EWI (an acronym for electric wind instrument, pronounced EE-wee) is the name of a wind controller, an electronic musical instrument invented by Nyle Steiner. The early models consisted of two parts: a wind controller and a synthesizer in a rackmount box. One of the current models from Akai, the EWI4000S, combines the two parts into one, placing the synthesizer in the lower section of the controller. It uses the Boehm fingering system and is designed to be similar in action to a soprano saxophone, although players familiar with the clarinet should have no problem adjusting to the fingering; the EWI instruments can also be played with a simpler fingering system that recorder players can play with very little adjustment. Modern instruments also can be switched to flute, oboe, and saxophone fingering modes. The EWI4000s and EWI USB also have a special EVI (acronym for electronic valve instrument) fingering mode that allows brass players to play the EWI. Similar to a soprano sax or clarinet, it is straight with a slight curve just below the mouthpiece, and is held in front of the body with a neck strap. Available models include the EWI4000s, EWI5000, and the EWI USB. There are also homemade and experimental EWIs with different designs.
The wind controller part of the EWI has a silicone mouthpiece with sensors for air pressure (volume control) and teeth pressure (vibrato). The EWI keys do not move, but work through electrical capacitance, sensing the positioning of the fingers by body capacitance; this allows for very fast playing. The octave is determined by a set of rollers operated by the left thumb, and portamento by a touch plate next to the rollers. Pitch bending is handled by two touch plates operated by the right thumb. The EWI can also be used to control a synthesizer. While earlier EWIs have to be attached to a specific synth module, the EWI4000s model can connect to any synthesizer using a standard MIDI output connector, while the EWI USB has only a USB connector which allows it to connect directly to any computer that has USB ports. The EWI4000s can be connected to a computer either indirectly, through a synthesizer module (connected to a computer) to which it is already connected via MIDI, or directly, by means of a MIDI-to-USB interface box or bus card. Once an EWI is connected to a computer, it can be used to play any software synthesizer that is installed.