IPA: /ˈʃrɪl.nəs/
KK: /ʃrɪlnəs/
The quality or state of having a high-pitched and piercing sound.
The shrillness of the alarm made it hard to concentrate.
Shrillness → It is formed from "shrill" (from Old English *scryllan*, meaning to cry out or scream) and "-ness" (meaning the state or quality of). The word "shrillness" refers to the quality of being shrill, or having a high-pitched, piercing sound.
Think of the word 'shrill' which describes a high-pitched sound, and remember that 'shrillness' means the quality of having that sharp sound.