control noise lab report

Introduction:

 

This lab was to measure the SPL for Huron church road at different locations. The measurements were taken using a sound level meter. The results were molded using an ORNAMENT model procedure.

 

 

Procedure:

 

1. Each group is to mount the Sound Level Meter on the tripod at least 20 metres from the edge of the selected roadway.
2. Measure and sketch the critical dimensions of the roadway

 

3. Use the Sound Level Calibrator to check the calibration of the Sound Level Meter after it has been turned on.
4. Measure the A-weighted one hour equivalent sound pressure level over a 10 minute period.
5. During the period that the Sound Level Meter is recording data, count the number of vehicles that pass in each direction including the breakdown of the three types of vehicles.

 

 

Figure1: Print of the measuring location

 

Equipment:

 

B&K Type 2250 Sound Level Meters, B&K Type 4231 Sound Level Calibrator, Tripod, Measuring Tape

 

Results:

 

Question 1:

 

1	Lanes/Road Section (Element)		Eastbound		Westbound
2	Volume Automobiles               (vph)		606		600
3	Medium Trucks          (vph)		36		6
4	Heavy Trucks             (vph)		318		240
5	Total Volume                           (vph)		960		846
6	Posted Speed                        (km/h)		60		60
7	Heavy Trucks                             (%)	Lines 4/5	0.33125		0.2836
	Adjusted Heavy Trucks
8	Road Gradient                  (%)		0		0
9	Adjustment Factor	Table 1	1		1
10	Adjusted Volume           (vph)	Lines 4*9	318		240
11	Total Trucks                            (vph)	Lines 3+10	354		246
12	Medium Trucks                          (%)	Lines 3/11	0.1016		0.024
13	Total Trucks/Total Volume         (%)	Lines 11/5	0.3687		0.2907
14	Reference Sound Level          (dBA)	Tables 3-6 or Eqn 1		62.74		62.02
	Effective Heights
15	Source (s)                        (m)	Table 8 or Eqn 2	2.4		2.30
16	Receiver (r)                      (m)	(1.5 Day, 4.5 Night)	1.5		1.5
17	Elevation Change, e          (m)	Figure 4	0		0
18	Barrier Height, h               (m)	Figure 4	0		0
19	Total Effective Height                 (m)	Figure 4	3.9		3.8
	Adjustments
20	Volume A v                                  (dBA)	Table 2 or Eqn 3		13.8		13.25
21	Distance                           (m)		53.4		36.8
22	A d	Table 7 or Eqn 4		-9.0		-6.38
	Finite Segment Size
23	Angle, O/ 1                             (degrees)	Table 10	-60		-60
24	Angle, O/ 2                             (degrees)	Table 10	90		90
25	Absorption Coefficient	Table 7 or Eqn 4	0.633		0.636
26	A f                                                           (dBA)	Table 9, 11		-1.9		-1.9
27	Pavement Surface, A p    (dBA)	Table 12		0		0
28	W oods, A w                                  (dBA)	Table 13		0		0
29	Rows of Houses, A h         (dBA)	Table 14		0		0
30	Barrier  Angle O- 1        (degrees)	Table C1	0		0
31	Angle O- 2        (degrees)	Table C1	0		0
32	Finite Barrier Index	Table C1	0		0
33	PLD                     (m)	Table C2	0		0
34	A b                                   (dBA)	Table C2		65.59		67.11
35	Segment Leq                          (dBA)			65		67
36	Road Leq                               (dBA)	69.42		69

 

 

Question 2:

 

Table 1: Residential receptors made for different types of Resident

 

Based on the results obtained for the east and west bound the SPL for both would be considered too high, since the limits of Residential areas are shown in the above table. Adjustments will have to be made to assure that the SPL of the current situation match the SPL of the residential areas.

 

Reasons why there may be discrepancies between the modelled and measured results:

 

1. Unnecessary sound around the sound level meter. That could change the outcome of the sound pressure level.
2. Improper measurements for the roadway, and the distance from the meter to the nearest road edge.
3. Not considering any obstacles around the area that can cause reflection, so results would be different than the modeled results
4. The sound level meter was not calibrated correctly, this could cause to different results.
5. Miscalculating the number of automobiles, medium trucks and heavy trucks.

 

 

Question 3:

 

As sound level measurements are directly related to count number of traffic so there is high possibility that number of vehicles were miscounted which can be taken as human error. There should have been more people to count the number of vehicles. Near to experiment location, pedestrian bridge was located. It could be more accurate for counting the vehicle if the person who was assigned to count the vehicle could go over the bridge and count those vehicles.

Another problem associated with sound level measurement was that number of pedestrians were talking while recordings were bring taken. That could also add some external noise to the measurements taken. That could be more precise if location was chosen where there was no pedestrian crossing. Birds chirping and tree noises could also affect the measurements

 

Conclusion:

 

The group has learnt how to use a sound level meter, and how to visualize the SPL data. Besides, the group learnt how to use an ORNAMENT model to measure the SPL for the situation assigned. The results seemed correct based on the calculations made.

 

 

References:

 

http://www.ambassadorbridge.com/!downloads/appendix_j_noise_study.pdf

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