Key (music)

In music theory, the key identifies the tonic triad, the chord, major or minor, which represents the final point of rest for a piece, or the focal point of a section. Although the key of a piece may be named in the title (e.g. Symphony in C), or inferred from the key signature, the establishment of key is brought about via functional harmony, a sequence of chords leading to one or more cadences. A key may be major or minor; music in the Dorian, Phrygian, and so on are usually considered to be in a mode rather than a key. When a particular key is not being described in the English language, different key naming systems may be used.

The concept of Keys in composition and the effects thereof

In Western musical composition, the key of a song has important ramifications for its composition:

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• As noted earlier, certain instruments are said to be designed for a certain key, as playing in that key can be physically easier or harder. Thus the choice of key can be an important one when composing for an orchestra, as one must take these elements into consideration.
• In the world of the professional clarinettist, for example, it is common to carry two instruments tuned a semitone apart (B-flat and A) to cope with the needs of composers. Even so, it is not unheard of for a piece published in B-flat to include notes a semitone (or more) below the range of the common B-flat clarinet. The piece must then be played on a more exotic instrument, or transposed by hand (or at sight) for the slightly larger 'A' clarinet. As a last resort, it is also not unheard of for a player to roll up a page of the score and insert it into the end of the instrument in order to lengthen it.
• Besides this though, the timbre of almost any instrument is not the exactly the same for all notes played on that instrument. For this reason a song that might be in the key of C might sound or "feel" somewhat different (besides being in a different pitch) to an observer if it is transposed to the key of A. This effect is more pronounced on instruments like the piano where certain notes have more strings associated with them or a thicker string. However, it is observed that some musicians overstate this element, and in fact this is a joke in the movie This Is Spinal Tap where the singer says something like "D is the saddest chord".
• In addition, since many composers often utilized the piano while composing, the key chosen can possibly have an effect over the composing. This is because the physical fingering is different for each key, which may lend itself to choosing to play and thus eventually write certain notes or chord progressions compared to others, or this may be done on purpose to make the fingering more effecient if the final piece is intended for piano.