Can loud music damage your hearing? - Heather Malyuk

702,551 views ・ 2021-03-02

TED-Ed


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翻译人员: Jiasi Hao 校对人员: Wanting Zhong
在听了她最爱的挪威金属乐队的 三小时演唱会后,
00:10
After a three-hour concert by her favorite Norwegian metal band,
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00:13
Anja finds it difficult to hear her friend rave about the show.
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安雅发现自己听不清 朋友对演出的痴迷爆吹。
00:17
It sounds like he's speaking from across the room,
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朋友仿佛是在房间的另一头和她说话,
00:20
and it’s tough to make out his muted voice over the ringing in her ears.
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她嗡嗡作响的耳朵 很难分辨出朋友喑哑的声音。
00:24
By the next morning, the effect has mostly worn off,
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第二天早上, 这种情况基本消失了,
00:27
but Anja still has questions.
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但是安雅依旧心存疑惑。
00:30
What caused the symptoms? Is her hearing going to fully recover?
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是什么导致了昨天的症状? 她的听力会完全恢复吗?
00:34
And can she still go to concerts without damaging her ears?
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她可以在不损伤耳朵的情况下 继续去现场演唱会吗?
00:38
To answer these questions,
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要回答这些问题,
00:40
we first need to understand what sound is and how we hear it.
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首先我们需要了解什么是声音, 以及我们是如何听到声音的。
00:44
Like a pebble creating ripples in water,
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如同鹅卵石在水中激起涟漪,
00:47
sound is created when displaced molecules vibrate through space.
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声音是由位移的分子 在空间中振动而产生的。
00:51
While sound vibrations can travel through solids and liquids,
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振动可以通过固体和液体传播,
00:56
our ears have evolved to process vibrations in the air.
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而我们的耳朵已进化到 能处理空气中传播的振动。
00:59
These waves of air pressure enter our ear canals and bounce off the eardrum.
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这些气压波进入我们的耳道, 并在鼓膜上反弹。
01:05
A trio of bones called the ossicular chain
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三块相互连接的听小骨 (名为听小骨链)
01:08
then carries those vibrations into the cochlea,
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随之将这些振动传递至耳蜗,
01:11
transforming waves of air pressure into waves of cochlear fluid.
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将气压波转化为耳蜗液体的振动,
01:15
Here, our perception of sound begins to take form.
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于是我们对听觉的感知开始形成。
01:20
The waves of fluid move the basilar membrane,
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液体机械波会使耳蜗基底膜移动,
01:23
a tissue lined with tens of thousands of hair cells.
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这是一个排列了数万毛细胞的组织。
01:28
The specific vibration of these hair cells and the stereocilia on top of each one
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这些毛细胞的特定振动 和每个毛细胞顶部静纤毛的摆动
01:33
determine the auditory signal our brain perceives.
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决定了我们大脑感知的听觉信号。
01:37
Unfortunately, these essential cells are also quite vulnerable.
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不幸的是,这些细胞十分重要, 但也相当脆弱。
01:42
There are two properties of sound that can damage these cells.
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两种声音属性能够损害这些细胞。
01:46
The first is volume.
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首先是音量。
01:47
The louder a sound is, the greater the pressure of its vibrations.
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音量越大,振动的压力越大。
01:52
While the ear’s upper limits vary from person to person,
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尽管耳朵能承受的上限因人而异,
01:55
close range exposure to sound exceeding 120 decibels
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但近距离接触超过 120 分贝的声音
01:59
can instantly bend or blow out hair cells, resulting in permanent hearing damage.
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会立即弯曲或振破毛细胞, 从而导致永久性听力损伤。
02:05
The pressure of more powerful sounds can even dislocate the ossicular chain
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更响声音的压力 甚至可以使听骨链脱位,
02:10
or burst an eardrum.
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或耳膜破裂。
02:13
The other side of this equation is the sound’s duration.
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另一个属性是声音的持续时间。
02:16
While dangerously loud sounds can injure ears almost instantly,
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危险的大音量 几乎能对耳朵造成瞬时伤害,
02:20
hair cells can also be damaged
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不过长时间暴露于较低的声压下
02:22
by exposure to lower sound pressure for long periods.
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也会损伤毛细胞。
02:26
For example, hearing a hand dryer is safe for the 20 seconds you’re using it.
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例如,在使用烘手机的 20 秒内, 它的噪音是安全的,
02:30
But if you listened for 8 consecutive hours,
