"Scat singing" is the term for jazz vocal improvisation. This means that while the chord changes of the song are played by the rest of the band, the singer creates his/her own melody and rhythm, instead of singing what what originally written by the composer. However, instead of lyrics, syllables are used, such as 'bee,' 'bop,' 'det,' etc. Singers choose their syllables to emulate specific instruments, such as a saxophone or trumpet. The singer's entire solo is referred to as his/her "scat."