In the 1920s, artists and audiences experienced the invisible interface and mysterious voice of the Russian-made Theremin, and witnessed the unusual technique and sounds that only the French-designed Ondes Martenot could produce.  These instruments, and others, inspired the innovators who followed; in particular, nearly a century later, the Ondes Martenot captured the imagination of a group of friends from France who formed Expressive E just about a decade ago.