Nov 4

Question 1

Noise

Answer 1

unwanted sound - acoustical energy that is transmitted be a source to a receptor

Question 2

sound

Answer 2

a mechanical wave that travels as a longitudinal way in air

Question 3

“loudness” is..

Answer 3

not a function of pressure directly, but of energy, which is a function of pressure squared

Question 4

outer ear

Answer 4

simply directs sounds into the ear

Question 5

middle ear

Answer 5

transfers sound to inner ear via vibrations of the tympanic membrane and corresponding movement of ossicular chain

Question 6

inner ear

Answer 6

• organ of corgi has tiny hair cells (cilia) which bend slightly and send electrical to brain
• repeated overstimulation of hair cells can destroy them and cause hearing loss
• inner ear responds differently to various frequencies –> lose high tones first

Question 7

bone conduction

Answer 7

something that vibrates skull will conduct its sound to inner ear

Question 8

Hearing conservation program

Answer 8

• employers are responsible for establishing this whenever potentially injurious noise levels are present
• employees also obligated to participate in this - required for compensation

Question 9

how many estimated workers will suffer compensable hearing loss

Answer 9

1/6 of workers

Question 10

OSHA requires workers be included in a hearing conservation program when noise exposures exceed

Answer 10

85 dBA TWA (TWA of all sounds over 80 dBA)

Question 11

exposed employees are required to wear hearing protection devices when what dBA TWA is exceeded?

Answer 11

90 dBA

Question 12

engineering standard

Answer 12

when 90 dBA TWA is exceeded, employers are required to implement feasible engineering controls

Question 13

psychophysical indices of loudness

Answer 13

phon and sone

Question 14

phon

Answer 14

equal loudness measures of sound

Question 15

sone

Answer 15

indicate the relative loudness of sounds (2 sones is double, etc)

Question 16

equivalent sound levels (Leq) example: 100 dBA for 1 hour, absolute silence for 4 hours:

Answer 16

Leq = 94 dBA for 5 hour period

Question 17

estimated TWA = ?

Answer 17

estimated TWA = (measured TWA) - [ (NRR - 7) / 2 ]

Question 18

employees should wear both inserts and muffs when exposure to noise levels exceed:

Answer 18

100 dBA

Question 19

rule of thumb for wearing hearing protection: Truism: arms length and noise

Answer 19

if you must be within arms reach to hear “normal” conversation, you are exposed to noise at or above 90 dBA