Noise-induced hearing loss is preventable and can affect a high number of workers.
As the PCBU, you must do all you can to reduce the risk of noise-related injury in the workplace. There are some things you must do to reduce the risk of noise-related injury, including:
identifying noise hazards
undertaking noise assessments
using suitable control measures
providing personal protective equipment to workers, and
testing noise levels.
The model Code of Practice: Managing Noise and Preventing Hearing Loss at Work guides you on how to do this. It also has a tool called a ‘noise ready reckoner’ to calculate workers’ noise exposure.
How noise damages hearing
Sound stimulates tiny hair-like cells in your inner ear, which send messages to your brain. Noise-induced hearing loss happens when those delicate cells are damaged.
Hearing loss can be temporary or permanent, and can get worse over time. Permanent hearing loss can’t be cured.
One way these cells can be damaged is by very loud sound. The sound can be sudden, like an explosion, or can happen over a long period of time.
Exposure to some chemicals can also result in hearing loss. These chemicals are known as ototoxic substances. Hearing loss is more likely to occur if a worker is exposed to both noise and ototoxic substances than to just one of them alone.
How much noise is too much?
Risk of noise-related injury increases depending on how loud the noise is and how long the worker is exposed to it.
For example, If a worker needs to raise their voice to talk to someone one metre away, the noise level is probably too high (the ‘1 metre rule’).
The noise level should be lower than:
50 decibels, if your work involves high concentration or lots of conversation, and
70 decibels, if your work is routine, fast-paced and demands attentiveness, and you need to have conversations
The noise exposure standard
As the PCBU, you must make sure that workers are not exposed to noise above the exposure standard as much as is reasonable.
Noise can be measured in two ways. One is for noise over an eight hour shift and one is “peak” or one-off noise.
Workers must not be exposed above 85 decibels (as an average) over eight hours at work. Machines like blenders, lawnmowers and leaf blowers are around 85 decibels. This rule changes depending on decibels and time exposed. For example, the risk at 91 decibels over two hours is the same as 85 decibels over eight hours.
Workers must not be exposed to a noise level above 140 decibels. Any exposure above this level could instantly damage hearing. Sledgehammering or gunshots can be 140 decibels or higher.
If you decide that a worker needs to frequently wear personal hearing protection to protect them from noise above the noise exposure standard, you must provide the worker with audiometric testing.
The most common instrument to measure decibels is a noise (or sound) level meter. This measurement can be taken by a competent person, such as a certified occupational hygienist, or if you or one of your workers have the skills and experience, you do not have to find a specialist.
Once you know how many decibels the noise at your workplace is, you can use the noise ready reckoner to calculate the equivalent exposure to 85 decibels over eight hours.