"Characteristics of Sound" Sound Phenomenon PPT courseware download

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"Characteristics of Sound" Sound Phenomenon PPT courseware download

Part One: Guidance Design

Learning Point 1: Tone

Experiment 1: As shown in Figure 2-2-4A, take a piece of cardboard and let it slide across the teeth of the wooden comb, one time faster and one time slower. When you swipe slowly, you can hear the paper making a "click" sound; when you swipe quickly, the sound the paper makes becomes louder.

Experiment 2: As shown in Figure B, stir the rubber bands with different tightness, listen to the sound and observe the vibration of the rubber bands.

think:

Question 1: In Experiment 1, why did the pitch of the sound produced by the paper change?

Answer: The pitch is determined by the frequency of the object's vibration. The frequency of the vibration of the paper changes, so the pitch changes.

Question 2: In Experiment 2, when the rubber band is moved with the same force, in which case does the sound produced have a higher pitch?

Answer: In picture (a), the rubber band is stretched tightly, the frequency of vibration is higher, and the pitch of the sound is higher.

Learning Point 2: Loudness

Experiment 1: As shown in Figure 2-2-5A, beat the drum with different forces and observe the vibration of the plastic foam on the drum surface when different sounds are made.

Experiment 2: Find a piece of rubber band, fix it, stretch the rubber band to a suitable length (as shown in Figure B), change the amplitude of the rubber band, and analyze what factors are related to the sound size of the rubber band.

think:

Question 1: According to Experiment 1, what is the relationship between the amount of force used when beating the drum, the vibration amplitude of the plastic foam, and the size of the drum sound?

Answer: The harder you hit the drum, the greater the vibration amplitude of the plastic foam and the louder the drum sound.

Experiment 2: Question 2: According to Experiment 2, what is the purpose of fixing the length of the rubber band? What is the relationship between the sound volume of a rubber band and the vibration amplitude of the rubber band?

Answer: Fix the length of the rubber band so that the sound frequency of the rubber band remains unchanged, that is, the pitch remains unchanged; the greater the amplitude of the rubber band, the louder the sound.

Learning Point 3: Tone

Experiment 1: Let a classmate cover his eyes with a handkerchief, and ask several classmates to call the name of the blindfolded classmate and ask him to "identify people by listening to the sound." Each classmate is blindfolded once to see who can tell the difference quickly and accurately.

Experiment 2: Let a student cover his eyes with a handkerchief, and ask three students to play the same piece of music on the violin, harmonica, and erhu respectively (as shown in Figure 2-2-7), and let them identify the types of instruments.

Characteristics of sound PPT, part 2: application examples

Type 1 Pitch and its influencing factors

Example 1 (Multiple choice) As shown in Figure 2-2-6, it is an experimental device for "exploring the factors that affect the pitch". Which of the following statements is correct ()

A． Change the frequency of vibration of the steel ruler by changing the length of the steel ruler extending from the table

B. In multiple experiments, the amplitude of the steel ruler vibration was kept the same, and the control variable method was used.

C. The longer the steel ruler extends out of the table, the faster it vibrates.

D. Objects vibrate quickly and at high frequency, producing high-pitched sounds.

[Analysis]When exploring the relationship between pitch and frequency, use the control variable method and control the amplitude to be the same. In the experiment, the frequency of vibration of the steel ruler was changed by changing the length of the steel ruler extending out of the table. The longer the steel ruler extends out of the table, the slower the vibration, the lower the frequency, and the lower the pitch of the sound it emits; the shorter the steel ruler extends out of the table, the faster the vibration, the higher the frequency, and the higher the pitch of the sound it emits.

[Method Guidance] Use the control variable method to explore the relationship between pitch and frequency

When several factors affect the research results at the same time, other factors should be controlled unchanged and the impact of one factor on the results should be explored at a time. For example, in this experiment, the amplitude of each vibration of the steel ruler is roughly the same, and the relationship between the pitch and the speed (frequency) of the object's vibration is explored. This method of studying the problem is called the controlled variable method.

