"Hazards and Control of Noise" Acoustic Phenomenon PPT Download

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"Hazards and Control of Noise" Acoustic Phenomenon PPT Download

The first part: sorting out new knowledge

1. Noise and its sources

1. From a physical point of view: Noise is the sound emitted when the sound-emitting body vibrates ______ (as shown in Figure 2-4-1, which is the waveform of noise).

2. From the perspective of environmental protection: All sounds that are caused by people's normal rest, study and work, as well as sounds that produce ______ sounds that people want to listen to, are noise.

2. Noise intensity levels and hazards

1. People use ________ as a unit to express the level of sound intensity. The greater the sound intensity level of noise, the greater the harm to people's physiology and psychology.

2. The weakest sound that a person can hear is ____dB; the ideal quiet environment is ______dB; in order to protect hearing, the sound should not exceed ______dB; in order to ensure work and study, the sound should not exceed ______dB; in order to ensure rest and sleep, the sound cannot exceed ______dB.

3. Control noise

Noise hazards and control PPT, Part 2: Application examples

Type 1: Discrimination of noise and music

Example 1 (Multiple choice) From the perspective of environmental protection, the following are noises ()

A. In the dead of night, the sound of piano practice suddenly came from

B. The eloquent and powerful speeches of college students at the venue

C. Voices in the quiet library reading room

D. The sound of rock music at the concert

[ Analysis The sound of piano practicing suddenly came in the dead of night, which affected people's rest, so it was noise, so A is in line with the meaning of the question; the sound of college students' eloquent and powerful speeches at the conference was not noise, so B was not in line with the meaning of the question; the sound in the quiet library reading room was not in line with the meaning of the question. The sound of voices affects people's reading, so it is noise, so C is in line with the meaning of the question; the sound of rock music in the concert is not noise, so D is not in line with the meaning of the question.

[Error-prone analysis]There are two perspectives for classifying noise: the physics perspective and the environmental protection perspective. From an environmental protection perspective, beautiful and melodious music can also be considered noise under certain circumstances (such as late at night).

Type 2: Noise intensity levels and hazards

Example 2: One day, Xiao Ming saw the noise monitoring equipment on the street. If the display screen of the device displayed the data of 90 at a certain moment, the unit of this data is ________. When there are no cars or motorcycles passing nearby, he finds that the data on the display will ________ (optional "increase" or "decrease"). After returning home, he checked the physics information and learned that ______ is the weakest sound that people can hear just now; in order to protect hearing, the noise should be controlled not to exceed _______; in order to ensure work and study, the noise should be controlled not to exceed _______ ________; To ensure rest and sleep, the sound should not exceed ________.

[Error-prone warning]0 dB is the weakest sound that people can hear, which is the lower limit of hearing of the human ear. However, it does not mean that 0 dB means there is no sound. For example, infrasound waves are also sounds, but people My ears can't feel it.

Type 3: Ways to control noise

Example 3: The students had fallen asleep at night, but the night market outside the school was still open. The sound of hawking woke up some students. A angrily got up and closed the window, B was lazy and just covered his head with a blanket and went back to sleep. C simply got up and walked to the window, stuck his head out of the window and shouted "Stop making noise". The methods they adopt to reduce noise are: A: _______________; B: ______________; C: _____________.

[ Summary of rules] To control and reduce noise, measures are mainly taken from three aspects: noise elimination, sound insulation and sound absorption. There are three ways to reduce noise, namely attenuation at the sound source, attenuation during propagation, and attenuation at the human ear.

Noise hazards and control PPT, part 3: classroom feedback

1. As shown in Figure 8-1, A, B, C, and D are the waveform diagrams of four sounds. From the diagram, we can know which picture the waveform of the noise is ()

2. Which of the following statements about music and noise is correct ( )

A． Music is the sound produced by musical instruments, noise is the sound produced by machinery

B. Good singing sounds pleasant to the ears and makes people feel happy. It must not be noise.

C. From the perspective of environmental protection, all sounds that hinder people from studying, resting and working are noise.

D. Noise is the sound emitted when an object vibrates regularly

3． When Xiaohua was repairing the kitchen table at home, there were constant sounds of knocking objects. In order to avoid disturbing Xiaoming's study next door, Xiaohua adopted three solutions: ① place a rag on the place where the knock was made; ② put a The doors and windows of the room and kitchen are closed; ③Instruct Xiao Ming to temporarily plug his ears with headphones. Among the above three solutions, the first is to reduce the noise at _______, the second is to reduce the noise at __________, and the third is to reduce the noise at _______.

Keywords: Free download of PPT courseware for eighth-grade physics volume 1 of the People's Education Press, PPT download on the hazards and control of noise, PPT download on acoustic phenomena, .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.

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Update Time: 2024-06-28

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