ah, harmony
喤 centers on vocal sound: an exclamation like 'ah' or a harmonious cry. It represents the sound of voices blending together.
喤 combines 口 (mouth) with 皇, which likely contributes the sound and suggests a grand or harmonious vocal quality. The exact historical development is uncertain.
A mouth 口 making a sound like 皇 (emperor) suggests a majestic, harmonious cry. Imagine a chorus of voices blending into a single 'ah'.
For コウ, picture a harmonious choir singing a single note: 'coh' -> コウ, as their voices blend together.