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This document specifies an engineering method for measuring the noise emitted by road vehicles of categories M and N by using a semi anechoic chamber with a dynamometer installed.

The specifications are intended to achieve an acoustical correlation between testing the exterior noise of road vehicles in a semi anechoic chamber and outdoor testing as described in ISO 362-1.

This document provides all necessary specifications and procedures for indoor testing to obtain results which are comparable to typical run-to-run variations of measurements in today.s type approval tests.

This document provides a method designed to meet the requirements of simplicity as far as they are consistent with the reproducibility of results under the operating conditions of the vehicle.

NOTE 1   The results obtained by this method give an objective measure of the noise emitted under the specified conditions of test. It is necessary to consider the fact that the subjective appraisal of the noise annoyance of different classes of motor vehicles is not simply related to the indications of a sound measuring system. As annoyance is strongly related to personal human perception, physiological human conditions, culture, and environmental conditions, there is a large variation and annoyance is therefore not useful as a parameter to describe a specific vehicle condition.

NOTE 2   If measurements are carried out in rooms which do not fulfil the requirements stated in this document, the results obtained can deviate from the results using the specified conditions.