Hearing loss

Normal hearing refers to a category of hearing sensitivity, it is the average value of normal ear hearing measurement of healthy young people, not an absolute value. Hearing impairment occurs when the transmission or sensory part of the auditory system is damaged or functionally impaired, which is often called hearing loss. Hearing loss ranges from mild to severe, with lighter hearing and deaf. Generally speaking, the deaf means that practical hearing is almost completely lost. Children have been deaf since they were young, and have lost the opportunity to learn a language.