Sound is an experimental method of object vibration.

The experimental methods of producing sound by object vibration are shared as follows:

Sound is the sound wave produced by the vibration of an object. It is a wave phenomenon, which propagates through media (air or solid or liquid) and can be perceived by human or animal hearing organs. The source of the object sound that vibrates (vibrates) at first.

Sound vibrates in waves. Sound is the movement formed by sound waves propagating through any medium. Sound is a wave. Sound that can be recognized by human ears (the frequency is between 20 Hz and 20 Hz and 20,000 Hz) is called sound.

In physics, sound is produced by the vibration of an object, and the object that emits sound is called a sound source. The number of times an object vibrates in one second is called frequency. The unit is hertz, and the letters are hertz. The human ear can hear the sound of 20~20000Hz, and the most sensitive is the sound of 200~800Hz.

The propagation speed of sound in different media is generally solid >: liquid > gas (except cork 500m/s, less than kerosene 25℃, distilled water (25℃), etc. ), the speed of sound propagation is related to the type and temperature of the medium.

Sometimes when we stand on the mountain and shout, we will hear our echo, because the sound will bounce back and be heard again when it encounters such obstacles in the process of propagation. When two kinds of sounds reach our ears and the time difference is less than 0. 1 second, we can't tell them apart.

When the sound source stops vibrating, the sound will last for a period of time, which is called reverberation. Of course, when a sound is emitted in a space with obstacles and obstacles, there will be echoes, that is, as long as the sound encounters obstacles in the propagation process, it will rebound and produce echoes.

In most cases, only the sound with a large decibel can be distinguished by the human ear in an open environment, and the human ear often collects echoes in daily life, but because the decibel of the echoes is low or in a noisy environment, the human ear cannot distinguish the echoes.

Therefore, we can't misunderstand that there is no echo in our daily life. In fact, it's just that our ears can't distinguish such sounds, or our brains can't distinguish them.

There are light energy and water energy in nature, and mechanical energy and electric energy in life. In fact, sound also has energy. For example, if two objects with the same frequency hit one object, the other object will vibrate and make a sound. This phenomenon is called * * *. Sound propagation drives another object to vibrate, indicating that sound also has energy.

People use decibels to express the strength of sound, and the symbol is dB. 0 decibels only caused hearing. People call the sound with a frequency higher than that which can be heard by human ears as ultrasonic waves, and the sound with a frequency lower than that which can be heard by human ears as infrasound waves.