Sound is a type of energy made by vibrations. When an object vibrates, it causes tiny air particles to move.
Imagine you are sitting in a quiet room with a friend. If you clap your hands, the shock causes the air around your hands to begin vibrating.
When air particles vibrate, they bump into other particles near them. Then these particles begin to vibrate and bump into even more air particles. When the air particles begin vibrating the air inside your ear, you hear a sound.
This chain reaction continues until the particles run out of energy. This is what we call a "sound wave."
So what happens when you turn the volume up on your stereo or television? Well, you're not only turning up the volume, you're actually turning up the amplitude!
Volume is the intensity of a sound wave. It is directly related to amplitude, which is the height of a sound wave.
Imagine a drawing of ocean waves. The highest part of the wave is the crest. The dips in-between each wave are called "troughs."
The distance from the highest part of the crest to the lowest part of the trough is amplitude. Sound waves and ocean waves may be made of different things, but they work the same way. Changing the amplitude of a sound wave changes its loudness or intensity.
If you are playing a guitar, the vibrations of the strings force nearby air molecules to compress and expand. The volume of your guitar playing depends on how hard or softly you pluck the strings.
When you pluck a string gently, the sound will be softer because you have transferred less energy to the string. By using less energy, the string does not vibrate as much and will move less air than if you had plucked the same string forcefully.
On the other hand, if you pluck the same string with a lot of force, the note will be much louder. When you use more force to pluck the string, you are using more energy.
This extra energy causes the string to vibrate more, which helps it move more air particles for a longer time. A string plucked with force has greater amplitude, and greater amplitude makes the sound louder when it reaches your ear.
Volume depends on amplitude. Greater amplitude produces louder sounds. Look at the following pairs and decide which item has greater amplitude:
- yell or whisper
- siren or cat meow
- mosquito buzz or car alarm
- fireworks or violin
Colorado University recently studied a small group of iPod users. The researchers found that some of the young people had their music cranked up loud enough to cause long-term hearing damage and didn't even realize it.
Many young people assume the maximum volume on an iPod is safe, but in some instances, listening to an MP3 player at maximum volume is just as loud as a chainsaw or rock concert. Over time, loud noises can damage fragile hair cells in the inner ear.
These hairs are responsible for receiving sound waves and sending sound information to the brain. Over time, repeated exposure to loud sounds, including music, can permanently damage these delicate hair cells and lead to permanent hearing loss.
Lowering the volume and limiting the amount of time spent listening to music on headphones is the best way to protect your hearing.