A series of four notes separated by three intervals

Tetrachord is a musical term used to describe a segment of a scale consisting of four consecutive pitches. In Western music theory, the tetrachord is considered a fundamental building block of scales.

Traditionally, tetrachords are constructed using a combination of whole and half steps. The most common tetrachords are the diatonic tetrachords (Dorian, Phrygian, Lydian, Mixolydian), each consisting of two whole steps and one half step. For example, the Dorian tetrachord is constructed with the intervals whole-whole-half.

Tetrachords can also be created with different combinations of intervals and structures depending on the specific musical context and style. Different musical cultures and genres may utilize tetrachords with different interval combinations.

In music theory and composition, the concept of tetrachords is often used for analyzing musical structures and establishing harmonic relationships. It can serve as a foundation for composing music or as a tool for understanding and interpreting interval relationships and harmonies in music.

Example of Tetrachord

What is a Tetrachord?