The beautiful, mysterious science of how you hear | Jim Hudspeth

106,316 views ・ 2020-04-15

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Please double-click on the English subtitles below to play the video.

00:00
Transcriber: Joseph Geni Reviewer: Camille Martínez
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Translator: Ellie Siu Reviewer: Thomas Tam
00:15
Can you hear me OK?
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你哋聽到嘛?
00:16
Audience: Yes.
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觀眾:聽到
00:17
Jim Hudspeth: OK. Well, if you can, it's really amazing,
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講者:聽到已係唔簡單
00:20
because my voice is changing the air pressure where you sit
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因為我嘅聲音正喺到改變緊 你哋周圍嘅空氣壓力
00:24
by just a few billionths of the atmospheric level,
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但只係大氣壓力十億分之幾
00:28
yet we take it for granted
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咁就係理所當然
00:29
that your ears can capture that infinitesimal signal
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耳仔會接收到呢啲微弱嘅聲音訊號
00:33
and use it to signal to the brain the full range of auditory experiences:
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仲將呢啲聽覺嘅體驗,傳畀大腦
00:37
the human voice, music, the natural world.
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而裡邊夾雜咗人聲 音樂同大自然嘅聲音
00:42
How does your ear do that?
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耳仔究竟係點樣聽到嘢?
00:44
And the answer to that is:
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答案就係:
00:45
through the cells that are the real hero of this presentation --
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透過某啲細胞 亦即係呢次演講嘅英雄——
00:49
the ear's sensory receptors,
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佢哋係喺耳仔裡嘅聽覺接收器
00:51
which are called "hair cells."
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稱為「毛細胞」
00:53
Now, these hair cells are unfortunately named,
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睇嚟佢呢個名無啦啦咁改咗
00:57
because they have nothing at all to do with the kind of hair
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但係同我啲頭髮越來越少
01:00
of which I have less and less.
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係完全無關係
01:02
These cells were originally named that by early microscopists,
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呢個名係由早期顯微鏡學家改嘅
01:07
who noticed that emanating from one end of the cell
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佢哋發現咗啲細胞嘅一邊
01:10
was a little cluster of bristles.
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有執小鬣毛
01:13
With modern electron microscopy, we can see much better
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如果我哋用而家嘅電子顯微鏡 仲會睇得更清楚
01:16
the nature of the special feature that gives the hair cell its name.
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睇到符合「毛細胞」呢個名嘅特徵
01:20
That's the hair bundle.
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就係呢執毛
01:22
It's this cluster of 20 to several hundred fine cylindrical rods
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佢哋係由二十、到多達數百條 纖細嘅圓柱條所組成
01:28
that stand upright at the top end of the cell.
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直立喺細胞嘅頂頭
01:31
And this apparatus is what is responsible for your hearing me right this instant.
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你哋家陣可以聽到我嘅聲音 就係拜呢啲毛細胞所賜
01:38
Now, I must say that I am somewhat in love with these cells.
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我一定要講我已愛上咗毛細胞喇﹗
01:41
I've spent 45 years in their company --
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我同佢哋,已經相處咗四十五年——
01:44
(Laughter)
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(笑聲)
01:45
and part of the reason is that they're really beautiful.
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部分原因、因為佢哋真係好鬼靚
01:48
There's an aesthetic component to it.
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有種美感
01:50
Here, for example, are the cells
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譬如話
01:52
with which an ordinary chicken conducts its hearing.
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喺雞用嚟聽嘢嘅細胞
01:55
These are the cells that a bat uses for its sonar.
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喺蝙蝠聲納裝置所用到嘅細胞
01:59
We use these large hair cells from a frog for many of our experiments.
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我哋喺好多實驗度 都用到嘅青蛙大型毛細胞
02:03
Hair cells are found all the way down to the most primitive of fishes,
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甚至乎最簡單嘅魚類身上 都搵到呢啲毛細胞
02:07
and those of reptiles often have this really beautiful,
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而嗰啲爬蟲類嘅毛細胞 通常都有呢種好靚
02:11
almost crystalline, order.
