"Experiment IV" is a song by the British singer Kate Bush. It was released as a single on 27 October 1986, in order to promote Bush's greatest hits album The Whole Story. The single peaked at 23 in the UK Singles Chart, simultaneously with "Don't Give Up", Bush's duet with Peter Gabriel, which reached number 9.

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).

The song is also notable for featuring Nigel Kennedy on violin, who at one point replicates the screeching violins from Bernard Herrmann's famous scoring of the shower scene in Alfred Hitchcock's 1960 film Psycho. At the end of the song a helicopter is heard which was taken from Pink Floyd's "The Happiest Days of our Lives" from their 1979 album, The Wall.

Catherine "Kate" Bush (born 30 July 1958) is an English singer-songwriter, musician and record producer. Her eclectic musical style and idiosyncratic vocal style have made her one of the United Kingdom's most successful solo female performers of the past 30 years.

In 1978, at the age of 19, Bush topped the UK Singles Chart for four weeks with her debut single "Wuthering Heights", becoming the first woman to have a UK number one with a self-written song. She has since released ten albums, three of which topped the UK Albums Chart, and has had 25 UK Top 40 hit singles including the Top 10 hits "Wuthering Heights", "Running Up that Hill", "King of the Mountain", "Babooshka", "The Man with the Child in His Eyes", and "Don't Give Up".

In 1987, she won a Brit Award for Best British Female Solo Artist, and in 2002, her songwriting ability was recognised with an Ivor Novello Award for Outstanding Contribution to British Music. During the course of her career, she has also been nominated for three Grammy Awards. After her 1979 tour – the only concert tour of her career – Bush released the 1980 album Never for Ever, which made her the first British solo female artist to top the UK album charts and the first female artist ever to enter the album chart at Number 1. She is also the first (and to date only) female artist to have Top 5 albums in the UK charts in 5 successive decades.