The previous page used two of the main chords with in a key.
The G chord = notes G .. B .. D. First scale degree = I = the tonic. Syllables used = do, me, sol.
The C chord = notes C .. E .. G. Fourth scale degree = IV = the sub dominant. Syllables used = fa, la, do.
Voice leading used on the chord change G stays on G, B moves to C, D moves to E. Syllablewise Do stays on do, Me moves to Fa, Sol moves to La. This is what the last lesson covered in written form plus the auditory sound. Some of this information you may not understand at this time, but that will come about if you want it to happen.
This page brings in a different chord, the third chord one in the progression. We now will use the following chords G(I), C(IV), and D7(V7). The order in sound will be G, C, G, D7, G. The notes in the V7 chord, the dominant, D7, are D, F#, A, C. Syllables are sol, ti, la, fa.
In vocal training the full dominant 7th chord is sometimes substituted with the leading tone chord, the diminished triad formed on the VII scale degree. The notes would be F#, A, C. Symbol F# dim.
Here is the sound of the three chords. G, C, and F# dim. The F# dim chord can't be played on the lower strings as one sound because you can't play two notes simultaneously on one string. With that in mind, the upper register will be used for the complete sound of this progression. I, IV, VII.