At the conclusion of a noise annoyance survey in air-conditioned offices a new parameter was proposed. The aim was to define a noise index well correlated with subjective ratings of noise annoyance and able to account for the imbalance of the noise spectrum. As the RC Mark 11 procedure for rating the noise of HVAC systems in buildings introduced the "quality assessment index" (QAI), which provides a measure of the spectral imbalance of a noise, the combination of this parameter with the RC criterion number (which only measures noise level) was proposed. In a previous paper, the combination factor that maximised the correlation was determined and a validation procedure was used to test the repeatability of the results. In this paper, a new procedure to calculate the mean subjective. ratings has been introduced and more demanding procedures to test the repeatability of the results have been used. Finally, it was found that a combination factor varying in a range from 0.24 to 0.31 provided the highest correlation between the new parameter and the subjective sensation of annoyance.