The aim of this study was to develop a sound quality index for assessing the sound of window lift modules during operation. Window lift operations were classified as "ascent" and "descent," and sound quality indices were developed for each operation and compared. A subjective test was performed by using six models and 12 samples based on a semantic differential method in which 76 jurors participated. In order to quantify the subjective sound quality preferences, correlations between factors were determined through factor analysis. The sound quality preferences from the subjective test were analyzed through regression analysis. For ascent, the relevant factors were determined to be described by luxuriousness and uniformity. For descent, the relevant factors were explained by luxuriousness and strength. Reliable equations that relate each of these factors with high preference were developed for both operations. A sound quality index was developed through regression analysis between the factors. Correlations between each factor and previously developed sound quality metrics were also analyzed to finally derive an equation that explains the preference in terms of sound quality metrics. (C) 2016 Institute of Noise Control Engineering.