Workplace Noise Measurement – The objective.
The objective of a Noise Assessment is to determine if a workplace complies with the requirement within the WHS/OHS Regulations which states that; employees must not be exposed to noise in excess of the Noise Exposure Standard.
The Noise Exposure Standard contains two parts;
- Noise at or above Leaq 8hr 85dB (A) or;
- Noise at or above Lc Peak 140db (C).
Leaq 8hr 85dB (A): is a sound pressure level equivalent to 85dB in an (A) filtered frequency range (noise in the frequencies audible to the human ear) over an 8 hour time period. This is in effect; an average of the amount of noise a person is exposed to in an 8 hour shift.
Lc Peak 140db (C): is a sound pressure level which occurs over any length of time when measured with (C) frequency filter. The (C) filter is sound which is audible the human ear combined with lower inaudible frequencies.
Noise testing in the workplace – How is it done?
Workplace noise measurement is an involved process which is completed in order to assess a business’s compliance with the Noise Exposure Standard.
There are two main ways to complete noise testing in the workplace; the first of which is a static noise assessment where a noise assessor will walk around with a sound level meter taking spot readings, the second is to have employees wear noise dosimeters and there is always a combinations of the two.
Each method of workplace noise measurement has its strengths and weaknesses and below we will summarise some of them;
Static Workplace Noise Measurement
This process involves having a noise measurement professional walk through the workplace and take spot measurements using a handheld sound level meter. The sound level meter must be constructed to the specifications as stipulated in the relevant Australian Standards and the assessor must be suitably qualified.
Using the spot reading results as taken during the assessment the data can then be used to calculate individual or employee group noise exposure.
Strengths of static Workplace Noise Measurement.
- Static noise testing in the workplace is often the more cost effective option.
- Static assessment allows the assessor to verify the data as it is being collected to ensure it is valid.
- Static workplace noise measurement allows the calculation of employee noise exposure profiles for varying conditions and as such the data can remain valid in multiple scenarios.
Example: Let’s take two scenarios;
- Employee 1 works 2 hours on an angle grinder, 4 hours in the storeroom and 2 hours on the forklift in a day.
- Employee 1 works 2 hours on an angle grinder, 4 hours in the storeroom and 2 hours on the forklift in a day but then completes 2hrs of overtime on the grinder.
Time Spent Completing Tasks
Calculated Leaq 8hr in dB (A) is:
As shown in the table above because we have the static noise readings for the activities (grinding, storeroom & forklift) we can calculate noise exposure profiles for scenarios which may occur in out of ordinary operations, overtime arrangements or rostering changes.
Weaknesses of Static Workplace Noise Measurement.
- Should a noise assessor not be sufficiently competent or have the experience required the assessor may overlook machinery, pieces of equipment or entire activities on the day of assessment.
Employee Dosimeter Noise Testing in the Workplace
Dosimeter noise testing in the workplace requires individual employees to wear noise dosimeters attached to their person, usually on their shoulders or collars. The dosimeter is itself a small sound level meter which will record the noise exposure for the period of time it is worn. The dosimeters must also be constructed to the specifications of the applicable Australian Standard.
Strengths of Employee Dosimeter Noise Testing in the Workplace
- The Dosimeters provide you with a daily noise exposure that if worn for 8hrs is extremely accurate and no further calculation is required.
Weaknesses of Employee Dosimeter Noise Testing in the Workplace
- In most cases the use of the dosimeter by employees will have to be monitored by a noise assessor and if testing of entire shifts is required this can result in a significant expense.
- Employees may tamper with the dosimeters by tapping on them and/or speaking/yelling into them. This can skew the results.
- Some assessment providers may only attach the dosimeters for 2-4 hours and then multiply the results out to calculate the daily exposure. This provides an inaccurate result.
- The data collected can only reflect what the employee was doing at the time they were wearing the dosimeter. This means the data cannot be manipulated to account for changes in shifts, changes in equipment or hours and if an item of plant or equipment was not used on the assessment day that noise cannot be calculated in.
Selecting your Correct Method for Noise Testing in the Workplace.
Selecting the best method for your workplaces noise measurement is not a decision to be made lightly. Discuss with your assessment provider the number of employees you have, the type of tasks they complete so that together you can select the right method.