I have lost some hearing in left ear, no fluid in ear, failed tympanic pressure test, what could the cause be? going for mri in 8 months.

Talk to your doctor: At your age, possible causes for decreased hearing in one ear include a benign nerve tumor called vestibular schwannoma, and middle ear disease. The failed tympanometry would tend to point to the middle ear, possibly a chronic infection or a benign process called cholesteatoma. If MRI is not readily available, a ct of the middle ear (temporal bones) may at least help rule out some conditions.