chirping, buzzing
喓 centers on small, high-pitched insect sounds: chirping or buzzing.
喓 combines 口 (mouth) with 要, which likely contributes the sound. The character is used for insect sounds, but the exact historical development is uncertain.
The mouth radical 口 beside 要 suggests a small mouth making a high-pitched sound, like an insect chirping or buzzing.
For ヨウ, imagine a tiny insect yo-yoing up and down while chirping: yo -> ヨウ, and the sound comes from its mouth.