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Have you ever wondered how a sound travels? Check out this blog post to learn about how sound waves travel through the air!
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What is sound?
Sound is a type of energy that travels through the air, or any other medium, as a vibration of pressure waves. We hear sound when these waves enter our ear and cause our eardrum to vibrate. The vibrating eardrum then sets bones in our middle ear in motion, which in turn causes vibrations to travel through a fluid-filled cochlea. The cochlea is coiled like a snail shell and lined with tiny hair cells. As the fluid in the cochlea moves, it bends the hair cells, which activates nerve signals that are sent to our brain. Our brain interprets these signals as sound.
How does sound travel?
Sound is a type of energy that travels through the air, or any other medium, as a vibration of pressure waves. Sound can also travel through solid and liquid mediums, but not through a vacuum.
When something vibrates, it sets off sound waves. The object that vibrates is called the vibrating object, and the sound waves it produces are called sound waves. The speed at which sound waves travel depends on the medium they are travelling through.
Sound waves travel more quickly through denser mediums, such as solids and liquids, than less dense mediums, such as gases. The molecules in a denser medium are closer together than in a less dense one, so the sound waves have less distance to travel between them. This is why sound travels more quickly through water than through air.
The speed of sound also depends on the temperature of the medium it is travelling through. Sound travels more quickly through hot mediums than cold ones. This is because hot molecules have more energy and move around more than cold molecules. As they move around more, they bump into each other more, which makes the sound waves travel faster.
The speed of sound
Sound is a type of energy that travels through the air, or any other medium, as a vibration of pressure waves. The speed of sound depends on the medium through which it is traveling.
In general, the speed of sound is fastest in gases, slower in liquids, and slowest in solids. The speed of sound in air is about 1,100 feet per second (340 meters per second). In water, the speed of sound is about 4,700 feet per second (1,430 meters per second), which is about four times as fast as in air. In steel, the speed of sound is about 16,000 feet per second (4,880 meters per second), which is about 14 times as fast as in air.
The speed of sound also depends on the temperature of the medium. In general, the speed of sound increases as the temperature increases. For example, the speed of sound in air at 77 degrees Fahrenheit (25 degrees Celsius) is 1,087 feet per second (331 meters per second). But at 86 degrees Fahrenheit (30 degrees Celsius), the speed of sound in air increases to 1,126 feet per second (343 meters per second), which is about 3.8 percent faster than at 77 degrees Fahrenheit (25 degrees Celsius).
The properties of sound
sound is a type of energy that travels through the air, or any other medium, as a vibration of pressure waves. At its simplest, sound is caused by something vibrating— turning back and forth quickly. The source of the vibrations could be anything, from a drum to your vocal cords.
As the object vibrates, it sets the surrounding air particles into motion. These particles bump into nearby particles, creating a pressure wave. The pressure wave then travels through the air until it reaches your ear.
Once the pressure wave reaches your ear, it causes your eardrum to vibrate. This vibration is passed on through a series of tiny bones in your middle ear and eventually reaches your inner ear. Inside your inner ear is a fluid-filled cochlea, which contains thousands of tiny hair cells. These hair cells are set into motion by the vibrations and trigger nerve signals that travel to your brain.
Your brain then interprets these signals as sound. The speed of sound is affected by the medium through which it is travelling—sound waves travel more slowly through liquids than they do through gases.
The human ear
The human ear is the organ of hearing and, in humans, balance. The ear is part of the auditory system, which includes both hearing and the brain. The outer ear consists of the pinna and the ear canal. The middle ear consists of the eardrum (tympanic membrane) and three tiny bones — the malleus, incus, and stapes (also called the hammer, anvil, and stirrup). The inner ear includes the cochlea, semicircular canals, and vestibule.
How we hear
We hear because sound waves travel through the air and vibrate our eardrums. The eardrum is a thin piece of skin that separates the outer ear from the middle ear. When the eardrum vibrates, it moves three tiny bones in the middle ear. The bones are called the hammer, anvil, and stirrup because they are shaped somewhat like these tools. The vibrations are passed along to the inner ear, where they are converted into nerve signals that are sent to the brain.
The Doppler effect
As sound waves travel through the air, they pressure the air molecules around them. These molecules then vibrate and pass on the energy to the next molecule, and so on. This is how sound waves are able to travel long distances.
However, sound waves don’t always travel in a straight line. When something is moving towards you, the sound waves bunch up together and this increases the pressure of the molecules. This is known as the Doppler effect.
Echoes
Most of us have had the experience of hearing an echo. Echoes are reflections of sound waves off of a hard surface. The waves reflect back to our ears, and we hear the sound again. Sound waves travel at different speeds in different materials. In general, sound travels fastest in solids, slower in liquids, and slowest in gases.
Echoes are usually heard when the reflecting surface is more than a quarter of a mile away from the person or animal making the noise. The time it takes for an echo to return can be used to calculate the distance to the reflecting surface. This process is called echolocation, and it is how bats “see” in the dark!
Reflection of sound
Reflection is when a sound wave hits an object and bounces off. The angle at which the wave hits the object will determine how much the sound is reflected. For example, if the sound wave hits the object at a 90 degree angle, it will be reflected back at the same angle. If the sound wave hits the object at a 45 degree angle, it will be reflected back at a 135 degree angle.
Absorption of sound
Sound waves are created when an object vibrates. The vibrations cause the air particles around the object to move, which in turn creates pressure waves that we interpret as sound. When these waves reach our ears, they cause our eardrums to vibrate, which our brains interpret as sound.
The vast majority of sounds are created by objects that are in contact with each other (e.g. two people talking, a drum being hit, etc.), but there are some sounds that can travel through the air without any contact (e.g. thunder, an ambulance siren).
When sound waves travel through the air, they eventually come into contact with another object (e.g. a wall, the ground, etc.). When this happens, some of the energy from the sound wave is transferred to the object and the wave is absorbed. The more contact there is between the wave and the object, the more energy is absorbed and the quieter the sound will be.
