Comparison of direct measurement methods for headset noise exposure in the workplace Free

Specialized equipment and techniques are required to carry out sound measurements under occluded ears for the purpose of assessing the noise exposure from communication headsets. Standard ISO 11904 describes two procedures: 1) the microphone in a real ear (MIRE) and 2) the acoustic manikin technique using an occluded ear simulator IEC 60318-4. Methods using simpler artificial ears, such as IEC 60318-1, have also been proposed in national occupational noise measurement standards. Such fixtures are more practical to use and more easily accessible. However, they have not been designed specifically for noise measurements under communication headsets and there is little comparative data to the manikin technique, which is considered the gold standard for simulated in-situ acoustic measurements. Fit-refit measurements were obtained under laboratory conditions with four measurement set-ups (artificial ear type 1, type 2, type 3.3, and acoustic manikin), three communication headset types (circum-aural, supra-aural, intra-aural) and six different communication signals. Data was transformed into equivalent-diffuse sound levels using third-octave procedures as well as single number corrections. Overall, results across measurement set-ups are in broad agreement, except for the type 1 artificial ear, but single number corrections reduce measurement accuracy.