The music being taught at the School of Notre Dame (Paris) had two significant innovations over single line Gregorian chant. Chant had no distinct rhythms or beats, so these two technical changes made a great impact in the way music was notated. and

- Measured rhythm, and syncopation.

Explanation:

As per the question, the given two blanks could be filled up by the words 'measured rhythm and syncopation' as these technical changes would help to have a significant impact on music notation. The 'measured rhythm' implies the placement of beats or sounds within a specified time would help produce the intended accent and pattern of the music while syncopation implies 'a temporary displacement of a regular(metrical) accent in order to lay stress on a weak beat' that would help produce distinct sounds leading to create a significant impact. Thus, 'measured rhythm and syncopation' is the answer.

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