Type 2 Loudness and its influencing factors

Example 2 As shown in Figure 2-2-7, in the experiment of "exploring the factors that affect the loudness of sound", if you hit the drum with different forces, you will hear the _________ of the drum sound change, and at the same time, the______ of the drum surface will change. _______ will also change, leading to the conclusion: ____________________. In the experiment, the purpose of sprinkling some paper scraps on the drum surface is to ____________________________. This method of studying the problem is called ________ (optional "control variable method" or "conversion method").

[Method Guidance]Use the conversion method to explore the vibration of sound emitters

Since it is not easy for the human eye to directly observe the vibration of some sound emitters, other objects can be used to display it during exploration. Even if the sound emitter comes into contact with light and small objects, the vibration of the sound emitter will be "amplified" into the movement of light and small objects for easy observation. . This method of studying a problem is called the conversion method.

Type 3: Discrimination of pitch and loudness

Example 3: The following description of the conversation between the bee and the old cow is correct ()

A. The sound made by bees when flying is high-pitched, and the cry of cows is loud.

B. Bees make low-pitched sounds when they fly, and cows make low-pitched calls.

C. Bees make low-pitched sounds when they fly, and cows make louder calls.

D. Bees make louder sounds when they fly, and cows make lower noises.

[ Analysis But the amplitude is small, so the sound emitted by the bee when flying is high-pitched and low-loud.

[Error-prone analysis] (1) A high-pitched sound is not necessarily loud, and a loud sound is not necessarily high-pitched. In physics, pitch is discussed as "high or low" and loudness is discussed as "large or small".

(2) In daily language, the high and low sounds sometimes refer to the pitch, and sometimes refer to the loudness. For example, if the voice is not "high", this "high" refers to the loudness, and for female "treble" singers, this "high" refers to the pitch.

(3) The pitch depends on the frequency of the object's vibration. The higher the frequency, the higher the pitch. The frequency of the vibration of an object depends on the length, thickness, tightness, etc. of the vibrating object. The shorter, thinner, and tighter the vibrating object, the higher the vibration frequency and the higher the pitch of the sound.

Characteristics of Sound PPT, Part 3: Class Feedback

1. As shown in Figure 6-1, press a steel ruler firmly on the table, extend one end of it from the edge of the table, stir the steel ruler, and listen to the sound it makes when it vibrates. Change the length of the steel ruler extending from the edge of the table, and push it hard again to make the two vibrations of the steel ruler roughly the same, and listen to the change in the sound it makes. This experiment is used to explore ()

A． Can sound propagate through solids?

B. The relationship between loudness and object amplitude

C. The relationship between pitch and vibration frequency of objects

D. What factors of the sounding body are related to the timbre?

2. When exploring what factors are related to loudness, Xiaoli conducted the following experiments, as shown in Figure 6-2.

(1) When the tuning fork is struck with different forces to make the tuning fork emit sounds of different loudness, the ping pong ball is bounced to different amplitudes, and the amplitude of the tuning fork vibration is different, indicating that the loudness is related to __________. The greater the bounce of the ping pong ball, the _________ the amplitude of the tuning fork and the _________ the loudness.

(2) Make the tuning fork emit sounds of the same loudness. When the distance is different, the loudness of the sound produced by the tuning fork is different, indicating that the loudness is related to _______________.

3. The sound of the violin heard at the concert is produced by the ________ of the strings. At the same time, we can also distinguish the sounds of different instruments based on the ________ of the sounds.

4. When boys and girls sing together in a chorus, if the baritone sings loudly and the soprano sings softly, the _________ will be louder and the________ will have a higher pitch.

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Update Time: 2024-10-03

This template belongs to Physics courseware People's Education Edition Physics for Grade 8, Volume 1 industry PPT template

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