MindMap Gallery Physics for Grade 8 - Hazards and Control of Noise Mind Map
This is a mind map about the harm and control of noise in physics for eighth grade students, including the sources of noise, control methods, noise monitors, etc. I hope it will be helpful for you to study physics!
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2.4 Harm and control of noise
source
traffic noise
Such as the whistles of various vehicles. Brake sound, etc.
industrial noise
Such as noise in machinery production workshops, etc.
construction site noise
Such as the sound produced when various machinery is used for excavation and stirring during construction
life noise
Such as household noise, noise in entertainment venues and markets
definition
musical sound
The sound produced by the regular vibration of the sound emitter
pleasant to the ear
noise
The sound produced by the sound-emitting body vibrating irregularly
Features
Harsh and annoying
too strong
harmful to health
harm
Affect people's normal communication
"Invisible Killer"
harmful to health
Double standard
When judging noise, judge it from two angles
How it came about and what impact it had
As long as one aspect is consistent, it is noise
physics perspective
Noise is generated by irregular vibrations of the sound source and is excessively intense.
Using an oscilloscope, you can observe that the waveform of the noise is irregular.
environmental protection perspective
All sounds that hinder people's normal rest, study and work, as well as sounds that interfere with the sounds people want to hear, are noises.
Music is sometimes noise
Strength level
Sound intensity level
Used to objectively describe the intensity level of sound
The intensity of the noise, refers to the loudness
unit
Decibel (dB)
People use decibels (dB) as a unit to express the level of sound intensity.
The impact of sounds of different sound intensity levels on people
0dB
The faintest sound one just heard
lower limit of hearing
0dB does not mean there is no sound, it refers to the sound that has just aroused our hearing.
10dB
Equivalent to the rustling of fallen leaves in the breeze
30~40 dB
An ideal quiet environment;
More than 50dB
Will affect sleep and rest
In order to ensure rest and sleep, the sound should not exceed 50dB;
70dB or more
Interfere with conversations and affect work and study
In order to ensure work and study, the sound cannot exceed 70dB;
More than 90dB
Living in a noise environment above 90dB for a long time will seriously affect hearing and cause neurasthenia, headaches, hypertension and other diseases.
150dB
If you are suddenly exposed to a noise environment of up to 159dB, the hearing organs will be damaged, causing periosteum rupture and bleeding, and complete loss of hearing in both ears.
Noise monitor
It can only monitor the noise level value and cannot reduce the noise.
control pathway
Carry out "rob and murder" at every step of the sound process from production to hearing
The process of hearing sound with the human ear
Control noise from these three aspects
Control and prevent noise at the source
attenuate at the source
Install mufflers at sound sources, prohibit honking, separate industrial areas from living areas, and limit the opening hours of entertainment venues, etc.
Improve the structure of the sound source
Adopt vibration reduction, vibration isolation and other technologies
Such as machine soundproof covers, vibration-absorbing pads, etc.
Install a muffler
muffler on motor vehicle
silent pistol
Control and block noise propagation during propagation
weaken during the propagation process
Sound insulation panels, planting trees and grass (absorbing noise), closing doors and windows
sound insulation
Such as sound insulation panels on the side of the road
Double soundproof windows
Sound absorption
Forestation belt along highway
Perforated panels such as auditorium cinema walls
silence
Sound silencing technology
Control at the human ear
Receiving link
Periosteum vibration causes hearing
Attenuated at the human ear
Prevent noise from entering your ears
Wear personal protective equipment such as earplugs, helmets, etc.