Audiogram

The standard hearing test chart

Overview

Pure tone audiometry maps the quietest sounds heard at each frequency, typically 250 to 8000 Hz, per ear. Air conduction tests the whole pathway, bone conduction bypasses the middle ear, the gap between them distinguishes conductive from sensorineural loss. Normal hearing is 0 to 20 dB, mild 20 to 35, moderate 35 to 55, severe 55 to 90, profound beyond 90. Speech reception thresholds and word recognition complete the picture. The shape, flat, sloping, notched, tells the story: noise notches at 4 kHz, presbycusis slopes in highs.