An octave band is a frequency band that spans one octave. In this context, an octave can be a factor of 2 or a factor of 100.3. 2/1 = 1200 cents ≈ 100.301. Fractional octave bands such as 1⁄3 or 1⁄12 of an octave are widely used in engineering acoustics.
Octave band analysis is often used in noise control, hearing protection and sometimes in environmental noise issues.