Figure 2. Serial audiograms of two
affected members (BT188 and BT189) shown for the right (R) and left (L)
ears separately. Pure tone air-conduction threshold (y-axis) is
expressed in decibels (dB). The blue one represents the audiogram from
18-year-old BT188. Both the red and the green represent the audiograms
for the patient BT189. The red audiogram was made when he was 24
whereas the second was made at the age of 28. BT188 was not available
for audiometric test at the beginning of the study. Audiometric test
showed a moderate sloping bilateral sensorineural HI in these two usher
patients. The green and the red audiograms for the patient BT189 showed
that there is no progression of hearing loss at an interval of four
years.