Which preposition to use with shrillness

of Occurrences 3%

The front seats were filled by children of various agesthe rear, of adults, rising above these tiny choristers, and softening the shrillness of their notes by the deeper tones of mature age.

down Occurrences 1%

While he was wondering, the small figure on the horse sent up a cry that rang like the note of a bell and echoed in sweet shrillness down the hill and along the valley.

Which preposition to use with  shrillness