argue, dispute, disturb, annoy
吵 centers on noisy conflict: arguing, disputing, disturbing, or annoying through loud or persistent sound.
吵 combines 口 (mouth) with 少, which likely contributes a phonetic element. The exact historical development is uncertain, but the mouth component fits the idea of noisy arguing.
A mouth 口 beside the small 少 strokes: imagine a small mouth making a big noisy argument, disturbing everyone around.
For ビョウ, picture a loud argument that sounds like a cat's meow: meow -> ビョウ, and the mouth 口 is wide open in dispute.