Noise

Question 1

What is noise?

Answer 1

Undesirable or unwanted sound

Subjective

Question 2

What is noise propagation?

Answer 2

Generated at a source and spreads spherically away from that source
Diminished with distance and loses engery

Question 3

What occurs as “sounds waves” when objects are encountered?

Answer 3

Bending and diffraction

Question 4

How is sound measured logarithmically?

Answer 4

bel (B)

Question 5

What is the more commonly used subunit for sound?

Answer 5

Decibel (dB)

1/10 bel

Question 6

The power of a sound wave is proportional to the…..

Answer 6

Square of the pressure

Question 7

Combinations of sounds may make ____ in the decibels.

Answer 7

Little

Question 8

At what level would a person receive painless damage?

Answer 8

85-125 dB

Question 9

At what level would a person start to feel pain?

Answer 9

Over 125 dB

Question 10

Frequency

Answer 10

Vibrating object moves molecules back and forth causing sound waves to move outward

Question 11

What is the range of normal hearing?

Answer 11

20 Hz to 20 kHz

Question 12

Steady frequencies

Answer 12

Pure tones

Tuning forks and electronic oscillators Uncommon

Question 13

Intensity

Answer 13

Directly proportional to sound pressure

Pascals (Pa) and micropascals (uPa)

Question 14

What is the normal range for intensity?

Answer 14

20 uPa to 20 Pa

Question 15

What is the A scale?

Answer 15

Sound measurement as an approximation of the sensitivity of the human ear
2 sounds with the pressure lvl may have different A levels

Question 16

Steady noises

Answer 16

Continuous, intermittent, impulse

Question 17

What are the effects of noise to the outer ear?

Answer 17

Minimal direct effects, possible physical damage to pinna or ear with small effects
Restriction of ear canal with cerumen causing mild to moderate hearing loss

Question 18

What are the effects of noise to the middle ear?

Answer 18

Effects due to the acoustic reflex of involuntary contractions in the ossicular chain due to high-intensity sound
Overtime stiffening of the chain impairing low frequency sounds

Question 19

What can occur if there is fluid in the middle ear and what else could cause this?

Answer 19

May produce mild to moderately severe hearing loss
Perforated ear drum
Fixed or disconnected ossicles

Question 20

What are the effects of noise to the inner ear ?

Answer 20

Sensorineural
Exposure to loud noise may produce temporary threshold shifts (may become permanent)
Intense bursts may cause permanent damage immediately

Question 21

Describe the cochlea.

Answer 21

Hair cells that change mechanical fluid vibrations into nerve impulses
Base: high frequencies
Apex: low frequencies
Inner hair: all sounds

Question 22

Presbycusis

Answer 22

Slow loss of hearing due to age

Question 23

What are some causes of age-related hearing loss?

Answer 23

Familial, repeated exposure to loud noises, smoking, medical conditions or medications

Question 24

What are the symptoms of age-related hearing loss?

Answer 24

Sounds may seem overly loud
Difficulty hearing things in noisy areas
HIgh pitches sounds like s or th may be hard to distinguish
Men’s voices easier to hear, some people sound slurred
Tinnitus

Question 25

What are some steps to help age-related hearings loss?

Answer 25

No cure
Hearing aids
Telephone amplifiers and other assertive devices
Sign language or speech reading

Question 26

Describe a cochlear implant.

Answer 26

Must have a functioning auditory nerve
Restores a sense of hearing, not actual ability to hear
Makes sounds louder
Should be considered in those with relatively short-term total hearing loss

Question 27

What are some other effects of noise?

Answer 27

Reduced ability to communicate, in BP, changes in hormone production, sleep disturbances, behavioral changes, dec task performance

Question 28

What are some way transport sources help control “environmental” noises of cars?

Answer 28

Noise barriers around road, sleep limits, highway surface texture, vehicle limits, tire design

Question 29

What are some way transport sources help control “environmental” noises of aircrafts?

Answer 29

Engine design, sound attenuation packages, alteration of flight path direction and timing

Question 30

Occupational noise has more…

Answer 30

Specific data and methods of control

Question 31

What are the OSHA standards?

Answer 31

85 dB = 8 hr time weighted average (TWA)
Each 4 dB rise dec time exposed by half;
85 db = 8 hrs
89 db = 4 hrs

Question 32

What scale does OSHA use for noise monitoring?

Answer 32

A scale

Question 33

When should a person wear hearing protectors?

Answer 33

Over 85 dB or impulse noise over 140 dB

Double protection needed at 108 dB