(Ger. Viertelton). Half a SEMITONE. An INTERVAL used by some modern composers, and also used in some non-Western music.

Quarter tones are not modern inventions. They are found in the ancient Greek enharmonic scale. Many ROMANTIC composers of the 19th century thought of reviving quarter tones. George Ives, father of CHARLES IVES and an Army bandleader during the Civil War, experimented with tuning his instruments a quarter tone apart.

The attraction of quarter tones for modern composers is explained by the desire to develop a finer and more subtle means of musical expression. A pioneer of the modern revival of quarter tones was Julián Carrillo of Mexico, who published a treatise on Sonido 13 in 1895. Alois Hába of Czechoslovakia codified the usages of quarter tones in his Neue Harmonielehre, published in 1928.

The first quarter-tone piano (with two keyboards tuned a quarter tone apart) was built in 1924. NIKOLAI RIMSKY-KORSAKOV'S grandson Georg founded a quarter-tone society in Leningrad in the 1920s. The Russian Ivan Wyschnegradsky wrote much music for two pianos tuned a quarter tone apart. Ives wrote a chorale for strings in quarter tones as early as 1914.

Several systems of notation for quarter tones have been proposed, the most logical of which is the one by Hába using slashed signs for flats and sharps. ERNST BLOCH used quarter tones in his Piano Quintet, notated simply as flatted or sharped notes.

See also MICROTONALITY.