Improve your music ear and understanding the structure of music.
As we play the theremin by ear, it helps if you have more experience with ear training. The exercises in this category combine some music theory and solfeggio experience. They aim to help your ear to find audio references and bring the system in understanding what a melody is built of. It might be helpful to play them on a keyboard and/or to sing them first. You find it helpful watching Anca Bold Martin | Recognizing Intervals