Friday, November 6, 2009

Naming the notes of a scale

In many musical circumstances, a specific note of the scale will be chosen as the "tonic" – the central and most stable note of the scale. Relative to a choice of tonic, the notes of a scale are often labeled with numbers recording how many scale steps above the tonic they are. For example, the notes of the C diatonic scale (C, D, E, F, G, A, B) can be labeled {1, 2, 3, 4, 5, 6, 7}, reflecting the choice of C as tonic. The term "scale degree" refers to these numerical labels. In the C diatonic scale, with C chosen as tonic, C is the first scale degree, D is the second scale degree, and so on.


Note that such labeling requires the choice of a "first" note; hence scale-degree labels are not intrinsic to the scale itself, but rather to its modes. For example, if we choose A as tonic, then we can label the notes of the C diatonic scale using A = 1, B = 2, C = 3, D = 4, and so on.


The scale degrees of a heptatonic (7-note) scale can also be named using the terms tonic, supertonic, mediant, subdominant, dominant, submediant, subtonic. If the subtonic is a semitone away from the tonic, then it is usually called the leading-tone (or leading-note); otherwise the leading-tone refers to the raised subtonic. Also commonly used is the (movable do) solfège naming convention in which each scale degree is given a syllable. In the major scale, the solfege syllables are: Do, Re, Mi, Fa, So (or Sol), La, Ti (or Si), Do (or Ut).




Scales may also be shown as semitones (or fret positions) as e.g. 0 2 4 5 7 9 11 for C-D-E-F-G-A-B.


All these naming systems, except for heptatonic/diatonic interval naming, are restricted to scales for a 12 note octave division, not distinguishing sharps and flats.

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