Cats fighting are noisy, viscous, bastards whom have added to an already fractured night's sleep. Psychoacoustics dictate we hear loudest around 300Hz through to about 600Hz which why a baby crying is difficult to ignore or an annoying YouTube advert's sound mixing choices - same volume but perceived as much louder. It's my contention that cat fights slap bang in that sweet spot , or at least the bits we can hear - they're are no doubt harmonics above the average human hearing thresholds.