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CETP > Noise exposure > Flashcards

Noise exposure Flashcards

1
Q

What is NIHL? (noise induced hearing loss).

A

It is the type of hearing loss associated with noise damage or acoustic trauma. Ex (gunfire, military, machinery, concerts, explosions, etc).

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2
Q

NIHL is also known as:

A

Man made hearing loss

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3
Q

What is TTS and PTS?

A
  1. TTS (temporary threshold shift): noise exposure that can cause hearing thresholds to shift for an amount of time and return back to normal).
  2. PTS (permanent threshold shift): noise exposure that can cause hearing thresholds to shift permanently.
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4
Q

What are 3 symptoms associated with NIHL?

A
  1. Tinnitus
  2. Hyperacusis
  3. Abnormal pitch perception
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5
Q

What is the primary site for of lesion for gradual NIHL?

A

Outer hair cells (OHCs)

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6
Q

Which frequency region is affected first?

A

The high frequencies (mainly 3-6kHz with 4kHz having the worst hearing loss).

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7
Q

OHCs are affected when there is a 40-60 dB hearing loss, at what point do the IHCs get affected?

A

When there is prolonged exposure and the hearing loss exceeds 60 dB HL.

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8
Q

What is the difference between dBA and dBC? Which scale do we use and why?

A

Both dBA and dBC are based on the loudness curves.
- dBA needs 40 dB SPL = 40 phons at 1kHz
- dBC needs 100 dB SPL = 100 phons at 1kHz.

Because dBC needs 60 dB SPL more, we don’t use it because it is too loud. It is most appropriate to use dBA.

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9
Q

What are 5 important aspects of hearing conservation programs?

A
  1. Noise reduction efforts
  2. Measurement of noise exposure
  3. HPDs (hearing protection devices)’
  4. Audiometric surveillance
  5. Education of workers
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10
Q

What are the two types of exchange rates (noise)? Which one do we use in Canada?

A
  1. 5 dB exchange rate
  2. 3 dB exchange rate, we use 3 dB
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11
Q

How many hours can someone be exposed to at 85 dBA?

A

8 hours

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12
Q

How many hours can someone be exposed to at 94 dBA?

A

1 hour

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13
Q

Can someone be exposed to 100 dBA? How much time would they be able to be in that condition?

A

15 minutes

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14
Q

When TTS occurs, what happens in the cochlea?

A

The tip links break between the OHCs and they lose contact with the tectorial membrane. This can cause a reduction in blood flow of the cells, but once removed from the sound environment they can heal.

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15
Q

When PTS occurs, what happens in the cochlea?

A

An overexposure of noise can lead to metabolic changes in the cells and results in loss of oxygen (hypoxia) causing the cells to die.

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16
Q

How many OHCs and IHCs do we have?

A

12k OHCs and 4k IHCs

17
Q

Is NIHL bilateral or unilateral?

A

It is usually bilateral but sometimes can be unilateral in the following conditions (guns, driving with windows open, etc).

18
Q

What is a noise level map?

A

It is a map used in a work industry that can indicate the noise levels in a specific area on the floor

19
Q

What is a dosimeter

A

A piece of equipment used to measure sound exposure in work areas

20
Q

What is an acoustic trauma?

A

A single-occurrence that cause a permanent hearing loss (ex. grenade, fireworks, speaker blown off)

21
Q

What is PEL and REL

A
  1. Permisible exposure level: what is technically allowed.
  2. Recommended exposure level: what is recommended based on personal and work factors.
22
Q

How does audiometric testing work for hearing conservation programs?

A

A baseline audiogram needs to be done within 6 months of first exposure, needs test done annually. If there has been a change, need to retest within 30 days.

23
Q

How long are records kept if employment ends?

A

At least 2 years

24
Q

What are the two types of HPDs and which one is better?

A
  1. Earmuffs: they enclose/encase the whole ear.
  2. Earplugs: placed inside the ear canal.

Earmuffs are better as they provide the most protection by covering the whole ear.

25
Q

What is REAT and MIRE?

A
  1. REAT (real ear attenuation threshold): thresholds obtained with and without hearing protections.
  2. MIRE (microphone in real ear): place a probe tube in ear with ear protection and another outside of ear, check difference between the two.
26
Q

What are the two compensation programs that cover noise damage in Ontario?

A
  1. VAC (veterans affairs canada)
  2. WSIB (workplace safety insurance benefits)
27
Q

Which frequencies are used to compared the baseline audiogram and the annual audiogram with noise exposure?

A

2000, 3000, 4000 Hz

28
Q

What is TWA?

A

Time-weighted average.
Usually in 8 hour periods - the average time in noise.

CETP (9 decks)

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