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Acoustic propagation
mode of transmission
Sound propagation is propagated through a medium. On account of
Vibration of body
In order to produce sound, sound is a wave generated by material vibration, which needs to be transmitted by the medium to be heard.
The speed at which sound waves travel through a medium is called the speed of sound (or
Speed of sound
Because the sound in different media, the speed of transmission is different, thus producing sound reflection and
refraction
. The production of sound is due to the vibration of the object, and sound is the wave generated by the vibration of the material, which needs to be transmitted by the medium to be heard.
As early as the 18th century, scientists had confirmed from experiments the idea that sound waves need a medium such as air to transmit. About 1,700 years ago, the Italian scientist Torricelli put forward the idea that sound is transmitted by air.
- Chinese name
- Acoustic propagation
- Foreign name
- Sound propagation
- rationale
- Object vibration
- mediator
- medium
- Characteristic point
- Reflection and refraction
The production of sound is due to the vibration of the object, and sound is the wave generated by the vibration of the material, which needs to be transmitted by the medium to be heard.
He also wanted to prove his claim by using the experiment that sound cannot propagate in a vacuum, but the technology to create a vacuum was not mature enough at that time, so he could not achieve his wish. Then the English physicist Boyle invented it
Air extractor
, will the container
commission
Vacuum, repeated the experiment, and confirmed the idea proposed by Torricelli.
In 1827 AD, scientists proved through experiments that sound can be transmitted in water, and at the same time measured the sound in water
Propagation speed
. Sound waves traveling through the air are
Longitudinal wave
, continuous vibration
Tuning fork
, make
Surrounding air
The molecules form dense, continuous waveforms. In a longitudinal wave, the vibrational force of the medium molecule is parallel to the direction of the wave.
Because sound in different media, the speed of transmission is different, and thus produced sound reflection and
refraction
. The phenomenon that sound waves encounter obstacles in the process and cannot pass through and return to the original medium is called reflection, and this phenomenon of sound wave reflection is also called reflection
echo
. The reflection of sound waves was experimentally proved as early as 1882.
If the sound is transmitted in different media, the phenomenon of deflection in the propagation direction due to different speeds is called refraction. For example: "midnight bell to the passenger ship". At night, due to higher temperatures near the upper air,
Velocity of sound
Faster, so that when the sound wave travels, it will be deflected downwards, so the bell located in Hanshan Temple will be transmitted to the passenger ship on the river.
A variable affecting the speed of sound
The speed at which sound waves travel through a medium is called the speed of sound (or the speed of sound). The speed of sound is often affected by the type and state of the medium. The speed of sound propagating through the air depends on the temperature, humidity, density... The difference is different. The higher the temperature, the faster the speed of sound. When the humidity is high, the speed of sound is faster. The speed of sound is known to be about 343 m/s in dry, windless air at 20°C, and 331 m/s at 0°C. If the object is moving faster than the air at the time
transacoustic
When the speed is called
Supersonic speed
. The speed of sound was measured as early as
A.d.
In 1636, Hong Kong Meyerson has measured that the sound transmission speed in the air is 316 meters/second, which has been continuously tested by various countries, but the correct method of finding the sound transmission speed in gas or solid was discovered and designed by German Conte in 1868, which is known as the "Conte experiment". As for the commonly used speed of sound (0°C air) 331 m/s, it is
World War I
The period of revision is still in use.
