Occupational Noise for Engineers

Question 1

Normal human ear hearing

Answer 1

Hear in the range of 20-20000 Hz, distinguish between 500Hz and 501.5Hz, distinguish differences in intensity levels of 1dB

Question 2

Noise induced leaving loss

Answer 2

Hair cells on the basilar membrane became damaged affecting specific frequencies.

Question 3

Threshold of hearing

Answer 3

Is the minimum intensity level at a certain frequency needed for someone to near a sound. Chart shows 3000 - 4000Hz is optimal

Question 4

Age related hearing loss

Answer 4

Increase in frequency, hearing gets worse as you age.

Question 5

Noise induced hearing loss

Answer 5

Frequency ~4000Hz is knocked out, independent to the frequency of noise that your exposed to

Question 6

Chemicals in the workplace that effect the rate of hearing loss

Answer 6

Organic solvents, gases, heavy metals

Question 7

Workplace impact noise/ impulse noise

Answer 7

Manufacturing, maintenance of metal products, construction (impact). Firearms, mining (impulse).

Question 8

Loudness

Answer 8

Is frequency dependent and person specific.

Question 9

Maximum daily allowable doses

Answer 9

The maximum safe daily exposure is 85 dBA for 8 hours and a 3 dB exchange rate (88 dBA for 4 hrs, 91 dB for 2hrs etc. The a-weighting is applied to instrument- measured sound levels to account for the relative loudness as perceived by the human ear. Must be less than 140 dBA at all times.

Question 10

Total noise dose

Answer 10

Accounts for the occupational sound levels + exposure times and the leisure sound levels + exposure times.