The AKAI EWI 4000S is a wind instrument controller designed to be used with synthesizers and other electronic instruments. It is a type of electronic wind instrument (EWI) that uses a breath sensor, finger keys, and a pitch bend wheel to control the sound. The EWI 4000S is capable of producing a wide range of sounds, including acoustic, electric, and synthesized sounds. It also includes a built-in vocoder, which allows the user to create vocal-like sounds.