We hear sound and ask how it makes us hear, which is the process by which sound travels.

Sound generation and propagation.

Sound is produced by vibrations. When you speak, you cause the air to vibrate, and the vibrations travel out, and as soon as someone's ears receive this vibration, they will hear you. Sound can travel in solids, liquids, or through air or other gases.

As the sound travels, the molecules in the air are squeezed together, then separated, then squeezed, and then separated, and so on, and so on, and sound waves are generated. The sound can be high-pitched or low-pitched. The pitch depends on the frequency of the sound (the number of vibrations per second).

The strength of the sound depends on the amount of vibration that produces the sound. If the vibration is large, the sound will be strong; The vibration is small and the sound is weak. The magnitude of sound is measured in decibels.

The noise generated by the drilling rig that repaired the road was more than 100 decibels. The brass horn in the picture, when the musician plays it, the air in the pipe vibrates, and the brass horn makes a sound. Brass pipes carry the sound so you can hear it.

In the cello pictured, when the musician pulls or plucks the string back and forth with the bow on the string, the string vibrates to make a sound. The guitar and violin also sound like this.

People walk and touch the ground, so the ground is involved in the propagation of sound (you can see some heroes crawling on the ground to listen to the footsteps in the distance), people are walking in the air, and the air is involved in the propagation of sound.

The sound waves cause the air to vibrate, causing the eardrum to vibrate, which is transmitted to the inner ear and to the auditory nerve

Sound is produced by objects, and the propagation of sound depends on , and sound is transmitted in the form of .

Sound is a sound wave produced by the vibration of an object. It is a wave phenomenon that propagates through a medium (air or solid, liquid) and can be perceived by the auditory organs of humans or animals. An object that initially emits vibrations (vibrations) is called a sound source.

Sound travels in the form of waves that vibrate (vibrate). Sound is the motion formed by the propagation of sound waves through any substance.

Sound is a wave, and the sound with a frequency between 20 Hz and 20 kHz can be recognized by the human ear.

Volume, also known as loudness and intensity, refers to the subjective feeling of the human ear about the strength of the sound heard, and its objective evaluation scale is the amplitude of the sound.

Sound is a thing, and it's a concrete thing. We can't see the sound, but we can hear it. Sound is produced by the vibration of an object and travels to our ears through the air.

The magnitude of the sound refers to the strength of the sound heard by the person, that is, the loudness of the sound referred to in our physics, which is related to the amplitude of the generator and the distance from the sound source, the greater the amplitude, the louder, the smaller the amplitude, the smaller the loudness, the closer to the sound source, the louder the louder. The height of the sound refers to the pitch of the sound, which is related to the vibration frequency of the emitter, the larger the vibration frequency, the higher the pitch, and the smaller the vibration frequency, the lower the pitch.

1. Sound production: all objects that are making sound are vibrating; The vibrations stopped, and so did the vocalizations.

2. Propagation of sound:

1) Sound is propagated by a medium, and gases, liquids, and solids can all propagate sound. Vacuum cannot transmit sound; (2) The sound propagates in the form of sound waves in the medium, and the propagation speed of the sound in the medium is related to the medium, and the sound propagates the fastest in the solid, the second in the liquid, and the third in the gas. (The exception is cork, which has thin cell walls and many internal bubbles).

3) The speed of sound is also related to temperature, the propagation speed of sound in the air of 15 is about 340m s, the higher the temperature, the faster the propagation speed of sound.

4) The sound wave is reflected at the interface of the two mediums, forming an echo. For the human ear to distinguish between an acoustic sound and an echo, the echo reaches the human ear more than later than the original sound. If not, the echo and the acoustic are mixed together, which only strengthens the acoustic sound.

5) The echo can be used to measure the distance, such as how deep the sea is and how far away it is from obstacles. (This is a bionic technology, from bats, dolphins, etc.) Sound can transmit energy and information.

1) Sound can propagate in solids, liquids and gases, but vacuum cannot transmit sound, that is to say, the propagation of sound requires a medium;

2) Sound can transmit information, for example: the doctor can understand the working condition of the patient's heart and lungs through the stethoscope; Thunder is a sign of possible rain

Sound can transmit energy, such as ultrasonic air humidifiers; Ultrasonic lithotripsy Therefore, the answer is: medium; information

The sound of the teacher's lecture is transmitted to our ears through the air In addition, some people who have lost their sense of hearing can use bone conduction to hear sounds

So the answer is: air; Bone conduction

The propagation of sound requires a medium;

The sound of the teacher's lecture can be transmitted through the air, so students can hear it;

So the answer is: medium; air

It is right that the moving object must make a sound, and the movement of the object will rub against the air, and the air will shake and shake, which will produce sound.

Solids, liquids, and gases are the three mediums through which sound can travel.

The speed of sound propagation must be 340 meters per second, which can only be said to be about 340 meters per second, in the air it is 340 meters per second, in the liquid body is slightly faster, in the solid is slightly slower, in the vacuum it cannot propagate, the speed is 0

The propagation of sound needs a medium, and the sound we hear is generally transmitted by air, so the answer is: medium; air

Usually, the cavity sound heard by the circle is transmitted by the air, and the speed of sound propagation is also related to the temperature, the higher the temperature in the empty macro stove, the greater the sound speed

So the answer is: air; Temperature

Sound is transmitted by the vibration of air, water and other media, so it cannot be transmitted in a vacuum.

The direction of propagation is determined by the direction of the vibration of the medium, which can be in all directions or "directional", but because the wavelength of the sound wave is long, it can bypass the object (diffraction phenomenon), so it can be "heard before Pei sees the sound of the Lingmin". As long as there is a medium, sound can be propagated, and the direction of propagation is three-dimensional spherical divergence.

If you encounter a place where there is no medium, such as a vacuum, the sound in that direction stops propagating.