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This paper describes an investigation into the sound quality of passenger car and light truck closure sounds. The closure sound events that were studied included side doors, hoods, trunklids, sliding doors, tailgates, liftgates, and fuel filler doors. Binaural recordings were made of the closure sounds and presented to evaluators. Both paired comparison of preference and semantic differential techniques were used to subjectively quantify the sound quality of the acoustic events. Major psychoacoustic characteristics were identified, and objective measures were then derived that were correlated to the subjective evaluation results. Regression analysis was used to formulate models which can quantify customers perceptions of the sounds based on the objectively derived parameters. Many times it was found that the peak loudness level was a primary factor affecting the subjective impression of component quality.

This paper describes a test-based process used to identify structural characteristics of a vehicle windshield wiper system that contribute to customer impression of the sound. The method of paired comparisons determined which wiper system sounds customers preferred. Annoyance ratings of sound components then identified contributors to customer preference. Wiper motor noise was identified as the major annoyance factor affecting system sound quality. This information guided a study of the structures responsible for radiated motor noise. Laser based test methods were used to interrogate the structures clearly identifying transmission paths into the surrounding structure. Paths were then modified reducing structure-borne motor sound as measured with acoustic retests. Thus, a logical technique for hardware testing and modification guided by customer perceptions is presented allowing efforts to be focussed on the most critical aspects of vehicle sound quality.

One factor believed to influence a customer's perception of vehicle performance is the powertrain sound. However, its influence relative to other factors, such as vehicle acceleration or transmission shift characteristics, remains largely unknown. Past studies of performance perception have either neglected the effect of powertrain sound, studied its effect independent of other factors (e.g., listening to powertrain sounds over headphones), or have confounded its effect with other factors. In this paper, we describe an in-vehicle system for methodically studying the influence of powertrain sound on a customer's perception of performance. The system is beneficial in that it allows the experimenter to electronically modify the sound associated with the powertrain while not affecting other possible performance factors. Results from a corresponding experiment are also presented, in which customers rated their perceived performance of the powertrain sounds.