Chronic Suppurative Otitis Media — Tubotympanic (Mucosal) Type

A 24-year-old woman presents with a 3-year history of intermittent painless ear discharge from the left ear, exacerbated by upper respiratory infections and swimming. Otoscopy shows a large central perforation of the tympanic membrane with healthy pink mucosa visible through it. No cholesteatoma, granulation tissue, or marginal perforation is noted. Pure-tone audiometry of the left ear is shown in the diagram. The pattern marked **A** in the audiogram—showing air-conduction thresholds of 35–45 dB across speech frequencies with bone-conduction thresholds remaining at 0–10 dB—is the hallmark of which type of chronic suppurative otitis media?