To whom did Robert Schumann compare Felix Mendelssohn?

The high-low quality of a musical tone is called pitch and is created by an object vibrating constantly at a fixed number of cycles per second, or pitch frequency. The faster (more frequent) the vibrations, the higher the pitch. Give examples of a high pitch and a low pitch

What will be an ideal response?

The notation of troubadour and trouvère melodies does not indicate ________. 

A. rhythm B. duration C. pitch D. All answers are correct.