CAOHC Audiogram Review and STS 2 — Questions and Answers
Question 1: What is the OSHA-defined standard threshold shift (STS)?
- An average shift of 10 dB or more at 2000, 3000, and 4000 Hz in either ear (Correct answer)
- A shift of 15 dB at any single frequency
- An average shift of 5 dB across all frequencies
- A shift of 25 dB at 4000 Hz only
Correct answer: An average shift of 10 dB or more at 2000, 3000, and 4000 Hz in either ear
OSHA defines STS as an average change of 10 dB or more at 2000, 3000, and 4000 Hz in either ear compared to the baseline audiogram.
Standard Threshold Shift is calculated by averaging the threshold changes at 2000, 3000, and 4000 Hz between the current audiogram and the baseline. If this average equals or exceeds 10 dB in either ear, an STS has occurred. Age correction may optionally be applied per OSHA guidelines.
Question 2: When reviewing an audiogram, which pattern most strongly suggests noise-induced hearing loss?
- A notch at 4000 Hz with recovery at 8000 Hz (Correct answer)
- Flat hearing loss across all frequencies
- Low-frequency hearing loss below 1000 Hz
- Conductive hearing loss in one ear only
Correct answer: A notch at 4000 Hz with recovery at 8000 Hz
The classic audiometric pattern of noise-induced hearing loss shows a notch at 3000-6000 Hz (typically 4000 Hz) with partial recovery at 8000 Hz.
Noise-induced hearing loss typically presents as a sensorineural hearing loss with a characteristic notch at 4000 Hz with improvement at 8000 Hz. This pattern distinguishes it from presbycusis, which shows a gradual high-frequency slope without recovery at 8000 Hz.
Question 3: How often must OSHA-mandated audiometric testing be performed for workers in a hearing conservation program?
- Annually (Correct answer)
- Every 6 months
- Every 2 years
- Only at hire and termination
Correct answer: Annually
OSHA requires annual audiometric testing for all workers included in the hearing conservation program to monitor for changes in hearing thresholds.
Under 29 CFR 1910.95(g)(6), employers must provide annual audiograms for each employee in the hearing conservation program. The annual audiogram is compared to the baseline to identify STS.
Question 4: What action is required when an employee audiogram reveals a confirmed STS?
- The employer must notify the employee in writing within 21 days (Correct answer)
- The employee must be immediately removed from the workplace
- No action is required if the employee wears hearing protection
- The employer must repeat the test within 72 hours
Correct answer: The employer must notify the employee in writing within 21 days
OSHA requires that employees be notified in writing within 21 days when their audiometric test results show a confirmed standard threshold shift.
Per 29 CFR 1910.95(g)(8), when an STS is identified, the employer must notify the affected employee in writing within 21 days, ensure hearing protectors are provided, and consider refitting or providing more effective hearing protectors.
Question 5: What is the purpose of age correction in STS determination?
- To account for expected hearing loss due to aging when calculating threshold shifts (Correct answer)
- To adjust audiometer calibration for older equipment
- To modify testing procedures for elderly workers
- To calculate the retirement age for noise-exposed workers
Correct answer: To account for expected hearing loss due to aging when calculating threshold shifts
Age correction tables allow employers to subtract the expected hearing threshold changes due to aging from the measured shift, potentially reducing the calculated STS value.
OSHA provides optional age correction tables (Appendix F of 29 CFR 1910.95). The correction is applied by subtracting age-related threshold changes from both the baseline and annual audiogram before computing the average shift.
Question 6: A revised baseline audiogram should be substituted when which condition is met?
- When an STS is persistent and the audiologist determines the new audiogram better represents the worker hearing (Correct answer)
- When the worker changes job positions within the company
- When the audiometer is replaced with a newer model
- Whenever the worker requests a new baseline
Correct answer: When an STS is persistent and the audiologist determines the new audiogram better represents the worker hearing
A professional reviewer may determine that a persistent STS warrants revising the baseline so future comparisons are more clinically meaningful.
The audiologist or physician reviewing audiograms may recommend revising the baseline when an STS is confirmed and persistent. This updated baseline becomes the new reference point for future annual comparisons.
CAOHC Audiogram Review and STS 2
What is the OSHA-defined standard threshold shift (STS)?