Musique concrète
However, noise music may consist mainly of noise. Musique concrète often consists only of sound samples of non-musical nature, sometimes in random juxtaposition. Ambient music may consist of recordings of wildlife or nature. The arrival of these avant-garde forms of music in the 20th century have been a major challenge to traditional views of music as being based around melodies and rhythms, leading to calls for broader characterizations.