翻譯 What causes hearing loss?
Project Description
What causes hearing loss?
Hearing loss can happen suddenly or gradually. Sometimes there’s an underlying medical reason, but for the most part, it’s simply age-related, and/or the result of being exposed to loud noises over time.
1. The outer ear
Sound waves enter the outer ear and travel through the ear canal to the eardrum, causing it to vibrate.
2. The middle ear
This part of the ear is unaffected by hearing loss. The vibrations travel to the eardrum, which is connected to three tiny bones in the middle ear called ossicles. The ossicles naturally amplify the sound before it enters the inner ear.
3. The inner ear
This part of the ear contains a fluid-filled cochlea lined with thousands of tiny hair cells. With more common hearing losses, hair cells can be damaged or missing along the cochlea. The frequency and severity of hearing loss depends on both the location and number of missing or damaged hair cells.
4. The auditory nerve
Impulses from the remaining intact hair cells travel up the auditory nerve to the brain. Here, the brain may have difficulty interpreting the sound due to the limited acoustic information that can be provided by the functioning hair cells.