Vignette

A 45-year-old who has worked on a factory floor for twenty years attends a routine occupational hearing screen. They report ringing in both ears after shifts. Otoscopy is normal.

O Right ear, air
X Left ear, air
< Right ear, bone
> Left ear, bone

Signature: Sensorineural notch at 4 kHz with partial recovery at 8 kHz — the classic noise notch.

Figure 1. The audiogram. The loss is bilateral and symmetrical. No air–bone gap.

Question

Which audiometric feature best supports the likely cause?

References

[16] Lanska DJ (2026). Noise-induced hearing loss.