Noise pollution can be defined as any disturbing or unwanted sound levels that may lead to adverse effects on humans, wildlife, other living organisms, and environmental quality. Noise becomes harmful when it exceeds 75 decibels (dB) and sound levels less than 75 dB are not damaging to living organisms. The word noise has come from the Latin word “nausea” which means a feeling of sickness in the stomach with an urge to vomit.
Type of noise pollutions
Noise can be classified into
- Transport noise
- Industrial noise
- Neighborhood noise
- Road traffic noise: – Main cause of road traffic noise is no. of road vehicles and their speeds. Faster moving vehicles produce high noise from gear box, exhaust system &horn.
- Rail traffic noise: – The rail traffic is maximum with steam engine. With diesel engine and electric engine the noise has reduced. The welded tracks have also improved coach suspension have reduced noise.
- Air craft: – Larger & faster aircraft produce high noise during takeoff, landing. Jet engines create noise around a radius of 16km.
Industrial processes like skip building, boiler making, pressing, blasting, steel plant operation produce more noise.
- Steel plant riveting-130dB
- Boiler maker shop-120dB
- News paper press-101dB
It includes loud TV, firework, marriage procession and etc. The Central Pollution Board has prescribed permissible sound levels:-
|Hospital, Schools up to 100 meters||50dB||40dB|
Effect on noise human body:-
The effect on human beings is classified into two categories.
- Auditory effect
- Non auditory effect
The impairing of hearing which may cause immediate auditory failure leading to deafness is known as an auditory effect.
Non auditory effect:-
Interference with speech communication annoyance leading to ill-temper, mental disorientation.
A dimensional unit used in the comparison of the magnitude of powers bell expresses the relative magnitude of two powers in the log on the basis of the ratio up to two powers.
One-tenth of a bell, denoted by dB. dB (A) refers to dB on. Weighted basis.
Noise also causes pathological (psychological) & non pathological (physiological) disorders .
Human Diseases Caused by Noise Pollution
Whether we realize we are subjected to it or not, noise pollution can be hazardous to our health in various ways.
- Hypertension is, in this case, a direct result of noise pollution caused elevated blood levels for a longer period of time.
- Hearing loss can be directly caused by noise pollution, whether listening to loud music in your headphones or being exposed to loud drilling noises at work, heavy air or land traffic, or separate incidents in which noise levels reach dangerous intervals, such as around140 dB for adult or 120 dB for children.
- Sleep disturbances are usually caused by constant air or land traffic at night, and they are a serious condition in that they can affect everyday performance and lead to serious diseases.
- Child development. Children appear to be more sensitive to noise pollution, and a number of noise-pollution-related diseases and dysfunctions are known to affect children, from hearing impairment to psychological and physical effects. Also, children who regularly use music players at high volumes are at risk of developing hearing dysfunctions. In 2001, it was estimated that 12.5% of American children between the ages of 6 to 19 years had impaired hearing in one or both ears
- Dementia isn’t necessarily caused by noise pollution, but its onset can be favored or compounded by noise pollution.
- Psychological dysfunctions and noise annoyance. Noise annoyance is, in fact, a recognized name for an emotional reaction that can have an immediate impact.
Important effect of noise pollution
- It causes contraction of blood vessels induced high blood pressure.
- Damage to heart, brain, kidney & liver.
- It induced contraction of muscles which ultimately lead to nervous breakdown.
- It induces anxiety, stress and fright.
- It damages some part of auditory system. Thereby impairment hearing.
- Excessive noise causing thickening of blood and changes in breathing amplitude.
- Jet engine rear causes gastric ulcer.
- Causes irritation, dissatisfaction & effects work efficiency. It induced chronic headache.
There are two most important measures of noise, sound pressure& sound intensity. The Scientific acoustic unit is the decibel (dB).
Decibel is defined as the sound intensity level
=10log10 (intensity measured/ reference intensity)
The reference intensity is Threshold of Hearing at Sound Pressure of 2×10-5N/m2 or Sound intensity of 10-12W/m2.
Sound level meter
- Sound level meter
- Octave band analyzer
- Magnetic tape recorder
- Statistical analyzer
- Noise analyzer
Sound lever meter-
It evaluates sound pressure linearly or weighted scale.
It determines the average sound pressure of standard octave pressure bands.
Magnetic tape recorder-
It is used for the storage of sound for later analysis.
Noise measurement falls into two main divisions source measurement & ambient noise measurement. A source may be a single piece of noise or a combination of equipment or system or even an entire plant. Ambient noise measurement ranges from studying a single sound level to making a detailed analysis showing hundreds of components of a complex vibration. Thus by measuring high noise levels at workplaces and interrogating workers regarding hearing difficulty and carry out noise surveys, noise values are evaluated and their effects are also determined by audiometric tests on workers. This suggests the necessary steps for noise control.
Control of Sound(Remedial measures)
The first step is to measure the quantity and quality of noise by sound level meter, octave band analyzer, sound dosimeters, and audiometer.
Control methods are-
- Controlling noise at source.
- Precluding the propagation, amplification &reverberation of noise (path).
- Isolating the workers (receiver).
Noise Control Methods
|AT SOURCE||AT PATH||AT RECEIVER|
|Isolation||Attenuation||Medical Supervision & audiography|
|Segregation||Barrier||Reduction in Exposure time|
|Relocation||Silencers||Isolating Worker by Booth|
|Redesign||Sound Proofing||Changing job schedule|
|Selection of machinery & method||Vibration damping||Giving rest and interval|
|Enclosures||Remote Control & Isolation|
|Reducing energy or forces|
Noise Induced Deafness:-
Noise-induced hearing loss is not controlled by the use of a hearing aid. Auditory ill effects are of two types.
- Temporary hearing loss.
- Permanent hearing loss.
Hearing ability can be greatly reduced by repeated or long exposure to high noise and this permanent effect is known as noise-induced hearing loss. It is impairment in-ear that obstructs receipt of sound and understanding of speech in a sentence form, it is deafness. It is irreversible & incurable. It can be corrected partly by a Hearing aid.
Hearing loss is of 2 types:-
Temporary Hearing loss
It can be caused by exposure to loud noise for up to a few hours, which numbs the hair cells. Hearing is usually restored after a period away from the noise.
Permanent Hearing loss
It occurs when exposure to loud noise permanently damages or destroys the hair cells. Hearing cannot be restored.
Tips for Avoiding Noise Pollution
- Wear earplugs whenever exposed to elevated noise levels
- Maintain a level of around 35 dB in your bedroom at night, and around 40 dB in your house during the day
- If possible, choose your residence as far removed from heavy traffic as you can
- Avoid prolonged use of earphones, especially at elevated sound levels
- If possible, avoid jobs with regular exposure to elevated sound levels
- Use Noise absorbents in noisy machineries
- Use Proper Lubrication and Better maintenance
- Notify Authorities about Disobedience of Noise Rules .