FROM THE FIELD: Preet Amin
One of the most common misconceptions identified during COR® audits is the belief that audiometric (hearing) testing can replace workplace noise monitoring. While both are essential components of an effective Hearing Conservation Program, they serve different purposes and one cannot replace the other.
What is noise monitoring?
Noise monitoring measures the amount of noise a worker is exposed to while performing normal job duties. In accordance with CAN/CSA Z107.56 – Measurement of Noise Exposure, this is commonly accomplished using a personal noise dosimeter. The dosimeter is worn by the worker throughout a representative portion of the shift, with the microphone positioned on the shoulder near the ear to measure the noise exposure reaching the worker.
The dosimeter calculates the worker’s Time-Weighted Average (TWA) noise exposure, which represents the average noise exposure over the work shift. The standard also requires that measurements be representative of normal workplace activities and be repeated when significant changes occur, such as new equipment, different processes, seasonal work, or changes in production levels.
Noise monitoring helps determine:
- A worker’s TWA noise exposure
- Whether occupational noise limits are being exceeded
- If hearing protection is required
- Whether noise controls are effective
- Which tasks or equipment contribute most to noise exposure
What is audiometric testing?
Audiometric testing measures a worker’s ability to hear sounds at different frequencies and volumes. These tests help identify changes in hearing over time and can detect early signs of hearing loss.
Audiometric testing helps determine:
- Whether a worker’s hearing has changed
- If hearing protection measures are effective
- Whether further investigation may be required
Key differences
| Noise monitoring | Audiometric testing |
| Measures workplace noise exposure | Measures a worker’s hearing ability |
| Uses a dosimeter worn during work | Uses specialized hearing test equipment |
| Produces a TWA exposure result | Produces a hearing assessment result |
| Identifies workplace noise hazards | Identifies hearing changes |
| Supports hazard prevention | Supports health surveillance |
Key takeaways
Noise monitoring measures the hazard, while audiometric testing measures the worker.
A worker may have normal hearing today and still be exposed to hazardous noise levels. Likewise, a hearing test cannot identify which tasks, tools, or equipment are causing excessive noise exposure. For this reason, CAN/CSA Z107.56 emphasizes the importance of conducting representative noise exposure assessments to understand and manage workplace noise hazards. Together, noise monitoring and audiometric testing help employers protect workers’ hearing and prevent occupational hearing loss before it occurs.
