1 . Hearing loss is unavoidable, but listening to loud music when you’re younger can make it worse. To reduce your risk of hearing loss via loud music, learn why and how it can cause hearing loss, and just how loud is too loud.
Hearing loss occurs in four ways: conductive hearing loss, sensorineural hearing loss, mixed hearing loss and auditory neuropathy spectrum disorder. Noise-induced (噪音诱发的) hearing loss is a type of sensorineural hearing loss.
Sensorineural hearing loss occurs when your inner ear becomes damaged. In the case of noise- induced hearing loss, most of the damage affects the cells of tiny sensory hairs in your inner ear.
When those cells get damaged or die, the electrical signal that your auditory nerve sends to your brain changes.
Noise-induced hearing loss can be acute or severe, and it can be temporary or permanent. You might be familiar with acute temporary noise-induced hearing loss, even if you didn’t realize what was happening at the time.
Acute temporary noise-induced hearing loss can occur from attending a loud concert or sporting event, going to a gun range without earmuffs or being near an explosion. It can make noises sound “stuffy” or far away, especially when talking on the phone or in a crowded room. Repeated exposure to those loud situations can eventually lead to permanent hearing loss.
Noise levels from earbuds and headphones can get as loud as 139 decibels, according to the journal Noise &Health, far greater than the recommended range of everyday sound exposure, which is 60 to 85 decibels. And the average level of noise from headphones, with the volume turned all the way up, is 94 to 110 decibels. For context, 60 decibels is about the volume of an average conversation, and 130 decibels is about the noise level of a rock concert. 85 decibels is considered the maximum volume at which you can listen to sound for eight hours without damaging your hearing. So if you were to listen to music from your headphones for eight hours a day, listening at a volume louder than 85 decibels can cause permanent damage to your ears.
Unfortunately, the relationship between decibels and time isn’t linear (线性的). For every three decibels, safe exposure time gets cut in half, according to the CDC. At 88 decibels, you can only safely listen for four hours; at 91 decibels, just two hours.
1. Which of the following statements is true according to the passage?| A．Noise-induced hearing loss belongs to sensorineural hearing loss. |
| B．Noise-induced hearing loss is always severe and permanent. |
| C．Occasional exposure to the loud situations can lead to permanent hearing loss in the end. |
| D．Listening to music from headphones for long at any volume won’t be harmful to your ears. |
| A．Participating in a heated debate. | B．Attending a rock concert. |
| C．Going to a gun range with earmuffs. | D．Watching an explosion at a distance. |
| A．Two hours. | B．Half an hour. |
| C．One and a half hours. | D．One hour. |
| A．Loud Music Damages Hearing | B．How to Prevent Hearing Loss |
| C．How Loud Is Too Loud | D．Music and Hearing |
2 . Wisdom teeth removal is common for many people in their late teens and early 20s. But why don’t they come in during childhood with the rest of our permanent teeth?
The answer comes down to child development. There’s not enough room in a child’s jaw for wisdom teeth.
However, many modern human jaws don’t grow long enough for wisdom teeth to come in. Ancient humans ate diets full of hard nuts, uncooked vegetables, and other tough foods.
There is another reason wisdom teeth grow in later.
Nowadays, dentists often remove wisdom teeth because their emergence can cause pain in crowded mouths. Or it can cause problems and tooth damage later on.
| A．Children have small jaws. |
| B．They’re not needed until then. |
| C．But as a kid grows, their jaw grows too. |
| D．Following this diet actually makes the jaw grow longer. |
| E．Most people have 32 teeth, including four wisdom teeth. |
| F．In other words, your wisdom teeth are programmed to erupt as a backup. |
| G．Not all wisdom teeth pop through the gums during the late teens and early 20s. |
