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

Specialized equipment and techniques are required to carry out direct 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 occupational noise measurement standards such as CAN/CSA Z107.56. Such devices 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. Furthermore, little is known about measurement reliability for the purpose of standardization. Fit-refit measurements were obtained under laboratory conditions with four different types of artificial ears (type 1, type 2, type 3.3, 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. Results illustrate that methods using single number corrections as well as fit-refit standard deviations vary according to measurement conditions.