Define pitch and shrillness

Pitch of sound is that characteristic of sound by which an acute or shrill note can be distinguished from a grave or a flat note. If a pitch is higher, the sound is said to be shrill and if the pitch is low, the sound is flat.

Shrillness is a word used to describe the quality of sounds that have a high-pitched, strident, raucous, screeching or harsh character, such as those produced by a trumpet or piccolo, but it can also be used to describe a widely recognised and puzzling phenomenon whereby certain sounds are perceived as psychologically painful or aversive to a degree that cannot be accounted for simply in terms of frequency content or loudness.Examples: the sound of fingernails scraping a chalkboard, the sound of chalk on a blackboard.

Pitch is a perceptual property of sounds that allows their ordering on a frequency-related scale.Pitch is the quality that makes it possible to judge sounds as higher and lower in the sense associated with musical melodies.Pitch can be determined only in sounds that have a frequency that is clear and stable enough to distinguish from noise.