'Shrillness' definitions:

Definition of 'shrillness'

From: WordNet
noun
The quality of being sharp or harsh to the senses; "the shrillness of her hair color"
noun
Having the timbre of a loud high-pitched sound [syn: shrillness, stridence, stridency]

Definition of 'Shrillness'

From: GCIDE
  • Shrillness \Shrill"ness\, n. The quality or state of being shrill. [1913 Webster]