Chronic Suppurative Otitis Media (Mixed Hearing Loss)

A 28-year-old man presents with a 6-year history of recurrent mucopurulent otorrhea from the right ear triggered by upper respiratory infections and water entry. He reports progressive hearing loss on the right with low-pitched tinnitus but denies otalgia, vertigo, facial weakness, or fever. Otoscopy reveals a large central perforation of the pars tensa in the anteroinferior quadrant with pale, mildly edematous promontory mucosa. The pars flaccida and posterosuperior quadrant are intact. Weber test lateralizes to the right ear, and Rinne test shows bone conduction better than air conduction on the right. Pure-tone audiometry demonstrates the pattern marked **A** in the diagram. Which of the following best explains the sensorineural component of this patient's hearing loss?