open-mouthed laughter, listen to, pound (sterling, lb)
听 centers on open-mouthed laughter, with a secondary sense of listening or paying attention. The pound (sterling) meaning is a phonetic loan and unrelated to the core idea.
听 combines 口 (mouth) with 斤, which likely contributes the sound. The original meaning is open-mouthed laughter, with the listening sense developing later. The pound (sterling) meaning is a modern phonetic borrowing.
The mouth 口 is wide open beside the axe-like 斤, like someone laughing so hard their mouth is as wide as an axe blade. That open mouth also suggests listening intently.
For キン, imagine a king laughing with his mouth wide open: king -> キン, and his laughter fills the hall.
pound (unit of weight)