Maurice Martenot, a cellist and radio telegraphist, met Leon Theremin in 1923 which lead Martenot to design an electronic instrument. The first model was patented on the 2nd of April 1928. He called his invention the "Ondes Martenot" (Martenot's waves). The player's right hand plays the keyboard while the left hand controls dynamics and timbre by manipulating switches that control filters. The keyboard allows lateral movement of the keys allowing the player to have vibrato by wiggling her finger. One function allows for a wide glissando where the player moves a finger ring attached to the metal ribbon which controls the frequency.