During recent workplace noise inspections, the HSE found that only 5% of employers carried out audibility assessments when issuing hearing protection.[1] Checking the audibility of warning sounds is crucial to keep wearers safe from other hazards.
Hearing protection is often necessary to combat noise exposure. However if the attenuation level is too high, the wearer may be overprotected and unable to hear things like alarms, vehicles and instructions from colleagues. The reduced situational awareness increases the risk of accidents, putting staff in danger.
An audibility assessment makes sure wearers can hear important warning signals with their ear defenders or ear plugs fitted.
Simple listening tests can be carried out in the workplace to check the audibility of:
- Fire alarms
- Machine alarms
- Vehicles and forklifts
- PA announcements
- Verbal instructions
Guidance states that warning signals must be able to attract attention over background noise – it is not sufficient to hear an alarm while listening out for it.
L108 Controlling Noise at Work contains more information about audibility assessments for warning signals and speech communication.
The HSE provide general guidance to help with selecting an appropriate SNR that offers adequate attenuation without overprotecting the wearer.
A-weighted noise level (dB) |
Select hearing protection with SNR of: |
85 to 90 |
20 or lower |
90 to 95 |
20 to 30 |
95 to 100 |
25 to 35 |
100 to 105 |
30 or higher |
A full risk assessment is required to measure noise levels and determine control measures.
If your risk assessment finds that hearing protection is necessary, it is important to carry out an audibility assessment. Noise must be controlled to prevent hearing damage but certain sounds need to be audible for safety purposes. Audibility assessments ensure that alarms and other warning signals can be heard with hearing protectors fitted to keep staff safe at work.