Introduction
Exposure in place that have a high noise level for a long time must hazard to hearing. In this measurement, a Chinese restaurant and a peak dining hour has been chosen to conduct the measurement, the aim of chosen peak hour and Chinese restaurant to conduct the measurement is to investigate the workplace noise level and how high level of noise level are impact to workers who need to exposure in noise for a long time, generally the noise level will be high in lunch peak dining hour, the data that collect in peak dining time will be representative to noise pollution impact to workers who work in restaurant. In this measurement, parameter Leq, L10 and L90 will be collect and conduct a comparation after measurement. And the noise exposure. On the other head, possible noise source has been observed due to measurement.
Methodology
In this measurement, precision sound level meter, calibrator and tripod are necessary in measuring procedure. Before measurement, calibration of sound level meter must be conduct to ensure the sensitive of sound level meter, to increase the accuracy of data measured. Parameter Leq, L10, L90 are necessary to measure at two location inside restaurant to show the different noise level inside a same restaurant, after a measurement at a place, it should repeat the same measure procedure at another position. Then, background noise level are also need to measure. At the end of measurement, a calibration of sound level meter is necessary to conduct once.
Result
In the measurement, two location: 501 and 606 are chosen as the measuring position inside restaurant, the result in Leq, L10 and L90 measured will be show below:
In 606, 30 minutes Leq was 78.3dB, and L10 and L90 were 80.9dB and 73.6dB respectively. To view the trend, the trend of noise level change at 606 was ups and downs. Overall, there were 5 downward and 4 upward trend at the measure interval. For the aspect of downward trend, downward trend had present in minute 0 to 3, 9 to 12, 15 to 18, 21 to 24 and 27 to 30 with noise level 79.6dB to 72.8dB, 79.3dB to 76.4dB, 78.3dB to 70.7dB, 74.7dB to 73.7dB and 77.2dB to 75.5dB respectively, the decrease rate were 1.3% to 10.7%. For the aspect of upward trend, upward trend was present tin minute 3 to 9, 12 to 15, 18 to 21 and 24 to 27 with noise level 72.8dB to 79.3dB, 76.4dB to 78.3dB, 70.7dB to 74.7dB and 73.7dB to 77.2dB respectively, the increase rate were 2.5% to 8.9%. Minute 9 to 15 had the highest noise level at whole measure interval.
In 501, 30 minutes Leq was 79.5dB and L10 and L90 was 101.4dB and 76.4dB respectively. To view the trend, the trend of noise level change at 501 was ups and downs. Overall, there were 4 upward trend and downward trend during the measurement. For the aspect of downward trend, downward trend was present in minute 0 to 3, 9 to 15, 18 to 21 and 24 to 27 with noise level 81.5dB to 76.1dB, 77dB to 73.6dB, 80.5dB to 79.5dB and 87.6dB to 73.2dB respectively, the decrease rate was 1.2% to 16.4%. For the aspect of upward trend, upward trend was present in minute 3 to 9, 15 to 18, 21to 24 and 27 to 30 with noise level 76.1dB to 77dB, 73.6dB to 80.5dB, 79.5dB to 87.6dB and 73.2dB to 75.6dB re4spectively, the increase rate were 1.2% to 10.2%, minute 24 had the highest noise level at whole measuring interval.
For the aspect of possible noise source, the noise source observed can be divide into 8 types: noise from diners talking, noise from porcelain collision, noise from working of restaurant workers (delivery of foods) noise from television, noise from ventilation system, noise from cooking in the kitchen, noise from cleaning dining tools and noise from working.
