- What are sound waves?
- How do sound waves travel through air?
- The role of air in sound wave travel
- The speed of sound waves through air
- The frequency of sound waves
- The wavelength of sound waves
- The amplitude of sound waves
- The reflection of sound waves
- The refraction of sound waves
- The diffraction of sound waves
Have you ever wondered how sound waves travel through air as a medium? We’ll take a look at how sound waves travel through air, how they are affected by different mediums, and how they can be used to create musical sounds.
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What are sound waves?
Sound waves are invisible waves of pressure that travel through the air (or any medium), causing objects to vibrate. The vibrating objects then create sound. The speed of sound is determined by the medium through which the sound waves are traveling. For example, sound travels about four times faster through water than it does through air.
How do sound waves travel through air?
Sound waves are longitudinal waves that travel through a medium such as air, water, or solid materials. The sound wave is created by the vibration of an object, such as a tuning fork. The sound wave travels through the air and is detected by our ears.
Sound waves travel at different speeds depending on the medium. In air, sound waves travel at approximately 343 meters per second. In water, sound waves travel at approximately 1,482 meters per second. In solid materials, such as wood or metal, sound waves travel at approximately 5,130 meters per second.
The speed of sound is affected by temperature. Colder temperatures cause the particles in the air to move more slowly, which results in a slower speed of sound. Warmer temperatures cause the particles in the air to move more quickly, which results in a faster speed of sound.
The role of air in sound wave travel
When a guitar string is plucked, it sets the surrounding air molecules into vibration. These vibrating air molecules bump into other molecules nearby, making them vibrate too. The process repeats and continues until the sound waves eventually die out or hit something that reflects them, such as a wall.
The speed at which sound waves travel through air depends on the density of the air particles. Warm air is less dense than cold air and thus allows sound waves to travel faster. This is why you can hear someone better when it’s warm out.
While the role of air in sound wave travel is not as significant as that of a solid object, it’s still necessary for the waves to propagate.
The speed of sound waves through air
The speed of sound is usually given the symbol c. Sound waves in air are longitudinal waves. This means that the particles of air vibrate in the same direction as the wave is travelling. The wave consists of areas of high and low pressure.
The higher pressure areas are called compressions and the low pressure areas are called rarefactions. The distance between compression waves is called the wavelength, denoted by λ (lambda). The time taken for one wavelength to pass a point is called the period, denoted by T. The frequency, f, is equal to 1/T.
You can see from these equations that the higher the frequency, the shorter the wavelength. Conversely, the lower the frequency, the longer the wavelength.
The frequency of sound waves
The frequency of sound waves is the number of times the particles in a medium vibrate per second. The higher the frequency, the greater the pitch of the sound. For example, a flute produces higher pitched sounds than a drum because the air particles vibrate more quickly when a flute is played.
The wavelength of sound waves
When sound waves travel through air, or any medium for that matter, the wavelength of the waves determines how the waves will interact with particles in the medium. The wavelength of a sound wave is the distance between two peaks of the wave. The frequency of awave is the number of times per second that a wave peaks. Wavelength and frequency are inversely related; as frequency increases, wavelength decreases. The speed of sound is determined by the medium through which the waves are traveling. For example, sound waves travel more slowly through water than they do through air.
The amplitude of sound waves
The loudness or softness of a sound is called its amplitude. The units used to describe the amplitude of sound are decibels (dB). The range of human hearing is approximately 20 dB.
The human ear can detect sounds with an amplitude as low as 20 dB, but it can also tolerate much louder sounds without damage. To be heard, a sound must have an amplitude that is above the absolute threshold of hearing. The loudness of a sound is related to its intensity, which is measured in watts per square meter. The intensity of a sound is proportional to the square of its amplitude. That means that a sound that is twice as loud as another will have an intensity that is four times greater.
The reflection of sound waves
Sound waves are longitudinal waves that travel through a medium by vibrating the particles of that medium. The speed of sound depends on the properties of the medium, such as its density and compressibility. In general, the denser the medium, the faster the sound waves will travel through it.
Sound waves can be reflected off of surfaces, just like light waves. When this happens, the wave changes direction and the reflected wave is called an echo. Echoes can be used to identify objects in space or to communicate over long distances.
The refraction of sound waves
When sound waves travel through different mediums, such as air, water or solid objects, they are bent or refracted. The speed at which sound waves travel is different in each of these mediums. In air, sound waves travel fastest, while in water they travel slower. Solid objects cause the sound waves to bend the most.
The angle at which sound waves bend when they enter a new medium is determined by the refractive index of that medium. The refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium. The higher the refractive index, the more the light bends.
Sound waves are bent when they enter a new medium because their speed changes. The change in speed causes the wavelength to change and this results in a change in direction (refraction).
The angle at which sound waves bend when they enter a new medium is determined by two things:
-The difference in speed between the medium they are travelling in and the new medium they are entering
-The wavelength of the sound wave
Longer wavelength sound waves bend less than shorter wavelength sound waves. This is why high pitched sounds (such as birds tweeting) can be heard better than low pitched sounds (such as thunder) from around corners.
The diffraction of sound waves
Sound waves travel through the air (or any other medium) by vibrating the particles in that medium. The particles then collide with the particles next to them, causing them to vibrate as well. This vibration then spreads outwards until it eventually reaches your ear, where it is converted into electrical signals and sent to your brain.
One of the properties of sound waves is that they can diffract, or bend, around obstacles. This is why you can still hear someone talking even if they are not in direct line of sight. The amount of diffraction depends on the wavelength of the sound wave – low frequency sounds will diffract more than high frequency sounds.