Hoover sound refers to a particular synthesizer sound in electronic music, commonly used in gabber and hard house. Originally called the "Mentasm" or "Dominator", the name that stuck was the one likening the sound to that of a vacuum cleaner (often referred to via the genericized trademark "hoover" in the UK and Ireland).
The Hoover is a complex waveform that can be created with three oscillators, each spaced an octave apart, a heavy use of pulse-width modulation and a thick chorus effect. The sound is characterised by its thick swirliness that stems from a fast LFO controlling the PWM and the chorus, It was originally created by Eric Persing for the Roland Alpha Juno, although the term 'hoover' was not introduced by him.
It is traditionally created with the Roland Alpha Juno-2, Alpha Juno 1, or rack mount version MKS-50 synthesizer using the built-in What the patch. The hoover sound generated on these synthesizers is unique for the use of a "PWM" sawtooth wave, which inserts flat segments of variable width into a sawtooth waveform.
The hoover sound is believed to first have appeared in a commercial production in "Mentasm" by Second Phase (1991), produced in a collaboration between Joey Beltram and Mundo Muzique, and sometimes is referred to as a "mentasm". However, mentasm normally refers to the sound sampled from this tune and re-used.
Another notable use of a record using a hoover sound is "Dominator" by Dutch techno pioneers Human Resource. This track gained fame in 1991 and became a top 10 hit worldwide. Characteristic for this track was not only the Hoover, but also the over the top rap: "I'm bigger and bolder and rougher and tougher, in other words, sucker, there is no other... I'm the one and only dominator.. Wanna kiss myself!"