difference tone

… by his discovery of the difference tone, also called the Tartini tone, a third note heard when two notes are played steadily and with intensity. He also devised a theory of harmony based on affinities with algebra and geometry, set forth in his Trattato di musica (1754; “Treatise on Music”)…

There are two varieties: difference tones (D) and summation tones (S), generated respectively by the frequency differential of the two pitches or the sum of their frequencies. The most commonly heard are difference tones lying below the original pitches; these were discovered by the celebrated violinist-composer Giuseppe Tartini (1692–1770),…

difference tones,