section_path: User interfaces
section_name: User interfaces
paragraph_text: User interfaces
  
  Regardless of how the sound is produced, many musical instruments have a keyboard as the user interface. Keyboard instruments are any instruments that are played with a musical keyboard, which is a row of small keys that can be pressed. Every key generates one or more sounds; most keyboard instruments have extra means (pedals for a piano, stops and a pedal keyboard for an organ) to manipulate these sounds. They may produce sound by wind being fanned (organ) or pumped (accordion), vibrating strings either hammered (piano) or plucked (harpsichord), by electronic means (synthesizer), or in some other way. Sometimes, instruments that do not usually have a keyboard, such as the glockenspiel, are fitted with one. Though they have no moving parts and are struck by mallets held in the player's hands, they have the same physical arrangement of keys and produce soundwaves in a similar manner. The theremin, an electrophone, is played without physical contact by the player. The theremin senses the proximity of the player's hands, which triggers changes in its sound. More recently, a MIDI controller keyboard used with a digital audio workstation may have a musical keyboard and a bank of sliders, knobs, and buttons that change many sound parameters of a synthesizer.