CAOHC Hearing Protection Device Fitting 2 — Questions and Answers
Question 1: What is the Noise Reduction Rating (NRR) and how is it used?
- A laboratory-tested attenuation rating used with a correction formula to estimate real-world protection (Correct answer)
- The actual noise reduction achieved in the workplace under all conditions
- A rating assigned by OSHA inspectors after workplace testing
- The maximum frequency the protector can block
Correct answer: A laboratory-tested attenuation rating used with a correction formula to estimate real-world protection
The NRR is derived from laboratory testing under ideal conditions. A correction formula must be applied to estimate real-world protected exposure levels.
The NRR is determined through ANSI S3.19 laboratory testing. OSHA recommends subtracting 7 dB from the NRR for A-weighted measurements. NIOSH recommends further derating: 50% for earmuffs and formable plugs, 70% for other earplugs.
Question 2: When fitting foam earplugs, what is the correct insertion technique?
- Roll the plug into a thin cylinder, pull the pinna up and back, then insert and hold until expanded (Correct answer)
- Simply push the plug directly into the ear canal without compression
- Cut the plug in half and insert only the tip
- Moisten the plug with water before insertion without rolling
Correct answer: Roll the plug into a thin cylinder, pull the pinna up and back, then insert and hold until expanded
Proper foam earplug insertion requires rolling tightly, pulling the pinna up and back to straighten the canal, and holding in place until fully expanded.
The correct technique involves rolling the entire plug tightly, reaching over the head to pull the pinna up and back, inserting deep into the canal, and holding for 30-60 seconds while it expands. Improper insertion is the leading cause of inadequate attenuation.
Question 3: What factor most commonly causes hearing protectors to provide less attenuation than their NRR indicates?
- Improper fit and inconsistent wear by the user (Correct answer)
- Manufacturing defects in the hearing protector
- Excessive ambient temperature in the workplace
- Using protectors that are less than one year old
Correct answer: Improper fit and inconsistent wear by the user
The primary reason for reduced real-world attenuation is improper fit and inconsistent wearing by employees.
Real-world attenuation is 50-80% less than laboratory NRR values, primarily due to improper insertion, poor fit, and intermittent wear. Removing protection for just 5 minutes in an 8-hour shift reduces effective protection significantly.
Question 4: What advantage do custom-molded earplugs offer over disposable foam plugs?
- Consistent fit and attenuation due to being shaped to the individual ear canal (Correct answer)
- They always provide higher NRR than any foam plug
- They never need replacement or cleaning
- They are required by OSHA for all noise-exposed workers
Correct answer: Consistent fit and attenuation due to being shaped to the individual ear canal
Custom-molded earplugs provide a personalized and consistent fit that can reduce variability in real-world attenuation.
Custom-molded earplugs are created from ear canal impressions, providing personalized fit. They must be regularly inspected for shrinkage or hardening and may need replacement every 3-5 years.
Question 5: When is dual hearing protection (earplugs plus earmuffs) recommended?
- When workplace noise exceeds 100 dBA TWA (Correct answer)
- For all employees regardless of noise level
- Only during audiometric testing
- When a single protector achieves an NRR above 30
Correct answer: When workplace noise exceeds 100 dBA TWA
Dual protection is recommended when noise levels exceed 100 dBA TWA, as single protectors may not provide sufficient attenuation.
NIOSH recommends adding 5 dB to the higher-rated protector NRR when calculating combined attenuation. The combined NRR is not simply additive.
Question 6: What is the purpose of hearing protector fit testing?
- To measure the actual attenuation an individual achieves with their specific hearing protector (Correct answer)
- To verify the manufacturer NRR label is accurate
- To determine if an employee needs audiometric testing
- To calibrate audiometric equipment before testing
Correct answer: To measure the actual attenuation an individual achieves with their specific hearing protector
Fit testing measures the personal attenuation rating that each worker actually achieves, identifying individuals who may need refitting.
Fit testing systems measure real-ear attenuation for each worker, providing a personal attenuation rating that reflects actual workplace protection. This identifies workers not achieving adequate protection.
CAOHC Hearing Protection Device Fitting 2
What is the Noise Reduction Rating (NRR) and how is it used?