Praxis Random Chp8 [working, stopped pg391]

What are the EDHI guidelines?

NBHS by 1 month

diagnosis of HL by 3 months (fit with HA w/in 1 month of diagnosis)

initiation of early intervention services by 6 months

What tests can be used for NBHS?

ABR or OAEs`

When is ABR preferred for NBHS?

Newborns with NICU stay over 5 days due to increased risk of neural HL/ANSD

What is typical pass/fail criteria for OAE NBHS?

OAE present at 2000, 3000, 4000 Hz at SNR of at least 6 dB

According to ASHA, when should school-aged children be screened?

When child first enters school or transfers to a new school and every year in Grades K-3, 7 and 11

When parent/caregiver/teacher/service provider has concerns

Part of speech-language evaluation

What is the school screening protocol?

Otoscopy

Pure-tone screening

*OAE

*Tymps

For school screening, what is the pure-tone screening protocol?

1000, 2000, 4000 in each ear at 20 dB HL

What is the allowable ambient noise level at 1000, 2000, and 4000 Hz?

1000 Hz = 50 dB SPL

2000 Hz = 58 dB SPL

4000 Hz = 76 dB SPL

If a school hearing screening is failed, what is the referral and rescreening policy?

Rescreen within 6-8wks based on expected timeline for spontaneous resolution from OME

What is NIHL? Why does it develop?

Noise-induced hearing loss

Develops when sensitive structures of inner ear are damaged by exposure to high noise levels for extended periods of time or to intense impulsive sounds

What is temporary threshold shift?

temporary metabolic changes to cochlea

listener may experienced decreased hearing, tinnitus, dull or muffled speech, and aural fullness

symptoms typically last less than 1 hour to several hours or days

symptoms may completely or incompletely resolve

What is a permanent threshold shift?

When metabolic changes to cochlea in response to loud noise do not recover

Describe the changes in the inner ear causing a permanent threshold shift

Noise exposure causes hair cells to swell to point of rupturing

Hair cells replaced by scar tissue

Stereocilia become fused together, interfere with transduction process

Auditory nerve terminals connected to damaged hair cells degenerate

What is the classic presentation of NIHL?

permanent bilateral SNHL with noise notch in high frequencies

Noise notch: decreased hearing sensitivity at 3000, 4000 or 6000 Hz

Often symmetric unless exposure was directed towards one ear

Tinnitus, hyperacusis/reduced dynamic range

What is acoustic trauma? How does it cause HL?

Exposure to sound greater than 140 dB SPL

pressure wave traveling is so intense that it causes mechanical damage (TM can rupture, ossicular disarticulation, cochlear tearing)

Causes severe to profound permanent HL

What is cochlear synaptopathy?

Permanent damage to synapses between the IHC and auditory nerve fibers

AKA hidden hearing loss

What is the exchange rate?

Time-intensity tradeoff or doubling rate

Relationship between noise levels and allowable exposure times

What is the OSHA exchange rate?

5 dB

Allowable exposure time is cut in half for every increase in exposure level of 5 dBA

Allowable exposure time is doubled for every decease in exposure level of 5 dBA

Ex: Exposure to 90 dBA for 8 hrs = 85 dBA for 16 hrs = 95 dBA for 4 hrs

What is the action level?

point at which workers must be enrolled in a hearing conservation program and HPDs must be made available

OSHA: when noise exposure is an 8hr time weighted average of 85 dBA or greater

What is TWA?

time weighted average

represents a constant sound level lasting 8 hours that would result in the same amount of sound energy as the noise that was measured

What is the OSHA permissible exposure level (PEL)?

Workers expsured to 8-hr TWA of 90 dBA or greater (or equivalent) must in enrolled in a hearing conservation program and feasible administrative or engineering controls must be used

What is the NIOSH exchange rate?

3 dB

every 3 dB increase in noise level halves allowable exposure time

every 3 dB decrease in noise level doubles allowable exposure time

What is the NIOSH recommended exposure level?

Workers exposed to 8-hr TWA of 85 dBA or greater (or equivalent) must be enrolled in hearing conservation program and feasible administrative or engineering controls must be used to reduce noise exposure

How are occupational noise levels measured?

sound level meter (SLM) or noise dosimeter

What is the dBA scale?

deemphasized low frequencies below 1000Hz, mimics human ear’s response to low-intensity sounds

required by OSHA and NIOSH for occupational noise exposure

What is the dBB scale?

deemphasized low frequencies (not as much as dBA), mimics ear’s response to moderate intensity sounds

What is the dBC scale?

slightly deemphasized very low and very high frequencies

mimics ear’s response to high-intensity sounds

used to assess peak sound pressure from loud, impulsive sources

Why do OSHA and NIOSH require use of the dBA scale?

human ear is not equally sensitive to all frequencies (most sensitive around 4000Hz, poor in low frequencies)

dBA most closely correlated with risk of developing NIHL

What is the peak level?

highest instantaneous sound level measures without using frequency weighting scale or response time

What is the maximum level?

Highest sound level measured using selected frequency weighting scale and response time

What is the Lavg?

logarithmic average sound level measured

ignores sounds below threshold (when set)

What is the Leq?

represents the true equivalent sound level

only used when exchange rate is 3dB and threshold is 0dB

How is the TWA calculated using OSHA’s 90dBA exposure limit and 5dB exchange rate?

TWA = 16.61 x log(D/100) + 90

where D = dose

How is the TWA calculated using OSHA’s 85dBA exposure limit and 3dB exchange rate?

TWA = 10.0 x log(D/100)+85

where D=dose

What is noise dose?

amount of actual noise exposure relative to amount of allowable exposure where 100% and above represents noise-hazardous exposures