Theremin has 2 antennae controlling pitch & volume respectively.

Download scientific diagram | Theremin has 2 antennae controlling pitch & volume respectively.   from publication: Towards anthropomorphic robot Thereminist | Theremin is an electronic musical instrument considered to be the most difficult to play which requires the player's hands to have high precision and stability as any position change within proximity of the instrument's antennae can make a difference to the pitch or volume. | Musical Instruments, Electronic Music and Play | ResearchGate, the professional network for scientists.

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