With the appearance of passing notes, the detection of parallel 8ves and 5ths becomes a little more complex. Guiding rules are
- Open : Parallel with a passing note in one voice. This is bad.
- Symmetrical : Parallelism on strong beats is bad. On weak beats is possible
- Asymmetrical : Parallelism not in corresponding places in the mesaure - 8ve in strong beat followed by an 8ve on a weak beat. This is possible and good.
If one of the perfect 5ths is used as an unessential, then that is ok.
Jul 27, 2008
Two voice counterpoint - basics
The broad principles are
1) Each line must be good in itself.
2) The lines must be independent in terms of direction and rhythmic motion.
- Avoid parallel unisons, fifths and octaves
- Avoid moving to a unison, perfect fifth or octave in similar motion (direct unison, 5th or octave). Exception is movement to octave when the lower voice moves in a strong root progression.
- Avoid movement from a diminished 5th to a perfect 5th. The resolution of the diminished 5th here is incorrect.
- As a general rule, the same interval must not be used more than 3 or 4 times in succession.
3) They must have enough in common so they will fuse into a convincing whole when combined.
- Voices must not be too divergent in terms of rhythmic patterns.
4) Yhe lines must imply good harmonic succession
- Choice of chord tones is important. Given that all 3 chord tones cannot appear in 2 voice counterpoint, which chord tones should be chosen? Analysis will show that it is best to have the root and the 3rd chosen. (3rd and 5th will lead to a confusion of whether the chord is I or III. 1st and 5th will not make it clear what the color of the chord is - major or minor). That said, exceptions are possible. If the 5th is present in a voice, and tonic harmony is called for, then 3rd and 5th or 1st and 5th (as context dictates) can be used. In fact 5th in lower voice, and 3rd in upper voice, also can be used quite satisfactorily.
- Doubling: Avoid doubling 3rds of chords at accented beats. However, this is still ok, of both voices move stepwise in contrary motion.
- Choice of harmonic progression: Progressions that are not good in 4 part are not good here either.
- The second inversion chord is usable here in cadential, passing, embellishment or chord repetition. Since the lower voice in 2 voice counterpoint sounds like a real bass, the second inversion occurs whenever the 5th of a chord occurs in the lower voice. If the above conditions are not satisfied, it must not be used. Never jump to or from the bass of a second inversion, other than in IIb-Ic-V-1 or in chord repetition (Ib - I - Ic). IIc, IIIc and VIc are useless. If the principles here are stuck to, second inversions on two different scale degrees can never appear successively.
- Harmonic Rhythm : To keep a sense of motion, it is required that the bass is not retained from weak to strong beat. This is because the bass must provide a sense of motion forward at these points. Also, a changing bass with no change in harmony sounds static. However it is less objectionable than a non-changing bass.
- Cadences : Authentic cadences must imply one of the following progressions
Ib-IV-V-I
Ib-Ic-V-I
Ib-iib-(Ic)-V-I
The dominant chord must always be employed in root position. The Ic (if used) must always be on a strong beat.
5) The voices must be primarily consonant, dissonance being present, but lesser than consonance :
- The most usable intervals are 3rd, 6th and 8ve. Perfect 5th sounds bare, and if used, is quickly followed by the 3rd of the chord. Perfect 4th is extremely rare as an essential interval (top-heavy in sound, and also implies a second inversion possibly at inappropriate places). Diminished 5th or Aug 4th are commonly used, mostly as representations of the dominant 7th. 2nd and 7th are also not frequently used as essential intervals.
1) Each line must be good in itself.
2) The lines must be independent in terms of direction and rhythmic motion.
- Avoid parallel unisons, fifths and octaves
- Avoid moving to a unison, perfect fifth or octave in similar motion (direct unison, 5th or octave). Exception is movement to octave when the lower voice moves in a strong root progression.
- Avoid movement from a diminished 5th to a perfect 5th. The resolution of the diminished 5th here is incorrect.
- As a general rule, the same interval must not be used more than 3 or 4 times in succession.
3) They must have enough in common so they will fuse into a convincing whole when combined.
- Voices must not be too divergent in terms of rhythmic patterns.
4) Yhe lines must imply good harmonic succession
- Choice of chord tones is important. Given that all 3 chord tones cannot appear in 2 voice counterpoint, which chord tones should be chosen? Analysis will show that it is best to have the root and the 3rd chosen. (3rd and 5th will lead to a confusion of whether the chord is I or III. 1st and 5th will not make it clear what the color of the chord is - major or minor). That said, exceptions are possible. If the 5th is present in a voice, and tonic harmony is called for, then 3rd and 5th or 1st and 5th (as context dictates) can be used. In fact 5th in lower voice, and 3rd in upper voice, also can be used quite satisfactorily.
- Doubling: Avoid doubling 3rds of chords at accented beats. However, this is still ok, of both voices move stepwise in contrary motion.
- Choice of harmonic progression: Progressions that are not good in 4 part are not good here either.
- The second inversion chord is usable here in cadential, passing, embellishment or chord repetition. Since the lower voice in 2 voice counterpoint sounds like a real bass, the second inversion occurs whenever the 5th of a chord occurs in the lower voice. If the above conditions are not satisfied, it must not be used. Never jump to or from the bass of a second inversion, other than in IIb-Ic-V-1 or in chord repetition (Ib - I - Ic). IIc, IIIc and VIc are useless. If the principles here are stuck to, second inversions on two different scale degrees can never appear successively.
- Harmonic Rhythm : To keep a sense of motion, it is required that the bass is not retained from weak to strong beat. This is because the bass must provide a sense of motion forward at these points. Also, a changing bass with no change in harmony sounds static. However it is less objectionable than a non-changing bass.
- Cadences : Authentic cadences must imply one of the following progressions
Ib-IV-V-I
Ib-Ic-V-I
Ib-iib-(Ic)-V-I
The dominant chord must always be employed in root position. The Ic (if used) must always be on a strong beat.
5) The voices must be primarily consonant, dissonance being present, but lesser than consonance :
- The most usable intervals are 3rd, 6th and 8ve. Perfect 5th sounds bare, and if used, is quickly followed by the 3rd of the chord. Perfect 4th is extremely rare as an essential interval (top-heavy in sound, and also implies a second inversion possibly at inappropriate places). Diminished 5th or Aug 4th are commonly used, mostly as representations of the dominant 7th. 2nd and 7th are also not frequently used as essential intervals.
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