Sampling location: Dragon Delight
Date of sampling:1/3/2019 Time of sampling: 13:15
List of possible noise source
1
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Noise from diners talking
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2
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Noise from porcelain collision
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3
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Noise from working of restaurant workers (delivery of foods)
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4
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Noise from television
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5
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Noise from ventilation system
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6
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Noise from cooking in the kitchen
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7
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Noise from cleaning dining tools
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8
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Noise from walking
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Measuring position 1 (606):
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Calibration before measurement: 92.5dB
Time (min)
|
Leq
|
L10
|
L90
|
Leq (30 min)
|
0
|
79.6
|
80.9
|
73.6
| |
3
|
72.8
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6
|
75.5
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9
|
79.3
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12
|
76.4
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15
|
78.3
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18
|
70.7
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21
|
74.7
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24
|
73.7
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27
|
77.2
| |||
30
|
75.5
|
78.3
|
Leq,L10 and L90 against time at 606
Measuring position 2 (501):
| ||||||||
Time
|
Leq
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L10
|
L90
|
Leq
|
Lmax
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(min)
|
(30-min)
|
(30-min)
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0
|
81.5
| |||||||
3
|
76.1
| |||||||
6
|
76.4
| |||||||
9
|
77
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12
|
76.7
| |||||||
15
|
73.6
|
101.4
|
76.4
| |||||
18
|
80.5
| |||||||
21
|
79.5
| |||||||
24
|
87.6
| |||||||
27
|
73.2
| |||||||
30
|
75.6
|
79.5
|
104.9
| |||||
Leq, L10 and L90 against time at 501
Discussion
In a restaurant, the location of seat will be a possible factor that may affect the representativeness of data. If choosing the seat that is far from other diners in the restaurant, the result measured is not representative because the result cannot reflect the real situation of noise level, due to the fact that sound pressure level will be decrease if the sound level meter is far from the sound source, molecules suspend in air will adsorb the energy of sound, sound will gradually weaken. On the other hand, the time slot of conduct measurement may affect the representativeness of data, it should not measure in latest afternoon base on restaurant will have a break in the latest afternoon generally, the number of diners are rare at that time, sound level of sound source are not stronger than at lunch time or dinner time, lead the noise level keep continue low, it is not representative to the noise level in the real situation of a restaurant.
The sensitive of sound level meter may be the factor that affect the representativeness of data, the sensitive of sound level meter will affect the accuracy of data measure directly, the data which are not accuracy is not representativeness. So, to ensure the sound level meter is sensitive, calibration should be conduct before measurement and after measurement.
To view about the daily personal noise exposure level, according to the noise dose set by the International Organization of ISO, the allowable noise dose set by ISO will be noise level 85dB during 8 hours currently. The noise exposure and noise dose that restaurant workers experience daily are calculate below;
Daily personal noise exposure level: LEP,d=10 log 1/8(10^7.83x8) =78.3
Noise dose：T1=8/2^((78.3-90)/5)
T1=8/0.197510328
T1=40.50421101
D=100x(8/40.50421101)
D=19.7510328%
Daily noise exposure level: 40.50421101dB
Noise dose: 19.7510328%
Noise dose: T2= 8/2^((79.5-90)/5)
T2= 8/0.2332582479
T2= 34.2967507988
D=100x(8/34.2967507988)
D= 23.32582479%
Daily noise exposure level: 34.2967507988dB
Noise dose: 23.32582479%
To comparing the result with the allowable noise dose set by the International Organization of ISO, the allowable noise dose set by ISO will be noise level 85dB during 8 hours currently, at this situation, the noise dose will be 100%. Look back to the result calculated, the noise dose just about 19.8% and 23.3% at two measuring position, if an employee is working in the monitoring location for 8 hours, it is much lower than the ISO standard.
If the employee work at the workplace with high noise dose for a long time, it is estimated that the hearing of employees will be damage. So, if the noise dose of workplace exceed ISO standard 100% and noise level 85dB during 8 hours, employer should decrease the noise dose exposure time of employees, make the average level of labor noise exposure on the eight-hour day of work no more than the specified value or equivalent dose value to avoid the hearing damage of employees. For laborers with an average sound pressure level of more than 85 dB or an exposure dose of more than 50% on an eight-hour day, workers should wear effective earplugs, earmuffs and other soundproofing protective gear.