A valid human biodynamic model is very useful for studying the human body's response to whole body vibration. Whole body vibration is one of the important factors in the study of vehicle ride comfort. The environmental vibrations are transferred to the human body through floor and seat. Seated posture is the most commonly used position in automobiles. Therefore, studying the human body response in a seated position has attracted a lot of attention. Because the human body is in direct contact with the seat, its design plays a very important role in vibration transmission. In seat design, two important components are seat suspension and cushion. The mechanical properties of these components are stiffness, damping and mass. These properties can be changed by adjusting cushion material and seat suspension linkages. In this paper, three types of seat models are used. The first one is a hard seat. The second one has only cushion, and the third one is called an isolated seat which has seat suspension and cushion. For evaluating responses, one linear 14-degree of freedom (DOF) multibody biodynamic model from literature is used. This model is in a seated position having a total mass of 71.32 kg with 5 body segments. Backrest support and feet contact are included in this model because a considerable amount of vibrations is transferred through it.