Sound quality as a tool to improve the noise climate at the operator's station in earth-moving machines

Binaural noise recordings at the operator's station of a construction machine have been taken and modified in sound levels and spectra in order to simulate the effects due to active noise control systems (ANCS) and to study how these modifications may influence the subjective ratings of some noise features. For this purpose, six sound stimuli have been used in laboratory listening tests carried out according to the paired comparison procedure, where sixteen subjects were asked to assess the stimuli in terrns of tiredness, concentration loss, loud and booming. The ratings, given on a 7-value scale, show that the overall level is the predominant factor for ali the features except for booming; the latter feature, instead, is more affected by the ANCS. To improve the operator's comfort and working safety, the ANCS should be applied in conjunction with a control of the noise components in the middle-high frequency range.