combination tone

In music, an acoustical phenomenon in which a third faint tone is heard when two notes are sounded loudly together. The frequency of the combination tone is the difference between the numerical frequencies of the two notes (see hertz). For example, given note 1 = 500 Hz, and note 2 = 300 Hz, the combination tone is: 500 Hz – 300 Hz = 200 Hz. Combination tones are often used and manipulated in electronic music.