Musically, the song is quite sparse, centering on Harvey's vocals – which have an airy, otherworldly quality to them – and a subtle, repetitive piano melody. According to critic Joshua Klein, "the simple repetitive pattern that gently drives 'When Under Ether' drips with menace."Klein, Joshua (2007). "PJ Harvey: White Chalk Review", Pitchforkmedia.com. Joshua Klein, 24 September 2007. Retrieved 10 June 2008. Drums, autoharp, and organ accompany the main components of the song and are low in the mix.
