One-third octave

A one-third octave is a way of dividing the frequencies that we hear into bands of frequencies. Imagine a piano. We can divide the different keys of the piano into groups of notes to describe which notes we can hear. For example, a group of notes could include the keys C, D, E, F, and G . This group is called a "third octave". We can divide the piano into many more of these group of notes, like C, C#, D, D#, etc. And these group of notes are called "one-thirds octaves".