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Speaker 1: Welcome to Brainstuff from house stuff works dot com, where

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Speaker 1: smart happens, brought to you by Visa. We all have

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Speaker 1: things we like to think about. Online fraud shouldn't be

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Speaker 1: one of them, because with every purchase, PISA prevents, detects,

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Speaker 1: and resolves online fraud safe secure Visa. Hi, I'm Marshall

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Speaker 1: Brain with today's question. What is a decibel and how

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Speaker 1: is it measured? The decibel, abbreviated dB, is the unit

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Speaker 1: used to measure the intensity of a sound. The decibel

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Speaker 1: scale is a little odd because the human ear is

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Speaker 1: incredibly sensitive. Your ears can hear everything from your fingertip

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Speaker 1: lightly brushing over your skin to a loud jet engine.

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Speaker 1: In terms of power, the sound of the jet engine

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Speaker 1: is about one trillion times more powerful than the smallest

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Speaker 1: audible sound. That's a huge difference on the decibel scale.

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Speaker 1: The smallest audible sound near total silence is zero dB.

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Speaker 1: A sound ten times more powerful as ten dB. A

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Speaker 1: sound a hundred times more powerful is twenty d B.

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Speaker 1: A sound a thousand times more powerful than total silence

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Speaker 1: is thirty d B. Here are some common sounds and

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Speaker 1: their decibel ratings. A whisper is about fiften dB. Normal

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Speaker 1: conversation is around sixty d B. A lawnmower is up

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Speaker 1: near ninety. A car horn is a hundred dB, a

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Speaker 1: rock concert or a jet engine is a hundred and

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Speaker 1: twenty d B, and a gunshot or a firecracker is

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Speaker 1: around a hundred and forty d B. These are the

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Speaker 1: levels when standing near the source of the sound. You

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Speaker 1: know from your own experience that distance affects the intensity

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Speaker 1: of sound. If you're far away, the power is greatly diminished.

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Speaker 1: Any sound above eight five dB can cause hearing loss,

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Speaker 1: and the loss is related both to the power of

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Speaker 1: the sound as well as the length of exposure. Sure

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Speaker 1: you know that you're listening to an eight five dB

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Speaker 1: sound If you have to raise your voice to be

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Speaker 1: heard by somebody else, eight hours of nine d dB

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Speaker 1: sound can cause damage to your ears. Any exposure to

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Speaker 1: a hundred and forty dB sound causes immediate damage and

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Speaker 1: may cause actual pain. Do you have any ideas or

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Speaker 1: suggestions for this podcast? If so, please send me an

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Speaker 1: email at podcast at how stuff works dot com. For

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Speaker 1: more on this and thousands of other topics, go to

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Speaker 1: how stuff works dot com.