【英语时差8,16】耳石-上（在线收听）

Ear rocks, also known as “otoliths,” are tiny pebbles of calcium carbonate in our inner ear that help keep us balanced. They’re located deep inside the inner ear in a small pouch called a utricle. When we move our heads, the tiny rocks move around and bump into nerve cells. These nerve cells send signals to our brain that tell it which way the head is oriented. It’s one way we know up from down. But problems with ear rocks can be a cause of chronic dizziness or vertigo. Occasionally the little pebbles fall out of the utricle and can get into another part of the inner ear canals. When this happens, the brain senses that we’re moving much more than we really are, resulting in sensations of unsteadiness or dizziness.