What is Basics of Sound? | Definition, Types, Formula & Examples
What is Basics of Sound?
Sound is a vibration or wave that travels through matter (solid, liquid, or gas) and can be heard.
How does sound move or propagate?
The vibration is triggered by a mechanical movement, such as someone plucking a guitar string or knocking on a door. This causes vibrations on the molecules in addition to the mechanical event (i.e. where your hand hits the door when knocking). When these molecules vibrate, they in turn cause the molecules around them to vibrate. Vibrations will travel from one molecule to another, causing sound to travel.
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Sound must travel through matter because it needs the vibrations of molecules to propagate. Since outer space is a vacuum without matter, it is very quiet. The carrier of sound is called the medium.
Speed of Sound
The speed of sound is the speed at which a wave or vibration travels through a medium or matter. The type of material has a big impact on the speed at which sound travels. For example, sound travels faster in water than in air. Sound travels even faster through steel.
In dry air, sound travels at 343 meters per second (768 mph). At this speed, sound would travel a mile in about five seconds. Sound travels four times faster in water (1,482 meters per second) and about 13 times faster in steel (4,512 meters per second).
What is the Sound Barrier?
When an aircraft flies faster than the speed of sound (aka Mach 1), it is called breaking the sound barrier. Most planes don’t fly that fast, but some fighters do. As they pass the speed of sound, the plane releases water droplets that condensate on the plane, creating a cold white halo (see image above).
When planes break the sound barrier, they also create what’s called a sonic boom. It was a loud noise that resembled an explosion made from several sound waves tying together when the plane was traveling faster than sound.
Volume
Loudness of sound is a measure of intensity. To quantify the loudness, we use decibels. The more decibels, the louder the sound. A small sound, like a whisper, will measure about 15 to 20 decibels. Sounds as loud as a jet engine like 150 decibels. The pain threshold is about 130 decibels.
Loud sounds can really damage your ears and lead to hearing loss. Even loud sounds like 85 decibels can damage your ears if you listen to them for a long time. For this reason, you should not listen to loud music or wear headphones that are too loud.