A 35-year-old woman presents with progressive conductive hearing loss and recurrent ear discharge for 5 years. She reports a history of chronic ear drainage since childhood following a severe ear infection. Otoscopy shows a retraction pocket in the posterosuperior quadrant of the tympanic membrane with keratinous material visible. Tuning fork tests show Weber lateralizing to the affected ear and Rinne showing bone conduction better than air conduction on the affected side. What is the most likely pathophysiologic mechanism underlying this presentation?