In your dreams
Do blind people dream in colors?Someone who is blind from birth has never seen a color or a shape. Since a person's dreams are based on what happens to them while they are awake, a blind person can't have dreams with pictures in them, says 3-2-1 Contact magazine.
But blind people do dream about what they touch or hear. For example, some blind people say they dream about food and drink. They feel things in their dreams instead of seeing them. This is because foods, drinks, surfaces and sounds are a big part of what a blind person experiences during the day.
So, in many ways, the dreams of blind people and the dreams of sighted people are similar. We all dream about the world around us. Blind people's dreams focus on what they experience with their other senses; touch, hearing, taste and smell.
When you breathe in heliu, why does your voice change?
Sound is vibration, a movement back and forth. When you speak, two stretchy strips of flesh in your throat, called vocal cords, do the vibrating. Throat muscles tighten the vocal cords to make high sounds and loosen them to make low sounds, says 3-2-1 Contact magazine.
Normally, your vocal cords are surrounded by ordinary air. Helium is a gas much lighter than air. (This is why helium balloons float.) If you inhale (or breathe in) helium, your vocal cords are surrounded by a much lighter gas than usual.
If you try to talk, your vocal cords will vibrate unusually fast. That's because they are moving through light, thin helium. These vibrations make your voice sound silly, as if it were coming from somewhere over the rainbow.
Even though it may sound funny to talk like a Munchkin, it can be dangerous to inhale a lot of helium. Your body needs plenty of fresh oxygen. Without it, you can faint or even suffocate.