Tinnitus is usually caused by an infection, a disease or exposure to loud sounds such as gun shots, bomb blast or may because of the head injury. Tinnitus may also occur with other disorders such as anaemia, heart and blood vessels disorders, including hypertension, Arteriosclerosis and low thyroid hormones levels in the blood. The other reasons may be ear infection, blockage of ear canal, blockage of eustachian tube, otosclerosis and tumours of the middle ear. It may be due to reactions of aspirin or some antibiotics. Ringing in the ear (Tinnitus) is a common problem, affecting hearing nerve in the inner ear, sensation of ringing, buzzing, hissing, chirping, whistling or other sounds. Sensation of complex sounds may be intermittent, continues or pulsating. Loud noise, background noise. Sometimes the tinnitus is caused by infections or blockage in the ear.