sound of a bell, small bell
鎤 centers on the sound of a bell, specifically a small bell. It refers to the ringing tone itself or the small bell that produces it.
鎤 combines 金 (metal) with 晃, which likely contributes the sound and carries a sense of brightness or shining. Together they suggest a metal object that produces a bright, ringing sound.
The left side 金 (metal) and the right side 晃 (bright, shining) together suggest a shiny metal bell. Imagine a small, polished bell that gleams as it rings.
For コウ, picture a small bell that makes a clear 'ko' sound when struck, echoing 'kou' as it rings out.