Quarter tone
The quarter-tone music, based on micro-intervals, created in the period from about 1920 in Central Europe as a branch of New Music. Here, a semitone our traditional tonal system is again halved, so that individual sounds in the distance of 50 cents is generated. Thus, there are 24 different pitches in the octave. For the special notation quarter-tone accidentals have been developed.
For fretless stringed instruments, the production of these sounds is not a technical problem, like for example, even with the slide trombone.
For keyboard instruments Willi Mollendorff invented a special keyboard with additional buttons. Any equipped bichromatic harmonium he presented in 1917 before the public. This keyboard but not prevailed. Other composers used quartertone
- Two conventional pianos that were voted shifted up 50 cents, or
- A special piano with additional strings and two manuals. Such an instrument of the company August Förster, Lobau is now in the National Museum in Prague " Czech Museum of Music ".
For brass instruments except the trombone, a special valve is fitted, which tube length is changed by about 3 % (most extended).
More difficult is the realization of woodwind instruments with predominantly flaps. In the Museum of Musical Instruments Mark Neukirchen exists a clarinet for quarter-tone music: This instrument mouthpiece after a changeover valve is fitted, which allows the use of two acoustically separate air columns with the respective proportional correctly drilled tone holes. Always both flap systems are equally operated Due to the design at each handle combination.
As composers have emerged except Willi Mollendorff Alois Haba, Ivan Alexandrovich Wyschnegradsky, Viktor Ullmann, Charles Ives or György Ligeti.
Others
The jazz musician Don Ellis wrote in 1975 the book Quarter Tones, a theoretical guidance for the use of quarter tones. It is very detailed and provides a high degree of historical and cultural backgrounds. It's hard to find because it was probably no longer reprinted after its first edition. Ellis also invented a trumpet with four valves to play quarter tones.