Questions: Tonicization and Secondary Dominants

Question 1

In C major, you hear the chord A7 (A dominant seventh) followed by G major, then a continuation clearly in C major. How should you analyze this harmonic event?

• A. A modulation to A major that briefly returns to C major
• B. Tonicization of the V chord (G major) via a secondary dominant — V7/V makes G sound briefly like a local tonic, then the original key continues
• C. A borrowed chord from A minor inserted for coloristic interest
• D. An error in voice leading, since A7 does not belong to C major

Answer: (B)

A7 is V7/V in C major — the dominant of the dominant. The C# in A7 functions as a chromatic leading tone that pulls toward D (the third of G major), giving the G chord a sense of arrival that a plain G never achieves. But the music continues in C major — no cadence establishes a new key center. This is tonicization: a momentary harmonic spotlight on G, not a departure from C. The A7 passes; G doesn't become home.

Question 2

A student hears E7 followed by Am in a C major piece and announces: 'The piece has modulated to A minor.' What is most likely wrong with this analysis?

• A. E7 does not resolve to Am in proper voice leading
• B. A single secondary dominant (V7/vi) constitutes tonicization, not modulation — modulation requires a cadential confirmation and sustained time in the new key
• C. The student has correctly identified a modulation, but to A major, not A minor
• D. E7 can only appear in minor keys, so no modulation from C major is possible

Answer: (B)

V7/vi (E7 → Am in C major) is tonicization: the E7 gives Am a brief sense of being a local tonic, then the progression moves on. Modulation requires establishing the new key with a cadence and staying there — a single secondary dominant that resolves and moves on is always tonicization. The student heard the chromatic E7 and jumped to 'modulation,' which is the classic confusion between a brief harmonic detour and a genuine key change.

Question 3

A secondary dominant chord introduces at least one chromatic note that does not belong to the original key, which is the audible signal that tonicization is occurring.

• T. True
• F. False

Answer: True

The 'borrowed leading tone' is chromatic relative to the home key — that's what makes it a secondary dominant rather than a diatonic chord. In C major, A7 contains C#, which doesn't belong to the key; E7 contains G#; D7 contains F#. When your ear hears a note that seems 'too bright' or 'outside,' that chromatic note is often the raised leading tone of a secondary dominant announcing a brief tonicization. Training yourself to notice these chromatic arrivals is the ear-training skill.

Question 4

The distinction between tonicization and modulation is primarily about quantity — one or two secondary dominants indicate tonicization, while three or more in succession indicate modulation.

• T. True
• F. False

Answer: False

The distinction is about duration and cadential commitment, not the count of secondary dominants. A single secondary dominant followed by a cadence in the new key and sustained time there IS modulation. Multiple secondary dominants that all resolve and return to the original key are still tonicization. The right question is: does the music commit to the new tonal center with a cadence and stay there? If yes, it's modulation. If the progression returns without establishing the new center, it's tonicization regardless of how many secondary dominants appeared.

Question 5

What is the crucial difference between tonicization and modulation, and how would you use it to correctly analyze a passage?

Model answer: Tonicization is a momentary harmonic spotlight — a secondary dominant makes one chord sound briefly like a local tonic, but the original key continues without cadential commitment to the new center. Modulation genuinely establishes a new tonic: the new key is confirmed with a cadence and the music stays there. To analyze a passage, ask: after the secondary dominant resolves, does the music continue as if the new chord is home (with a cadence and extended time there), or does it move on? If it moves on, it's tonicization; if it cadences and commits, it's modulation.

A useful metaphor from the explainer: tonicization is a brief glance in another direction — your ear turns toward a new tonic, then turns back. Modulation is actually walking there. The structural test is always cadential: has the music gone through the effort of establishing a new key, or was the secondary dominant a passing accent?