the hearing, to listen, astute, clever, quick of apprehension
聦 centers on sharp, perceptive hearing: the ability to listen well and quickly grasp what is heard, leading to astuteness and cleverness.
聦 combines 耳 (ear) with 怱, which likely contributes the sound and possibly the idea of quickness or intelligence. The exact historical development is uncertain.
The ear 耳 on the left and the heart 心 at the bottom right suggest listening with one's heart, making one astute and quick to understand.
For ソウ, imagine a clever person listening so intently that they hear the soft sound of sewing: sew -> ソウ, and their sharp ears catch every stitch.