Regarding the propagation of sound, what is the need for sound propagation?

The sound of the train will definitely reach your home (if it is closer). The propagation of sound travels far, far away, theoretically infinitely. However, because sound waves have the characteristics of waves, there will be losses in the process of propagation, reflections when encountering obstacles, and so on.

It depends on whether your home is quiet, first, to see whether your home is well closed (generally the house is not very well closed, and the plastic steel windows are not very ideal), and second, to see whether there are other buildings or woods and other things that can absorb noise between your building and the railway.

Also, the best thing to do is to experience it for yourself. Stand downstairs, or go into the house, (rough houses usually have windows now) and see if it's noisy when a train comes.

I don't know, but I live next to the train tracks, about 600 meters from the tracks, there is no vibration or noise, only the occasional train horn can be heard in the middle of the night!! I don't think there is such a problem as you say!!

Hehe, how can it be so magical? Rest assured, you will definitely hear it, you are talking about the reflection of sound, and this phenomenon only occurs in low-frequency sound propagation.

Sound generation and propagation.

Phenomenon: Speaking on Earth, even if you are far away, you can still hear it, but when you speak in space, even if you are close, you have to communicate with radio.

Ask the question: What conditions are needed for sound to propagate?

Make a guess: air may be needed for sound to propagate.

Design an experiment: Use a controlled experiment to compare whether you can hear sound with and without air.

Procedure: Put a thing that makes a sound in one place, then pump out the air in that place, and then slowly put the air back in**.

Result: When the air is pumped out again, the sound will slowly become quieter, until it will slowly become louder when the air is not slowly put back there, and then it will be again.

Conclusion: Air is required for sound to propagate.

That's why astronauts need to communicate with radio in space, because there is no air in space.

Your question: Can sound travel in other gases? Yes, but in some gases, the sound will change but it can still be heard.

Ask the question: Can sound travel in water?

Make a guess: sound can travel through water.

Design an experiment: Use a control experiment to compare the difference between sound when there is water and when there is no water.

Procedure: Put an alarm clock in a sealed bag, put it in the water, and then take it out.

Result: When the alarm clock is placed in the water, the sound can be heard, but the sound is also quieter when it is outside the water.

Conclusion: Sound can travel in water, but it will be quieter.

Your question: Can sound travel in other liquids? Yes, for example, if you change the water from the experiment to oil, or to some other liquid.

Ask the question: Can sound travel through solids?

Make a conjecture: sound can travel through solids.

Design experiment: Compare the difference between sound propagated through a solid and sound heard directly.

Procedure: Place your ear against the table, then tap the table with your hands, then raise your head and hit the table with the same force.

Result: Sound can travel through solids, and it becomes louder when it travels through solids.

Conclusion: Sound can travel through solids, and it can get louder.

Magnitude of sound propagation: The sound propagated through solids is the largest, the sound propagated through the air is moderate, and the sound propagated by liquids is minimal.

This can also prove why we usually listen to other people's recordings? Our own sound will be different because we hear our own voice, not only airborne, but also solid and recorded sound that allows us to hear only air.

How exactly does sound travel? When it spreads, is there any special medium that can be transmitted? Let's start with the experiment.

In a normal environment, there is air around us, and there are various other objects, and then when we speak, the other party can hear normally, but if the mountain is too far away, the sound may become smaller, become blurred or covered by the surrounding volume, so it proves that in the environment with air, that is, our normal environment, it can be transmitted normally, but if it is said that in the vacuum situation, can the sound be transmitted?

First of all, there is such a phenomenon in space, if the sound can be transmitted in the normal environment, in the vacuum environment, then why astronauts when they are so close, they also need to use the walkie-talkie to call for help, or to talk to the phone, this proves that the sound cannot be transmitted in the vacuum environment. First of all, let's do an experiment.

My guess is that you can't make sound in a vacuum environment, first of all, how did our experiment work, first start to take an alarm clock and put it in a cover, and then use a special instrument to drain the air inside, and then turn it into a vacuum environment, and then set an alarm clock on the alarm clock, and then when the time comes, the little hammer on the top of the alarm clock has begun to vibrate, but we can't hear any sound outside, so this can be proved first, The sound can't be transmitted in a vacuum environment, can it be said that the volume is too small, and then this time I didn't change to a bigger speaker and put it in a vacuum environment, and then turn the sound to the maximum, but it still can't be transmitted. So in the end, it was proved that sound cannot be transmitted in a vacuum environment.

Sound can travel in gases, so can sound travel in solids? The answer is yes, for example, we are separated by a wall between the two of us now, and the rest of the environment is closed, and there is a wall between the two of us, and when I knock on the wall, of course you can hear the sound on the other side, which proves that sound can also be transmitted in solids, so can both gases and solids be transmitted, so can it be transmitted in liquids?

This experiment is much simpler, when swimming, we can first dive underwater, try to open the mouth and make a sound, and then we let a person close to your mouth, you can hear the sound, so that the sperm production under the water can also spread normally, but the sound will be quieter.

