Hearing Conservation - Exam 1 Solved
Correctly To Score A+
What is the acoustic definition of noise? CORRECT ANSWERS sound with random
energy distribution across its frequency range
What is the industrial definition of noise? CORRECT ANSWERS unwanted sound or
any sound presented at a high enough level to impair hearing
What is noise induced hearing loss? CORRECT ANSWERS sensory neural hearing
loss resulting from damage to the peripheral auditory system from traumatic noise
exposure. CANS changes can also occur but are secondary to peripheral changes (with
the exception of blast changes)
What are the two types of noise injury? CORRECT ANSWERS TTS - temporary
threshold shift
PTS - permanent threshold shift
What are the symptoms of TTS? CORRECT ANSWERS -loss of hearing sensitivity
-tinnitus
-aural fullness, due to HF hearing loss
-recovery
What is the cause of TTS? CORRECT ANSWERS -typically 75 or more dB(A) required
to cause TTS
-cochlear pathology underlying tts can occur without actual tts
What determines if you will get TTS vs PTS? CORRECT ANSWERS -TTS vs PTS
depends on the level of the noise, the frequency content and the duration of the noise
What are the symptoms of PTS? CORRECT ANSWERS -same as TTS but without
recovery
(HL, tinnitus, aural fullness)
What is the cause of PTS? CORRECT ANSWERS -85 or more dB A required to cause
PTS
-cochlear pathology underlying PTS can occur without actual PTS
What is a compound threshold shift? CORRECT ANSWERS a combined TTS and PTS
-much NIHL that results in PTS beings as CTS
-depends on intensity and duration of the noise
,What two elements must we consider when thinking as NIHL as a public health issue?
CORRECT ANSWERS 1. prevalence - what percentage of a population gets the
condition
2. severity - how much of a life impact does the condition create
What is the definition of NIHL according to OSHA? CORRECT ANSWERS a 10dB
change in the average of 2, 3, 4kHz thresholds
What is the definition of NIHL according to AMA? CORRECT ANSWERS 25dB or
greater average threshold at .5, 1, 2, 3 kHz
The NIDCD/CDC estimates what percent of americans have NIHL? CORRECT
ANSWERS NIDCD - 15 percent of americans b/w the ages of 20-69
CDC - 12.5% of children and adolescents aged 6-19 yrs have NIHL
How much of a life impact does NIHL create? CORRECT ANSWERS -complex issue
-not life threatening but definitely life altering
-wide range of susceptibility
Why is NIHL still an issue? CORRECT ANSWERS -world is getting more noisy
-significant sacrifices required to avoid noise in many cases
-invisible problem
-long-term manifestation
*its preventable BUT noise is caused by things we have come to rely on as a population
What are the key noise parameters? CORRECT ANSWERS 1. type of exposure
2. intensity
3. duration
4. frequency content
*intensity and duration combine to make the noise dose, determines if they should be in
a hearing conservation program
What are the types of traumatic noise exposures? CORRECT ANSWERS 1. continuous
a. steady-state
b. fluctuating
c. intermittent
2. short-duration
a. impact
b. impulse
c. blast
**dont know how much injury any of these could cause
***very hard to quantify and measure
What is a steady state noise? CORRECT ANSWERS a noise at a fixed level that does
not vary by more than 5dB, it is present without breaks for long time periods
, What is fluctuating noise? CORRECT ANSWERS fluctuates by more than 5dB of the
exposure duration
What is intermittent noise? CORRECT ANSWERS steady-state or fluctuating noise with
periods of hazardous exposure (short breaks have sig. impact in reducing the amount of
damage)
What is an impact noise exposure? CORRECT ANSWERS short-duration sound that
results from the collison of two objects (hammer striking a nail)
What is an impulse noise exposure? CORRECT ANSWERS short-duration that results
from a burst or small explosion (rifle fire)
What is blast noise exposure? CORRECT ANSWERS massive, extremely high level
sound that results from a large explosion (explosion of a bomb)
What is acoustic trauma? CORRECT ANSWERS massive cochlear damage resulting
from high-level short duration exposure
What is kurtosis? CORRECT ANSWERS -a measure of how much fluctuation occurs in
the level of the noise (continuous and short duration noises can be combined, forming
the most toxic form of noise exposure)
-amount a sound fluctuates in its intensity level from moment to moment
-high kurtosis = more fluctuating a lot from moment to moment = more damaging
How is intensity related to threshold shift? CORRECT ANSWERS -the greater the
intensity induces more threshold shift in less time
-BUT relationship between intensity and TS becomes much less clear with impulse,
impact, and blast exposures (above 130dB a all bets are off)
How is duration related to threshold shift? CORRECT ANSWERS -longer exposure
times do not increase the magnitude of the TS
-increase the chances of PTS instead of TTS
-greater exposure time = less recovery
What is the asymptotic threshold shift? CORRECT ANSWERS -based on lab animal
experiments
-longer duration of exposure will shift the TS to a point where it hits a ceiling/plateau
(once same population of cells are dead no matter the amount of time, HL cant get
worse)
-assumption is that if a person were left in the same noise environment for the rest of
his/her life, the maximum hearing loss developed would not exceed the ATS
-ATS = maximum PTS
Does ATS actually occur? CORRECT ANSWERS -yes and no
