"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 4

Description

"Hazards and Control of Noise" Acoustic Phenomenon PPT Courseware 4

Review questions

1. What determines the pitch of a sound?

Frequency, the higher the frequency, the higher the pitch

2. What is frequency? What is the unit?

Number of vibrations per second Hz

3. What is the relationship between frequency and vibration speed?

The higher the frequency, the faster the vibration

4. What is the range of human hearing?

20Hz-20000Hz

5. What does the loudness of sound relate to?

amplitude and distance

6. On what basis do we distinguish various sounds? Related to what?

Timbre timbre is related to the characteristics of the sound emitter itself

1. Noise

In physics, the sound produced when a sound-emitting body vibrates irregularly is called noise.

From the perspective of environmental protection, any sound that hinders people's normal rest, study and work, as well as any sound that interferes with the sounds people want to listen to, is noise.

2. Source of noise

1. Noise generated by nature: storms, tsunamis, thunder, earthquakes, volcanic eruptions, etc.

2. Noise in social life: noise made by people in public places, sounds made by people that are inconsistent with the environment

3. Electromagnetic noise: the sound emitted by electric fans, refrigerators, fluorescent lamps and other electrical appliances when they are working

4. Traffic noise: the sound emitted by motor vehicles such as cars, trains, and airplanes

5. Industrial noise: the sound emitted by various machines and equipment in the factory when they are working

6. Construction noise: the sound emitted by the construction site during construction

Class exercises

1. At night, the dance hall is playing beautiful dance music, and the sound is very loud. Which of the following statements is correct ( )

A. Beautiful dance music that sounds melodious must not be noise

B. From a physical point of view, beautiful dance music is musical sound

C. Dance music is noise to nearby residents who want to take a rest.

D. No matter from any angle, melodious and melodious dance music should be considered music.

2. Which statement about music and noise is correct (　)

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

B. Music is pleasant and makes people feel good; noise makes people restless and harmful to human health.

C. From an environmental perspective, all sounds that interfere with people's study, rest and work are called noise.

D． The vibration of music follows certain rules, while the vibration of noise is chaotic and has no rules to follow.

3. In order to ensure normal work and study, the noise intensity should be controlled not to exceed ( )

A. 30 decibels B. 50 decibels

C. 70 decibels D. 90 decibels

4. Partitions are generally installed on both sides of urban overpasses. Why is this?

Because there are mostly residential buildings or office buildings on both sides of urban overpasses, sound spreads in the air. If there are no obstacles, it can directly enter the room. The roar of cars will inevitably affect the work and rest of the residents living in the building day and night. Installing partitions on both sides of the overpass can block part of the noise, which is a protective measure for residents.

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Update Time: 2024-09-27

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

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