During her time at Columbia, Carlos met Robert Moog at the annual Audio Engineering Society show, which began a partnership; Carlos gave advice and technical assistance in the development of the Moog synthesizer, Moog's new electronic keyboard instrument, convincing Moog to add a touch-sensitive device for greater musical dynamics, among other improvements. By 1966, Carlos owned a small Moog synthesizer, which she used to record sound effects and jingles for television commercials, which earned her "anywhere from $100 to $1000.” In 1967, Carlos befriended Rachel Elkind, a former singer who had a musical theatre background and worked as a secretary for Goddard Lieberson, then-president of Columbia Records. The two shared a home, studio, and business premises in a brownstone building in the West Side of Manhattan in New York City.