Getting Started
In 18th-century chorale style, the foundational structure is often a simple, quarter-note harmonic progression. This chapter focuses on moving beyond that basic framework by adding rhythmic and melodic interest. We will explore how to compose a more sophisticated bass line against a given soprano melody by incorporating specific eighth-note embellishments.
What You Should Be Able to Do
Compose a stylistically appropriate bass line in eighth notes against a given soprano line.
Correctly write unaccented passing tones and neighbor tones to connect chord tones in the bass.
Identify and create desirable voice-leading patterns with the soprano, including parallel thirds, parallel sixths, and voice exchange.
Ensure your composed bass line supports the underlying harmony and adheres to standard voice-leading conventions.
Analyze the interaction between a soprano and an embellished bass line.
Key Concepts & Analysis
The primary goal of adding embellishing tones to a bass line is to create a smoother, more conjunct melodic contour and to increase rhythmic activity. This is achieved while respecting the underlying harmony and the principles of good counterpoint. The relationship between the outer voices—soprano and bass—is paramount.
Defining the Embellishing Tones
An embellishing tone, or non-chord tone, is a note that does not belong to the harmony it accompanies. For this topic, we focus on two specific unaccented types that occur on a weak beat or the weak part of a beat.
Unaccented Passing Tone (PT): A non-chord tone that fills the melodic space between two different chord tones. It is approached by step and left by step in the same direction. For example, in a C major chord, a bass line moving from C to E could be embellished as C-D-E, where the D is an unaccented passing tone.
Unaccented Neighbor Tone (NT): A non-chord tone that decorates a single chord tone. It is approached by step and left by step in the opposite direction, returning to the original chord tone. For example, a bass line holding the note G could be embellished as G-A-G, where A is an unaccented upper neighbor tone.
Key Soprano-Bass Interactions
When writing a bass line with eighth-note embellishments, your choices should be guided by the movement of the given soprano line. There are three principal textures to create.
1. Complementing a Stationary Soprano
This occurs when the soprano holds a single note (e.g., a quarter note) while the bass moves in two eighth notes. The first bass eighth note is a chord tone, and the second is an unaccented passing or neighbor tone that smoothly connects to the next chord tone. This technique creates rhythmic interest in the bass without disturbing the stability of the soprano.
Example: If the soprano holds C (^1) for a full beat over a I chord in C major, the bass could move from C to G on the next beat. An embellished bass line could use two eighth notes: C, followed by the passing tone B, leading to A (^6) for the next chord (vi).
2. Moving in Parallel Thirds or Sixths
When the soprano line also contains eighth-note motion, the bass can move along with it in parallel motion. To maintain consonance and pleasing counterpoint, this parallel motion should form the intervals of a third or a sixth between the two voices. This creates a rich, harmonious texture and is one of the most common and effective ways to coordinate embellished lines. Avoid parallel fifths and octaves, which are forbidden.
Example: If the soprano moves C-D-E in eighth notes, a bass line moving A-B-C in parallel would create a constant interval of a third (or, more accurately, a tenth). This is a strong and desirable voice-leading pattern.
3. Engaging in Voice Exchange
A voice exchange is a contrapuntal pattern where two voices trade notes from the same harmony. For instance, if the soprano moves from C down to A, the bass might simultaneously move from A up to C. The two voices have "exchanged" their starting pitches. This technique uses contrary motion to reinforce the harmony and create a sophisticated melodic connection between the parts. It is a powerful tool for enlivening static harmonies.
Example: Over a I6 chord in C major (bass on E), the soprano might have the notes G-F-E. A bass line using a voice exchange could move E-F-G, exchanging the starting E and G with the soprano over the course of the beat.
Data & Organization Tools
To write a functional bass line, you must know the diatonic chords available in a given key. The table below outlines the basic triads in a major key, which form the harmonic foundation that embellishing tones decorate.
| Key of C Major | Diatonic Triad | Roman Numeral | Function |
|---|---|---|---|
| C-E-G | C major | I | Tonic |
| D-F-A | d minor | ii | Predominant |
| E-G-B | e minor | iii | (Tonic/Dominant) |
| F-A-C | F major | IV | Predominant |
| G-B-D | G major | V | Dominant |
| A-C-E | a minor | vi | (Tonic/Predominant) |
| B-D-F | B diminished | vii° | Dominant |
Evidence Bank
Unaccented Passing Tone: A non-chord tone approached by step and left by step in the same direction on a weak beat. Used to create smooth, conjunct motion between two different chord tones.
