Tinnitus can be described as "ringing" ears and other head noises that are perceived in the absence of any external noise source. It is estimated that 1 out of every 5 people experience some degree of tinnitus. Tinnitus is classified into two forms: objective and subjective.
Objective Tinnitus is rare and consists of head noises audible to other people in addition to the sufferer. The noises are usually caused by vascular anomalies, repetitive muscle contractions, or inner ear structural defects. The sounds are heard by the sufferer and are generally external to the auditory system. This form of tinnitus means that an examiner can hear the sound heard by the sufferer by using a stethoscope. Benign causes, such as noise from TMJ, openings of the eustachian tubes, or repetitive muscle contractions may be the cause of objective tinnitus. The sufferer might hear the pulsatile flow of the carotid artery or the continuous hum of normal venous outflow through the jugular vein when in a quiet setting. It can also be an early sign of increased intracranial pressure and is often overshadowed by other neurologic abnormalities. The sounds may arise from a turbulant flow through compressed venous structures at the base of the brain.
Subjective Tinnitus is more common, may occur anywhere in the auditory system and is much less understood, with the causes being many and open to debate. Anything from the ear canal to the brain may be involved. The sounds can range from a metallic ringing, buzzing, blowing, roaring, or sometimes similar to a claanging, popping, or nonrhythmic beating. It can be accompanied by audiometric evidence of deafness which occurs in association with both conductive and sensorineural hearing loss. Other conditions and syndromes which may have tinnitus in conjunction with the condition or syndrome, are otosclerosis, Menier's syndrome, and cochlear or auditory nerve lesions.
Hearing loss, hyperacusis, recruitment, FMS, and balance problems may or may not be present in conjunction with tinnitus.