The song tells a story about a secret military plan to create a sound that is horrific enough to kill people. The ending of the story is unclear, but in the music video nearly every person working on the project is killed by the horrific sound, which is personified by Bush herself as she changed from an angelic woman into a banshee (a horrifying screaming apparition of Irish lore).
On the B-sides of both the 7" and 12" singles a re-working of "Wuthering Heights" was included, the song which catapulted her to stardom in 1978. On the 12" single the 1980 song "December Will Be Magic Again" was included as an additional B-side.
An extended version of "Experiment IV" appeared on the 12" vinyl release of the single. Both versions of the song were included on the second CD, second cassette or second LP of rarities on the This Woman's Workbox set released in 1990.
The music video for the song adapts the "storyline", and chronicles the destruction of a secret military installation by a creature made of sound. The science fiction film-in-miniature includes appearances from Dawn French, Hugh Laurie, Gary Oldman, Richard Vernon, Peter Vaughan and Del Palmer. Bush appears on screen as an orderly officer serving tea, as the sound creature and at the end entering a van. The video was banned from Top of The Pops because it was considered too violent.