"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 8

"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 8

Experience 1 Feel the music and noise

Activity 1: (1) Listen to a piece of beautiful music; (2) Scratch the glass with a nail and listen to the sound produced.

Activity 2: (1) Everyone sings a song together; (2) Everyone is studying in class, and a classmate sings loudly next to them.

(1) In activity 1, which sound do you like? Why?

(2) In Activity 2, which kind of singing influenced other students? Why?

Tips: (1) I like beautiful music, it can make me feel good.

(2) The second type of singing affects other students because it cannot allow other students to study with peace of mind.

Experience 2 Control Noise

Activity: The students were in class, and the sound of rumbling machines came from outside the door.

How to reduce the impact of machine noise on students? Please tell me your solution.

Tips: (1) Close the windows.

(2) Discourage the machine from being stopped.

(3) Students covered their ears and taught themselves.

Default is questionable

1. What is noise from a physical perspective?

2. What is noise from the perspective of environmental protection?

3. What is the grading unit that expresses the strength of sound?

4. What are the ways to control noise?

Explore 1 Source of noise

Combined with "Experience 1", think about the following questions:

1. Combined with "Activity 1", explain what noise is from a physical perspective?

Tip: Noise is a type of sound, so the generation of noise is also caused by the vibration of objects. The sound emitted when the sound-emitting body vibrates irregularly is noise.

Reference answer: The sound produced when the sound-emitting body vibrates irregularly.

2. Combined with "Activity 2", explain what noise is from the perspective of environmental protection?

Tip: From the perspective of environmental protection, all sounds that hinder people's normal rest, study and work, as well as sounds that interfere with the sounds people want to listen to, are noises. From this perspective, under certain circumstances, musical sounds can sometimes become noise.

Reference answer: Sounds that hinder people's normal rest, study and work, as well as sounds that interfere with the sounds people want to listen to.

Study 2 Controlling Noise

Combined with "Experience 2", think about the following questions

1. What steps does sound go through from generation to hearing?

Tip: First, a sound source vibrates to produce sound, and then the sound is transmitted to the human ear through the medium. The sound enters the human ear, causing the tympanic membrane to vibrate. The tympanic membrane drives the auditory ossicles to vibrate. The auditory nerve transmits the sound information to the brain, and the person perceives the sound.

Reference answer: The vibration of the sound source produces sound → the propagation of air and other media → the vibration of the eardrum

2. In which aspects can noise be controlled?

Tip: According to the three stages that sound goes through from generation to hearing, noise control should also start from these three aspects, that is, preventing noise generation, blocking noise transmission, and preventing noise from entering the ears.

Reference answers: (1) Prevent the generation of noise (2) Block the spread of noise (3) Prevent noise from entering the ears

Knowledge summary

1. Source of noise

1.Physical perspective:

The sound produced when the sound emitter does ___________.

2. Environmental protection perspective:

Sounds that interfere with people's normal _____, _____, and _____, and sounds that interfere with the sounds people want to hear.

3. Waveform:

The waveform of musical sound is _______, and the waveform of noise is _______________.

2. Noise intensity level and noise hazards

1. The unit of sound intensity is _____, and the symbol is ___.

2. The weakest sound that a person can hear is __dB.

3. Provisions:

(1) In order to protect hearing, the sound cannot exceed ___dB.

(2) In order to ensure work and study, the sound should not exceed ___dB.

(3) In order to ensure rest and sleep, the sound should not exceed ___dB.

(4) The ideal quiet environment is _______dB.

Test Points Noise Control Methods

[Typical example] (2012 Wuhan High School Entrance Examination) In order to reduce the noise of cars outside the campus, the teaching

interference, the following measures are feasible ()

A.Plant trees around campus

B. Open the classroom windows

C. Install noise monitoring devices in classrooms

D. Each student wears a noise-proof earmuff

[Idea Guide] The key to answering this question is to be familiar with the three ways to control noise.

