Last month, Shri Jairam Ramesh, Minister of State for Environment and Forests had launched the Real time Ambient Noise Monitoring Network (see attached Press Release for more information).
In Phase-I, seven metros viz. Delhi, Hyderabad, Kolkata, Mumbai, Bangalore and Chennai have been selected and in each Metro five Remote Monitoring Terminals have been installed in different noise zones for continuous monitoring.
In Phase-II, another 35 Noise Monitoring Stations will be installed in the same seven cities.
In Phase III, Real Time Noise Network will be expanded by 90 stations to cover 18 other major cities by 2012. Phase-III of the project will include Kanpur, Pune, Surat, Ahmedabad, Nagpur, Jaipur, Indore, Bhopal, Ludhiana, Guwahati, Dehradun, Thiruvananthpuram, Bhubaneswar, Patna, Gandhinagar, Ranchi, Amritsar and Raipur.
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Correction in Acronym Table
Please replace 'A-weighted' with 'C-weighted' within the description for 'LCE'.
Corrected:
"LCE = Equivalent Continuous Noise Level, C-weighted Sound Level"
Dear Rekha,
Many thanks for the update. I just visited the website and realized that I should try to explain specially the acronyms used to present data, because there is no help available for the naive visitors.
Regards, Sudhanshu
Further information:
Time Weightings
Slow(S) and Fast (F) are time-weightings; Fast corresponds to a 125 ms time constant. Slow corresponds to a 1 second time constant.
Frequency Weighting
A Weighting
The most common weighting that is used in noise measurement is A-Weighting. Like the human ear, this effectively cuts off the lower and higher frequencies that the average person cannot hear. A-weighted measurements are expressed as dBA or dB(A).
C Weighting
The response of the human ear varies with the sound level. At higher levels, 100 dB and above, the ear's response is flatter, as shown in the C-Weighted Response to the right.
Although the A-Weighted response is used for most applications, C-Weighting is also available on many sound level meters. C Weighting is usually used for Peak measurements and also in some entertainment noise measurement, where the transmission of bass noise can be a problem. C-weighted measurements are expressed as dBC or dB(C).
Leq
The Leq is best described as the Average Sound Level over the period of the measurement. The calculation is relatively simple; the Leq algorithm just divides the integrated sound pressure by the total duration of the signal. The result is expressed in dB.
Noise level measured after every 10 minutes are 65dB, 70dB, 80 dB, 60dB, 75dB. Calculate the Leq.
Here Lmin = 60 dB, Lmax = 75 dB
Leq = 10 log 1/5(10^[65/10] + 10^[70/10] + 10^[80/10] + 10^[60/10] + 10^[75/10])
=74.65 => 75 dB