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One of the characteristics that may influence customers in vehicle purchasing is the level of comfort of the vehicle’s sound vibration in the vehicle cabin. The basic principle suggests that the sound vibration discomfort level is affected by a few factors which are mainly based on magnitudes, frequencies, directions and also the exposed periods. Normally, the phenomenon of sound vibration disrupts the performance of the driver by affecting the driver’s vision and also inducing a certain degree of stress due to the sound and vibration to which the driver and his or her passengers are exposed. The sound vibration is generally contributed by a few sources originated from the transmission of the vehicle’s engine, tire interactions with the road surface and also the exposure of vehicle’s body vibration during the movement. The objective of this study is to propose an approach that clusters the level of sound and vibration into a few categories and classifies them into those categories without implementing the subjective test that normally involves human assessment. The study has observed the changes of the sound quality and the level of vibration at particular points in the vehicle cabin over the changes of engine speeds. In reference to the results, the study has successfully provided a technical procedure in order to cluster, and also to classify, the level of sound vibration by taking into account the correlation between experienced noise and exposed vibration in the vehicle cabin. [ABSTRACT FROM AUTHOR]

Two factors for customers to consider when purchasing a vehicle are the vehicle acoustical comfort and the vibration in the vehicle cabin, both of which contribute to a comfortable driving environment. The amount of discomfort is included by frequency, magnitude, direction, and the period during which the noise is experienced and also where the vibration is experienced in the cabin. The main sources of vibration that have been identified previously are the vibration transmitted from engine and the vibration transmitted from the interaction of the tires with the road surface. In this study, we investigate the effect of the vibration caused by the tire interaction with the road surface by estimating the amount of noise produced due to this phenomenon. The methodology focuses on the trends which occur in the noise exposure and on the vibration exposure that has been generated throughout the engine operating rpm range in both stationary and non-stationary conditions. The vibration dose value (VDV)f was used to assess the amount of vibration exposure that is transmitted to the driver's body in the cabin. Through the study, we have proved that the vibration caused by the tire-road surface contact is a major contributor to the cabin's interior noise. Based on the results, a goal programming method was developed to optimise the noise levelin the cabin by considering the vibration as an input in the model. Finally, a multi-objective goal programming was developed successfully which could be used to optimize the noise level in the cabin by looking at the value of the VDV required at particular engine speeds (rpm). [ABSTRACT FROM AUTHOR]

Vehicle acoustical comfort and vibration in passenger car cabin are the factors which attract buyers to a vehicle, in order to have a comfortable driving environment. The comfort of the driving will affect the driver by influencing their driving performance. Vehicle acoustical comfort index (VACI) has been introduced to represent the level of annoyance in passenger car cabin. This index has been used in the computation related to the acoustics aspect in the car cabin. Noise annoyance is categorised into five states: most annoying, medium annoying, marginal, medium pleasant and most pleasant. In order to improve the VACI index, this study carries out an approach to classify and categorise the aforementioned five states using the fuzzy set theory approach. At the end of several studies, the noise annoyance fuzzy index (NAFI) has been introduced. By using NAFI, automotive researchers will be able to classify and make judgement about the state of annoyance from the exposed noise in the car cabin numerically, where the use of this index is regarded to be more precise and has practically been used in engineering fields especially where the fuzzy logic system is concerned. [ABSTRACT FROM AUTHOR]

Car cabin acoustical comfort is one of the main features that may attract customers to purchase a new vehicle. The noise in a passenger car cabin is closely related to the vibration generated in the vehicle system. In this study, the effects of vibration on noise in the passenger car cabin have been studied. The vehicle acoustical comfort index (VACI) was used to evaluate the noise annoyance level and the vibration dose value (VDV) was used to evaluate the vibration level. Because engine noise is one of the dominant sources of interior noise, an approach has been used to study the correlation between engine speed and the level of generated vibration. According to the changes in the noise and the vibration level as a function of engine speed, a goal programming model was used to optimise the noise annoyance level in the passenger car cabin. At the end of the study, a multi-objective model was successfully built to optimise the noise annoyance levels by looking at the required vibration dose value at certain engine speeds. [ABSTRACT FROM AUTHOR]