choke, suffocate, vomit, laugh heartily
嗢 centers on a sudden, forceful blockage or expulsion from the throat: choking, suffocating, vomiting, or laughing so hard it feels like choking.
嗢 combines 口 (mouth) with 昷, which likely contributes the sound. The exact historical development of 昷 is uncertain, but the character is associated with throat-related actions.
The mouth 口 beside 昷 suggests something violent happening in the throat. Picture a mouth choking, vomiting, or laughing so hard it can't breathe.
For オツ, imagine an 'oats' grain stuck in the throat causing choking: oats -> オツ, and the mouth 口 is struggling.