An analysis was performed of the regression of the individual hearing threshold on age in the affected persons in a six-generation Dutch family with nonsyndromic autosomal dominant sensorineural hearing loss, which showed linkage to the DFNA2(1p34) region, similar to at least four previously reported nonrelated families. The offset threshold was significantly higher at the high frequencies (around 30 dB at 2 to 8 kHz) than at the lower ones (approximately 0 dB at 0.25 to 1 kHz). Hearing impairment at the higher frequencies may therefore have been present already at birth or in early childhood. The regression coefficient, or the 'annual threshold increase,' expressed in dB/y, was about 1 dB/y on average, but the higher frequencies (1 to 8 kHz) showed significantly more rapid progression than the lower frequencies (0.25 to 0.5 kHz).