drum
鼛 centers on a large drum, specifically a type of big drum used in ancient contexts. The meaning is straightforward and concrete.
鼛 combines 鼓 (drum) with 咎, which likely contributes a phonetic element. The character is associated with a large drum used in ancient ceremonies or military contexts.
The top component 鼓 is a drum, and the bottom 咎 looks like a person beating it. Imagine a large drum being struck with force.
For コウ, picture a large drum making a deep 'koh' sound when struck: koh -> コウ, and the drum resonates.