SummaryWe consider a gearbox fitted out with a single helical gear and a housing with only one elastic face which radiatesnoise. For a gearbox manufactured in large number, a high noise level variability can result from variability of geometryfaults induced by tolerances on each gear design parameter. In this paper, this noise variability is assumed to be inducedby only tolerances on two gear design parameters: profile and helix angle. Two main issues are addressed here: thefirst goal is to rank the influences of each geometrical parameter and to analyze their interaction on the total radiatedsound power with a full factorial experiments and a variance analysis. The second issue consists of an estimation of themean value and the standard deviation for noise level using a modified Taguchi’s method. For two quality classes ofthe gear, the obtained results reveal a predominance of helix angle error on the variability of the radiated sound power.Furthermore, interaction between the two studied parameters has been demonstrated.