Scientists studied ear muscles in people. Scientists played sounds. People listened. They used their ear muscles when they were trying to hear.
Photo Credit: ia_64/Getty Images
In the Know
Nature’s Light Show
Then, they all stop. It’s so dark. You can’t see … read more
In the Know
Patterns in the Sky
The Sun gives us heat and light. When the Sun … read more
In the Know
What Is Air Quality?
This map shows a day when the air quality was … read more