1. The OSHA standard for hearing conservation program is _________?

29.CFR.1910.95

2. When an employer implements a continuing hearing conservation program?

Noise exposure equals or exceed 85 decibel

3. One of the more useful sound measuring device is ________?

Octave Band Analyzer

4. What is CAOHC?

Council for Accreditation In Occupational Hearing Conservation

5. Audiometers must meet the requirements of _____?

ANSI S3.6-1969

6. _______is a change in the hearing threshold relative to the baseline audiogram of an average

of 10 DB or more at 2000,3000 and 4000Hz in either ear ?

Standard Threshold Shift (STS)

7. Natural hearing loss caused by the ageing process is called _____?

Presbycusis

8. Nose exposure measurement records are required every ____years?

2
9. How long an audiometric testing must be maintained in an employee’s records ?

Till the duration of the employment

10. Unbroken sound waves are called _________ ?

Continous Nosie

11. Broken sound waves are called __________ ?

Intermittent Noise

12. ______is oscillations in pressure above and below the ambient atmosphere pressure?

Sound

13. _______is the number of complete cycles of a sound wave in 1 second?

Frequency

14. Frequency measured in _______?

Hertz
 15. The normal range of hearing from human being is ________?

20-20,000Hz

16. Time required for one cycle is called ____?

Period

17. ______is the reciprocal of frequency?

Period

18. Distance travelled in one pressure cycle is called ______?

Wavelength

19.”Pinna” is in which part of the body?

“Ear”

20. Which are the 3 smallest bones in the human body?

Incus, Stapes and Malleus

21. Name of the part of ear which equalizes the pressure between the middle and outer ear?

“Eustachian Tube”

22.”Ossicle” is which part of the human body?

Ear

23.The snail shell-shaped organ in ear is called ______?

“Cochlea”

24.Which are the major causes of hearing loss?

Obstruction and disease, Acoustic trauma, Presbycusis/Sociocusis, Noise Induced

25.Hearing loss as a result of Continous noise exposure is called _____?

Sociocusis
26.How many types of hearing loses?

5
27.The type of hearing loses which occurs in outer and middle ear?

Conductive
28.Hearing loss which can cause built up of ear wax?

Conductive

29.Hearing loss occurs at inner ear called_______?

Sensorineural

30.Damage to the ear part of “Corti” is irreversible. Is it right or wrong?

Right

31.Name the type of hearing loss which is not due to noise exposure?

Central Nervous System (CNS)

32.Name the hearing loss due to emotional trauma?

Psychogenic

33. As per OSHA requirements permissible noise exposure for 8 hours is ________?

90
35.Which are the 3 entities of sound/noise?

Sound Power, Sound Pressure and Sound Intensity

36.Write the sound power reference level?

10 rasie to the power of (-12)

37.Write the sound pressure reference level?

 0.00002 N/meter square

38. Sound intensity is a vector quantity. Yes or no?

Yes (Both magnitude and direction)

39.An employee is exposed to 80(dBA) for 4 hours. What is the permissible exposure time?
T = 8
_____________
L-90/5
2 raise to the power of

40.Calculate the employees total exposure to noise,expressed as a dose or percentage of PEL;90

(dB) for 4 hours,92 (dB) for 2 hours and 80 (dB) for 2 hours?

D = 100 Sigma (Ci/Ti) Where I from 1 to N

D = 89%
41.How many hours away from noise environment is required to prior audiometric testing?

14

42. Type 1 sound level meter is the minimum standard and has an accuracy of ____?

+/- 2(dB)

42. An employee has been monitored using a noise dosimeter and the results are that the employee
has been exposed to 72%of the permissible exposure. What is the TWA expressed in sound
pressure level?

TWA = 16.61 Log 10 D/100 +90

Answer is 87.63 (dB)

43. Find out the combined noise level in a workplace in the following machines ?
Machine # 1 = 79 (dB)
Machine # 2= 85
 Machine # 3 = 90

Machine # 4 = 95

Combined Sound Pressure Level (Lpt) =10 Log Sigma of 10 rasie to the power of Lpi/10
Lpi is individual measured sound pressure level

Lpt = 10 Log Summation of (10 rasie to the power of 79/10) + (10 rasie to the power of 85/10) +
(10 rasie to the power of 90/10) + (10 rasie to the power of 95/10)

Lpt = 96.59 (dB)

44. The sound level measurement 4 feet from a noise source and that measurement was 92 (dBA) .
What is the noise level measurement at 10 feet?

(dB 1) = (dB0)+20log10 (d0/d1)

Answer is (dB1)= 84 (dB)

45.You have a source that is generating 0.02 W.What is the sound power level (Lw) in Decibels ?
Lw = 10log10 (W/W0)

Lw=Sound Power Level

W=Acoustic power units in watts
W0=Reference acoustic power (10 rasie to the power of (-)12W

Lw = 103 (dB)

46.Given a measured sound pressure level of 0.002 N/m square. What would be the sound pressure
level expressed in Decibels?

Lp = 20 log10 p/p0 (dB)

Lp=Sound pressure level in (dB)

p=measured sound pressure level in (N/m square)
p0=measured sound pressure level(0.00002 N/ m square)
Lp=40(dB)
47. Given a sound pressure level of 0.0796 N/m square. Calculate the sound intensity level in watts
 per square meter?

I = P square/density of medium speed of sound

Density of medium in air = 1.2 kg/m square

Speed of sound in air is 344 m/s

Putting the values in equation=0.0000153 W/m square

48.______is equal to the square footage of surface times the noise reduction coefficient?

“Sabin”

49. You have a 20 ft X 20 ft room with hardwood flooring, and you wish to install carpeting over the
flooring in order to reduce sound pressure levels. What would be the overall noise reduction in
decibels(NRC for hardwood-0.15 and NRC for carpet-0.48)?

NR = 10log 10 (A2/A1)

NR-Noise reduction (dB)

A1=Total number of absorption units(sabins)before treatment
A2=Total number of absorption units(sabins)in the room after treatment

Answer – 5.05 (dB)

50.You have a duct perimeter of 5 feet (60 inches) in length with a diameter of 1 feet.The absorption
coefficient for the packing material is rated 0.54.What is the NR in decibels per foot of length ?

NR = 12.6 P alpha raise to the power of 1.4/A (dB)/feet

NR-Nose reduction (decibels per foot of length)

P=perimeter of the duct(in inches)
Alpha-Absorption coefficient of lining materials

A= cross sectional area of duct in inches

Answer is 2.82 (dB)/ft

Additional Information
Speed of sound in air - 332m/s
Speed of sound in water - 1500m/s
Speed of sound in steel - 6100m/s

Speed of sound = Wavelength X Frequency

Conductive hearing loss occurs due to physical obstruction of the Eustachian Tube, Perforation of the
tympanic membrane

Permissible noise exposure as per OSHA 29.CFR.1910.95

Exposure Time(h) Sound Level (Decibel)
32 80
8 90
6 92
4 95
3 97
2 100
11/2 102
1 105
1/2 110
1/4 115

The above Table to be in mind as its requires for noise dosage calculation.

A simple method of determining sabins is to multiply the square footage area by the “noise reduction
coefficient”