Figure 5. Pure tone audiometry. Pure tone audiometry (250–8000 Hz) in the two affected siblings. The initial recording is shown as a dashed line, and the second recording (about 1 year later) as a solid line. A: This panel shows pure tone audiometric thresholds of over a 1-year period of patient IV:1. B: This panel shows pure tone audiometric thresholds of over an 18-month period of patient IV:2.