A hi-hat (hihat, high-hat, etc.) is a combination of two cymbals and a pedal, all mounted on a metal stand.

Algorithmic composition is the technique of using algorithms to create music.

Data sonification is the presentation of data as sound using sonification. It is the auditory equivalent of the more established practice of data visualization.

Ultrasound wave is produced when an electric current is applied to an array of piezoelectric crystals. 

Quadraphonic sound uses four audio channels in which speakers are positioned at the four corners of a listening space.