AccordionAccordions (from 19th-century German Akkordeon, from Akkord—"musical chord, concord of sounds") are a family of box-shaped musical instruments of the bellows-driven free reed aerophone type (producing sound as air flows past a reed in a frame). The essential characteristic of the accordion is to combine in one instrument a melody section, also called the diskant, usually on the right-hand manual, with an accompaniment or Basso continuo functionality on the left-hand.
Tala (music)article A tala (IAST tāla) literally means a 'clap, tapping one's hand on one's arm, a musical measure'. It is the term used in Indian classical music similar to musical meter, that is any rhythmic beat or strike that measures musical time. The measure is typically established by hand clapping, waving, touching fingers on thigh or the other hand, verbally, striking of small cymbals, or a percussion instrument in the Indian subcontinental traditions.
Interval graphIn graph theory, an interval graph is an undirected graph formed from a set of intervals on the real line, with a vertex for each interval and an edge between vertices whose intervals intersect. It is the intersection graph of the intervals. Interval graphs are chordal graphs and perfect graphs. They can be recognized in linear time, and an optimal graph coloring or maximum clique in these graphs can be found in linear time. The interval graphs include all proper interval graphs, graphs defined in the same way from a set of unit intervals.
Pitch classIn music, a pitch class (p.c. or pc) is a set of all pitches that are a whole number of octaves apart; for example, the pitch class C consists of the Cs in all octaves. "The pitch class C stands for all possible Cs, in whatever octave position." Important to musical set theory, a pitch class is "all pitches related to each other by octave, enharmonic equivalence, or both." Thus, using scientific pitch notation, the pitch class "C" is the set {Cn : n is an integer} = {..., C−2, C−1, C0, C1, C2, C3 ...}.
