Measurement of Sound Pressure Level in Various Settings

Maximum noise level in road is due to the heavy traffic at that time which adds loud horn and other sound.

Permissible noise level given by WHO are:

1. Roadside

2. Residental area

3. College/silent Zone

REQUIREMENTS

1. Noise level meter
2. Global positioning system (GPS) trackers
3. Notebook and pencil
4. Stop watch

Theroy

    Sound is a vibration that typically propagates as audible wave of pressure, through transmission medium such as gas,liquid or solid. Also it is the form of energy giving sensation.

      According to world health Organization(WHO) noise is a unwanted sound. Environmental noise is noise emitted by all sources except noise at industrial work place(WHO). Noise is characterised by its unpleasant and annoying nature, that can even lead to some ill effects. In the modern era there seems, infinite source of noise, developmental activities along with industrialization and urbanization have enormous contribution towards the noise pollution.

     Environmental noise pollution is a form of air pollution is a threat ton health and well being. The potential health effect of noise pollution are numerous pervasive, persists and medically and socially significant noise produces direct and cumulative adverse effects that impair health and that degrade residential ,social, working and learning environments with corresponding real and intangible losses. The aim of enlightened governmental controls should be protected .Citizens from the adverse effects of air born pollution, including those produced by noise. People have the right to choose the nature of their acustical environments.

      Usually threshold of hearing is the minimum sound level of pure tone that an organisms can hear with no others sound present. Sound pressure level (SA) is the ration of absolute sound pressure and reference level usually threshold of hearing of people.

 SPL is measured in dB and using sound level meter. SPL is calculated by using following formula:

SPL= z₀log(p/p₀)dB

Noise can be measured by using various types of equipments. Most commonly used equipment is noise level meter. The sound level meter has various characteristics such as; slow, fast, impulse, impulse hold, peak and peak hold.

PROCEDURE:

  Three sites were selected to measure the noise level representing roadside, residental and college silent zone. Geographical positioning system (GPS) was tracked of that location. Similarly name of the location and noise level measurements time was noted at the same time. 30 noise level data were taken from different places at 1 min interval.

OBSERVATION TABLE:

1. Roadside Noise Level data Ghsntaghar: Kathmandu.

S.N	Time	Noise level(dB)
1	09:51:00	70.1
2	09:52:00	79.4
3	09:53	70.5
4	09:54	71.6
5	09:55	73.2
6	09:56	74.3
7	09:57	74.8
8	09:58	74
9	09:59	72.6
10	10:00	70.6
11	10:01	71.9
12	10:02	70.5
13	10:03	69.6
14	10:04	74.9
15	10:05	72.5
16	10:06	69.4
17	10:07	72.8
18	10:08	81.4
19	10:09	69.8
20	10:10	72.9
21	10:11	71.3
22	10:12	72.1
23	10:13	80.9
24	10:14	74.9
25	10:15	73.9
26	10:16	72.7
27	10:17	74.6
28	10:18	78
29	10:19	70.3
30	10:20	74.9

2.Residental Noise level Data Ashan Kathmandu

S.N	Time(min)	Noise level(dB)
1	09:51	61.9
2	09:52	62.3
3	09:53	59.3
4	09:54	50.4
5	09:55	60.9
6	09:56	61.5
7	09:57	60.5
8	09:58	60.9
9	09:59	60.7
10	10:00	60.5
11	10:01	66.3
12	10:02	67.1
13	10:03	67.2
14	10:04	69.3
15	10:05	67.3
16	10:06	65.3
17	10:07	63.4
18	10:08	66.3
18	10:09	65
20	10:10	63.7
21	10:11	65
22	10:12	70.1
23	10:13	67.6
24	10:14	67.2
25	10:15	64.2
26	10:16	64.7
27	10:17	63.6
28	10:18	63.3
29	10:19	64.4
30	10:20	65.8

3. College area noise level, Trichandra

S.N.	Time(min)	Noise level (dB)
1	09:51	64.1
2	09:52	64.3
3	09:53	60.7
4	09:54	63.1
5	09:55	64.2
6	09:56	64.4
7	09:57	57.7
8	09:58	62.7
9	09:59	60.7
10	10:00	60.7
11	10:01	60.3
12	10:02	67.2
13	10:03	67.8
14	10:04	69.3
15	10:05	66.4
16	10:06	67.2
17	10:07	65.3
18	10:08	63.4
19	10:09	66.3
20	10:10	65
21	10:11	63.7
22	10:12	65
23	10:13	70.1
24	10:14	67.6
25	10:15	68.1
26	10:16	69.3
27	10:17	67.8
28	10:18	63.3
29	10:19	64.4
30	10:20	65.8

RESULT AND DISCUSSION:

                   The maximum, minimum and average noise level of all region are tabulated below:

	Roadside ares	Residental area	College/Silent
Maximum	81.1 dB	69.6 dB	70.1 dB
Minimum	69.4 dB	50.4 dB	57.7 dB
Average	73.32 dB	62.91 dB	64.57 dB

Maximum noise level in road is due to the heavy traffic at that time which adds loud horn and other sound.

Permissible noise level given by WHO are:

Nepal has its own noise level standards:

S.N.	Area	Day(Noise level Db)	Night(Noise level Db)
	Silent Zone	50	40
1.	Industrial Area	75	55
2.	Business Area	65	40
3.	Urban Residential	545	45
4.	Mixed Residential		40
5.	Rural Residental	45	40
6.

 

By comparing above noise level with standard and permissible noise level we can say that all three micro environmental seting experienced moderate kind of noise level. 

                                  The average noise level in road side, residental area and college/silent Zone was 73.32 dB, 62.91 dB and 64.57 dB respectively.

                          Some health harzards due to noise pollution are:

1. Anoyance
2. Hearing damage
3. Pain threshold
4. Nausea and vomiting
5. Pain in the ear

CONCLUSION:

                 Hence, sound pressure level of different microenvironmental settings was measured and analysed.