Towards an objective evaluation of the annoyance caused by interior noise in earth moving machines

Laboratory listening tests have been carried out in order to investigate how the spectral content of a noise signal affects the annoyance sensation of the subjects. In this respect the noise at the operator's station of a skid-steer loader has been recorded binaurally by a dummy head and six diotic stimuli were generated, each having the same equivalent continuous linear sound pressure level but a different noise level distribution. The agreement between objective and subjective parameters has been evaluated in terms of correlation between the subjective preference score and each of the measured objective variables. The results showed that the subjective judgements were generally affected either by the equivalent continuous A-weighted sound pressure level or by the loudness level rather than by differences in the spectral content of the signal. Nevertheless, the influence on the subjective responses of other signal characteristics turned out to be significant any time stimuli with similar A-weighted overall levels were compared.