Noise pollution | Noise Dosimeter | Noise Dosimetry
This page covers noise pollution and mentions basics of noise dosimeter equipment. The measurement of noise radiation is known as noise dosimetry. Noise dosimeter vendors are also mentioned.
About Noise: The term noise refers to any unwanted sound energy emitted by vibrating body. There are two types of sound energies produced by vibrating bodies viz. audible and unaudible. The frequency limits which are audible fall in the range from 20Hz to 20KHz. The sound with frequencies less than 20Hz are called infrasonic frequencies while greater than 200MHz are called ultrasonic frequencies.
Noise may be continuous or intermittent. Noise can also be high frequency or low frequency. The three elements can be thought of source, transmission path and receiver in any system. Noise can be generated from many sources viz. domestic, natural, commercial and industrial. Domestic sources include use of mixers, movement of utensils etc. Commercial sources include automobiles, planes, labs etc. Industrial sources include transport vehicles, generators, boilers etc. Natural sources include birds or animals shouts, wind movement, sea tide movement etc.
About Noise Pollution and controlling techniques: Though there are many sources of noise, road traffic is considered to be major source of noise pollution. Noise levels can be measured in dB or dB(A). The term dB(A) is the short form of A-Weighted SPL(Sound Pressure Levels).
The noise pollution occurs at the source or in the transmission path before it reaches to the
receiver. There are many techniques to control the noise pollution as listed below.
• Reducing noise level from domestic sectors
• maintenance of machines and automobiles
• control over vibrating devices
• Reduce the levels of sound emitted from loud-speakers
• Low voice speaking
Noise level measurement equipments
Following table mentions noise level measurement equipments with their specific functions.
|Noise level measurement equipments||Functional usage|
|Sound level meter (SLM)||Type-0: lab. reference standard, Type-1: Lab and field use in controlled environments, Type-2: General field use, Type-3: Noise survey|
|Impulse meters||It is used to measure impulse noise levels such as hammer blows etc.|
|Frequency analyzers||Used along with filters for design and analysis|
|Graphic recorders||It is used in tandem with SLM. It is used to plot SPL with respect to time.|
|Noise dosimeter||As described here|
|Calibrator||It is used to check accuracy of SLMs.|
3M Noise dosimeter specifications
Following are the specifications of 3M noise dosimeter (product eg5-D model).
• Easy USB connection with PC where Detection Management Software runs.
• Noise measurement range: 70 to 140 dB.
• This model support 5 independent noise dosimeters.
• Displays various parameters such as LAVG, LEQ, SPL, Dose, Min/Max levels, TWA, SEL etc.
• Indicators-Battery, Dose exposure indicator
• Supports battery of 40 Hours.
• Supports ANSI S1.25, IEC61252 and other intrinsic safety standards.
Noise dosimeter or noise dosimetry Vendors
Following table mentions Noise dosimeter vendors with their product details.
|Noise Dosimeter, company||Description|
|FLIR Systems India Pvt. Ltd.||Extech SL400, used to test noise exposure levels, supports USB interface, compact and light weight|
|Pulsar Instruments Plc.||doseBadge|
|3M||Noise dosimeter user for noise dosimetry as mentioned above.|
|Noise Meters Inc.||manufactures sound level meters, dosimeters, noise monitors and controllers, dust meter, vibration meters etc.|
|Casella CEL Inc.,||models 350, 352 plus dosimeters and accessories|