Simplify the following text for a Grade 9 native English-speaking person.
Original: The terpsitone was an electronic musical instrument , invented by LÃ on Theremin , which consisted of a platform fitted with space-controlling antennae , through and around which a dancer would control the musical performance .
Simplified: The terpsitone was an electronic musical instrument invented by LÃ on Theremin . It consisted of a platform fitted with antennas , through and around which a dancer would control the musical performance .