A translation on the section on the Delle Dissonanze, o sia legatura di quarta, or suspension of the fourth in Fedele Fenaroli’s Partimenti ossia basso numerato, Book III, Naples (1775) Ed. Gjerdingen, with adaptions to the guitar.
Preparation
The interval of a perfect fourth, classified as a dissonance in traditional contrapuntal theory, may be effectively prepared by any of the four primary consonances: the octave, major or minor third, perfect fifth, and major or minor sixth.
1. Preparation by the Octave
The fourth may be prepared by the octave when the bass (i.e., the partimento) ascends by a perfect fifth or descends by a perfect fourth. This motion establishes a strong tonal foundation for the introduction of the dissonance.
(Refer to Example A: ① → ⑤ )
2. Preparation by the Third
Preparation by the third occurs when the bass descends stepwise, thereby maintaining smooth melodic motion.
(Refer to Example B1: ⑥ → ⑤ or B2: ② → ①)
3. Preparation by the Fifth
When preparing the fourth via the perfect fifth, the bass should ascend stepwise, allowing for a seamless connection between the preparatory and dissonant sonorities.
(Refer to Example C1: ④ → ⑤ or C2: ① → ②)
4. Preparation by the Sixth
A fourth may also be prepared by the sixth if the bass ascends by a third, creating a consonant framework from which the dissonance may emerge.
(Refer to Example D: ③ → ⑤)
On Dissonant Preparations
Though less common, the fourth can also be prepared by certain dissonant intervals under specific circumstances:
5. Preparation by the Minor Seventh
In this case, the bass ascends a perfect fourth, resulting in the fourth appearing above the preceding minor seventh.
(Refer to Example E: ⑤ → ①)
6. Preparation by the Diminished Fifth
Alternatively, the fourth may be prepared by a diminished fifth, which is introduced by a semitonal ascent in the bass.
(Refer to Example F: ⑦ → ①)
Structural Consideration
It is imperative to note that the dissonance of a fourth must always be accompanied or underpinned by the consonance of a fifth. This requirement stems from the fourth’s inherent instability when placed above a bass note that does not admit a fifth, rendering the interval acoustically and structurally unsupported within the contrapuntal framework.
Note: In Partimenti ossia basso numerato, Book III (ed. Gjerdingen), only examples in the major key are provided. I have applied the same principles to the minor key examples below.
Now follows each of the variants A through F,
presented in six major and minor key signatures.
This concludes this essay on the suspension of the fourth as instructed by Fedele Fenaroli in his Partimenti ossia basso numerato. You can download this essay as a PDF for free.
Karl Michelson 