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Extras

Video thumbnail: How We Got to Now Measuring Sound

How We Got to Now

Measuring Sound

Introducing Harvey Fletcher, the man who invented a meter to measure noise pollution.

Measuring Sound

Video thumbnail: How We Got to Now Episode 6 Preview | Sound

How We Got to Now

Episode 6 Preview | Sound

Get a closer look at Episode 6, "Sound."

Episode 6 Preview | Sound

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