Frequently Asked Questions - Noise

How do I know if people at work are at risk of hearing damage from noise levels?

A noise assessment by a person with suitable qualifications and experience would need to be carried out to determine if a person was at risk of hearing damage from noise levels. Generally, as an informal guide, a workplace noise assessment should be considered when someone would need to raise their voice to talk with someone else one metre away.

An example of a noise assessor with suitable qualification, may include, for example, a member of the Australian Acoustical Society at the level of ‘Fellow’ or ‘Grade MA’ who hold educational qualifications and several years of professional experience (see http://www.acoustics.asn.au/)

The employer has a responsibility under the Safety Standards Regulations to arrange for a noise assessment to be carried out where there is a risk to an employee or contractor from exposure to noise levels at, or above, the exposure standard.  If the noise level is found to be dangerous, appropriate control measures must be implemented.

Part 3 of the Safety Standards Regulations prescribes legislative requirements in relation to noise at work. These requirements outline the exposure standards for noise. Regulation 3.03 describes the exposure standard for noise as:

(a) an eight-hour equivalent continuous A-weighted sound pressure level, L_Aeq.8h of 85 dB(A) referenced to 20 micropascals, or

(b) a C-weighted peak sound pressure level L_c,peak of 140 dB.

Essentially this means that persons exposed to continuous noise at 85 dB(A) are at risk of receiving hearing damage after 8 hours exposure  However, if the noise level is under 85 dB(A), or if the exposure time is shorter than 8 hours, hearing damage is unlikely to occur.

Exposure to noise in excess of 140 dB may cause almost instantaneous hearing damage in exposed persons, 140 dB is the highest level of noise to which persons may be exposed in the workplace and only as a peak sound. There is more information about exposure times at defined decibel levels in Part 3: Noise of the OHS Code 2008.

It is important to understand that as noise levels increase, the amount of exposure time before being at risk of receiving hearing damage decreases exponentially.  For every 3 decibel increase in the noise level the "safe" exposure time halves. While an employee exposed to a continuous noise level of 85 dB(A) is at risk of suffering hearing damage after eight hours, an employee exposed to a noise level of 88 dB(A) is at risk of hearing damage after only four hours and an employee exposed to a noise level of 91 dB(A) is at risk after only two hours.

As a guide here are some decibel levels of some common sounds:

30 m from a jet aircraft       -             140 dB(A)

Chainsaw                             -             110 dB(A)

Nightclub                              -       90-100 dB(A)

Kerbside of busy road          -         70-80 dB(A)

Conversational speech         -         50-60 dB(A)

What is the maximum level of noise allowable in an office environment?

The exposure standard prescribed in the Safety Standards Regulations (see previous question) applies to all employees and contractors at work  for an employer under the Commonwealth legislation. The same standards apply for people working in or out of an office.

However, while no worker is likely to suffer hearing damage in a noisy office, noisy offices can be uncomfortable for workers and may pose or contribute to other problems, including production issues and increased stress levels. Refer to Officewise (OHS01) for more information on managing noise in office environments.