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If you've ever played Marco Polo,
如果你玩過馬可波羅這個游戲，
you know that it can be pretty tricky to locate sounds with your eyes closed.
你就會知道閉著眼睛定位聲音很難。
But assuming you don't swim violently into a wall trying to tag someone,
但是如果方法得當，
you can do it.
你做得到的。
Your brain can figure out the difference between what each of your ears is hearing
大腦可以分辨出每只耳朵聽到內容的差別
and use that to tell where a sound is coming from.
以此分辨聲音從哪里來。
But how do we do it,
但是我們怎么做呢，
and what would happen if our right ear suddenly switched places with the left?
如果我們的右耳突然和左耳交換一下位置會發生什么事呢？
This might seem like a silly question,
這個問題看起來很傻，
but it's actually one that people study with a device called a pseudophone.
但實際上，人們用一種叫做“假聲器”的設備來研究這個問題。
The pseudophone was invented in the 1920s,
假聲器發明于20世紀20年代，
and it makes it seem like a sound is coming from somewhere that it's not.
通過它，聲音像是來自某個其它地方的聲音。
It's basically a couple of old-school ear trumpets with sound-proof tubing attached to them.
從根本上說，它就是一對帶有隔音管的舊式助聽器。
The user puts an ear trumpet on either side of their head,
使用者在頭兩邊各放一個助聽筒，
and then runs the tubing from each trumpet to their other ear.
然后聲音從每一個喇叭上沿著導管傳至另一只耳朵。
More modern pseudophones electronically flip-flop the sound going to each ear in a pair of headphones,
更現代的假聲器以電子方式通過耳機將聲音傳到耳朵，
but… just savor that ear trumpet image for a second.
但是…只要想一下那個助聽器的樣子。
Generally, humans can adapt to most things—
一般來說，人類可以適應大多數事物—
like when you suddenly step into bright sunlight,
就像你突然接觸耀眼的陽光，
or when you get used to loud music at a concert.
或者習慣了音樂會上喧鬧的樂曲。
But one thing we can't seem to adapt to is switching around our ears.
但有一件事我們似乎無法適應，那就是轉動耳朵。
This one researcher in the '20s, I kid you not,
我不騙你，20年代的研究員，
wandered the streets of Berlin for more than 80 hours while wearing a pseudophone.
戴著假聲器在柏林街頭游蕩了80多個小時。
He was trying to see if he could become habituated to it
他正在試著看自己是否能適應，
and train his brain to flip-flop the sounds back to normal. Turns out he couldn't.
并訓練大腦把聲音恢復到正常，事實證明是不行的。
With his eyes closed, he still pointed in the wrong direction when he heard sounds.
他閉著眼睛聽著聲音仍指錯了方向。
If anything, all that practice made him better at pointing to exactly 180 degrees
如果有什么成果的話，所有這些練習使他更擅長指向反方，
opposite from where the sound was actually coming from.
這與聲音的真正來源截然相反。
All of this suggested to researchers that there really is something important about
研究表明，
how and when each of our ears encounters a sound
我們的耳朵是如何及何時遇到聲音真的很重要
that allows us to tell where it's coming from.
這種聲音可以幫助我們分辨出聲音的來源。
See, under normal circumstances, we're actually really good at localizing sound.
正常情況下，實際上我們很擅長定位聲音。
We can determine the angle that a sound is coming from within one to two degrees.
我們可以確定聲音在1~2度之間準確的角度。
We do it through a process called binaural sound localization,
此次定位通過一個叫做雙耳聲音定位的程序來完成，
which means exactly what it sounds like:
雙耳聲音定位指的就是：
We use both ears to pinpoint a sound's location.
我們用兩只耳朵來定位聲音。
We locate sound horizontally using the difference in intensity between what each ear is hearing
根據每只耳朵聽到聲音強度的差別
and the tiny time delay between when one ear hears it and when the other one does.
以及它們之間的細微延遲來確定聲音的發出位置。
So, for example, if headphones played a sound in both your ears at the same time,
例如，如果聽筒同時在耳朵里播放聲音，
your brain would do the math and conclude that the sound was happening inside your head.
大腦會進行數學運算，并得出結論：聲音正在你的頭腦中發生。
To do the same thing vertically,
縱向地做同樣的事
we use the flappy external parts of our ears, which are called pinnae or auricles.
耳朵外部有絨毛，我們稱之為外耳。
The different shapes and contours of our auricles at different angles make sounds sound different.
外耳的不同形狀以及不同角度的輪廓使得聲音聽起來會有所不同。
Auricles also help us sort out the location of stuff that's in the cone of confusion—
外耳也幫助我們在錐形干擾區準確找出物體的位置
and, yes, that is totally a technical term.
