A phrase is a length of musical material existing in real time with a discernible beginning and ending. Phrases are usually eight to sixteen measures in length but may be longer. When relating musical phrases to melodic lines, it is important to realize that while melodies are comprised of complete phrases of patterned tones, each individual melodic phrase may be broken down into smaller incomplete units of melodic structure known as motives . In sum, the micro level or musical structure is comprised of two units the smaller and incomplete motive , and the larger and complete phrase . The mid-level of musical structure is made up of sections of music.
Phrases combine to form larger sections of musical structure.
Sections are punctuated by strong cadences . Longer songs and extended pieces of music are usually formed into two or more complete sections, while a shorter song or melody may be formed of phrases and have no sectional structure. At the macro-level of musical structure exists the complete work formed of motives , phrases and sections . This is the manner in which Western music is conceptualized as structure. Many other world musics are conceptualized in a similar manner.