According to the query of Geographic Knowledge Network, sound is transmitted through matter, and the density and elasticity of the medium determine the way of sound transmission. When propagating in solid or liquid, sound propagates in the form of longitudinal waves, while when propagating in gas, sound generally propagates in the form of a mixture of transverse waves and longitudinal waves. Therefore, whether sound propagates in solid, liquid or gas, there is no fixed propagation direction, but it propagates in all directions. In addition, in the high altitude of the earth's atmosphere, due to the difference of density and the change of temperature, acoustic refraction similar to the refraction phenomenon in optics will occur, which may lead to a slight deviation in the direction of sound propagation.
The speed of sound in different media is generally different. Generally speaking, sound travels fastest in solids and slowest in gases. The speed of sound propagation in the air of 15℃ is 340m/s. Every time the temperature rises by 65438 0℃, the distance of sound propagation in the air increases by about 0.6m per second. The temperature in different areas of the air is different, and the direction of sound propagation is always in the direction of low temperature. For example, people at the top of the mountain are more likely to hear voices coming from halfway up the mountain than people at the foot of the mountain.