Auditory Brainstem Response (ABR) waves I-V

A 45-year-old man presents with progressive unilateral hearing loss and tinnitus. Audiometry shows sensorineural hearing loss. Auditory Brainstem Response (ABR) testing is performed with click stimuli delivered via earphones, with scalp electrodes recording from vertex (active) and mastoid (reference). The ABR waveform shows a normal Wave I, but the structure marked **C** (Wave V) is significantly delayed compared to the contralateral side, with an interaural latency difference of 0.25 milliseconds. The interpeak latency between Waves I and V is 4.6 milliseconds. Which of the following is the most likely diagnosis?