"The Generation and Propagation of Sound" Sound Phenomenon PPT

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"The Generation and Propagation of Sound" Sound Phenomenon PPT

Part One: Preview Perception

1. The production of sound

1. Production of sound: Sound is produced by the _________ of objects. All sound-producing objects ________, stop vibrating, and stop producing sounds.

2. Sound source: The object that is making sound is called the sound source.

3. Recording of sounds: In the early days, mechanical records were used to preserve sounds. Later, people invented methods of recording sounds using _________, _______________ and _______________.

2. Propagation of sound

1. Sound waves.

Sound travels in the form of ________.

2. Conditions.

The propagation of sound requires _________, ________ cannot transmit sound.

3. Speed ​​of sound

1. Meaning.

The physical quantity that describes the _________ of sound propagation.

2. Size.

The distance that sound travels in ________.

3. Influencing factors.

(1)Media: The propagation speed of sound in different media ________.

(2) Temperature: At 15 ℃, the propagation speed of sound in the air is ________.

4. Echo.

(1) During the propagation of sound, if it encounters obstacles, it will be reflected back to form ________.

(2) If the echo arrives at the human ear more than ________ later than the original sound, the human ear can distinguish the echo from the original sound; if it is less than ________, the human ear cannot distinguish the echo from the original sound, and the echo can strengthen the original sound.

4. How do we hear sounds?

1. The basic process of how the human ear perceives sound: Sound from the outside causes vibration in ________, which is transmitted to the auditory nerve through _______________, and the auditory nerve transmits the signal to ________, so that people hear the sound.

2. Sound can also be transmitted to the auditory nerve through the skull and jaw, causing hearing. This method of sound transmission is called ________. It is another way of propagation and conduction of sound in the human body.

PPT on the production and spread of sound, part 2: interactive classroom understanding

1. The production of sound

The conditions for sound generation: first, there must be a sound-emitting body, and second, the sound-emitting body must vibrate.

1. The sound-emitting body can be either solid, liquid, or gas.

2. When the sound-emitting body vibrates, it emits sound. When the vibration stops, the sound production also stops, but the sound will not disappear and can continue to spread outward.

3. Sometimes it is difficult for us to observe the vibration of an object when it makes a sound. At this time, we can convert the vibration of the object into the vibration of light and small objects such as small pieces of paper. This method is called the conversion method.

[Example 1] In order to explore the causes of sound, Xiao Ming and Xiao Hua did the following experiment: Xiao Ming put his hand on his throat and spoke loudly, and felt his throat vibrating; Xiao Hua put the sounding tuning fork in the water, and the water surface stirred up Splash. By analyzing these two experimental phenomena, the conclusion you can draw is ______________. Xiaohua hit the table hard with his hand, and the table made a loud noise, but he barely saw the vibration of the table. In order to clearly see the experimental phenomenon, your improvement method is ________.

Tip: The key to answering this question is to know that sound is produced by the vibration of an object. For small vibrations, the conversion method can be used to amplify the vibrations.

Analysis: When you speak loudly, you feel your larynx vibrating, and the sounding tuning fork is put into the water to stir up water, indicating that the sounding object is vibrating. When you knock on the table, the table vibrates and makes a sound. Since the vibration of the table is very small and difficult to observe, we can put scraps of paper or small objects on the table and use the vibration of the small objects to show that the table making the sound is vibrating.

Answer: The sounding object is vibrating. Sprinkle some paper scraps or put some light objects on the table.

2. Propagation of sound

1. Sound propagates outward in the form of waves, which we call sound waves.

2. The propagation of sound requires a medium. Gas, liquid, and solid can all be used as media for sound propagation. In general, solids have the best sound transmission effect, followed by liquids, and gases have the worst sound transmission effect.

3. Use the ideal experimental method to explore the fact that vacuum cannot transmit sound:

[Example 2] "Children's Fishing" written by the Tang Dynasty poet Hu Lingneng: "A child with unkempt hair is learning to fish, sitting sideways on the strawberry grass. Passers-by ask questions and wave from a distance, for fear of frightening the fish and responding to the person." The fishing child did not dare to answer. , because he knew that the sound might scare away the small fish that were about to take the bait. This incident shows that ________ and ________ can communicate.

Tip: To determine the medium through which the sound emitted by an object mainly reaches the human ear, you should look at what kind of material between the object and the human ear serves as the medium for transmitting the sound. If there is no other material between the object and the human ear except air, the sound is transmitted to the human ear through the air. If there are other objects, the sound is mainly transmitted to the human ear through the object.

Analysis: The fish were scared away because the fish heard the sound of people talking. The substances between people and fish are air and water, so the propagation path of sound is people-air-water-fish. The fact that the fish were scared away means that air and water All can spread sound.

Answer: Air (gas) Water (liquid)

The production and propagation of sound PPT, the third part: try the application

1. The production of sound

1. Among the following things, the one that is not a sound source is ()

A. The harmonica in the school bag

B. The tinkling spring water

C. A whistle that makes a pleasant sound

D. Vocal cords of cows when they bray

2. When doing experiments on sound phenomena, gently insert the sounding tuning fork into the water, and you will see water splashing, as shown in the picture. The main purpose of doing this is _____.

Sound is produced by the vibration of the sound-producing body. When exploring the vibration of the sound-producing body, various methods can be used to display the tiny vibrations of the sound-producing body. In this question, the water splashing of the tuning fork very clearly shows that the sound-producing tuning fork is vibrating.

2. Propagation of sound

3. Look at the pictures and answer the questions:

(1) Diagram A shows that sound can propagate in ________.

(2) Picture B illustrates that sound can propagate in ________.

(3)The problem studied in Figure C is ______________.

(1) Solids (2) Liquids and gases (3) Can sound be transmitted in a vacuum?

3. Speed ​​of sound

4. The same sound propagates in an iron rod, water, and air respectively, and the sound speed is compared ()

A. The smallest in the air B. The smallest in the water

C. The smallest among the iron rods D. The same size among the three

Normally, the propagation speed of sound in liquids is greater than that in gases, and the propagation speed in solids is greater than that in liquids.

5. Under normal circumstances, the speed of sound in the air is ________m/s. On a thunderstorm day, it takes about 3 seconds for Xiaoyun to see lightning and hear thunder. From this, you estimate that the distance from the thunder to Xiaoyun is about _________m.

4. How do we hear sounds?

6. We can hear sounds, and the correct way of transmission is ()

A. Good ears → medium → object vibration

B. Medium → object vibration → good ears

C. Object vibration → medium → good ears

D. Object vibration → good ears → medium

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Update Time: 2024-10-03

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