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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.

Impulsive sound events (i.e. door closing) are often characterized as being undesirably sharp sounding. A high degree of perceived sharpness is normally related to large amounts of high frequency energy relative to the low frequency energy. In this project third octave data generated from a filterbank was used to calculate the center of gravity (cg) of the third octave bands. The result is the frequency corresponding to the centroid of the third octave data. Sounds with substantial high frequency energy have a centroid location that occurs at a higher frequency. The mean of the third octave cg over the duration of the transient event was investigated, in addition to sharpness as defined by Aures [1] and calculated on a commercially available analyzer. Correlation analyses to subjective data indicate that the mean third octave cg and the commercially available method produce comparable results for the vehicle closure sounds studied here.

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.