A Nordic Round Robin Test on hearing protectors. The influence of the sound field on measured REAT attenuation

The international standard ISO 4869-1 describes a method for the measurement of the attenuation of hearing protectors by means of the ‘real ear attenuation at threshold’ method, REAT. The measurements are performed in an approximated diffuse sound field using one-third octave noise bands. In order to gain information about the possible influence of the sound field characteristics on the measured attenuation values an inter-laboratory test was performed among Nordic test laboratories with different sound field realizations.

The results show that some of the common sound field realizations do not fulfil the diffusivity requirements when measured with a highly directional microphone. No systematic relation was found between the sound field variation and variation in the measured attenuation values. PACS numbers: 43.50Hg, 43.66 Vt, 43.15+s