Tone Scale

Debussy’s ‘Voiles’ features harmonic ambiguity, suggesting that the application of a non-conventional theory in order to reveal its fundamental harmonic structure may be appropriate. The French word ‘Voiles’ can be translated at veils, which have the ability to hide things and are the ‘visible means catching the invisible’. On the surface, the piece follows a binary tonal structure, in which A is based on a whole-tone scale and B on a pentatonic scale. Throughout the movement, however, various collections of pitches and rhythms interact are repeated and developed. These collections of pitches not only reveal harmonic significances in the piece, but also associate themselves with specific motives, forming distinct layers within the thematic organisation. In carrying out an analysis of ‘Voiles’, therefore, initially undetectable but important features of the piece begin to emerge, reflecting the meaning of the title.

According to Matthew Greenbaum, Debussy’s ‘Voiles’ is in dialectical form, in which the music gradually introduces a contrasting idea. The most fundamental level of antithesis is the use of whole-tone and pentatonic keys to separate the various sections of the piece. This concept does notexplain the piece in great detail, however, as its definition seems to include a wide range of pieces, rather than being specific to Debussy’s preludes. Greenbaum also notes the use of Symbolism in the piece; the absence of conventional techniques of development so that sounds can be linked to their particular moment in time. This concept of Symbolism is particularly evident in the piece, in the form of repeating small phrases which appear frequently throughout the piece. These phrases do not, however, establish a sense of regularity in the overall structure of the piece, but rather cause the listener to lose sight of their direction, unable to predict how the phrases are going to develop throughout the piece.

Roy Howat describes the five main tonal characteristics of ‘Voiles’ which can be derived from the whole-tone and pentatonic modes; ‘(1) a fixation on Bb; (2) a modal polarity of whole-tone instability versus relative pentatonic stability, involving (3) mirrored chromatic motion; (4) an underlying dominant-tonic polarity; and therefore (5) a dual system of tonal tension: classical tonality in dialogue with modal polarity.’ The fixation on Bb can be seen throughout the piece in the form of the bass pedal. The opening immediately signals instability with the harmonic interference of the descending figure from G# to Ab by the C-G# to Bb-F# figure in bar 2. Whereas, in the pentatonic section starting in bar 42, the note Eb is deeply rooted within the music, particularly during the four cadences in Eb minor from bars 45 to 47. By using dotted lines to connect the pitches between the two staves in Figure 4, Howat demonstrates the mirrored chromatic motion. It can be observed that the first two pitches of both modes is identical; Ab and Bb. Then, the next three pitches of the whole-tone scale equate to the next two pitches of the pentatonic scale. Finally, the last two pitches of the whole-tone scale can be matched with the last two remaining pitches of the pentatonic scale. Howat also suggests that the title is linked to the tonal structure of the piece; under veils of tonal ambiguity, there is an underlying perfect cadence which spans the whole piece.

David Goldman possesses a similar view to Howat, in that he believes that the piece is based on a tonic-dominant relation which results from Debussy’s new intervallic relations, in which the role of the perfect triads has been transferred to augmented triads. Goldman also argues that the whole-tone scale starting on C is only a veil formed by combining these augmented triads, and that it is the ‘altered diatonic harmonies [that] create the forward motion of the work’. He then similarly regards as a veil the common interpretation of the piece being in A-B-A form with whole-tone A sections and a pentatonic B. Although I agree with Goldman’s argument, I regard the whole-tone scale as having slightly more importance, due to its pervasive presence when initially hearing the piece.

In order to analyse the harmonic structure of Debussy’s ‘Voiles’ I have applied Allen Forte’s theory on pitch-class sets. This provides the means by which to identify any potential smaller collections of pitches which are appear throughout the piece, so that the harmonic form can be explained further than the immediately detectable use of whole-tone and pentatonic scales.      The analysis reveals that under the veils of Debussy’s ‘Voiles’ which suggest that the tonality is solely based on whole-tone and pentatonic harmonies, there is in fact a simple tonal structure which reveals a tonic-dominant relation. The analysis also shows that there are a number of features which create a sense of coherency, despite floating phrases and metric ambiguity. The piece is based on smaller units of pitch collections, as well as the note Ab/G#. The pedal in the bass line which appears throughout is also a grounding feature of ‘Voiles’.

The harmony in the initial A section can be grouped into a number of collections of pitches, which recur throughout, creating a sense of unity. In the opening, there is a descending whole-tone figure in thirds, containing the pitches Bb, C, D, E, F#, and G#. These pitches can be grouped into the pitch-class set, 5-33 with the interval vector [0,2,4,6,8]. The set 5-33 is also a subset of the whole-tone collection WT0, [0,2,4,6,8,10]. Despite the opening section being based on the whole-tone scale, the note Ab and its enharmonic equivalent appear particularly prominent. This is because the descending figure in the opening begins and ends on this note. In addition, once the rest of the piece is taken into account, the note Ab is discovered to be the melodic centre. This descending figure is then suddenly interrupted by an octave displacement. In the fifth bar, a Bb pedal is heard in the bass part. This subtle pedal on Bb is established as a recurring feature throughout the movement, as well as unifying the A and B sections. The fact that the pedal is always present seems reminiscent of the wind, which has connections with the title of the piece. Then in bar 7, the beginning of a rising chant-like melody in octaves is heard, containing the pitches Ab, Bb, and C, which can be grouped into the pitch-class set 3-6, with the interval vector [0,2,4]. The opening theme returns in bar 10 with a slight alteration, layered with the now full version of the chant-like melody, over the bass pedal. Hearing the full version of the chant gives rise to the realisation that it begins and ends on Ab, the same pitch which opens the piece. Bar 14 presents a similar combination, other than the chant figure being replaced by its chordal version. This chordal figure, however, brings simplicity to the phrase rather than intensity, as the whole-tone scale consists of only two augmented scales, thus eliminating any harmonic tension.

