and so helps delay the
arrival of the home key of A until the downbeat of bar 6. (Ger. Tonikalisierung).
The
act of establishing a new key centre, or of giving a degree other than the
first the role of tonic. This is accomplished by emphasizing the crucial
properties of that tonic, in particular its fourth scale degree and leading
note, both of which are part of its dominant 7th chord. For example, at the
beginning of the slow movement of Mozart's String Quartet k160/159a
(ex.1), the first chord tonicizes B and so helps delay the
arrival of the home key of A until the downbeat of bar 6.
Haydn's String Quartet op. 74 no.1 begins with a V7–I progression; though the first chord is not a tonic, it nevertheless ‘tonicizes’ the home key of C major. By contrast, the opening chord of Beethoven's First Symphony, a tonic chord with an added flattened 7th, behaves initially as a V7 of IV and so tonicizes the subdominant, F (see Cadence, ex.15).
The term Tonikalisierung originates in the second part of Heinrich Schenker's Harmonielehre (1906, chaps. 2–3), where examples of tonicization are used to show how one diatonic collection can be musically enriched by the implication of another (through the presence of a single foreign note), and how the concept of Stufe (i.e. a significant harmony identified with a particular scale degree) is more useful than the notion of transitory modulation.
The term ‘tonicization’ is sometimes used in a non-Schenkerian context to characterize modulation at a low level, where a new key is touched on only briefly.
WILLIAM DRABKIN