A student classifies the minor seventh as consonant, arguing it 'sounds fuller and richer' than the minor second. What is the error in this reasoning?
AThe student is right — the minor seventh is a consonance in most tonal contexts
BConsonance and dissonance are not determined by perceived richness or fullness, but by whether an interval creates harmonic tension requiring resolution — the minor seventh does, so it is dissonant
CBoth the minor seventh and the minor second are consonances; neither requires resolution
DThe minor seventh is consonant only when it appears between upper voices, not above the bass
The student is confusing acoustic richness (a perceptual quality of timbre and complexity) with harmonic stability (the functional question of whether an interval requires resolution). A minor seventh may sound 'full' in isolation, but in tonal music it creates tension that demands resolution — typically by one voice moving down by step. Consonance and dissonance are functional categories: dissonances drive harmonic motion by creating expectations; consonances fulfill them. Size alone does not determine which category an interval belongs to.
Question 2 Multiple Choice
In a four-voice chorale, a perfect fourth appears between two upper voices. In a second version, the same interval appears between the bass and a tenor voice. Which statement correctly describes these two contexts?
ABoth instances sound equally consonant because the interval size and quality are identical
BBoth instances are dissonant and require the same voice-leading resolution
CThe upper-voice instance functions as a consonance; the above-bass instance functions as a dissonance requiring resolution
DThe perfect fourth is always dissonant regardless of register or voicing
The perfect fourth is the canonical borderline case in tonal consonance/dissonance. Between two upper voices, it sounds stable and consonant — it can sit without resolving. But when a perfect fourth appears above the bass, it creates a second-inversion chord (6/4), which functions as a dissonance in tonal voice leading: the fourth must resolve downward to a third. This context-dependence is not arbitrary — it reflects the role the bass plays as the harmonic foundation. The same interval can be consonant or dissonant depending on its relationship to the lowest voice.
Question 3 True / False
The tritone is the most harmonically unstable interval in tonal music, spanning exactly half an octave, and requires resolution in voice leading.
TTrue
FFalse
Answer: True
The tritone (augmented fourth or diminished fifth) divides the octave precisely in half and creates maximum tonal instability. In a dominant seventh chord, the tritone between the third and seventh is what drives the chord's resolution: the two voices move inward (diminished fifth resolving to a third) or outward (augmented fourth resolving to a sixth). Composers have used the tritone's tension and instability deliberately throughout tonal music, and 20th-century composers exploited unresolved tritones specifically for their unsettling effect — which only works because the expectation of resolution is so strong.
Question 4 True / False
In tonal music, larger intervals are generally more dissonant than smaller intervals.
TTrue
FFalse
Answer: False
This is a common misconception: interval size and dissonance are not correlated. Major and minor thirds (smaller intervals) are imperfect consonances — restful and stable. Major and minor sixths (larger intervals) are also consonant. Meanwhile, the minor second (very small) and major seventh (large) are both dissonant. The tritone, a medium-sized interval, is the most dissonant. Consonance and dissonance reflect acoustic and functional properties of the interval, not its size. A student who relies on size as a proxy for dissonance will misclassify most intervals.
Question 5 Short Answer
Why is the perfect fourth classified as a 'borderline' case in consonance/dissonance classification, and what determines whether it functions as a consonance or dissonance in practice?
Think about your answer, then reveal below.
Model answer: The perfect fourth is borderline because its classification is context-dependent rather than fixed. Between two upper voices in a chord or two-voice texture, the fourth sounds stable and consonant — it does not create tension requiring resolution. But when the perfect fourth appears above the bass voice, it creates a second-inversion sonority (a 6/4 chord) that functions as a dissonance in tonal voice leading: the fourth is heard as an unstable suspension over the bass that must resolve downward by step to a third. The determining factor is the interval's relationship to the bass: the bass is the harmonic foundation, and a fourth built on it creates a conflict between the bass pitch and the expected root-position harmony above it.
This context-dependence reveals that consonance/dissonance is not purely an acoustic property of an interval in isolation — it is a functional property that depends on harmonic context. The same interval can fulfill different roles. This is why the interval must be analyzed within its voice-leading and harmonic context, not simply classified by its size or quality.