Before Exercise 1.2, the course book asks for the analysis of the cantus firmus and its given solutions for the first species counterpoint, which I will tackle here.
This is the given cantus firmus:
The melody is formed of 8 whole notes, each lasting a bar, and starts and ends on the tonic – F. The range of the melody is only up to the 4th – the note Bb, which is also the climax of the melody. It is mostly calm and wave-like, in a way circling and revolving around the same notes that move in step-wise motion, except the one small jump to the 3rd – the climax note, which is then ‘filled’, with the melody coming back the opposite direction.
Next task is analyzing the solutions, while following the first species points given on page 21. In solution 1, the cantus firmus is places in the lower voice-part:
As advised, the interval beginning and ending the counterpoint exercise is the octave, while the thirds and sixths fill out the rest, from the 2nd until the penultimate bar. The dominating motion between the parts is the contrary motion, which as the points indicate, represents a good way of asserting the independence of each melodic line. The only consecutive intervals are the 6ths near the end, with no prohibited consecutive or exposed fifths or octaves. Like the cantus firmus, the upper melody is also flowy and wave-like, revolving around the same pitches, with two small jumps of 3rds that aren’t in a row. Similarly, the range of the upper part is also the 4th.
Finally, here is the cantus firmus in the upper voice, while the added voice of solution 2 is in the lower part:
The aim here is to answer why I think the whole setting and sound is different when cantus firmus is in the lower part, while also going through the bullet points. First of all, when cantus firmus is in the upper voice, in order not to blur the modality, the lower part must start on the same degree, an octave lower. In order to achieve the contrary motion and the more calm, step-wise flow of melody, as the one in the solution, this means the intervals will be larger (I have marked them with their real gap, while in parentheses put the intervals they would be if they were without the octave distance, but unison as the beginning). All these could influence the sound, but there may also be another thing in question. For me personally, as I was trained to listened to both melodic lines, but for those that weren’t, the cantus melody in solution 2 could seem more recognizable in a sense, because of its placement in the higher voice, which tends to be more noticeable for people. I should also mention that there is one fifth (or 12th actually) in the 3rd bar, which is not as sonorous as the third or sixth that are usually preferred at a place like this (between 2nd and penultimate bars), however, it does provide the continuation of the contrary movement between the voices.
Overall, it was nice analyzing the given solutions before attempting the exercise, as this presented me with a kind of critical tool to evaluate my own future solutions. I think this is a very important aspect to keep in mind when practicing counterpoint.