Today I will teach you how to connect tonic and subdominant (and vice versa) or tonic and the dominant (and vice versa) in four-part harmony. These chords are a perfect fourth or a fifth apart.
At this point you may remember that the tonic chord (T) is build on the 1st degree of the scale, subdominant (S) - on the 4th degree and the dominant (D) - on the 5th degree. Also T and D or T and S have one common note - T-D - 5th scale degree, T-S - 1st scale degree. In four-part harmony, we double the bass (or the root of the three-note chord).
So here are the two main methods of connecting such chords:
If you want to connect these chords by harmonic method, do the following:
1) The bass jumps by a fourth or a fifth from the root of one chord to the root of another chord.
2) Keep the common note unchanged.
3) The other two notes move in a stepwise manner to the closest chordal note of the next chord (in S-T progression, the notes move downward, in D-T progression, the notes move upward and vice versa).
By connecting the chords with melodic method, here is what you have to do:
1) The bass moves by a perfect fourth from the root of one chord to the root of another chord.
2) The top three voices move to the closest notes of the next chord by the contrary motion with the bass - if the bass goes up, the other voices go down and vice versa. Note that two of these voices will move by an interval of the third and one by a stepwise motion.
Try these exercises on paper and later on the organ or keyboard in various keys (major and minor) today. When playing with organ pedals, use the following disposition of voices: the right hand plays soprano and alto, the left hand takes the tenor, and the pedals - the bass. When playing without pedals - take the two upper voices in the right hand part and the two lower voices - in the left hand part.
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