Sound can travel in gases, solids, and liquids, except where there is no air.

In this world, sound, like light, is particularly easy to transmit.

Sound travels through a medium, including air, liquid, or solid, and sound cannot travel in a vacuum. The speed at which sound travels in different media is also different. The propagation speed of sound is related to the counter-equilibrium force of the medium, which means that when a molecule of a substance deviates from its equilibrium position, the surrounding molecules will squeeze it back into the equilibrium position, and the greater the counter-equilibrium force, the faster the sound will propagate.

Water resists equilibrium more than air, and iron resists equilibrium more than water. The propagation of sound is also related to temperature and resistance. Sound can also be refracted by external materials, such as when a person shouts in front of a mountain, he can hear his own echo.

The characteristics of sound, the volume of the sound (commonly known as the volume) that people subjectively feel, are determined by the amplitude and the distance between the person and the sound source, the greater the amplitude, the greater the loudness, and the smaller the distance between the person and the sound source, the greater the loudness.

In the 18th century, scientists experimentally confirmed the idea that sound waves need air and other media to transmit them. About 1,700 years ago, the Italian scientist Torricelli proposed the idea that sound is transmitted through air.

The production of sound is due to the vibration of the object, and sound is the fluctuation produced by the vibration of the substance, which needs to be transmitted by the medium to be heard.

He also thought about using experiments that could not propagate sound in a vacuum to prove his claim, but he was unable to achieve his wish because the technology for creating a vacuum was not mature at the time. Later, the British physicist Boeel invented the extraction machine, which pumped the vessel into a vacuum and redid the experiment, thus confirming the concept proposed by Torricelli.

In 1827, scientists experimentally proved that sound can be transmitted in water, and at the same time measured the speed of sound propagation in water. The sound waves that propagate in the air are longitudinal waves, tuning forks that vibrate continuously, causing the surrounding air molecules to form a dense and continuous waveform. In the longitudinal wave, the vibrating force of the dielectric group is parallel to the direction of the wave.

After finishing the production of sound and the characteristics of sound, we continued the study of sound, and we found another phenomenon. On Earth, we can hear others even if we are far away, but in the universe, we can't hear others even if we are very close. We made our initial guess because there is air on Earth, but there is no air in the universe.

But we still need to do experiments to prove whether air is necessary for sound to propagate.

Design experiment: Compare whether sound can travel in an environment with and without air.

Experimental materials: vacuum chamber, alarm clock.

Procedure: Put the alarm clock that is ringing into the vacuum chamber and slowly extract the air.

Results: When there is air, the alarm clock can make a sound. After slowly pumping out the air, the sound slowly faded away.

Sound Conclusion: Sound propagation requires air, and sound propagation will slowly become smaller and less as the air decreases, until it disappears.

At this point, we've learned that airborne transmission requires air. But then we think, since sound can travel in gases, can it travel in liquids and solids?

Purpose: Whether sound can be transmitted in liquids.

Procedure: Put the alarm clock in the plastic bag, and then put the plastic bag in the water.

Results: The alarm clock is still ringing, but the sound is getting weaker.

Conclusion: Sound can travel in liquids, but it becomes weaker.

We know that sound can travel in gases and liquids, and the next question is whether sound can travel in solids.

Experimental idea: Whether sound can propagate in solids.

Materials: table, hands, ears.

Procedure: Hold your ear to the table and tap your hand on the table.

Results: Sounds become super loud as they reach their ears through the table.

Conclusion: Sound can be transmitted through solids.

Materials: Doors, hands.

Procedure: Knock on the door with your hand.

Results: A knock can be heard on the other side of the door.

Conclusion: Sound can be transmitted through solids.

At this time, we can learn that sound can travel in three states, gas, solid and liquid.

Now that we've learned about the production of sound, the characteristics of sound, and the propagation of sound, what else will we learn about sound?

1. The propagation of sound requires a medium, and all solids, liquids and gases can propagate sound. Sound is a sound wave produced by the vibration of an object. It is a wave phenomenon that is transmitted through a medium and can be perceived by the auditory organs of humans or animals.

Sound travels at different speeds in different media.

2. The propagation of sound requires a substance, which is called a medium in physics, which can be air, water, and fixed rent mountain slow body. Of course, in a vacuum, sound cannot travel. The speed at which sound travels in different mediums is also different.

3. In physics, sound is generated by the vibration of an object, and the number of times an object vibrates in one second is called frequency, and the unit is hertz, the letter Hz. The human ear can hear the sound of 20-20000Hz, and the most sensitive is the sound between 200-800Hz. The propagation speed of gases and sound is related to the type of medium and the temperature of the medium.

4. Sound is a kind of pressure wave: when playing a musical instrument, slapping a door or knocking on the tabletop, their vibration will cause the rhythmic vibration of the medium-air molecules, so that the surrounding air will produce dense changes, forming a dense longitudinal wave, which will produce sound waves, and this phenomenon will continue until the vibration disappears.