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近乎結晶嘅排列
02:13
But above and beyond its beauty,
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除咗靚之外
02:15
the hair bundle is an antenna.
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毛束都係一種天線
02:18
It's a machine for converting sound vibrations into electrical responses
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佢都係一種機械,將聲音振動
02:23
that the brain can then interpret.
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轉變成大腦能夠解讀嘅電流反應
02:26
At the top of each hair bundle, as you can see in this image,
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由呢張相,睇到毛束嘅頂頭
02:30
there's a fine filament connecting each of the little hairs,
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有一條細絲將所有嘅細毛連結起嚟
02:33
the stereocilia.
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呢條叫靜纖毛
02:35
It's here marked with a little red triangle.
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就係圖上用紅色三角形指住嗰部分
02:38
And this filament has at its base a couple of ion channels,
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靜纖毛嘅底部,有啲離子嘅通道
02:41
which are proteins that span the membrane.
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係由橫跨細胞膜嘅蛋白質所組成
02:44
And here's how it works.
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佢嘅運作係咁
02:47
This rat trap represents an ion channel.
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呢個捕鼠器代表一條離子通道
02:50
It has a pore that passes potassium ions and calcium ions.
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佢有個小毛孔 能夠俾啲鉀離子同鈣離子通過
02:54
It has a little molecular gate that can be open, or it can be closed.
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又有個小型嘅分子閘門 可以打開,也可以關閉
02:58
And its status is set by this elastic band which represents that protein filament.
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閘門狀態係由蛋白質彈性帶所帶動
03:05
Now, imagine that this arm represents one stereocilium
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想像呢隻手臂係代表一條立體纖毛
03:09
and this arm represents the adjacent, shorter one
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呢隻手臂代表另一條 鄰近比較短嘅立體纖毛
03:12
with the elastic band between them.
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兩條纖毛中間、又有彈力帶連結
03:14
When sound energy impinges upon the hair bundle,
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喺聲音能量撞擊到毛束時
03:17
it pushes it in the direction towards its taller edge.
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聲音嘅能量會推向比較高那邊
03:20
The sliding of the stereocilia puts tension in the link
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立體纖毛嘅滑動 會使連接處產生張力
03:23
until the channels open and ions rush into the cell.
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直至通道打開,離子湧入細胞度
03:27
When the hair bundle is pushed in the opposite direction,
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喺毛束被推向反方向時
03:29
the channels close.
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通道就關閉
03:31
And, most importantly,
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最重要嘅係
03:32
a back-and-forth motion of the hair bundle,
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喺有聲波嗰時
03:35
as ensues during the application of acoustic waves,
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毛束會產生來來回回嘅運動
03:39
alternately opens and closes the channel,
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構成通道嘅開開合合
03:42
and each opening admits millions and millions of ions into the cell.
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每次開啟就會俾 數百萬嘅離子進入細胞
03:47
Those ions constitute an electrical current
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嗰啲離子就會構成電流
03:49
that excites the cell.
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刺激啲細胞
03:51
The excitation is passed to a nerve fiber,
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刺激訊號會被傳送到神經纖維
03:53
and then propagates into the brain.
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然後大腦
03:57
Notice that the intensity of the sound
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要注意嘅係,聲音嘅強度
03:59
is represented by the magnitude of this response.
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會造成唔同程度嘅反應
04:01
A louder sound pushes the hair bundle farther,
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較大嘅聲音會將毛束推得更遠
04:04
opens the channel longer,
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令通道打開較長時間
04:06
lets more ions in
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等更多離子進入通道
04:07
and gives rise to a bigger response.
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造成更大嘅反應
04:12
Now, this mode of operation has the advantage of great speed.
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呢種模式嘅優勢,就係運作速度好快
04:16
Some of our senses, such as vision,
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我哋嗰啲感官,例如視覺咁
04:19
use chemical reactions that take time.
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要靠化學反應,係需要時間
04:22
And as a consequence of that,
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造成嘅結果就係
04:23
if I show you a series of pictures at intervals of 20 or 30 per second,
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如果我給大家看一連串嘅圖片 每一秒鐘播放二十或三十張
04:27
you get the sense of a continuous image.
