Why is it that the farther away from the sound source, the quieter it is? 10

In the process of propagation, the sound will friction with the medium, and the energy will be transferred, and the wavelength will increase with the increase of distance, so that the original energy in the sound will gradually decrease, until it is completely transferred.

Because we often say that sound is transmitted in the air, the air is the medium of sound propagation, and the sound will have acoustic impedance when it propagates in the medium, so the louder the sound, the farther it travels, but there will eventually be a time when it disappears.

Sound should be called sound waves to be precise, which is a wave phenomenon that is generated by the vibration of an object, transmitted by any substance, transmitted through a medium (air or solid, liquid) and can be perceived by the auditory organs of humans or animals.

The most critical factor in the propagation of sound is to have a medium, which refers to all solids, liquids and gases, which is the premise for sound to be able to propagate. The speed of sound propagation is related to the type of medium and the temperature of the medium, and only these two conditions do not change, no matter how far the sound travels, the speed will not change. If the energy loss during the transmission is not taken into account, the sound waves are transmitted forever.

If the loss of energy is taken into account, the sound wave will become weaker and weaker until it disappears during propagation, but the wave velocity does not change during both transmission processes.

Sound is propagated by sound waves, and in the process of propagation, through air or other media, there will also be a loss of energy, and eventually the sound wave energy is exhausted and disappears. The louder the sound, the greater the energy, the greater the amplitude of the sound wave, and in the same case, the energy is weakened to zero for a longer time and travels farther.

The greater the vibration amplitude of the emitter, the louder the sound emitted, and the farther away from the sound source, the lower the sound will be heard, that is, the loudness of the sound will be reduced, but the pitch will not change;

Therefore, C

1. There will be a loss of sound wave transmission in the air.

2. The general sound source is similar to the point sound source, the sound wave surface emitted is spherical, the farther the distance, the larger the wave surface, the smaller the energy per unit area, and the smaller the listening volume. Professional sound reinforcement often says: the sound emitted by a point sound source, for every doubling of the distance, the sound pressure drops by 6dB

1. It's not the concept of loudness, the farther away from the sound source, the amplitude of the sound wave will be smaller and smaller, and the energy of the sound wave will be smaller and smaller.

2. A The structural form of the intact wheel is different from the damaged structural form, so the frequency of the sound emitted is also different, resulting in a difference in tone.

Simply put, it has nothing to do with height.

Generally speaking, the sound waves emitted by the ground sound source, the upper half is transmitted upward, the lower half is reflected by the ground, and also propagates upward, and the surrounding various buildings and facilities will also cause reflection, so that more sound waves reach the 20th floor, and the 20th floor is far from the ground, and other environmental noise is very low, so the shouting sound of the bus is more obvious.

If there is a sound source on the 20th floor, then half of the sound waves emitted by it are uploaded to the sky and are not reflected, and the other half is transmitted to the ground, so the sound intensity is weak, and the ambient noise of the ground itself is relatively high, which is easy to cover up the sound from the 20th floor.