|This article does not cite any references or sources. (October 2006)|
A music roll is a storage medium used to operate a mechanical musical instrument. They are used for the player piano, mechanical organ, electronic carillon and various types of orchestrion. The vast majority of music rolls are made of paper. Other materials that have been utilized include thin card (Imhof-system), thin sheet brass (Telektra-system), composite multi-layered electro-conductive aluminium and paper roll (Triste-system) and, in the modern era, thin plastic or PET film.
The music data is stored by means of perforations. The mechanism of the instrument reads these as the roll unwinds, using a pneumatic, mechanical or electrical sensing device called a tracker bar, and the mechanism subsequently plays the instrument.
After a roll is played, it is necessary for it to be rewound before it can be played again. This necessitates a break in a musical performance. To over come this, some instruments were built with two player mechanisms allowing one roll to play while the other rewinds.
Each hole is connected to a valve in the interior of the organ which operates the organ pipes such as these wooden ones.
See also 
|This technology-related article is a stub. You can help Wikipedia by expanding it.|