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各位就會覺得影像係連續嘅
04:30
Because it doesn't use reactions,
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因為毛細胞無使用化學反應
04:32
the hair cell is fully 1,000 times faster than our other senses.
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佢會比其他感官,快足足一千倍
04:37
We can hear sounds at frequencies as great as 20,000 cycles per second,
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我哋可以聽到每秒鐘 高達兩萬次嘅聲音頻率
04:42
and some animals have ever faster ears.
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有啲動物嘅耳仔更加靈敏
04:44
The ears of bats and whales, for example, can respond to their sonar pulses
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譬如,蝙蝠同鯨魚嘅耳仔
可以接收每秒鐘十五萬次 聲納脈衝嘅振動同時作出反應
04:49
at 150,000 cycles a second.
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04:53
But this speed doesn't entirely explain why the ear performs so well.
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但呢種速度都無辦法解釋 點解耳仔嘅性能會咁好
04:59
And it turns out that our hearing benefits from an amplifier,
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研究結果顯示我哋嘅聽覺 仲受惠於一種放大效果
05:03
something called the "active process."
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叫做「主動接收過程」
05:07
The active process enhances our hearing
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主動接收過程會加強我哋嘅聽覺
05:09
and makes possible all the remarkable features that I've already mentioned.
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造成我剛才提到,非同凡響嘅效能
05:15
Let me tell you how it works.
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究竟佢係點樣運作嘅?
05:17
First of all, the active process amplifies sound,
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首先,聲音會被放大
當聲音達到臨界點嘅時候 你可以聽到
05:21
so you can hear, at threshold, sounds that move the hair bundle
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連微小到只將毛束移動 十分之三奈米嘅聲音
05:26
by a distance of only about three-tenths of a nanometer.
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05:29
That's the diameter of one water molecule.
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嗰個長度等如一個水分子嘅直徑
05:31
It's really astonishing.
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咁你話係唔係好驚人呢﹗
05:33
The system can also operate
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呢個系統能夠運作喺
05:38
over an enormously wide dynamic range.
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好寛闊嘅動態範圍
05:41
Why do we need this amplification?
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我哋點解需要咁樣嘅放大效果?
05:43
The amplification, in ancient times, was useful
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古時,呢種放大嘅功能好有用
05:47
because it was valuable for us to hear the tiger before the tiger could hear us.
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能夠喺老虎聽到我哋之前 我哋就先聽到老虎嘅聲音
05:51
And these days, it's essential as a distant early warning system.
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家陣佢嘅重要,係喺警覺性 能夠聽到遠程嘅預警系統
05:56
It's valuable to be able to hear fire alarms
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包括聽到火警鐘喇
05:59
or contemporary dangerous such as speeding fire engines or police cars or the like.
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或者係現代嘅危險,譬如 超速行駛嘅消防車、或者警車之類
06:06
When the amplification fails, our hearing's sensitivity plummets,
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喺呢啲聲音嘅放大效果失靈嗰陣 我哋聽覺嘅敏感度會直線下降
06:11
and an individual may then need an electronic hearing aid
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嗰時,我哋就需要一個電子助聽器
06:16
to supplant the damaged biological one.
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替代受損咗嘅生理聽覺
06:19
This active process also enhances our frequency selectivity.
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助聽器嘅主動接收過程 亦會加強我哋嘅頻率辨識度
06:24
Even an untrained individual can distinguish two tones
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既使我哋沒有受過訓練都能夠分辨 兩個頻率差別只有 0.2% 嘅音調
06:27
that differ by only two-tenths of a percent,
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06:30
which is one-thirtieth of the difference between two piano notes,
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呢個差別等同鋼琴上 兩個音符差距嘅三十分之一
06:34
and a trained musician can do even better.
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受過訓練嘅音樂家 能分辨更微細嘅變化
06:37
This fine discrimination is useful
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呢種細緻嘅分辨能力
06:39
in our ability to distinguish different voices
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等我哋可以區別出唔同嘅聲音
06:42
and to understand the nuances of speech.
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同感受到說話中微細嘅差別
06:44
And, again, if the active process deteriorates,
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同樣咁,如果主動接收過程變差
06:47
it becomes harder to carry out verbal communication.
