Emissions Control & Environmental Compliance Flashcards
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Read the first 7 Emissions Control & Environmental Compliance flashcards as text
Auditory neuropathy spectrum disorder (ANSD) is most classically characterized by which OAE and ABR pattern?
Answer: Present OAEs (or cochlear microphonic) with absent or severely abnormal ABR
ANSD reflects intact outer hair cell function (present OAEs or CM) combined with disrupted auditory nerve synchrony (absent or grossly abnormal ABR).
Middle ear effusion most directly attenuates OAE amplitude because it:
Answer: Increases acoustic impedance, reducing sound transmission to and from the cochlea
Fluid in the middle ear increases impedance at the tympanic membrane, attenuating both the ingoing stimulus and the returning OAE signal that must traverse the middle ear twice.
According to JCIH guidelines, if a neonate fails the initial OAE hospital screen, the recommended pathway is:
Answer: Rescreening with OAE before 1 month, followed by ABR if still failing, with diagnosis by 3 months
The JCIH 1-3-6 framework recommends screening by 1 month, audiologic diagnosis by 3 months, and early intervention by 6 months if hearing loss is confirmed.
A cochlear microphonic (CM) can be mistaken for a TEOAE response but is identified by the fact that it:
Answer: Inverts in polarity when the stimulus polarity is reversed, whereas true OAEs do not
The CM directly follows stimulus polarity (it is a linear receptor potential), so reversing click polarity inverts the CM while true nonlinear OAEs remain unchanged.
Which environmental factor most commonly causes falsely absent OAEs in a clinical or newborn screening setting?
Answer: Excessive ambient noise raising the recording noise floor
High ambient noise levels elevate the noise floor of the OAE recording, preventing the instrument from detecting the small cochlear signal above the background.
When OSHA Appendix D ambient noise limits are exceeded in a hearing conservation audiometric booth, the audiologist should:
Answer: Retest in a compliant environment before recording thresholds as part of the hearing conservation record
Ambient noise exceeding OSHA Appendix D limits invalidates the audiometric results; testing must be repeated in a compliant environment to ensure threshold accuracy.
A worker's hearing conservation audiogram reveals a confirmed, work-related STS. Under OSHA, the employer's required actions include all of the following EXCEPT:
Answer: Permanently removing the worker from all noise-exposed job duties
OSHA does not require removal from noise-exposed duties; the required responses are written notification, HPD re-evaluation, and provision of test results, with the goal of preventing further loss.