Unaccented Neighbor Tone: A non-chord tone approached by step and left by step in the opposite direction on a weak beat. Used to decorate a single, stationary chord tone.
Stationary Soprano Embellishment: The technique of adding two bass eighth notes (chord tone + embellishment) against a single, sustained soprano note. Used to create rhythmic motion in the bass.
Parallel Thirds: A desirable voice-leading pattern where soprano and bass move in the same direction, maintaining the interval of a third. Used to ensure consonance during parallel motion.
Parallel Sixths: A desirable voice-leading pattern where soprano and bass move in the same direction, maintaining the interval of a sixth. Also used to ensure consonance during parallel motion.
Voice Exchange: A contrapuntal device where two voices trade pitches of a harmony. Used to create melodic interest and strengthen the underlying chord through contrary motion.
18th-Century Chorale Style: The musical idiom governing this practice, emphasizing four-part harmony, clear phrases, and adherence to traditional voice-leading rules.
Normative Harmonic Procedures: The conventional syntax of functional harmony (e.g., tonic moving to predominant, then to dominant, and back to tonic). The bass line must support this progression.
Skill Snapshots
Functional
I - V6/5 - I: A simple tonic expansion where the bass line often moves ^1-^2-^3, with ^2 acting as a passing tone within the V6/5 chord.
I - ii6 - V - I: A standard phrase where the bass could be embellished between the chords, such as adding a passing tone between the roots of ii6 and V.
I - IV - V - I: The bass line ^1-^4-^5-^1 can be enlivened with neighbor tones around ^1 or a passing tone between ^4 and ^5.
Voice-Leading
Rule: When the soprano holds a note for a full beat, the bass can be activated with an eighth-note chord tone followed by a passing or neighbor tone.
Effect: This creates rhythmic interest and flow in the bass line without disrupting the harmonic stability provided by the soprano.
Rule: If the soprano and bass both move in eighth notes, ensure they move in parallel 3rds or 6ths.
Effect: This produces a consonant, pleasing contrapuntal relationship that avoids forbidden parallel 5ths and octaves.
Rule: Employ a voice exchange when a single harmony is held for a beat or more.
Effect: This generates compelling contrary motion, reinforces the harmony, and creates a sophisticated melodic link between the outer voices.
Form
Baseline Phrase: A simple four-beat phrase in C major: Soprano C-B-C over Bass C-G-C, creating a I-V-I progression.
Contrast: The same soprano C-B-C could be harmonized with a bass line C-G-A, creating a I-V-vi deceptive cadence, which avoids closure.
Continuity: Adding eighth-note passing tones (e.g., Bass C | G-F#-G | C) makes the bass line feel more continuous and melodically driven, connecting the chords more smoothly across the phrase.
Common Misconceptions & Clarifications
Passing Tones vs. Neighbor Tones: Remember the key difference: passing tones move in one direction (A-B-C), while neighbor tones return to the original note (A-B-A).
Accented vs. Unaccented: The techniques in this chapter apply only to unaccented embellishments that fall on weak beats or parts of beats. Accented non-chord tones are a separate topic.
Creating Forbidden Parallels: Be careful that your embellishments do not create a situation where the main chord tones on the downbeats form parallel fifths or octaves. The embellishments themselves do not count as part of the parallel, but the notes they connect do.
Choosing the Right Note: Passing and neighbor tones are not random. They should be diatonic to the key and connect two chord tones that are a step or third apart.
Ignoring the Soprano: The choice of embellishment in the bass is not made in a vacuum. It must create a correct and desirable contrapuntal relationship with the given soprano line.
Summary
Composing an embellished bass line is a crucial skill for adding sophistication and fluidity to basic harmonic progressions. By using unaccented passing and neighbor tones, a simple quarter-note bass can be transformed into a melodically engaging line. The success of this technique depends on the careful coordination between the bass and the given soprano. The most effective applications involve creating complementary rhythm against a stationary soprano, moving in consonant parallel thirds or sixths, or engaging in a voice exchange. These methods, when applied within the normative procedures of 18th-century harmony, elevate a simple exercise into a piece of well-crafted counterpoint.