是的，錐形干擾區完全是一個技術術語,
It's the region in front of and behind you where sound generally reaches each ear at the same time.
它是你前方和后方區域，通常在這個區域內聲音到達每只耳朵的時間是一致的。
With hearing, it's generally accepted that
有了聽覺，人們普遍認為，
we don't really build out a map of 3D space on the eardrum or anything like that.
我們并沒有在耳膜或類似的東西上建立三維地圖。
Instead, it's really all about your brain constantly doing these calculations,
相反，一切都是大腦不斷計算出來的，
most of which are done in a region called the superior olivary complex in the brain stem.
其中大部分是在腦干中稱為上橄欖核復合體區域完成的。
Except… that's probably not the whole story, either.
除了…這可能也不是全部。
For one, there’s a lot of evidence that moving the head
首先，很多證據表明移動頭部
and body changes our ability to figure out where sounds are coming from, too.
和身體也會改變我們辨別聲音來源的能力。
A 1980 pseudophone study and a 2018 blindfold study found that
1980年的假聲器研究和2018年的蒙眼研究發現，
people were better at localizing sounds when they could move their head and walk around—
當人們晃動頭部并四處走動時，他們更擅長定位聲音。
although moving their head made them worse at it when they were wearing the pseudophone.
盡管戴著假聲器時，頭部晃動的效果更差。
This kind of hearing—where we think about
這種聽覺值得我們思考
a sound's location in relation to ourselves— is called egocentric hearing.
聲音的位置與我們自身的關系，我們稱之為以自我為中心的聽覺。
And a 2017 study from PLOS Biology suggested that
2017年，PLOS生物學研究表明，
there might be a difference between it and so-called allocentric hearing,
以自我為中心的聽覺和所謂的集中聽覺之間或許會有所不同，
where we think about a sound's location more objectively.
集中聽覺會讓我們更客觀地思考聲音的位置。
It's kind of the difference between thinking about your buzzing phone as being "on your left" or "over there on the table."
這是把嗡嗡作響的手機想象成“在你的左邊”或“在桌子那邊”的區別。
When the researchers recorded ferret brains,
當研究人員記錄雪貂的大腦時發現，
they found that some cells fired differently when the ferrets turned their heads to reflect the fact that
雪貂轉頭時，一些細胞發出的聲音與它們發出的聲音不同，
the sound was now coming from somewhere else in relation to them.
這些現象反映出聲音現在來自其它相關的地方。
But other neurons didn't change how they fired.
但其他神經元并沒有改變發射方式。
This suggests that, if we're anything like ferrets,
這表明，如果我們是雪貂，
we maybe do build out some sort of audio map of the world after all.
或許我們確實建立了世界的某種音頻地圖。
Studies have also shown that our sense of sight can also play a role in how we process where sound is coming from.
研究還表明，視覺也在我們處理聲音來源的過程中發揮著作用。
And for people who are blind,
對于盲人來說，
it's possible to use sound to build out a kind of map the way most seeing people do with sight.
使用聲音構建一種地圖是可能的，就像大多數人有視覺一樣。
Other weird things can affect our sense of sound, too.
其他奇怪的東西也會影響我們的聽覺。
There are a couple of studies that suggest that for evolutionary reasons,
其它研究表明，出于進化的原因，
"looming" sounds—you know,
你知道，“隱隱約約”的聲音，
like when something big and loud is approaching you— are perceived differently.
人們對這種隱隱約約聲音（就像某個巨大響亮的東西靠近你一樣）的感知不同。
We're likely to overestimate the intensity of sounds that are getting closer to us.
我們可能會過高估計漸近聲音的強度。
And there's actually a different pattern of neural activity for sounds that are getting closer
實際上，漸近聲音的神經活動模式是不同的
as opposed to those that are moving away.
這與漸遠聲音截然不同。
From a survival standpoint, that makes sense.
從生存的角度來看，這是有道理的。
But regardless, as always when it comes to our brains,
但不管怎樣，就像人類大腦一樣，
things are more complicated than they appear.
事情比表面看起來要復雜得多。
Except how silly people must've looked with an old-fashioned pseudophone on their head.
除了人們頭上戴著舊式假聲器看起來真傻。
That seems pretty straightforward. Thanks for watching this episode of SciShow Psych!
這似乎非常簡單。感謝收看本期的心理科學秀！
If you'd like to keep learning about the brain with us,
如果您想繼續了解大腦，
you can go to youtube.com/scishowpsych and subscribe.
可以訪問并訂閱youtube.com/scishowpsych。
