put in the mouth, bite, chew
噆 centers on taking something into the mouth and working it with the teeth: putting food in the mouth, biting, or chewing.
噆 combines 口 (mouth) with 朁, which likely contributes the sound. The exact historical development of 朁 is uncertain, but the character is built around mouth-related actions.
The mouth radical 口 on the left is next to a complex right side that looks like a person bending over food. Picture someone putting food into their mouth and chewing it thoroughly.
For ソウ, imagine the sound of chewing: 'sow, sow, sow' as you bite and chew. The repetitive 'sow' sound cues ソウ while you work the food in your mouth.