The Optimus Red integrating sound level meter from Cirrus Research is specially designed to measure the basic indices of noise in the workplace. A simple measurement at a workstation provides precise information about the worker’s exposure and enables the right hearing protection to be chosen for the job.
To protect workers’ hearing against excessive noise, a sound level meter must be able to measure noise accurately using methods that really understand the effect of noise on humans. Research into the dangers of noise exposure shows that there are two main adverse effects.
1. Accumulation of noise over a long period
The first harmful effect is symbolised by the acoustic quantity LAeq (or Leq in ‘A’ weighted decibel). It expresses the accumulation of relatively low noise levels over a long period and is the basis for calculating LEX,8h. The latter is required by the regulations and must not exceed 85dB(A) if a worker does not use hearing protection.
2. Instantaneous noise level
The second harmful effect is symbolised by the acoustic parameter LCpk (or Peak in ‘C’ weighted decibel). It describes the extreme noise levels measured instantaneously that can cause immediate damage to hearing, such as detonations, blowing noises or fireworks. The LCpk value is required by the regulations and must not exceed 135dB(C) if a worker does not use hearing protection.
As in both cases hearing problems are permanent, it is essential to carefully monitor exposure in the workplace in order to determine the level of protection to adopt.
Choosing hearing protection using the SNR (Single Number Rating) method
The Optimus Red sound level meter simultaneously measures LAeq and LCpk, as well as the acoustic parameter LCeq (average ‘C’ weighted noise), which is used to apply the SNR method. This calculation method provides the result of the LAeq attenuated by the hearing protection by simply subtracting ‘LCeq – SNR’. The result must therefore be below 87dB(A) for 8 hours. The SNR is provided by PICB manufacturers and gives information about the overall attenuation of hearing protection.
The Optimus Red sound level meter measures LAeq, LEX, LCPeak and LCeq in a single measurement. With or without a computer, Optimus Red makes it possible to quickly identify hearing hazards at a workstation and choose the most appropriate hearing protection for the job.
Cirrus has over thirty years’ experience in the design and manufacture of cutting-edge acoustic instruments. Reliability, robustness and compliance with the latest standards are the hallmarks of the Cirrus brand, which enjoys a worldwide reputation.
