Erro ao obter a exposição diária a ruído usando dosímetros face a sonómetros

Resum

Inextricably noise dosimeters are not as accurate as sound level meters. In fact, accordingly to the technical regulations that classify this noise measuring instruments, the first ones are considered to be “type 2” while the second ones are scored “type 1” because of its highest accuracy. Also wide variations on noise measurements can be registered when using a microphone usually in a worker´s shoulder. This is of great importance for all international legislation on occupational hazards establishes limit values and of action, according to the measurements results. Not withstanding the provisions of the sub-paragraph above, there are not any rigorous field studies that can present real incertitude values associated with noise measurements as consequence of the dosimeter and microphone location. The general objective of this study is to acquire information about the error that occurs in measurement procedures involving dosimeters taking into account its minor accuracy regarding sound level meters and also its location on the worker´s body. The investigator intents to quantify the referred error as accurately insofar as this is possible. As a result, a noise measurement real uncertainties, or at the very least those that are reasonably comparable will be determined. This doctoral thesis is based on the comparison between dosimeters and sound level meters and aims to provide conclusions related to incertitude and error on measuring noise as for the equivalent level as for the peak level. The following methodology was used: a) selection of noise measurement equipments; b) comparison of noise measurement results in a context of semi-controlled conditions; c) comparison of noise measurement results in the field. The analysis of the results confirms the dosimeters general trend to overestimate the level of noise in comparison with sound level meters. This is even more outstanding regarding the “peak” evaluation, when the dosimeters results can be unacceptable because it fails to reflect the associated risk. Also the location of the microphone on the workers body introduces a remarkable risk in the measurement results.