Estimation of noise levels and hpd attenuation in the workplace using microphones located in the vicinity of the ear

Noise levels and hearing protection devices (HPD) attenuation were estimated in the workplace using microphones located in the vicinity of the ear. In the first part of the study, tests were conducted in a diffuse field in a reverberant room and in a free field in a semi-anechoic room on 4 subjects with 5 different earmuffs and without earmuffs. In the second part of the study, a controlled simulation of a workplace environment was performed to validate the approximation. The objective was to create a sound field which could be more directional at certain location. The regression lines can be used to correct the earmuff microphone readings as long the source location can be determined. While a difference of 0 dB represents the target to achieve, it is found that applying the proposed correction allows to obtain a reasonable estimate within a ∓2 dB range.