noisy
聒 centers on intrusive, overwhelming sound: noise that fills the ears and makes it hard to think. The core idea is clamor or din, not just any sound.
聒 combines 耳 (ear) with 舌 (tongue), suggesting noise that assaults the ear as if a tongue were wagging incessantly. The exact historical development is uncertain, but the component choice clearly points to auditory disturbance.
An ear 耳 next to a tongue 舌: imagine a tongue flapping right into your ear, creating unbearable noise.
For カツ, picture a noisy cat screeching right into your ear: cat -> カツ, and the racket is deafening.