Addition of a Third Voice to a Two-Voice Suspension

Explanation of suspensions in three voices is simplified if we have a name for each of the three voices involved. In two-voice fourth species we simply referred to the “syncopated voice” and to the C.F. But in three parts it is important, when dealing with dissonant suspensions, to be clear about the function of each of the three voices. We shall refer to the voice with the syncope—the suspension itself—as the suspension voice. The voice against which the suspension is dissonant is called the accompanying voice. The remaining one is the third voice.

In Example 11-1 sing each voice while playing the other two. Do this several times, listening carefully to yourself. Then play all three parts together.

It is important to be able to distinguish between the accompanying voice and the third voice. In Example 11-1(a), the bass is the accompanying voice because it is the bass note D3 that causes the C5 in the suspension to be dissonant. In Example 11-1(b), the soprano is the accompanying voice because its B4 causes a dissonant ninth with the suspension. While it is true that the third voice (the alto) is also dissonant with the suspension, 9–10 is a viable two-voice suspension, while 4–5 is not. In Example 11- 1(c) and (d) the bass is the accompanying voice because it causes a ninth and a fourth, respectively, with the suspensions in the alto. Whenever the suspension voice is dissonant against the bass, it is the bass that is considered to be the accompanying voice, even though another dissonance with an upper voice may be present.

The suspension voice and the accompanying voice are the same for three-part suspensions as for two- part. The question to be asked is, “What note is appropriate for the third voice?” There are two basic rules that govern the determination of its pitch at the moment of the suspension:

1. The third voice’s note must form a consonance with the other two voices at the moment of the sus- pension’s resolution. This means the third voice and the accompanying voice must be consonant with each other. (Remember that the augmented fourth or diminished fifth in the upper voices of a dimin- ished triad count as consonant, as well as the perfect fourth in upper voices.)

2. The third voice must not have the same pitch class as the resolution of the suspension.

The principle behind the first rule has to do with Aloysius’ statement regarding the harmony resulting from the resolution of a dissonant syncope.

We know that the dissonances in themselves are altogether lacking the grace and charm of harmony; and that whatever pleasantness and beauty they may give the ear have to be attributed to the beauty of the succeeding consonances to which they resolve.

Behind the second rule is the principle of fulfilled expectation basic not only to music but to any temporal art—drama, film, fiction, or poetry. A situation is set up which arouses certain expectations on the part of the listener, reader, or viewer, this expectation subsequently being fulfilled or frustrated. In Western music, much of the interest comes about because of this principle. If the third voice anticipates the note of resolution, it is as if the listener is not given a chance to experience the expectation. The situation is somewhat akin to hearing the punch line of a joke prematurely. Of course, in the case of the 9–8 or 2–1 suspension, the pitch class of the resolution is indeed sounding. But this is a different situation, for here it is the accompanying voice, the voice that causes the dissonance in the first place, that is sounding the pitch class of resolution. The rule stipulates that the third voice must avoid it.

A glance back through Example 11-1(a), (b), (c), and (d) will confirm these rules. In each case the third voice is consonant with the other two voices at the moment of resolution (and therefore inevitably consonant with the accompanying voice at the moment of suspension). This consonant note is never the same pitch class as the resolution. If these rules are followed mistakes will not occur. But certain intervals are nevertheless preferable to others. A careful perusal of suspensions as practiced from the sixteenth to the nineteenth centuries will reveal certain tendencies on the part of the best composers. Example 11-2 shows the various suspensions with different pitches in the third voice. The preferred simultaneity is placed first in the list and marked with an asterisk.

A glance down the preferred sonorities (with asterisks) reveals that, when the suspension is in the upper voice the preferred note for the third voice is a third above the bass. The inevitable exception is the 4–3, for the third above the bass would anticipate the note of resolution. The preferred tone for the 4–3 is a perfect fifth above the bass rather than the sixth, as the former produces a stronger dissonance for the suspension. Though the six-four is possible, it is quite a mild dissonance and, as we shall see shortly, its very mildness makes it possible to act, under certain conditions, as a consonance.

When the suspension is in the lowest voice, the perfect fourth or perfect fifth above the bass are both about equally dissonant and both result in resolutions to full triads. The less preferred sonorities should be used only when necessary to avoid incorrect progressions or to produce an improved melodic line.