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  • [MUSIC]

    如果有台能瞬間將我任意傳送的機器,則空氣

  • If I had a machine that allowed me to suddenlytransport myself elsewhere, the air filling

    會急速填滿剛才我消失之處留下的真空, 力量大到足以轟爆耳膜,

  • the vacuum where I used to be would collapse with enough force it would burst the eardrums

    並讓站在旁邊的人感到反胃。

  • and cause nausea in anyone standing nearby.

    遠距傳送聽起來很酷,但對於「聽」而言就相當危險。

  • Teleportation may sound like a cool idea, but thanks to sound itself, it's a pretty dangerous proposition.

    聲波是機械性的,需要有介質才能傳播,

  • [MUSIC]

    現在我講話的聲音使空氣前後搖動,

  • A sound wave is mechanical, it needs a medium to travel through.

    製造高壓區和低壓區。

  • Right now, the wave created by my voice is wiggling the air back and forth, creating

    當我們說到聲音大小,實際上再說空氣壓力波

  • areas of higher and lower pressure.

    的強度。聲音越大,則波動越強。

  • When we talk about how loud a sound is, were really talking about the intensity of that

    不似池塘漣漪,聲音從來源以球形傳播出去。

  • pressure wave. The louder the sound, the more intense the wave.

    就像泡泡越大表面越薄,越遠離音源

  • Unlike ripples on a pond, sound moves out from its source in the shape of a sphere.

    則同樣面積的聲波壓力越小,

  • Just like a bubble gets thinner as it gets bigger, the farther we are from the source

    也就是離聲源兩倍遠處,聲音強度僅四分之一。

  • of a sound, the less pressure there is on a given area of the sound sphere.

    可聽見的最小聲音,導致我們耳膜振動的幅度

  • This means that if we move twice as far from a sound, it will be at one-fourth the intensity.

    小於一個氧分子寬度! 我們可以安然聽到十億倍強度的聲響。

  • The smallest sound pressure wave we can hear vibrates our eardrum less than the width of

    聽覺是已知感官中接收強度範圍最廣者, 因此我們需要更寬的指標

  • a single oxygen molecule! Yet we can comfortably hear sounds a billion times more intense.

    以便測量。為此我們使用分貝(dB)。

  • Hearing has the widest range of any of our senses, by far, so we need a wide scale to

    分貝是指數性的,某聲響大十分貝,其強度就大十倍。 三十分貝?

  • measure it. To do that we use decibels.

    就是一千倍強。讓人耳朵作痛的界線

  • dBs are logarithmic. Something 10 decibels louder is ten times as intense. 30 decibels?

    比我們能聽到最小的聲音大十兆倍。

  • A thousand times as intense. Our threshold for pain comes at sounds 10

    高速公路大約有90分貝。

  • trillion times more intense than the quietest sound we can hear.

    槍聲可達130分貝以上。

  • Highway traffic is about 90 decibels.

    1883年,南太平洋喀拉卡托火山爆發, 煙塵噴上大氣17英里高,

  • [gunshots]

    發出沙皇炸彈的四倍能量,

  • [jet noise]

    即世上最強的核爆。喀拉卡托爆發的聲音近180分貝, 爆炸足以震破

  • In 1883, the island of Krakatoa in the South Pacific erupted, sending ash nearly 17 miles

    40英里外的耳膜,空氣震波繞行地球四圈。

  • into the atmosphere, with a force four times more powerful than the Tsar Bomba, the most

    想像你聽到這個......而人在三千英里外。如果

  • powerful nuclear weapon ever detonated. At nearly 180 dB, this explosion shattered

    你靠得夠近,這會是你一輩子聽到最後一聲巨響。

  • eardrums 40 miles away, and pushed a wave of air around the globe four times.

    但聲音大小有個上限,提示:不是「刻度11」。

  • Imagine hearing thisBANG! only three thousand miles away. Get close

    聲音在波峰推擠耳膜,在波谷放開耳膜。

  • enough to that, and it'll be the last sound you never hear.

    要是波谷達到真空,就無法再更大聲,此一上限

  • But there’s an upper limit to how loud a sound can be, and, hint: It’s not “11”.

    是194分貝,它將扭曲、加熱並超越音速。

  • Sound waves push air together at their peak, and leave low pressure in the valleys. Once

    更強大的聲波只能轉化成衝擊波。

  • this part reaches a vacuum, the sound can’t get any louder. Push the wave any harder than

    NASA的農神五號火箭可以發出750萬磅推力,

  • 194 dB, then it distorts, heats up, it’s moving faster than the speed of sound.

    高達200~220分貝。這力量足以點燃1.5公里內的草,

  • We can go higher, only then it's stopped being sound and has become a shock wave.

    並殺光數百公尺內的一切生物。

  • NASA’s Saturn V rocket was capable of shooting out 7.5 million pounds of space-fire thrust

    為了發射火箭,NASA每分鐘把九十萬加侖的水

  • at 200-220 dB. That’s enough pressure to ignite grass a kilometer and a half away and

    倒入發射台下方的池子,才讓聲波不至於拆掉發射器。

  • kill everything within a few hundred meters.

    倒入發射台下方的池子,才讓聲波不至於拆掉發射器。

  • For Space Shuttle launches, NASA dumped water at a rate of 900,000 gallons per minute into

    當然,大氣更濃厚的行星,可以維持更強大的

  • a pool underneath the launch pad to keep the sound waves from literally ripping the shuttle

    聲波,更高的分貝數。

  • apart.

    我不禁思考,土星上的雷暴聽起來是怎樣?

  • Of course, planets with more dense atmospheres, like Venus or Saturn, could sustain more intense

    事實上,我真的想要找到答案。

  • sound waves, and even higher decibel levels.

    保持好奇心吧。

  • It makes me wonder, what would a lightning storm on Saturn sound like?

  • In fact, I’d like to find out.

  • Stay curious!

  • BANG! [ringing sound]

[MUSIC]

如果有台能瞬間將我任意傳送的機器,則空氣

字幕與單字

影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

B1 中級 中文 聲波 聲音 強度 空氣 發射器 真空

最大聲的聲音是什麼? (What's The Loudest Possible Sound?)

  • 376 20
    kinkwanhappy 發佈於 2021 年 01 月 14 日
影片單字