Tonicization

What it means

Tonicization is the brief touching of another key without actually leaving the home key. One or a few chords momentarily suggest a foreign key, usually through a secondary dominant or a short-lived key reference, before the music returns to its starting point.

Musical use

Tonicization most often happens through a secondary dominant: a dominant seventh chord that belongs not to the main key but to a scale degree within it makes that degree sound, for a moment, like a key of its own, without a full modulation process complete with a new cadence and a lasting sense of a new key. Briefly touching the relative key or the dominant key within a phrase also counts as tonicization.

Tonicization should be distinguished from modulation: modulation establishes the new key as a genuine goal, usually confirmed by its own cadence, whereas tonicization stays episodic – the home key remains the point of reference during and after it. German music theory calls this brief touching of another key Ausweichung ("evasion").

Tonicization is especially common in Viennese Classicism and nineteenth-century music, where it enlivens development sections and transitional passages harmonically without abandoning a movement's overarching key structure.

Performance practice

To spot a tonicization, watch for chromatic, out-of-key notes that resolve quickly without a new cadence following. When performing such a passage, you can bring out its brief harmonic color with a slight delay or emphasis, without overstating it.