The album was the first piece in popular music to incorporate the Electro - Theremin as well as the first in rock music to feature a theremin - like instrument .
The Electro - Theremin is an easier - to - play version of the theremin .
The album was the first piece in popular music to incorporate the Electro - Theremin , an easier - to - play version of the theremin , as well as the first in rock music to feature a theremin - like instrument .