Metre (music)

In music, metre (also spelled meter in American English) refers to the regularly recurring patterns and accents that structure the rhythmic organization of music. It provides a framework for understanding and performing musical time. It is closely related to, but distinct from, rhythm, which is the actual arrangement of durations in a musical passage. Metre is the underlying pulse and grouping, while rhythm is the specific pattern of sounds and silences that occur within that framework.

Metre is typically characterized by two elements: the beat (or pulse) and the grouping of beats into larger units called measures (or bars). The beat is the basic unit of time, a regular pulse that can be felt or tapped along with the music. Measures are formed by grouping beats together, usually in consistent and predictable patterns.

Common types of metre include:

• Duple metre: Measures contain two beats. (e.g., 2/4 time, 2/2 time).
• Triple metre: Measures contain three beats. (e.g., 3/4 time, 3/8 time).
• Quadruple metre: Measures contain four beats. (e.g., 4/4 time, also known as "common time").

These metres are considered simple metres because each beat can be divided into two equal parts.

• Compound metre: Measures contain beats that are divisible into three equal parts. These are often indicated by time signatures such as 6/8 (duple compound), 9/8 (triple compound), and 12/8 (quadruple compound).

• Irregular metre: (also known as complex or additive metre) uses measures that have a combination of simple and compound beats, or a constantly changing number of beats per measure. Common irregular metres include 5/4 and 7/8.

The time signature (or metre signature) is a notational convention used to indicate the metre of a piece of music. It typically consists of two numbers stacked vertically, resembling a fraction without the dividing line. The top number indicates the number of beats in each measure, and the bottom number indicates the note value that receives one beat (e.g., 4/4 means four beats per measure, with the quarter note receiving one beat).

Understanding metre is crucial for musicians, as it informs their interpretation of rhythm, tempo, and phrasing. It also allows composers to create a sense of order and predictability in their music, or to disrupt those expectations for expressive effect. Changes in metre can create a feeling of instability or excitement, and are a common feature of many musical styles.