The Phrygian cadence rule defines a distinctive harmonic progression primarily found in minor keys, characterized by a subdominant chord in first inversion (iv6) moving to the dominant chord (V). This creates a specific "Phrygian" sound, often used to indicate a half cadence, leaving a sense of anticipation.
Understanding the Phrygian Cadence
At its core, the Phrygian cadence is a unique type of half cadence. Unlike other cadences that aim for resolution, a half cadence creates a moment of repose or a pause on the dominant chord, signaling that the music is not yet complete.
- Chord Progression: The fundamental rule dictates a progression from the subdominant chord in its first inversion (notated as iv6 in a minor key) directly to the dominant chord (notated as V).
- Bass Line Movement: A crucial defining characteristic involves the bass line. The root of the final chord (the dominant, V) is approached from a half step above. For example, in C minor, the
iv6chord would be F-Ab-C with Ab in the bass. TheVchord is G-B-D with G in the bass. The bass moves from Ab to G, a descending half step, where Ab is indeed a half step above G. This particular bass motion is central to the cadence's distinctive feel.
Key Characteristics and Voice Leading
The unique sonic signature of the Phrygian cadence comes from several contributing factors:
- Minor Key Context: It is almost exclusively found in minor keys, leveraging the specific intervallic relationships inherent to the minor mode.
- First Inversion Subdominant (iv6): The use of the subdominant chord in its first inversion means the third of the chord is in the bass. In a C minor
ivchord (F-Ab-C), theiv6has Ab in the bass. This Ab (the flattened sixth scale degree) then resolves down by a half step to the dominant's root (G, the fifth scale degree). - Half-Step Bass Motion: As noted, the bass line descends by a half step from the 6th scale degree (of the minor scale) to the 5th scale degree, leading directly to the dominant chord. This specific melodic movement in the lowest voice is highly characteristic and creates its "Phrygian" flavor.
- Function as a Half Cadence: It typically marks the end of a phrase or a section, creating a temporary pause before the music continues, rather than a final resolution.
Examples and Context
The Phrygian cadence was particularly common in Baroque music, especially within slow movements or as a lead-in to a new section.
Example in C Minor:
Consider a simple progression:
| Chord 1 (iv6) | Chord 2 (V) |
|---|---|
| Ab - C - F (Ab in bass) | G - B - D (G in bass) |
Here, the bass moves from Ab to G, a descending half step, which aligns with the rule that the root of the final chord (G) is approached from a half step above (Ab).
Practical Insights:
- Sense of Gravity: The half-step descent in the bass creates a strong sense of gravity pulling towards the dominant, making it feel weighty and conclusive for a half cadence.
- Dramatic Effect: Composers like J.S. Bach frequently employed this cadence to create a solemn or reflective mood, often appearing at the end of slow movements in sonatas or concertos, or within chorales.
Distinguishing from Other Cadences
While the Phrygian cadence is a type of half cadence (ending on V), it differs from other common cadences:
- Perfect Authentic Cadence (PAC): V-I (or V-i in minor) with both chords in root position and the tonic in the soprano. Provides a strong, definitive resolution.
- Imperfect Authentic Cadence (IAC): Also V-I (or V-i), but either chords are inverted, or the soprano does not end on the tonic. Less conclusive than a PAC.
- Plagal Cadence (PC): IV-I (or iv-i in minor). Often called the "Amen" cadence, it offers a gentler resolution.
- Deceptive Cadence (DC): V-vi (or V-VI in minor). Creates an unexpected resolution, diverting from the anticipated tonic.
The Phrygian cadence's unique iv6-V progression and specific bass movement set it apart, making it an instantly recognizable and powerful harmonic device.
