Occupational Noise Survey - Pdf Download - CiteHR
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Dear Sir
Thanks for participation into the thread and come up with your answers...
Dear Kesava Sir
Expect to get your feedback with a source on web where we can get all the desired results related to occupational noise...

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Dear Neeraj

Thanks you, all the answers you gave are right.

One that is missing from yours can be noted from the answers given below.


1. The reference sound pressure is defined as:

• O0.00002N/m²

• 20 µa

• Both A and B

2. At what frequency are A, B, and C weighting scales equal?

• 1000 Hz

3. A type II sound level meter has an accuracy of

• +/-1 db

4. Determine the total percent dose for the following noise measurements:

1 hour @ 85 dB

3 hours @ 95 dB

0.5 hours @ 105 dB

3.5 hours @ 80 dB

• 142%

5. What is the cumulative resultant noise exposure (approximately) for three machines with the following noise ratings (hint: use the short cut method)?

1. 89 dB

2. 92 dB

3. 99 dB

• 100 dB

6. What is the SPL at 200 feet if the SPL at 20 feet is 103 dB?

• 83 dB

SPL2 = SPL1 + 20 • log (d1 / d2)

SPL2 = 103 + 20 • log (20/200)

SPL2 = 83 dB

7. At 30 feet away one piece of equipment registers a SPL of 80 dB. A second piece of equipment at 30 feet away registers a SPL of 85 dB. What is the SPL when both units are operating at 30 feet away?

• 86 dB

8. An Octave Band analyzer is defined as an instrument to determine

• the frequency distribution of sound energy

9. Two separate noise sources of 98 dBA and 96 dBA respectively are installed and operated together. What is the combined noise level?

b. 100 dBA

10. Theoretically, the minimum number of sound pressure level measurements needed to determine the sound power output from a non-directional noise source in a free field is

• one

11. Which classification of noise is described as: sharp burst of sound, lasting less than 0.5 seconds, and repeated less than 1 time per second?

• Impact

12. What is NRR?

• The noise reduction rating of hearing protection.

13. Why is audiometric testing required?

• To test for any hearing loss during your employment.

14. Where are the Noise Dosimeters to be clipped?

Close to the ear (In to the collar)


Kesava Pillai
Dear Keshav
My hearful gratitude for such an excellent post.
Regarding Q-10 I wish to have a bit more insight - if you can help.
Frankly I did not and am not able to catch the question - even when the answer is 1.
Is it related to SPL monitoring in congested plants?
Again many thanks for excellent post - keep posting. I am going to post these question to our corporate HSE too.
Dear Neeraj
In measuring sound we divide the field as follows:
Free Fields
• Sound radiates from a point source spherically
• The power in the sound source is distributed across the surface of the sphere.
• No contribution to measured field from reflections.
Reverberant field :
• Enclosed or partially enclosed space
• Sound reflected repeatedly
Near Field :
• Less than one source distance from source
• Highly variable change in SPL with distance.
Far Field:
• Several source distance away
• Predictable sound behavior with distance
• Source act as a point source.
Since in a free field there is no contribution to measured field from reflections we need only one reading.
Hope the information is useful
Kesava Pillai
Dear Keshav
My bow with gratitude.
Now I am little learned.... Jokes apart but really thanks.
I was really confused and you have cleared the doubt.
My Thanks to Dilip too who took me to this valuable thread.
Please keep posting.

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