Harmony explained: Chopin's Waltz in A minor Op. Posth.

Summary

This video script offers an in-depth analysis of a waltz composed by Chopin in 1843. It discusses the piece's key, A minor, and its harmonic progressions, focusing on the absence of the dominant chord in the first section. The script delves into the function of dominant chords, their pull towards the tonic, and the piece's surprising harmonic turns. It also explains cadential chords and their significance in classical music, culminating in the piece's strong and defining cadence.

Takeaways

• 🎵 The piece is in A minor, identified by the tonic chord appearing at both the start and end of the piece.
• 🎶 The key signature has no sharps or flats, meaning the piece could be in either C major or A minor, but the A minor chord confirms it's in A minor.
• 🎹 The harmonic progression develops the main theme over four parts, with each section featuring different chords like A minor, D minor, G7, and C major.
• 🎼 The G7 chord, a dominant chord, creates tension that resolves to its tonic, C major, which is a feature of dominant-tonic relationships.
• 🧐 In the first section, there is an unexpected absence of the E7 dominant chord, which would traditionally resolve to A minor.
• 🎻 The second section finally introduces the E7 chord, creating a dominant-tonic movement between E7 and A minor, reaffirming the home key.
• 🎵 A surprise modulation occurs when a B7 chord is followed by an E7 chord, chaining dominants together, which creates harmonic instability.
• 🔄 Dominant-tonic alternation is frequent, especially in the second section, but a shift to A major instead of A minor introduces variation.
• 🎶 The use of cadential chords, such as the tonic chord in second inversion, followed by the dominant seventh, adds harmonic weight to the conclusion.
• 🎹 The piece ends with a strong cadence, using the cadential chord, dominant seventh, and tonic (A minor) to reaffirm the key and resolve the tension.

Q & A

What is the key of the piece being analyzed?

The piece is in the key of A minor, as indicated by the tonic A minor chord at the beginning and end of the section.

How do you determine whether the piece is in A minor or C major?

To determine the key, we check the tonic chord at the beginning and end. Since the tonic chord is A minor, the piece is in A minor rather than C major, even though both keys share the same notes.

What is a dominant chord and why is it important?

A dominant chord is a major triad with a minor seventh, and it creates tension that 'pulls' toward its tonic, usually a perfect fifth below it. This attraction keeps the musical line cohesive and directs the harmonic progression.

Why is it surprising that the dominant chord of A minor isn't used in the first section?

It's surprising because dominant chords are typically used to resolve into their tonic. In A minor, the dominant chord would be E7, but instead, the piece resolves to G7, the dominant of C major, creating an unexpected harmonic progression.

How does the second section differ from the first in terms of harmonic progression?

In the second section, the missing dominant chord (E7) from the first section finally appears, creating a stronger pull towards the tonic (A minor), unlike the first section where this dominant-tonic relationship was avoided.

What happens when dominant chords are 'chained' together, as mentioned in the analysis?

Chaining dominant chords involves moving from one dominant to another, where each dominant chord resolves to the next chord, creating harmonic tension and instability. This technique builds anticipation in the music.

What is a cadential chord, and what role does it play?

A cadential chord is a tonic chord in the second inversion, used before a dominant seventh chord to strengthen the cadence. It maximizes the instability created by the dominant chord and provides a strong sense of resolution when followed by the tonic.

Why is the use of a cadential chord significant in classical harmony?

The cadential chord creates a very strong cadence, as it leads directly into the dominant chord, heightening tension and providing a powerful resolution when the tonic chord follows. This sequence of cadential-dominant-tonic is the most defining type of cadence in classical harmony.

How does Chopin’s use of B7 and E7 chords contribute to the harmonic tension in the piece?

Chopin uses the B7 chord, which is the dominant of E, followed by the E7 chord, which is the dominant of A minor. By chaining these dominants, he creates a progression that enhances harmonic tension and instability, leading to a more dramatic resolution.

What harmonic surprise occurs at the end of the piece?

The piece concludes with the expected dominant (E7) resolving to A minor, reaffirming the home key. However, the surprise comes from Chopin’s earlier avoidance of the A minor dominant chord, which finally appears at the end, creating a satisfying resolution.