還記得上次去聽搖滾音樂會，或者看煙花展之后，你的耳朵一直出現奇怪的聲響嗎？一時間，你聽不到周圍的任何聲音，而你的腦中一直出現嗡嗡聲，好像你的耳朵都要爆炸了。這就是耳鳴。那么，它是怎么產生的呢？下面這篇文章將為你解釋這個現象。

Noise levels louder than a shouting match can damage parts of our inner ears called hair cells. Hair cells act as the gatekeepers of our hearing. When sound waves hit them, they convert those vibrations into electrical currents that our auditory nerves carry to the brain. Without hair cells, there is nothing for the sound to bounce off, like trying to make your voice echo in the desert.

Hair cells reside in the inner ear inside the shell-shaped cochlea（耳蝸）. Bundles of hair-like extensions, called stereocilia（纖毛）, rest on top of them. When sound waves travel through the ears and reach the hair cells, the vibrations deflect off the stereocilia, causing them to move according to the force and pitch of the vibration. For instance, a melodic piano tune would produce gentle movement in the stereocilia, while heavy metal would generate faster, sharper motion. This motion triggers an electrochemical current that sends the information from the sound waves through the auditory nerves to the brain.

When you hear exceptionally loud noises, your stereocilia become damaged and mistakenly keep sending sound information to the auditory nerve cells. In the case of rock concerts and fireworks displays, the ringing happens because the tips of some of your stereocilia actually have broken off. You hear those false currents in the ringing in your head, called tinnitus（耳鳴）. However, since you can grow these small tips back in about 24 hours, the ringing is often temporary

（來源：howstuffworks.com 實習生吳昭文 英語點津 Annabel 編輯）