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亦會增加語言溝通嘅難度
06:51
Finally, the active process is valuable in setting the very broad range
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嚟到最後,主動接收過程 仲有一個價值
就係能夠設定我哋嘅耳仔 忍受廣濶嘅聲音範圍
06:55
of sound intensities that our ears can tolerate,
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從你可以聽到最微弱 譬如一枝筆跌落地上嘅聲音開始
06:59
from the very faintest sound that you can hear, such as a dropped pen,
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07:03
to the loudest sound that you can stand --
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到可以忍受最強大嘅——
07:05
say, a jackhammer or a jet plane.
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譬如電鑽或者噴射機發出嘅聲音
07:07
The amplitude of sounds spans a range of one millionfold,
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聲音振幅跨越咗一百萬倍嘅範圍
07:12
which is more than is encompassed by any other sense
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其他感官都比唔上
07:15
or by any man-made device of which I'm aware.
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就我所知嘅任何人造裝置一樣比唔上
07:18
And again, if this system deteriorates,
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同樣咁,如果呢個系統變差咗嘅人
07:21
an affected individual may have a hard time
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可能會好難聽見最微小嘅聲音
07:24
hearing the very faintest sounds
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07:26
or tolerating the very loudest ones.
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或者無辦法忍受到最強大嘅聲音
07:30
Now, to understand how the hair cell does its thing,
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而家為咗了解毛細胞點樣運作
07:32
one has to situate it within its environment within the ear.
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我哋就必須了解 喺耳仔入面係乜嘢嘅環境
07:36
We learn in school that the organ of hearing
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喺學校,我哋學到聽覺嘅器官
07:39
is the coiled, snail-shaped cochlea.
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係盤繞蝸牛形嘅耳蝸
07:41
It's an organ about the size of a chickpea.
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得鷹嘴豆咁大
07:44
It's embedded in the bone on either side of the skull.
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喺頭骨兩側嘅骨頭中間位置
07:48
We also learn that an optical prism
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我哋有學過光學棱鏡
07:51
can separate white light into its constituent frequencies,
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將白光拆開成不同組成嘅頻率
07:55
which we see as distinct colors.
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就係我哋所見到嘅唔同顏色
07:58
In an analogous way,
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同樣咁
07:59
the cochlea acts as sort of an acoustic prism
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耳蝸嘅功能就類似聲學棱鏡
08:03
that splits apart complex sounds into their component frequencies.
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將複雜嘅聲音拆開做組成嘅不同頻率
08:08
So when a piano is sounded,
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所以,彈鋼琴嗰時
08:10
different notes blend together into a chord.
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唔同嘅音符會混合成一個和音
08:13
The cochlea undoes that process.
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耳蝸會逆轉呢個過程
08:15
It separates them and represents each at a different position.
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將每個音符分開 用唔同嘅位置來代表佢哋
08:19
In this picture, you can see where three notes --
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喺圖上大家睇到三個音符——
08:21
middle C and the two extreme notes on a piano --
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中央 C 音同鋼琴兩個極端嘅音符——
08:24
are represented in the cochlea.
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喺耳蝸靜止時對應音域嘅位置
08:26
The lowest frequencies go all the way up to the top of the cochlea.
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最低嘅頻率會直達耳蝸嘅頂頭
08:30
The highest frequencies, down to 20,000 Hz,
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最高嘅頻率,二萬赫以上
08:33
go all the way to the bottom of the cochlea,
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會直達耳蝸嘅底部
08:35
and every other frequency is represented somewhere in between.
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其他頻率則落喺兩者之間嘅某處地方
08:40
And, as this diagram shows,
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喺圖中見到
08:42
successive musical tones are represented a few tens of hair cells apart
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相鄰嘅音調喺耳蝸表面上
距離會係幾十個毛細胞
08:46
along the cochlear surface.
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08:49
Now, this separation of frequencies
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呢種頻率嘅距離
08:51
is really key in our ability to identify different sounds,
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就係我哋能辨別唔同聲音嘅關鍵
08:55
because very musical instrument,
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因為每一種樂器
08:56
every voice,
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每一個聲音
08:58
emits a distinct constellation of tones.
