Tinnitus

Tinnitus is a sound subjectively perceived by the human ear in the absence of external acoustic or electrical stimulation. It is worth noting that tinnitus is an illusion occurring in the auditory system, and it is a symptom rather than a disease. Some people often feel special sounds in their ears, such as buzzing, hissing, or sharp whistling, but no corresponding sound source can be found in the surrounding environment; this condition is tinnitus. Tinnitus makes people feel agitated and restless, and in severe cases, it can affect normal life and work. The causes of tinnitus are divided into two categories: tinnitus and cranial tinnitus. Brain damage is called cranial tinnitus, while auditory nerve and hearing abnormalities are called tinnitus. Tinnitus sensations are further divided into unilateral tinnitus and bilateral cranial tinnitus, generally collectively referred to as tinnitus. Tinnitus refers to a subjective auditory sensation produced in the absence of a corresponding external sound source; this sound is not generated by sound waves but is caused by abnormal or damaged neural signals. The transmission of external sounds into the human ear and their eventual perception by the auditory cortex depends on the following three links: First, the impedance-matching function of the sound-conducting structures in the middle ear. Second, the conversion of acoustic energy into neural impulses by the auditory receptors in the inner ear. Third, the unobstructed neural conduction from the cochlear nucleus through the brainstem to the auditory cortex of the temporal lobe. A malfunction in any of these three links can produce tinnitus. Based on cause and anatomy, tinnitus can be divided into two major categories: subjective tinnitus and objective tinnitus. Subjective tinnitus refers to tinnitus that, in the absence of a sound source, can only be heard by the patient himself, while the examiner cannot hear it; it is also called subjective tinnitus or non-pulsatile tinnitus.