Final answer:
Acute labyrinthitis affects the saccule and cochlea, structures in the inner ear responsible for balance and hearing.
Step-by-step explanation:
Acute labyrinthitis affects structures in the inner ear that are involved in both hearing and balance. The structures typically affected are the saccule, which is part of the vestibular labyrinth responsible for sensing head position, and the cochlea, which is responsible for transducing sound waves into neural signals. Damage to these structures can result in both hearing and balance deficits.