cry, call
喊 centers on vocal outbursts: crying out, shouting, or calling to someone. The two given meanings are direct expressions of raising one's voice.
喊 combines 口 (mouth) with 咸, which likely contributes the sound and may carry a sense of calling out or shouting.
The mouth 口 on the left and the right side 咸 (which looks like a person shouting with a weapon 戈) together suggest a loud cry or call.
For カン, imagine a can being used as a makeshift megaphone to cry out: can -> カン, and the mouth 口 amplifies the call.