Key (music)
In Music theory,key istonal center ofpiece. Itdesignated bynote name (the tonic), such as C,can be eithermajor or minor mode. Other modesalso possible,example: dorian, phrygian, lydian, but most popular music uses eithermajor (Ionian)minor (aeolian) modes. 18th19th century music also tendsfocus on these modes.The major mode has half-steps between scale steps 3478. The natural minor mode has half-steps between 2356.
Whatkey designates toperformer isscalewhich alldiatonic notes ofpiece lie. Thisslightly more complicated inminor key, becausepitch ofsixthseventh scale degrees inminor key can change depending on their harmonic context. The primary key ofpiecemusicindicated atbeginning ofpiece withkey signature.
A piece may change key at some point. Thiscalled modulation. Modulationsometimes done by just starting innew keyno preparation - this kindkey changecommonvarious kindspopular music, whensudden change tokeywhole tone higher isquite frequently heard device atend ofsong. In classical music, however,"smoother" kindkey changemore usual -- this kindkey changecalled modulation.
Certain musical instrumentssometimes saidplay incertain key, or have their music written incertain key. Instruments which do not play inkeyCknown as transposing instruments. The most common kindclarinet,example,saidplay inkeyB flat. This means thatscale writtenC majorsheet music will actually sound asB flat major scale when played; that is, notes soundwhole tone lower than written. Likewise,French horn, normally inkeyF, plays notesmajor fifth lower than written.
Similarly, some instruments may be saidbe built incertain key. A brass instrument built in, say, B flat, will playfundamental noteB flat,will be ableplay notes inharmonic series starting on B flat without using valves, fingerholes, slides or otherwise alteringlength ofvibrating columnair. An instrument built incertain key will often, but not always, have its music written insame key (see trombonean exception).
