Can loud music damage your hearing? - Heather Malyuk

譯者: Lilian Chiu 審譯者: Amanda Zhu

After a three-hour concert by her favorite Norwegian metal band,

在聽完三小時她最愛的 挪威金屬樂團的音樂會之後，

Anja finds it difficult to hear her friend rave about the show.

安妮亞發現她聽不清楚 友人對這場表演喋喋不休的讚揚。

It sounds like he's speaking from across the room,

聽起來好像他在房間的另一頭說話，

and it’s tough to make out his muted voice over the ringing in her ears.

且很難在她的耳鳴中 辨認出他那變小的聲音。

By the next morning, the effect has mostly worn off,

隔天早上，那個情況幾乎都消失了，

but Anja still has questions.

但安妮亞仍然有著疑慮。

What caused the symptoms? Is her hearing going to fully recover?

那些症狀是什麼造成的？ 她的聽力能完全恢復嗎？

And can she still go to concerts without damaging her ears?

她如果再去聽音樂會， 耳朵能不受到損傷嗎？

To answer these questions,

要回答這些問題，

we first need to understand what sound is and how we hear it.

首先我們得要了解聲音是什麼， 以及我們如何聽到聲音。

Like a pebble creating ripples in water,

就像石頭丟到水中造成漣漪，

sound is created when displaced molecules vibrate through space.

當空間中的分子因為移動 而震動時，就會產生聲音。

While sound vibrations can travel through solids and liquids,

雖然聲音的震動 可以通過固體和液體，

our ears have evolved to process vibrations in the air.

但我們的耳朵已經演化成 會處理空氣中的振動。

These waves of air pressure enter our ear canals and bounce off the eardrum.

這些空氣壓力波進入 我們的耳道，振動鼓膜。

A trio of bones called the ossicular chain

三塊聽小骨形成的聽骨鏈

then carries those vibrations into the cochlea,

接著把這些振動送到耳蝸，

transforming waves of air pressure into waves of cochlear fluid.

將空氣壓力波轉換為耳蝸液波。

Here, our perception of sound begins to take form.

我們對於聲音的感知在此開始成形。

The waves of fluid move the basilar membrane,

液波會移動基底膜，

a tissue lined with tens of thousands of hair cells.

一種覆蓋著數萬個毛細胞的組織。

The specific vibration of these hair cells and the stereocilia on top of each one

這些毛細胞及其上方的靜纖毛 所產生的特定震動，

determine the auditory signal our brain perceives.

會決定我們大腦感知到的聽覺訊號。

Unfortunately, these essential cells are also quite vulnerable.

不幸的是，這些重要的 細胞也相當脆弱。

There are two properties of sound that can damage these cells.

聲音有兩項特性 會對這些細胞造成損傷。

The first is volume.

第一是音量。

The louder a sound is, the greater the pressure of its vibrations.

聲音越大，其震動的壓力就越大。

While the ear’s upper limits vary from person to person,

雖然耳朵的上限因人而異，

close range exposure to sound exceeding 120 decibels

近距離暴露在超過 120 分貝的聲音之下

can instantly bend or blow out hair cells, resulting in permanent hearing damage.

馬上就會讓毛細胞彎曲或爆裂，

造成永久性的聽力損傷。

The pressure of more powerful sounds can even dislocate the ossicular chain

更強的聲音所產生的壓力 甚至有可能會讓聽骨鏈脫位，

or burst an eardrum.

或者讓耳膜破裂。

The other side of this equation is the sound’s duration.

另一個影響因素 則是聲音持續的時間。

While dangerously loud sounds can injure ears almost instantly,

雖然聲音大到非常危險時， 幾乎馬上就會傷害耳朵，

hair cells can also be damaged

毛細胞也可能因為長時間

by exposure to lower sound pressure for long periods.

暴露在不那麼大聲的聲壓之下而受損。

For example, hearing a hand dryer is safe for the 20 seconds you’re using it.

