Close your eyes and listen. What do you hear? Noises from inside your house? Outside? Close to you? Far away? Did you hear anything?
Those are SOUNDS!
Sound is made by vibrations. When an object vibrates, it causes movement in the molecules that are close to it. Those molecules bump into other molecules that are close to them. The collisions make the other molecules vibrate and push them into even more molecules.
This pattern of bumping and vibrating, or “sound”, keeps going until it runs out of energy. If your ears are close enough to the sound waves traveling through the air, you’ll hear it when they bump up against your ear drum!
Sound waves that repeat at random times just sounds like noise. However, sound waves that repeat in regular patterns makes music
Fun fact: Sound waves can travel through air at 1,120 feet per second!
Can sound travel through water? Yup! It can.
Can sound travel through solid surfaces? Yup, it can!
Can sound travel in outer space? Nope!
Remember that we talked about all those molecules bumping into each other? Well, there is no air in space, so there’s nothing to vibrate!
- Sheet of paper
- Roll up the sheet of paper along the long edge.
- Tape it into a tube.
Note: don’t use too much tape – one or two pieces is plenty.
- Put both hands on the tube and talk through it.
- Do you notice anything with your hands?
- Talk in a deep low voice, then a high squeaky voice.
Can you FEEL the sound?
Sound travels in waves.
Higher frequency sounds are shorter and quicker waves. They are short high noises like a siren.
Lower frequency sounds are longer and slower waves. They are low deep noises like a fog horn.
We can feel the differences in those vibrations and waves as they travel through the tube!
Sound Wave Detector!
- Metal can or bowl – like a coffee can
- Alternatives – a large plastic cup, plastic bowl, metal bowl
- Plastic wrap
- Rubber band or tape – to keep the plastic wrap tight around the an or bowl
- Colored sugar or sand, rice or other small light items
- Noise makers – pot and large spoon or anything else that can make a loud sound
- Build a sound wave detector by starting with a metal can, like a large coffee can or metal or plastic bowl.
- Cover the top of your can or bowl with plastic wrap. Be sure to cover it so the wrap is very taut. You want to make sure there aren’t any tears in the wrap, but it is pulled tightly across the opening of the can or bowl.
- Sprinkle colored sugar, across the plastic wrap on the top of the bowl.
- You have created a sound wave detector!
- Time to make some sound!
- Try not to make lots of movement close to the top of the bowl so that you aren’t using air to move the sugar.
- Bang pots and pans together lower than the rim of the detector and observe!
Sound travels in waves. When we make loud sounds, those waves move out away from the noise makers, hitting things in their path. If the bowl or can is close enough, the sound waves will hit the walls of the bowl causing it to vibrate. When that happens, the sound travels through the bowl or can up to the plastic wrap causing the items on the plastic wrap to move. This movement allows us to SEE sound!