Musical Elements: Tonality

Tonality is the principle by which notes are arranged into a system of hierarchy.
This hierarchical system gives particular weight or importance to certain notes, particularly the tonic (the ‘home’ note around which the rest of the piece is centred).
Other important notes in a key include the dominant (the fifth note of a scale, which often creates a sound of tension or suspense that is resolved by returning to the tonic) and the leading tone (the seventh note of a scale, which strongly ‘leads’ back to the tonic).

Keys can be either major or minor, with major keys often said to have a bright, happy sound and minor keys often said to have a darker, sad sound.
Parallel keys are pairs of keys that share the same tonic (for example C major and C minor), while relative keys are pairs of keys that share the same key signature (for example A minor and C major).

Modulation is the process of changing key within a piece of music.
In tonal music, modulation can provide variety and contrast, and can be used to create tension or drama.
Common types of modulation include direct modulation (a sudden and abrupt change to a new key), pivot modulation (using a chord common to both the current key and the new key to provide a smooth transition), and chromatic modulation (using a series of chromatic (non-diatonic) notes to ‘bridge’ the gap between the two keys).

Atonality refers to music that rejects the system of tonal hierarchies, and treats every note as being equally important.
Atonal music often sounds dissonant and lacks a clear tonal ‘centre’, which can make it challenging to listen to.

In addition to the major and minor keys, music can also be composed in a variety of other scales known as modes.
Knowledge of modal scales is important in understanding and analysing a range of types of music, from Renaissance and Baroque music to jazz and pop.