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A quiet passenger compartment is highly desired by today's customers. Vehicle design teams spend significant time and resources to minimize the vehicle's interior noise due to different exterior noise sources. Drive-by vehicles on the highways generate one of these noise sources. The objective of this study is to establish a correlation between customer's on-road experience due to drive-by noise and Noise Reduction Level (body transparency) tests conducted in a reverberation room. The average Noise Reduction Level (NRL) obtained in the reverberation room tests correlates (R2=0.89) with the peak loudness of on road tests. A sound quality listening study was also conducted to determine the most preferred NRL spectral distribution and its frequency range sensitivity.

Visual movement of automotive components can induce a sense of poor quality and/or reliability to the customer. Many times this motion is likely to induce squeaks and rattles that further degrade customer opinion. For both of these reasons, it may be necessary to quantify the visual motion of certain components. This paper deals with a study in which the angular displacement from the observer to a passenger-side seat back was correlated to the subjective impression of seat back motion. Minutes Of Arc (MOAs) were found to correlate well to the perception of 17 subjects who evaluated the seat back motion of a seat mounted to a TEAM Cube in which road vibrations were played into a passenger seat and subjects were instructed that the evaluation surface was a “rough road” surface. This was confirmed for both the driver observing the unoccupied passenger seat from the side and a rear seat passenger viewing the unoccupied front seat from behind.

Transient road disturbances excite complex vehicle responses involving the interaction of suspension/chassis, powertrain, and body systems. Typical ones are due to the interactions between tires and road expansion joints, railway crossings and other road discontinuities. Such transient disturbances are generally perceived as “impact harshness” due to the harshness perception as sensed by drivers through both sound and vibration. This paper presents a study of quantifying the effects of sound, steering wheel and seat/floorpan vibrations on the overall perception of the “impact harshness” during impact transient events. The Vehicle Vibration Simulator (VVS) of the Ford Research Laboratory was used to conduct this study. The results of the study show that sound and vibration have approximately equal impact on the overall perception of impact harshness. There is no evidence of interaction between sound and vibration.