Questions: Canonic Imitation and Structural Analysis

Question 1

A student listening to a Bach canon notices that one voice occasionally deviates from exact pitch-for-pitch replication of the other voice. She concludes the piece is not a 'true' canon. What does this reveal about her understanding?

• A. She is correct — any deviation from exact imitation disqualifies a piece from being called a canon
• B. She is confusing canon with fugue, which requires strict imitation at every point
• C. She misunderstands that canons are defined by their imitation rules (time lag and transposition level), and most allow free passages and harmonic adjustments within that framework
• D. She is applying the wrong standard; canons only require imitation at the beginning and ending cadences

Answer: (C)

Most canons — including many of Bach's — permit free passages, intervallic adjustment, and harmonic adaptation while maintaining the underlying imitation structure. The defining features of a canon are the time lag between voices and the transposition level of the answering voice, not mechanical note-for-note replication throughout. A canon can be 'strict' or 'free' in how closely it adheres to exact imitation, but neither variety requires perfect replication at every moment.

Question 2

In a canon at the fifth above (dux in C major, comes entering a fifth higher), the imitation constraint forces the harmonic progression to behave in a specific way. Which best describes the relationship between imitation rules and harmony?

• A. The imitation rules are melodic constraints only; the composer can choose any harmony independently
• B. Since both voices must agree on consonant intervals at each beat, the time lag and transposition level together determine which harmonic intervals are available, shaping the tonal progression
• C. Strict canons cannot produce tonal harmony because the mechanical imitation overrides harmonic logic
• D. Harmony in canon depends entirely on free passages, since the imitation sections are harmonically indeterminate

Answer: (B)

The imitation rule is not just melodic — it has direct harmonic consequences. When the comes enters at a specified interval and time lag, each moment of the canon involves the dux's current pitch sounding against the comes's current pitch (which is an earlier moment of the same melody transposed). The consonance or dissonance of that vertical interval is determined by the interaction of the imitation rules. The composer must either write a melody whose imitation consistently produces acceptable harmonies, or use free passages to navigate cadential and harmonic goals that strict imitation cannot reach.

Question 3

A fugue is a specific kind of strict canon in which the subject appears in multiple voices with exact intervallic imitation.

• T. True
• F. False

Answer: False

Fugue is a broader, more complex form than canon. While a fugue uses imitative entries (and sometimes employs canonic passages called 'stretto'), it also includes episodes without strict imitation, developmental passages, modulations, and varied treatments of the subject (inversion, augmentation, diminution). A fugue is defined by its procedure of imitative counterpoint, not by strict canonic rule application throughout. Canon is one specific technique that fugue may incorporate; the two are not equivalent.

Question 4

The time lag in a canon — the interval of time between the entry of the dux (leader) and the comes (follower) — is not merely a procedural parameter but directly shapes the harmonic content of the piece.

• T. True
• F. False

Answer: True

Because the comes sounds a delayed version of the dux, the harmonic intervals created at each beat depend on what pitch the dux is playing *now* against what pitch the comes is playing (which is the dux's pitch from the lag duration ago). Changing the time lag changes which pairs of pitches sound simultaneously, and thus changes the harmonic color. A canon at a one-measure lag versus a half-measure lag will produce fundamentally different harmonic textures even with an identical melodic line, because different moments of the melody are combined vertically.

Question 5

How do the imitation constraints in a canon — specifically the time lag and transposition level — generate harmonic progressions rather than merely constraining them? Why does this mean a canon composer cannot independently control melody, counterpoint, and harmony?

Model answer: In a canon, the harmonic intervals at each moment are determined by the transposition of the comes against the current position of the dux — the two voices are the same melody sounding at different times and pitch levels. The composer does not freely choose the harmony; it emerges from the interaction of the melodic line with its own time-shifted, transposed version. This means the three dimensions (melody, counterpoint, harmony) are not independent: the choice of melody and imitation rule fixes the harmony. Composing a good canon therefore requires writing a melodic line whose every vertical alignment with itself — under the given time lag and transposition — produces acceptable harmonic intervals and drives the desired tonal motion.

This interdependence is what makes canon composition technically demanding and analytically rich. When the imitation produces an unwanted dissonance or prevents arrival at a cadence, the composer must adjust the melodic line itself (changing the canon), use a free passage to navigate around the constraint, or accept an unconventional harmonic effect. Understanding this explains why canonic analysis focuses on tracing the imitation rules first — the harmony is a consequence of those rules, not an independent design choice.