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Physics

Sound Intensity

Quick fact

The faintest sound a human can hear has an intensity of about 10⁻¹² W/m², while the threshold of pain is about 1 W/m²—a range of one trillion times in power per unit area.

Why this is interesting

You can hear a whisper from across a quiet room, but a shout from the same distance feels uncomfortably loud. What physical quantity determines that difference in loudness?