Specification of component sound quality applied to automobile power windows

As cars become quieter the sound quality of components with electric motors becomes more important in the customer perception of vehicle quality. This has created a need to develop methods for the specification of component sounds. The objectives of this study were to identify perceptually important aspects, link them to acoustic metrics and, based on this, develop guidelines for the determination of requirements for power window sound. Seven prominent attributes were identified: dull, loud, annoying, steady, powerful, overall product quality and under-dimensioned. Effects of auditory stream segregation influenced the results. Power window sounds mainly consist of two sources: motor and window seal scratching. Subjects tended to judge only motor sound. Prediction models developed on isolated motor sound correlated well with judgements. Low loudness, sharpness and motor speed fluctuations led to perceived high product quality. The results emphasise the importance of handling auditory stream segregation and temporal variations in the sound design process.