Tests Pure tone audiometry Early stage: a decrease in conduction in the low frequency, especially below 1000 H As the disease progresses, the air line flattens, because the otosclerotic focus has a mass affect on the entire system, carhart notch is noted a Further progression of otosclerosis to involve the cochlea may res increased bone conduction threshol h7走 ats ane in high frequency, A-B gap exists in low frequen More isolated cochlear otosclerosis may sometimes result in a mixed hearing loss with a" cookie-bite ttern with both air and bone lineTests ◼ Pure tone audiometry ◼ Early stage: a decrease in air conduction in the low frequency, especially below 1000 Hz. ◼ As the disease progresses, the air line flattens. because the otosclerotic focus has a mass affect on the entire system, carhart notch is noted. ◼ Further progression of otosclerosis to involve the cochlea may result in increased bone conduction thresholds in high frequency, A-B gap exists in low frequency. ◼ More isolated cochlear otosclerosis may sometimes result in a mixed hearing loss with a “cookie-bite” pattern with both air and bone lines