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但如果连续听 8 小时,
02:34
this relatively low-pressure sound would overwork the stereocilia
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这个相对较低的声压 会过度使用静纤毛
02:38
and swell the hair cell’s supporting tissue.
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并使毛细胞的支持组织肿胀。
02:41
Swollen hair cells are unable to vibrate with the appropriate speed and accuracy,
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肿胀的毛细胞 无法以正确的速度和精度振动,
02:46
making hearing muffled.
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令听力变得模糊不清。
02:48
This kind of hearing loss is known as a temporary threshold shift,
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这种听力损失被称为 暂时性阈值偏移(即听觉疲劳),
02:52
and many people will experience it at least once in their lifetime.
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很多人一生中至少会经历一次。
02:56
In Anja’s case, the loud sounds of the concert
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在安雅的例子中,演唱会的喧闹
02:59
only took three hours to cause this condition.
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只需 3 小时就能导致这种情况。
03:03
Fortunately, it's a temporary ailment that usually resolves
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幸运的是,这是一种暂时的疾病,
通常会随着时间推移、 肿胀消退而消失。
03:06
as swelling decreases over time.
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03:08
In most cases,
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大部分情况下,
03:09
simply avoiding hazardous sounds gives hair cells all they need to recover.
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只需避免危害性的声音 就足以让毛细胞恢复。
03:15
One temporary threshold shift isn’t likely to cause permanent hearing loss.
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一次暂时性听阈偏移不太可能 会造成永久听力损失,
03:19
But frequent exposure to dangerous sound levels
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但是频繁暴露在危险的声音水平
03:22
can lead to a wide range of hearing disorders,
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会导致各种听力障碍,
03:25
such as the constant buzz of tinnitus
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例如持续嗡嗡作响的耳鸣,
03:28
or difficulty understanding speech in loud environments.
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或在嘈杂的环境中难以分辨他人说话。
03:32
Overworked hair cells can also generate dangerous molecules
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过度工作的毛细胞也会产生
03:35
called reactive oxygen species.
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名为活性氧的危险分子。
03:38
These molecules have unpaired electrons,
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这些分子携带未配对电子,
03:41
driving them to steal electrons from nearby cells
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驱使它们从附近细胞中偷取电子
03:44
and cause permanent damage to the inner ear.
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并造成内耳的永久性损伤。
03:47
There are numerous strategies you can adopt for preventing hearing loss.
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你可以采用很多方式 预防听力损失。
03:51
Current research around earbud headphone use suggests keeping your volume
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有关耳塞式耳机的最新研究建议,
如果一天使用耳机 90 分钟以上, 最好将音量控制于 80% 以下。
03:55
at 80% or less if you’ll be listening for more than 90 minutes throughout the day.
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04:00
Noise-isolating headphones can also help you listen at lower volumes.
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降噪耳机也能帮助你 降低音量收听。
04:05
Getting a baseline understanding of your hearing
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对你的听力有一个基本的认识
04:08
is essential to protecting your auditory system.
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对保护听力系统极为重要。
04:11
Just like our eyes and teeth, our ears also need annual check-ups.
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和眼睛与牙齿一样, 我们的耳朵也需要年检。
04:16
Not all communities have access to audiologists,
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尽管不是所有地方都有听力学家,
04:19
but organizations around the world are developing portable hearing tests
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但是全球相关组织正在研发 便携式听力测试
04:23
and easy-to-use apps to bring these vital resources to remote regions.
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以及方便使用的 app , 将这些重要资源带到偏远地区。
04:28
Finally, wear earplugs when you’re knowingly exposing yourself
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最后,在你知道自己要长时间 暴露于大音量声响时,
04:32
to loud sounds for extended periods.
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戴上耳塞。
04:34
An earplug’s effectiveness depends on how well you’ve inserted it,
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耳塞的有效性取决于你戴得多好,
04:38
so be careful to read the instructions.
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所以请仔细阅读使用说明。
04:41
But when worn correctly,
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不过只要正确地使用,
04:43
they can ensure you'll be able to hear your favorite band
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耳塞能确保你在未来的无数夜晚
04:46
for many nights to come.
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可以继续欣赏你最爱的乐队。
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