Song structure in the context of "Thirty-two-bar form"

A song is a musical composition performed by the human voice. The voice often carries the melody (a series of distinct and fixed pitches) using patterns of sound and silence. Songs have a structure, such as the common ABA form, and are usually made of sections that are repeated or performed with variation later. A song without instruments is said to be a cappella.

Written words created specifically for music, or for which music is specifically created, are called lyrics. If a pre-existing poem is set to composed music in the classical tradition, it is called an art song. Songs that are sung on repeated pitches without distinct contours and patterns that rise and fall are called chants. Songs composed in a simple style that are learned informally by ear are often referred to as folk songs. Songs composed for the mass market, designed to be sung by professional singers who sell their recordings or live shows, are called popular songs. These songs, which have broad appeal, are often composed by professional songwriters, composers, and lyricists; art songs are composed by trained classical composers for concert or recital performances. Songs are performed in studios and an audio recording is made, or they are performed live for audience. (In some cases a song may be performed live and simultaneously recorded.) Songs may also appear in theatre (e.g., opera), films and TV shows.

Noise music (or simply noise) is a subgenre of experimental music that is characterised by its use of unwanted noise as a primary musical element. The genre has roots in early 20th century avant-garde music, but later drew influence from industrial music. It is characterized by a rejection of conventional music theory and traditional song structures, often featuring little or no melody, rhythm, or harmony. This type of music tends to challenge the conventional distinction between musical and non-musical sound.

"Noise as music" originated as an avant-garde music style in the 1910s through the work of Luigi Russolo an Italian Futurist, who published the manifesto The Art of Noises in 1913. Elements of noise music were later explored by artists in the Dada and Fluxus movements, as well as through electroacoustic music, modern classical and musique concrète. Composers such as John Cage, Edgard Varèse and James Tenney would explicitly use the term "noise" to describe some of their experimental practices. During the 1960s and 1970s, compositions such as Robert Ashley's "The Wolfman" (1964) and Pauline Oliveros "A Little Noise In The System" (1967) were among the earliest examples of contemporary noise music. While works by non-academic artists such as Lou Reed's Metal Machine Music were influential for later noise artists.