A 41-year-old factory worker attends occupational hearing surveillance. Pure-tone thresholds are near-normal except for a notch at 4 kHz. DPOAEs are reduced specifically in the high frequencies, most markedly around 4 kHz.
Findings
○ Right — PTA 15 dB (Normal)✕ Left — PTA 18 dB (Normal)
Pure-tone audiogram companion. dB HL increases downward, following clinical convention. Illustrative thresholds — not recorded patient data.
● DP emission▮ Noise floor
A normal DP-gram. The emission sits comfortably above the noise floor at every test frequency — the margin between the two is the signal-to-noise ratio. Simplified teaching model, not calibrated normative data.
Diagnostic question
What does the high-frequency DPOAE reduction, with a notch matching the audiogram, most likely represent?