Auditory adaptation, short exposure time under strong noise, hearing threshold increase of more than 10 dB, and recovery after a few minutes away from the noise environment. Auditory adaptation is a phenomenon in which a continuous sound stimulus causes a decrease in auditory perception. The auditory system generally decreases in perception of a stable sound source within the first 1-2 minutes, and then quickly stabilizes at a level where auditory adaptation is characterized as a homeostatic process. The research method of auditory adaptation is the loudness balance method. That is, a pure tone of a certain sound intensity (e.g., 80 decibels) is applied to the left ear, and another sound of the same frequency but with variable sound level is applied to the right ear at the same time, so that both are equally loud. Then, the sound in the right ear is stopped and the left ear is allowed to continue listening for 3 minutes. After this adaptation period, the right and left ears are made equally loud again, at which time the equal sound level in the right ear often decreases, e.g. to 60 dB, with an adaptation amount of 20 dB. Pathological auditory adaptation should be noted and the following diseases differential diagnosis: a. Auditory fatigue When you walk into a strong noise environment, you will feel harsh and uncomfortable, and after stopping for a period of time, you will feel that your hearing has become dull, and the slight sound that you could hear can not be heard, which is because your hearing threshold has shifted upward, thus causing your hearing to decline. But as long as you leave the noise environment to rest for a period of time, human hearing will gradually return to its original state, this phenomenon is called temporary hearing offset, also known as auditory fatigue. It is only a temporary physiological phenomenon, the auditory organs are not damaged. If one works under strong noise conditions for years and years, the inner ear auditory organ is often stimulated by strong noise, this auditory fatigue will be fixed and will not return to normal, and a permanent hearing loss or hearing threshold shift is produced. This phenomenon is called noise-induced deafness. Hearing hypersensitivity Hearing hypersensitivity means that the tympanic membrane tensor muscle, which keeps the tympanic membrane tense, is innervated by the internal pterygoid nerve of the trigeminal nerve branch, and the stapedius muscle is innervated by the facial nerve, and these two muscles are in antagonistic relationship to keep the balance. When the facial nerve is paralyzed, the stapedius muscle is paralyzed, therefore, the tympanic membrane tensor muscle is relatively tense, the tympanic membrane tension is high, and the small sound produces strong vibration, resulting in auditory hypersensitivity, which is seen in the lesion of the facial nerve above the stapedius muscle branch. Hearing impairment refers to a congenital or acquired defect in the structure of the auditory organ or a partial or total impairment in its function, resulting in difficulty in hearing or recognizing sounds; the criteria for identification are as follows: (1) After receiving a self-conscious pure tone hearing examination, the euphonic frequency hearing is 25 decibels or more. (2) If the person is unable to undergo the pure tone hearing examination in the preceding paragraph, the person will be determined by other hearing examination.