Noise Basics

Question 1

What is amplitude

Answer 1

• Loudness
• Variation in sound pressure

Question 2

What is a decibel?

Answer 2

• A convenient way to compare sound pressure levels with different orders of magnitude
• Comparison made to the reference point

Question 3

By how many decibels does sound pressure level decrease if you double the distance from the source?

Answer 3

6 db

Question 4

What is the OSHA PEL for noise?

Answer 4

8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent.

Question 5

What is the OSHA PEL exchange rate for noise?

Answer 5

5 dB

Question 6

What is the OSHA PEL action level for noise?

Answer 6

8-hour time-weighted average sound level (TWA) of 85 decibels measured on the A scale (slow response) or, equivalently, a dose of fifty percent.

Question 7

What types of noise are incorporated when monitoring for noise?

Answer 7

All continuous, intermittent and impulsive sound levels

Question 8

What range of noise is integrated into noise measurements?

Answer 8

80 decibels to 130 decibels

Question 9

What is the ACGIH TLV for noise?

Answer 9

8-hour time-weighted average sound level (TWA) of 85 decibels

Question 10

What is the ACGIH exchange rate for noise?

Answer 10

3 dB

Question 11

dBA frequency weighting is used most commonly…

Answer 11

In EHS. It weighs human frequencies more heavily

Question 12

dBC frequency weighting is used most commonly…

Answer 12

for peak noise measurements. It heavily weights all but extremely high and low frequencies

Question 13

What is dBZ most commonly used for?

Answer 13

Octave band analysis. It has a flat response (“unweighted”)

Question 14

Why use frequency analysis?

Answer 14

• Ears have varying sensitivity based on frequency
• Useful in determining appropriate engineering controls

Question 15

How are frequency categorized?

Answer 15

• Octave bands
• Octave band is range of frequencies where upper frequency is twice the lower frequency

Question 16

How are octave bands generally described?

Answer 16

By their center frequency

Question 17

What are engineering controls for noise control?

Answer 17

Absorption and sound barriers

Question 18

What are types of absorption engineering controls?

Answer 18

• Porous: acoustic energy causes fibers to vibrate generating heat (good for high frequencies)
• Diaphragmatic: thin piece of material vibrates when hit by sound-absorbing energy (good for low frequencies)
• Resonant: pocket of air absorbs sound energy

Question 19

What are examples of barrier engineering controls?

Answer 19

• Baffle: Barrier between source and person, good for high frequencies
• Partial enclosure: top on the baffle
• Complete enclosure: box around the person or the source

Question 20

What are negative health outcomes that can result from noise exposure?

Answer 20

• Tinnitus
• Temporary threshold shift
• Standard threshold shift
• Higher frequency hearing is lost first

Question 21

What frequencies are tested in audiometric testing?

Answer 21

• 500
• 1000
• 2000
• 3000
• 4000

Question 22

What is a standard threshold shift?

Answer 22

• Exceed 10 dB drop in 2000, 3000, or 4000 in either ear

Question 23

What is the noise reduction rating?

Answer 23

• The NRR is conducted in a laboratory
• Actual results will likely vary
• OSHA regulation 20 CFR 1910.95 Appendix B provides details on using the NRR