To mark a new section, a new figure based on a whole-note “turn” and beginning on Ab is then presented in the melody line from bar 22, and this is accompanied by a repeating dotted quaver figure containing the pitches C, D, and F#, forming the set 3-8 with the interval vector [0,2,6] as well as the underlying Bb pedal. Following a continuation starting in bar 24, the neighbour note figure returns in a fragmented form which gradually rises in pitch by sequence. In a similar way to the earlier material in the movement, Debussy once again uses multiple layers in this section. There is a demisemiquaver figure which is has a significant role in the piece as it features rising minor thirds, which reappears throughout. Adding to the rising demisemiquaver figure and the Bb pedal, he introduces a new accompaniment figure; a rising whole-tone scale starting on a F# and ending on an E.

In bar 33, the chordal figure from bar 19 returns, now with a continuation. This variation is also layered with a simple semiquaver accompaniment featuring an octave leap. Then in bar 38, there initially seems to be a new idea in the upper staff, but opening legato melody is simply disguised by different rhythm; the lowest pitches of the first three chords belong to the same set; 3-6, and are identical to the start of the opening version. Furthermore, the rising minor thirds in the second half of bars 38 and 39, as well as the fragmentation in bar 40 can be traced back to the musical content starting in bar 29. In comparison with 29, the highest pitches of bars 38 and 39 are also the same.

In addition to Ab, the note D is also emphasised throughout the piece; bar 10, bar 21 in three octaves, and in bars 38 to 41. Considering the Bb bass pedal which first appears in bar 5, it is possible to notice an underlying dominant seventh of Eb minor in the piece. This consideration of a dominant seventh would lead one to expect a resolution in bar 42, meaning that all the preceding material would have been the preparatory material for a perfect cadence. However, Debussy rejects conventional techniques by launching into a pentatonic section which takes the resolution to second inversion. In addition, any importance of the leading note D vanishes at this point, as the emphasis is now on the note Db. Although the chromatic difference between the Ds indicates that the end of the whole-tone section at bar 41 is tonally disconnected from the pentatonic section, Howat proposes that by combining the two modes of the piece, a larger chromatic convergence forms (Fig. 3). Howat shows how the chromatic convergence results from the notes C-D-E and Db-Eb, which are surrounded by unchanging pitches. He then identifies a symmetry within these notes, which can be connected to the piece’s concluding C-E dyad; the resolution of the opening melody in bar 5.

The B section starts in bar 42, featuring ascending pentatonic scales on Bb and four cadences in Eb minor. Despite this section contrasting with the A section in terms of its character, the Bb pedal continues to appear consistently throughout. Although different in tonality, the return of A in bar 48 is similar to the B section, with its rising whole-tone scale filling out the wide intervals, as well as the Bb pedal. This section contains the chordal chant figure from earlier, based on the set 3-6. In bars 54 and 56, there are dense chords, with each consecutive one having the same intervals. Finally, the last section of the piece features the opening thematic material and a series of ascending whole-tone arpeggios from F#.

It is only at the end, however, when Debussy exposes the true tonality of the piece. He does this by presenting the final chord in C major, which although lacks the fifth degree, includes the third so that the tonality is identifiable. Once the key of C major becomes apparent, it becomes possible to see through the veils which were hiding it. For example, in the opening, the top last three pitches in the descending motive outline the first three degrees of a C major scale. Furthermore, it also becomes noticeable that the G# (Ab) which frequently appears throughout the piece, is in fact acting as a G-natural, except with the sharp accidental being a veil. This therefore reveals the top notes of the opening motive to be outlining a C major triad. If the conventional structure of a final perfect cadence was to be used as reference, the presence of a tritone formed between F# and C can be seen as taking the place of a dominant chord. Debussy highlights this unusual leap by eliminating the Bb pedal at the end. Due to the missing fifth in the final chord, however, the tritone is left unresolved. When considering the combination of the final three notes, F#, C, and E, the pitch-class set can be identified as 3-8, with the interval vector [0,2,6].

To conclude, Debussy’s prelude ‘Voiles’ conceals with its veils its fundamental core; the use of diatonic harmony, in which a tonic-dominant relation is presented by augmented triads. Although application of Forte’s pitch-class set theory shows that the whole-tone scale is prevalent throughout the piece, it also reveals that the whole-tone scale is in fact a veil, covering the smaller intervals into which it divides. The analysis suggests that there are potentially undiscovered aspects in pieces especially from the nineteenth century and onwards, however simple they initially seem to be. The application of pitch-class set theory may also provide a deeper understanding of post-tonal music, with its mathematical approach giving an alternate view towards a piece. Nevertheless, approaching a piece such as ‘Voiles’ in hope for finding exclusively modern harmony may surprisingly reveal more traditional harmony.