Octave Band Analysis

Last updated: March 12, 2024

What Does Octave Band Analysis Mean?

Octave band analysis is a method for measuring noise. In occupational settings, it is used to determine the type of hearing protection needed in a specific working environment.

Unlike traditional noise measurements, which measure the volume of noise in decibels (dB), octave band analysis measures both the volume of noise in an environment and the frequencies at which those noises occur. The range of sound frequencies that exist within a given space is referred to as that space’s “frequency composition.”

Safeopedia Explains Octave Band Analysis

Octave band analysis is an important component of occupational noise protection studies, because most types of hearing protection are not equally effective at all frequencies.

Ordinary earplugs will reduce exposure to most forms of environmental noise by approximately 35dB. However, the same earplug will only reduce exposure by 10 to 25dB if that noise occupies a very low audible frequency. Understanding a workplace’s noise frequency composition thus allows employers to recognize whether they need to introduce hearing protection that offers greater protection at frequencies that exist within that environment.

Octave band analysis allows noises with similar physical properties to be grouped together so that environmental noise can be understood in terms of the cumulative volume of all the sounds that exist within a particular band. Many sound meters are also equipped to filter sound into 1:3 (one-third) octave bands for situations in which it is necessary or useful to group sounds into categories that are smaller than a full octave range.

Why Is It Called an Octave Band Analysis?

The test is known as the “octave band analysis” because it relies on categorizing sounds into separate categories called “bands.” As the name suggests, the frequency range of each band is referred to as an “octave.”

Each band includes all frequencies that exist between an upper band limit and a lower band limit, and the upper band limit is always double the value of the lower band limit. While each band contains a range of frequencies, it is named for the median value. For instance, the 2 kHz band includes frequencies below and above 2 kHz but yield it as a median when taken together.

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