翻譯：曲薈龍
審校：潘磊
People who use echolocating mouth clicks to compensate for low vision increase the number and intensity of clicks when objects are harder to detect. Christopher Intagliata reports.
來自克里斯多福·因塔利亞塔的報導：視力障礙者會使用口部發聲，回聲定位方法來彌補自身缺陷，當物體難以識別時，他們常常會增加發聲的次數和強度。
Many bats use a system similar to sonar to navigate in the dark. They send out high frequency sound, sometimes as clicks, and get information about their surroundings by the timing and quality of the sound that bounces back. And just as turning up the light in a darkened room helps to illuminate the objects there, bats are known to turn up the intensity of their clicks when they have trouble detecting a target.
蝙蝠能在黑暗中飛行，這是因為它們具有類似聲納的系統。他們發出高頻聲波，通過接收到回聲的時間和強度來獲取周圍環境的信息。就和在黑暗的房間裡你會把燈打開以照亮物體一樣，當蝙蝠發現偵測目標有困難時，它們使用回聲定位系統的強度就會提高。
"Now, bats have had millions of years of evolution basically to develop these mechanisms to dynamically adjust their emissions." Lore Thaler, a neuroscientist at Durham University in the U.K. "And what we were wondering is, well, do people do the same?」
「經歷數百萬年的進化，蝙蝠的回聲定位系統已經演化到能夠動態地調整聲波的發射。」勞爾·塞勒是英國杜倫大學的神經學家，她表示，「我們想知道的是，人類是否會做同樣的事情?」
Because some people with impaired vision can indeed navigate using the echoes of finger snaps, hand claps, or mouth clicks <<clicking sound>>. But it's not known how dynamic that ability is. So Thaler and her team presented eight expert echolocators with a challenge: could they tell whether a small dinner-plate-sized object was being held up about three feet from their head, by clicking alone?
一些視力受損的人確實會通過響指、拍手或是口哨的回聲來幫助自己進行辨別方向。但截至目前，我們還不清楚他們回聲定位中的聲音如何變化。因此，塞勒和她的團隊向八位擅長回聲定位的人發起了一個挑戰：他們能否僅通過回聲定位這項技能，判斷出一個餐盤大小的物體是否被舉到自己頭頂三英尺高的地方?
You can try this at home by the way, with a plate or a book. "And if you hold it very close to your face while you're speaking you can notice that the sound that you hear really changes. This is because the sound that comes out of your mouth when you speak is reflected by the object you're holding in front of you. And that's an echo.」
另外，你也可以在家裡試試這個實驗，你需要準備的只有一個盤子或者一本書。「把盤子或書舉起，放在臉的正前方，如果距離足夠近，你說話時就會發現自己聽到的聲音確實在發生變化。這是因為說話時，你發出的聲音會被你面前的物體反彈回來。就是回聲。」
But move the plate 45 degrees to the side…then 90…then behind your head. And the task gets harder. But similar to the way bats do, the study subjects increased the number of clicks, and their loudness, <<loud clicks>> as the object became harder to detect—perhaps as a way to amplify the weak sounds echoing back.
把書或餐盤移動到面前四十五度的方向，然後是九十度…接下來移到頭後面。隨著角度變化，實驗的難度逐步增加。不過與蝙蝠的做法類似，實驗者增加了回聲定位的次數，還有發出聲音的強度。當物體變得更加難以探測時，他們發出的聲音就會變得更大，這也許為了增強微弱的回聲。
The subjects still had trouble detecting the object a full 180 degrees behind them—they did only slightly better than chance. But they guessed correctly 80 percent of the time when the object was diagonally behind them. And nabbed nearly perfect scores when the disc was to the front or to the side. The results are in the Proceedings of the Royal Society B. [L. Thaler et al., Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles]
儘管如此，實驗者很難知道放在他們身後的物體是否發生了變化——他們的正確率只比隨機猜好一點。但當物體放在他們斜後方，他們有百分之八十的比例都判斷對了。而當盤子或書被放置到頭的前方或側面時，他們的回答近乎完美。這項研究的結果發表在《英國皇家學會學報B》上。[L. Thaler et al., Human echolocators adjust loudness and number of clicks for detection of reflectors at various azimuth angles]
Thaler says the study gives echolocating learners a shortcut: "If you're not sure, make a couple more clicks, and also make them louder." To produce echoes that more accurately reflect the world.
塞勒認為，這項研究為回聲定位法學習者提供了一個竅門：「如果你無法確定，就多嘗試幾次，同時發出更強的聲音。」這都是為了產生能反映世界的更為精確的回聲。