Correctly To Score A+
What is the acoustic definition of noise? CORRECT ANSWERS sound with random
energy distribution across its frequency range
What is the industrial definition of noise? CORRECT ANSWERS unwanted sound or
any sound presented at a high enough level to impair hearing
What is noise induced hearing loss? CORRECT ANSWERS sensory neural hearing
loss resulting from damage to the peripheral auditory system from traumatic noise
exposure. CANS changes can also occur but are secondary to peripheral changes (with
the exception of blast changes)
What are the two types of noise injury? CORRECT ANSWERS TTS - temporary
threshold shift
PTS - permanent threshold shift
What are the symptoms of TTS? CORRECT ANSWERS -loss of hearing sensitivity
-tinnitus
-aural fullness, due to HF hearing loss
-recovery
What is the cause of TTS? CORRECT ANSWERS -typically 75 or more dB(A) required
to cause TTS
-cochlear pathology underlying tts can occur without actual tts
What determines if you will get TTS vs PTS? CORRECT ANSWERS -TTS vs PTS
depends on the level of the noise, the frequency content and the duration of the noise
What are the symptoms of PTS? CORRECT ANSWERS -same as TTS but without
recovery
(HL, tinnitus, aural fullness)
What is the cause of PTS? CORRECT ANSWERS -85 or more dB A required to cause
PTS
-cochlear pathology underlying PTS can occur without actual PTS
What is a compound threshold shift? CORRECT ANSWERS a combined TTS and PTS
-much NIHL that results in PTS beings as CTS
-depends on intensity and duration of the noise
,What two elements must we consider when thinking as NIHL as a public health issue?
CORRECT ANSWERS 1. prevalence - what percentage of a population gets the
condition
2. severity - how much of a life impact does the condition create
What is the definition of NIHL according to OSHA? CORRECT ANSWERS a 10dB
change in the average of 2, 3, 4kHz thresholds
What is the definition of NIHL according to AMA? CORRECT ANSWERS 25dB or
greater average threshold at .5, 1, 2, 3 kHz
The NIDCD/CDC estimates what percent of americans have NIHL? CORRECT
ANSWERS NIDCD - 15 percent of americans b/w the ages of 20-69
CDC - 12.5% of children and adolescents aged 6-19 yrs have NIHL
How much of a life impact does NIHL create? CORRECT ANSWERS -complex issue
-not life threatening but definitely life altering
-wide range of susceptibility
Why is NIHL still an issue? CORRECT ANSWERS -world is getting more noisy
-significant sacrifices required to avoid noise in many cases
-invisible problem
-long-term manifestation
*its preventable BUT noise is caused by things we have come to rely on as a population
What are the key noise parameters? CORRECT ANSWERS 1. type of exposure
2. intensity
3. duration
4. frequency content
*intensity and duration combine to make the noise dose, determines if they should be in
a hearing conservation program
What are the types of traumatic noise exposures? CORRECT ANSWERS 1. continuous
a. steady-state
b. fluctuating
c. intermittent
2. short-duration
a. impact
b. impulse
c. blast
**dont know how much injury any of these could cause
***very hard to quantify and measure
What is a steady state noise? CORRECT ANSWERS a noise at a fixed level that does
not vary by more than 5dB, it is present without breaks for long time periods
, What is fluctuating noise? CORRECT ANSWERS fluctuates by more than 5dB of the
exposure duration
What is intermittent noise? CORRECT ANSWERS steady-state or fluctuating noise with
periods of hazardous exposure (short breaks have sig. impact in reducing the amount of
damage)
What is an impact noise exposure? CORRECT ANSWERS short-duration sound that
results from the collison of two objects (hammer striking a nail)
What is an impulse noise exposure? CORRECT ANSWERS short-duration that results
from a burst or small explosion (rifle fire)
What is blast noise exposure? CORRECT ANSWERS massive, extremely high level
sound that results from a large explosion (explosion of a bomb)
What is acoustic trauma? CORRECT ANSWERS massive cochlear damage resulting
from high-level short duration exposure
What is kurtosis? CORRECT ANSWERS -a measure of how much fluctuation occurs in
the level of the noise (continuous and short duration noises can be combined, forming
the most toxic form of noise exposure)
-amount a sound fluctuates in its intensity level from moment to moment
-high kurtosis = more fluctuating a lot from moment to moment = more damaging
How is intensity related to threshold shift? CORRECT ANSWERS -the greater the
intensity induces more threshold shift in less time
-BUT relationship between intensity and TS becomes much less clear with impulse,
impact, and blast exposures (above 130dB a all bets are off)
How is duration related to threshold shift? CORRECT ANSWERS -longer exposure
times do not increase the magnitude of the TS
-increase the chances of PTS instead of TTS
-greater exposure time = less recovery
What is the asymptotic threshold shift? CORRECT ANSWERS -based on lab animal
experiments
-longer duration of exposure will shift the TS to a point where it hits a ceiling/plateau
(once same population of cells are dead no matter the amount of time, HL cant get
worse)
-assumption is that if a person were left in the same noise environment for the rest of
his/her life, the maximum hearing loss developed would not exceed the ATS
-ATS = maximum PTS
Does ATS actually occur? CORRECT ANSWERS -yes and no