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都會發出獨一無二嘅音調組合
09:01
The cochlea separates those frequencies,
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耳蝸能將呢啲頻率分辨出來
09:04
and the 16,000 hair cells then report to the brain
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然後,一萬六千個毛細胞 會向大腦報告
09:08
how much of each frequency is present.
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每個頻率應該有多少
09:10
The brain can then compare all the nerve signals
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接著,大腦比較所有嘅神經訊號
09:13
and decide what particular tone is being heard.
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然後判定聽到嘅係邊一種特定嘅音調
09:17
But this doesn't explain everything that I want to explain.
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但仲係無講清楚我想解釋嘅一切
09:21
Where's the magic?
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魔法喺邊度?
09:23
I told you already about the great things that the hair cell can do.
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我已經講過給大家聽 毛細胞能夠做到了不起嘅嘢
09:27
How does it carry out the active process
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咁佢要如何執行主動嘅接收過程
09:29
and do all the remarkable features that I mentioned at the outset?
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才能做到我一開始提到 所有特出嘅功能?
09:33
The answer is instability.
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答案係:變化無常
09:36
We used to think that the hair bundle was a passive object,
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我哋之前認為毛束係被動嘅
09:39
it just sat there, except when it was stimulated.
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無受到刺激嘅時候,佢就係喺處等
09:42
But in fact, it's an active machine.
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事實上,毛細胞係主動嘅機器
09:44
It's constantly using internal energy to do mechanical work
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佢一直使用內部嘅能量 嚟做機械嘅工作
09:48
and enhance our hearing.
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加強我哋嘅聽覺
09:50
So even at rest, in the absence of any input,
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所以,即使係休息緊 無任何聲音進入
09:53
an active hair bundle is constantly trembling.
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活躍嘅毛束經常響處震動
09:55
It's constantly twitching back and forth.
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不斷咁來回抽動
09:58
But when even a weak sound is applied to it,
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但當佢接收到一個弱小嘅聲音,
10:00
it latches on to that sound and begins to move very neatly
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就會開始配合嗰個聲音,
以一對一嘅方式,一齊移動
10:03
in a one-to-one way with it,
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10:05
and by so doing, it amplifies the signal about a thousand times.
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咁樣做,會將訊號放大一千倍
10:10
This same instability also enhances our frequency selectivity,
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呢個不穩定嘅變化 同時增強咗我哋嘅頻率辨識度
10:15
for a given hair cell tends to oscillate best
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因為每個毛細胞嘅振盪
10:18
at the frequency at which it normally trembles
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都傾向喺未受刺激嗰時嘅震動頻率
10:21
when it's not being stimulated.
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10:25
So, this apparatus not only gives us our remarkably acute hearing,
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所以,呢個器官不僅造成 我哋擁有無比嘅敏銳聽覺
10:30
but also gives us the very sharp tuning.
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仲可以準確咁辨別音調
10:37
I want to offer you a short demonstration
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我想做個有關嘅簡短示範給大家睇
10:39
of something related to this.
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10:41
I'll ask the people who are running the sound system
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我會請控制音響嘅人
10:44
to turn up its sensitivity at one specific frequency.
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調高一個特定頻率嘅敏感度
10:48
So just as a hair cell is tuned to one frequency,
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就好似毛細胞咁 被調教到一個頻率一樣
10:51
the amplifier will now enhance a particular frequency in my voice.
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家陣放大器會加強 聲音中嘅一個特定頻率
10:56
Notice how specific tones emerge more clearly from the background.
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請你哋留心聽呢個特定嘅音調 點樣喺背景度突顯出嚟
11:02
This is exactly what hair cells do.
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呢個就係毛細胞嘅功能
11:04
Each hair cell amplifies and reports one specific frequency
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每一個毛細胞會針對 一個特定嘅頻率做放大同回報
11:09
and ignores all the others.