【Exquisite analysis】Choose A. Noise control is mainly carried out in three ways: first, weakening at the sound source, second, weakening during the propagation process, and third, weakening at the human ear. Planting trees around will weaken the noise during its propagation, A is correct; opening the classroom windows will make it easier for the noise from cars outside the campus to enter the classroom, causing greater interference to teaching. B is wrong; the noise monitoring device will only detect the noise. The decibel will not weaken the noise, C is wrong; after the students wear anti-noise earmuffs, they can no longer hear the teacher's lecture and cannot study, D is wrong.

[Method Summary] Noise control methods

(1) Silencing: Preventing the sound-emitting body from vibrating and producing sound.

(2) Suction (isolation) sound:

① During the propagation process, set up obstacles to reflect and absorb sound.

② Prevent sound from entering your ears, such as wearing earplugs, earmuffs, etc.

1. From an environmental perspective, the following are not noises ( )

A. Whispers in the reading room

B. When I was in physics class, I heard singing coming from the music class in the next classroom.

C. Late at night, when people were about to fall asleep, the sound of a skillfully played piano suddenly came from

D. An eloquent and powerful speech that attracts people

[Analysis] Choose D. From the perspective of environmental protection, whispering in the reading room affects other people's study, so option A is wrong; if beautiful music affects people's normal work, study or rest, it will become noise, so options B and C are wrong ;The purpose of the audience is to listen to the speech, so the sound of the speech is not noise, so option D is correct.

2. Which of the following is the correct understanding of "0 dB" ( )

A.0 dB means the object is not vibrating

B.0 dB is the weakest sound that the human ear can hear

C.0 dB means the frequency is lower than 20 Hz

D.0 dB means the frequency is higher than 20 000 Hz

[Analysis] Choose B. Decibel is a grade that divides the intensity of sound, and it is related to loudness and has nothing to do with pitch, that is, frequency. 0 dB is the lower limit of human hearing, that is, the sound that can just be heard, so the correct option is B.

3. (Multiple choice) The picture shows a noise monitoring and decibel display device standing in an urban area. It can be known from the decibel number displayed on the device ( )

A. The noise here can cause people to lose hearing

B. The noise here can hinder people’s work and study

C. The noise here hinders people’s rest and sleep

D. The noise here is an ideal quiet environment

[Analysis] Choose B or C. The decibel level displayed by this device is 72 dB. When the sound exceeds 90 dB, it will affect people's hearing; when the sound exceeds 70 dB, it will affect people's work and study; when the sound exceeds 50 dB, it will hinder people's rest and sleep. 30~40 dB, which is an ideal quiet environment. Therefore, choose B and C.

Find out where you tend to go wrong?

The figure shows the waveforms of two sounds vibrating. It can be seen from the picture that the musical sound among the two sounds is ________.

【Students' own answer】B

[Teacher Comments]

①First of all, it is clear that musical sound is emitted when the sound-emitting body vibrates regularly.

②The so-called "regular vibration" refers to periodic changes.

[Correct answer] A, B

Keywords: Acoustic phenomenon teaching courseware, Noise hazards and control teaching courseware, Shandong Education Edition eighth grade physics PPT courseware download, Eighth grade physics slide courseware download, Acoustic phenomenon PPT courseware download, Noise hazards and control PPT courseware download, .PPT format;

For more information about the "Hazards and Control of Acoustic Phenomenon Noise" PPT courseware, please click the "Hazards and Control of Acoustic Phenomenon Noise ppt" ppt tag.

"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 10:

"The Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 10 Introducing a new lesson The high-spirited march is exciting, and the melodious singing is mesmerizing. The March of the Chinese People's Liberation Army, violin playing, the harsh sound of car horns and the roar of machines on the construction site make people...

"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 9:

"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 9 1. Noise and its sources Read the text and discuss: 1. From a physical point of view, what is noise? �2�What is noise from the perspective of environmental protection? Why is music sometimes also noise? �3�..

"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 7:

"Hazards and Control of Noise" Sound Phenomenon PPT Courseware 7 Review Review 1. What are the uses of sound? (1) Sound waves can transmit information (2) Sound waves can transmit energy. What adverse effects does sound have on our daily lives? 1. What kind of sound is noise?