Guillaume Dufay is a French composer and theorist who lived between 1397-1474c. He was well known as a leading composer of his day. He also held position in many of the musical centres of Europe and his music was copied and performed everywhere. His genres include masses, magnificats, motets and secular chansons with French texts.
Gloria ad modum tubae probably is a four parts Cantus firmus Mass. From this piece we can obviously find the free rhythm and flowing counterpoint, which make up the mainly music characteristics for early Renaissance. The use of intervals of third and sixth can be heard in this piece, what's more, he strengthened the controlling of dissonance that second and seventh are hardly find. Meanwhile, the imitation technique was widely used in this piece. The two bass parts alternated with each other in almost the same rhythm and the two upper voices were written in canon all the way down to the authentic cadence.
In contrast to this work, Quam pulchra es, a motet written by another early Renaissance composer Dunstable, has three parts voicing moving together. It has an easy rhythm and single text like Gloria ad modum tubae. However, this melody lines are combined based on the harmony of triad and the texture in middle part most like a duet which emphasize the counterpoint, a lot. Compare with Gloria ad modum tubae, seldom canonic imitation technique was found in Quam pulchra es.
Over all, compare with the other important composers at the same time, Dufay was good at using the early imitation technique that canon goes through the whole piece. Compare with the early Ars nova, the dissonance was painted out, no more double leading tone cadence and chromaticism was found. More activity rhythm, more full chords and expanded ranges appeared.
“Dunstable: Quam Pulchra Es.” Youtube video. Posted by “Ruey Yen.” Uploaded Feb. 16, 2011.http://www.youtube.com/watch?v=8FTw9xl5h-Y
"Gloria ad modum tubae." Youtube video. Posted by "Jaetoo." Uploaded Oct.23, 2011. http://www.youtube.com/watch?v=lEcbGXy5kxw
Dufay, Guillaume. Gloria ad modum tubae. Score. IMSLP. Accessed Feb. 4, 2014. http://conquest.imslp.info/files/imglnks/usimg/b/bf/IMSLP202875-WIMA.8d6c-tubae.pdf