Equipment used and Methods of Measurement:
In general two types of measurements were made for collection of noise level data in various cities of India. For one type of measurement a correct Sound Level Meter (SLM) was selected from which readings were manually read for about a minute. As a single reading indicates noise level for a time lasting 12 seconds so that 5 readings were taken in one minute.
In a second type of measurement for measuring ambient noise levels the Sound Level Meter was placed at a height of approximately four feet above ground with the sensor facing sky-wards. For obtaining continuous noise levels Sound Level Meter was connected with battery operated recorder. The Both Sound Level Meters were checked for obtaining identical noise levels in the operation areas.
ADVERTISEMENTS:
In general the noise levels at particular place were recorded between the period 10 a.m. to 1 p.m. The average levels of noise in different locations are shown in different tables given below.
According to Central Pollution Control Board, New Delhi, the optimum desirable level of noise in commercial locations has been suggested as 65 dB (A) but in many locations the value has been observed higher than the prescribed limit indicating noise places of the city where continuous presence of human beings for a long time may cause hard of hearing, skin ailments, mental disorders and undesirable physiological effects.
This high level may also cause errors in their day to day work and also in the deterioration of staff and customer relations. Hence it becomes necessary to give attention to acoustics inside the noise places of public activity.
High noise levels at airport were measured before and after takeoff a Boeing 707 and other aircrafts. The highest level measured was 90 dB (A), the minimum was 70 dB (A) with an average value of 80.0 dB (A). This noise level is alarming and may cause mental ailments.
For railway stations the maximum observed noise level was 103 dB (A) the minimum being 62 dB(A) with an average value 82.5 dB(A). This is a high value and needs immediate attention for acoustics at some busy railway stations.
The noise levels in the hospital were measured at different places in the premises. The maximum level of 85 dB(A) was observed in the emergency OPD while according to Central Pollution Control Board the maximum limit for a hospital is 50 dB (A). The difference in the two values indicates to the misery of sick persons in the OPD.
ADVERTISEMENTS:
The noise levels have also been observed at the counters of cash for slip and at medicine distribution centre. It is surprising that such noise levels have been noticed at places which are called sensitive areas or peace zones. Immediate steps are needed to check it and to bring down this high level to tolerable limits.
The noise levels were observed in GPO between 10 a.m. to 1 p.m. on a working day. The maximum observed level was 82 dB (A) and the minimum 53 dB (A) with an average of 77.5 dB (A). This high level may also cause mistakes in registration of letters, many orders and other works of GPO.
In the university (or college) the noise levels were observed at cycle/scooter stands and near class rooms or union buildings. The maximum level was 90 dB (A) and the minimum 55 dB (A) with an average of 72.5 dB (A).
This high noise level may create tension in students resulting in fighting and other mental tensions. The high levels can also be responsible for irritation and occasional brawls among students and also in public dealings.
Noise Pollution Standards:
ADVERTISEMENTS:
The Central Board for pollution control, New Delhi has proposed some standards for silence zone, residential, commercial and industrial areas (day time -6 a.m. to 9 p.m. and night time -9 p.m. to 6 a.m.) as given in Table 1.
Noise levels in Some Cities of India:
The noise levels in some cities of India have been presented in Tables 2 to 17 indicating noise pollution at almost all places – university area, G.P.O. market, Banks or other busy places as discussed above.