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但係忽略其他頻率
11:11
And the whole set of hair cells, as a group, can then report to the brain
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將所有毛細胞嘅接收集合起嚟 就可以向大腦報告
11:15
exactly what frequencies are present in a given sound,
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聽到邊啲聲音頻率
11:18
and the brain can determine what melody is being heard
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接著大腦會判別 聽見係乜嘢嘅旋律
11:21
or what speech is being intended.
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或者講緊啲係乜嘢
11:25
Now, an amplifier such as the public address system
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譬如公共廣播系統嘅放大器
11:29
can also cause problems.
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都可能會造成問題
11:31
If the amplification is turned up too far,
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如果聲音放大過頭
11:33
it goes unstable and begins to howl
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就會變得唔穩定,開始出現爆音
11:35
or emit sounds.
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11:37
And one wonders why the active process doesn't do the same thing.
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你可能會問點解 毛細胞嘅接收過程唔會變成咁?
11:40
Why don't our ears beam out sounds?
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點解我哋嘅耳仔唔會發出聲音?
11:43
And the answer is that they do.
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答案係,其實佢地會
11:45
In a suitably quiet environment, 70 percent of normal people
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喺適當安靜嘅環境度 有七成嘅正常人
11:50
will have one or more sounds coming out of their ears.
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耳仔會聽到一種或多種聲音
(笑聲)
11:54
(Laughter)
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11:55
I'll give you an example of this.
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等我舉個例子給你聽
11:59
You will hear two emissions at high frequencies
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各位會聽到喺正常人耳仔裡邊 發出嚟兩種高頻率嘅聲音
12:03
coming from a normal human ear.
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12:04
You may also be able to discern background noise,
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仲有可以察覺到背景嘅噪音
12:07
like the microphone's hiss,
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譬如麥克風嘅嘶嘶聲、胃嘅咕嚕聲
12:09
the gurgling of a stomach, the heartbeat, the rustling of clothes.
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心跳聲、衣服嘅沙沙聲
(嗡嗡聲、麥克風嘶嘶聲 水龍頭滴水聲、同衣服沙沙聲)
12:14
(Hums, microphone hiss, dampened taps, clothes rustling)
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12:29
This is typical.
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係好典型嘅聲音
12:31
Most ears emit just a handful of tones,
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多數耳仔只會發出少量音調
12:33
but some can emit as many as 30.
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但係也有發出多達三十種音調
12:35
Every ear is unique, so my right ear is different from my left,
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每隻耳仔都係獨一無二
無論我嘅左耳同右耳 我嘅耳仔同你嘅都係唔同
12:38
my ear is different from your ear,
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12:41
but unless an ear is damaged,
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除非佢哋受損
12:42
it continues to emit the same spectrum of frequencies
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否則,喺數年、甚至數十年間
12:46
over a period of years or even decades.
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佢都會發出相同嘅聲波頻譜
12:49
So what's going on?
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咁係乜嘢嘅一回事呢?
12:50
It turns out that the ear can control its own sensitivity,
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研究結果顯示,耳仔可以控制 佢自己嘅敏感度
12:55
its own amplification.
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同決定要放大嘅程度
12:57
So if you're in a very loud environment, like a sporting event
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如果喺好嘈雜嘅環境裡邊 譬如喺比賽緊嘅運動場或者音樂會
13:00
or a musical concert,
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13:02
you don't need any amplification,
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就唔需要放大聲音
13:04
and the system is turned down all the way.
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系統就會完全關閉
13:07
If you are in a room like this auditorium,
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如果你喺呢個講堂嘅環境
13:09
you might have a little bit of amplification,
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聲音可能需要放大啲
13:11
but of course the public address system does most of the work for you.
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但係公共廣播系統 都會幫你放大聲音,令你哋聽得到
13:15
And finally, if you go into a really quiet room
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最後,如果你進入寧靜到 連枝針跌落地都聽得到嘅房間
13:17
where you can hear a pin drop,
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13:18
the system is turned up almost all the way.
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呢個系統就會幾乎全部開晒
13:21
But if you go into an ultraquiet room such as a sound chamber,
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但係若你進入到超寧靜嘅房間 譬如隔音室裡邊
13:25
the system turns itself up to 11,
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呢個系統就會自動調節到最大
13:27
it goes unstable
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會變得好唔穩定
13:29
and it begins to emit sound.
