Sound is everywhere around us and nearly everything we do makes a sound. Clapping your hands together, laughing, tapping a keyboard, even flushing the toilet creates a unique sound.
Sound is the energy that things produce when they vibrate. For example, if you bang a drum the energy moves across the skin of the drum as it vibrates at high speeds. These vibrations eventually make their way to your ears and cause them to start vibrating too, which lead to you perceive these vibrations as a familiar sound – a drum beat. Sound always needs something to travel through (a medium), and metal, wood, glass and air are all capable of acting as these mediums.
Sound acts very much like waves moving over water, which start out where there is wind and travel in the direction that the wind blows them. A good example of this would be an alarm clock – energy is set off inside the clock and travels through the air, eventually making its way to your ears.
An English scientist by the name of Robert Boyle was the first to discover that sound needs a medium to travel, by placing a ringing alarm clock inside of a glass jar. As the alarm clock rang, Boyle used a pump to remove air from the jar and observed that the sound died down as he sucked the air out, eventually falling silent when none was left. This is because the sound waves no longer had a medium to travel through, so they had no way of reaching the ear!
A more in-depth explanation of sound can be found in the video above.
There are so many ways to experience sound waves and explore the variance in sound.
Try creating different pitches in sound and maybe your own bottle music.
Fill 8 glass bottles to different levels. Using a metal rod gently hit each bottle. What happens? Why the difference in sound per bottle?
Try tipping out or adding water in and see if you can create an octave – 8 notes of music!