Noise-induced hearing loss 4 kHz notch

A 42-year-old factory worker with 18 years of unprotected exposure to stamping machines (>95 dB SPL) presents with high-pitched tinnitus and difficulty hearing his children speak. Otoscopy is normal. The audiogram shown displays the pattern marked **C** — bilateral symmetric sensorineural hearing loss with a notch at 4 kHz and recovery at 8 kHz, with preserved low frequencies. Which of the following BEST explains the pathophysiology of this audiometric finding?

A 38-year-old male steel factory worker presents with a 4-year history of bilateral high-pitched tinnitus and difficulty understanding speech in noisy environments. He has worked with power presses and angle grinders for 15 years with inconsistent ear protection use, and also engages in recreational firearm use without hearing protection. Otoscopy is normal, Weber test is central, and Rinne test shows air conduction greater than bone conduction bilaterally. Tympanometry reveals type A tracings with normal compliance and intact acoustic reflexes. Pure-tone audiometry demonstrates the pattern marked **A** in the diagram. Based on this characteristic audiometric finding, what is the most likely diagnosis?