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同時開始發出聲音
13:31
And these emissions constitute a really strong demonstration
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嗰啲發出嚟嘅聲音,清楚咁話俾你知
13:34
of just how active the hair cell can be.
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毛細胞嘅主動性能
13:39
So in the last minute, I want to turn to another question that might come up,
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最後,我想要講一個 可能會有人提出嘅問題
13:43
which is: Where do we go from here?
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跟著會點?
13:45
And I would say that there are three issues
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我會講有三方面
13:47
that I would really like to address in the future.
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將來我會好想研究
13:50
The first is: What is the molecular motor
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第一:毛細胞能做到放大
13:52
that's responsible for the hair cell's amplification?
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背後嘅分子摩打係乜嘢?
13:56
Somehow, nature has stumbled across a system
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大自然以某種方式 偶然發現咗一個系統
13:59
that can oscillate or amplify at 20,000 cycles per second,
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佢每秒鐘能夠振盪或放大到
兩萬次頻率、或者更高
14:04
or even more.
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14:06
That's much faster than any other biological oscillation,
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呢個速度比任何其他生物嘅 振盪頻率都更快
14:09
and we would like to understand where it comes from.
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我哋好想知道佢嘅來頭
14:12
The second issue is how the hair cell's amplification is adjusted
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第二方面,係毛細胞 如何針對聲音環境
14:16
to deal with the acoustic circumstances.
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嚟調節佢嘅放大程度
14:19
Who turns the knob to increase or decrease the amplification
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喺寧靜或者嘈雜嘅環境裡邊
14:23
in a quiet or in a loud environment?
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係乜嘢喺到控制佢嘅放大程度?
14:26
And the third issue is one that concerns all of us,
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第三方面同大家都有關
14:29
which is what we can do about the deterioration of our hearing.
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就係對於人類嘅聽力退化 我哋可以做啲乜嘢?
14:34
Thirty million Americans,
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三千萬美國人同全世界至少四億人
14:35
and more than 400 million people worldwide,
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都係日常生活度 面對一個明顯嘅問題:
14:38
have significant problems on a daily basis
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14:40
with understanding speech in a noisy environment
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喺嘈雜嘅環境裡邊、或係電話度 好難聽清楚對方講啲乜
14:43
or over the telephone.
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14:45
Many have even worse deficits.
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好多人嘅狀況仲會更差
14:47
Moreover, these deficits tend to get worse with time,
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此外,隨著年齡嘅增長 情況會繼續惡化
14:50
because when human hair cells die,
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因為當人類嘅毛細胞死咗
14:52
they're not replaced by cell division.
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佢哋唔會用細胞分裂嚟再次生長
14:56
But we know that nonmammalian animals can replace their cells,
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但係我哋知道非哺乳類動物 佢哋嘅毛細胞可以再生
15:00
and those creatures' cells are dying and being replaced throughout life,
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呢啲生物嘅毛細胞 死咗後會一直再生
15:03
so the animals maintain normal hearing.
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所以佢哋能夠一直維持正常嘅聽力
15:06
Here's an example from a little zebra fish.
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我用小斑馬魚做個例子
15:09
The cell at the top will undergo a division
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最上方嘅細胞會進行分裂
15:11
to produce two new hair cells.
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產生兩個新嘅毛細胞
15:14
They dance for a little bit,
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佢哋會先搖擺一陣
15:16
and then settle down and go to work.
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之後就會定下嚟,開始工作
15:19
So we believe that if we can decode the molecular signals that are used
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我哋相信,若果能了解 呢啲動物嘅毛細胞
15:22
by these other animals to regenerate their hair cells,
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再生嗰時使用邊啲分子訊號
15:26
we'll be able to do the same thing for humans.
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我哋就能夠喺人類做到同樣嘅事
15:29
And our group and many other groups are now engaged in research
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我哋同好多其他團體,正努力研究
15:32
trying to resurrect these amazing hair cells.
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嘗試創造嗰啲不可思議 可重生嘅毛細胞
15:35
Thank you for your attention.
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多謝各位
15:37
(Applause)
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(掌聲)
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