比如，使用乾手機只要 20 秒， 在這段時間聽它的聲音是安全的。

But if you listened for 8 consecutive hours,

但如果連續聽 8 小時，

this relatively low-pressure sound would overwork the stereocilia

這種相對聲壓較低的聲音 會讓靜纖毛過度使用，

and swell the hair cell’s supporting tissue.

讓毛細胞的支持組織腫起來。

Swollen hair cells are unable to vibrate with the appropriate speed and accuracy,

腫起來的毛細胞無法用 適當的速度和正確地產生振動，

making hearing muffled.

讓聽力減弱。

This kind of hearing loss is known as a temporary threshold shift,

這種聽力喪失就是 一般所知的暫時性聽力損失，

and many people will experience it at least once in their lifetime.

許多人在一生中都至少會經歷一次。

In Anja’s case, the loud sounds of the concert

在安妮亞的例子中， 音樂會的音量很大，

only took three hours to cause this condition.

只花了三小時就造成了這種狀況。

Fortunately, it's a temporary ailment that usually resolves

幸運的是，它只是暫時性的輕症，

通常隨時間，腫脹會減輕， 症狀也就會消失了。

as swelling decreases over time.

In most cases,

在大部分的情況中， 只要避開有害的聲音，

simply avoiding hazardous sounds gives hair cells all they need to recover.

就能讓毛細胞好好復元。

One temporary threshold shift isn’t likely to cause permanent hearing loss.

一次暫時性聽力損失 不太可能造成永久性的聽力喪失。

But frequent exposure to dangerous sound levels

經常暴露在危險級的音量之下，

can lead to a wide range of hearing disorders,

有可能會造成多種聽力相關病症，

such as the constant buzz of tinnitus

比如經常性的耳鳴

or difficulty understanding speech in loud environments.

或者很難在吵鬧的環境中聽人說話。

Overworked hair cells can also generate dangerous molecules

過度使用的毛細胞 也有可能會產生危險分子，

called reactive oxygen species.

稱為活性氧類。

These molecules have unpaired electrons,

這些分子有不成對電子，

driving them to steal electrons from nearby cells

導致它們會向鄰近的細胞偷取電子，

and cause permanent damage to the inner ear.

對內耳造成永久性的損傷。

There are numerous strategies you can adopt for preventing hearing loss.

有許多策略都可以 用來預防聽力喪失。

Current research around earbud headphone use suggests keeping your volume

關於使用耳塞式耳機的近期研究

建議如果一天要聽聆 90 分鐘以上，

at 80% or less if you’ll be listening for more than 90 minutes throughout the day.

音量應該設在 80% 以下。

Noise-isolating headphones can also help you listen at lower volumes.

抗噪耳機也可以協助你 用較低的音量來聆聽。

Getting a baseline understanding of your hearing

對於聽力有基本的了解，

is essential to protecting your auditory system.

對於保護你的聽力系統是很重要的。

Just like our eyes and teeth, our ears also need annual check-ups.

和眼睛及牙齒一樣，

耳朵也需要每年做檢查。

Not all communities have access to audiologists,

並非每個社區中都有聽力學專家，

but organizations around the world are developing portable hearing tests

但世界各地都有組織在開發 可攜式聽力測驗

and easy-to-use apps to bring these vital resources to remote regions.

以及簡單易用的應用程式， 將這些重要資源帶到偏遠地區。

Finally, wear earplugs when you’re knowingly exposing yourself

最後，如果你知道自己會長時間

暴露在大音量之下，可以戴耳塞。

to loud sounds for extended periods.

An earplug’s effectiveness depends on how well you’ve inserted it,

把耳塞置入的方式會影響它的有效性，

so be careful to read the instructions.

所以一定要仔細閱讀說明書。

But when worn correctly,

如果能正確配戴，

they can ensure you'll be able to hear your favorite band

可以確保你將來還可以去聽很多場

你最愛的樂團所舉辦的音樂會。

for many nights to come.