Chord Identification and the Chromatic Clock

Section 3.2 describes how fundamental triadic chords (triads) provide an underlying basis for choosing notesin diatonic melodies. Here we provide some additional discussion, showing how plotting notes on the chro-matic clock helps us find which triads provide the harmonic structure for a passage of diatonic music. Thefollowing diagram shows how major and minor triads appear on the chromatic clock.

This diagram illustrates the following principle: Reading clockwise, a major chord always has 4 hours,followed by 3 hours, separating its notes. While a minor chord always has 3 hours, followed by 4 hours,separating its notes. Using this principle we can identify underlying chords in musical passages.

Example 1 In Figure 1, the first measure of Beethoven’s Moonlight Sonata is shown along with its noteson the chromatic clock. These notes clearly delineate the notes, C], E, and G], for the C]-minor chord.

Figure 1: Left: First measure from Beethoven’s Moonlight Sonata. Right: Notes occurring in first measure are markedon chromatic clock. They mark off the C]-minor chord.

Example 2 In Figure 2, the first musical phrase from the traditional ballad, House of the Rising Sun isshown, along with its notes plotted on the chromatic clock. The majority of notes lie at the hours correspond-ing to D, F, and A, which are the notes of the D-minor chord. The first note in the passage is an A, which isthe dominant for D, creating anticipatory tension for the D that does indeed follow it. This D note also beginson the downbeat1 of the first full measure. Furthermore, the notes beginning on the downbeats of the nexttwo measures are F and A. So these three downbeat notes form an ascending series through the notes of theD-major chord. All these facts make it clear that the chord governing the harmonic structure of the musicalphrase is D-minor.

Example 3 In Figure 3, a single measure from Handel’s Suite No. 7 in G]-minor is shown. Two chromaticclocks are needed to analyze its chord structure. The first chromatic clock shows the notes for the first twobeats. They include one G note, three C notes, and three E[ notes, corresponding to a C-minor chord. The

1The musical term downbeat refers to the first beat of a measure.

Figure 2: Left: Intro to the traditional ballad, House of the Rising Sun. The musical phrase corresponding to the firstphrase in the lyrics is enclosed in the rectangle. Right: Notes occurring in the musical phrase, marked on the chromaticclock. Notes in parentheses are passing tones in the melody.

other two notes are an F note and a D note. The only triad that can be formed from the collection of all thesefive notes is the C-minor chord; the chord iv in the key of G-minor. Also, the score shows that D is clearlyinterpretable as a passing tone between two notes, C and E[, belonging to the G-minor chord notes. Since Fbegins the measure, and is a repeat of the F from the previous measure, we classify it as a neighbor tone. Asimilar analysis of beats 3 and 4 shows that their organizing chord is B[-major; the chord III in the key ofG-minor.

Figure 3: Bottom: Measure 4 from Andante movement of Handel’s Suite No. 7 in G-minor. Red vertical lines markoff four beats, each having quarter note duration, as specified by the time signature. Top left: Notes on chromatic clockfor beats 1 and 2. The note F is a neighbor tone (marked n). The note D is a passing tone (marked p). Top right: Noteson chromatic clock for beats 3 and 4.

Exercises

1. The following passage is from Beethoven’s Fur Elise. Identify the chord for Measure 2, and the chord forMeasure 3. (The answer for this problem is on the next page.)

2. The following passage is from Bach’s Toccata and Fugue in D-Minor. Identify the chord for Beat 2, andthe chord for Beat 3.

REMARK: This passage is interesting because each beat’s chord is repeated twice, once on each half-beat.

3. The following passage is from Bach’s B-flat Major Prelude. Identify the two chords for Beat 1, one oneach half-beat.

Answer for Exercise 1: A-minor for Measure 2, and E-major for Measure 3.