the TU as the decibel, classifying it as one-tenth (hence the “deci”) of a “bel” (which was named after Alexander Graham Bell, inventor of the telephone—The full scientific name of the bel is the Alexander Bell which explains why the B in “dB” is capitalized).

## Understanding the Decibel

In the National Bureau of Standards Yearbook of 1931, decibel was defined as follows:

The decibel may be defined by the statement that two amounts of power differ by 1 decibel when they are in the ratio of 100.1 and any two amounts of power differ by N decibels when they are in the ratio of 10N(0.1). The number of transmission units expressing the ratio of any two powers is therefore ten times the common logarithm of that ratio.

The bel signifies the logarithm of a 10:1 ratio between two power quantities (the ratio of measured power to reference power), or the logarithm of a ratio between two field quantities (the ratio of the squares of measured field and reference field) of √10:1.