## 1 Introduction  
The study of the effects of whole-body vibration (WBV) on human health is a topic of significant interest, particularly due to the increased exposure of individuals to whole-body vibration resulting from vehicular transport. Prolonged exposure to WBV can lead to discomfort and adversely affect the health of passengers, particularly in a constrained sitting posture [1; 2]. In this regard, it is essential to investigate how vibration is transmitted to the human body, especially in seated posture. The region of the resonant frequency of vibration that affects passengers is of critical importance. The effect of WBV on the seated human body is more dominant under low-frequency excitation, specifically below 30 Hz [3]. Several studies have reported the principal resonant frequencies within less than 13 Hz, with the dominant peak in the frequency range of 4-6 Hz under vertical vibrations [4; 5; 6]. Therefore, studying the effects of vertical vibrations in regions within 0-15 Hz on different body segments is important to design systems that ensure that the human natural frequencies do not coincide with excitation frequency within this range. One effective technique for investigating the dynamic response of humans to WBV is the development and use of biodynamic seated human models with different postural and excitation conditions. Biodynamic models are used to augment experimental measurements, which are not only time-consuming but limited by safety considerations. Existingbiodynamic models are primarily categorized into finite element (FE), multibody (MB), and lumped parameter (LP) models. While complex models like finite elements and multibody systems may provide a more detailed representation of human body dynamics, a lumped-parameter model can be sufficient for investigating the dynamic response of humans to vibration. The simplicity and computational efficiency of lumped-parameter models make them ideal for exploring different scenarios and investigating the effects of different parameters on the system's response [6]. Furthermore, lumped-parameter models have been extensively validated against experimental data and can be customized to include more detailed features of the human body, making them a viable option for investigating the dynamic response of humans to vibration [7; 8; 9; 10]. The estimation of appropriate human parameters using biodynamics models is another widely reported issue in WBV studies. It is highly difficult to measure human mechanical parameters such as stiffness and damping coefficient from live tissues. Likewise, seats are made from viscoelastic materials whose mechanical properties are also difficult to measure [9; 11; 12]. Therefore, researchers estimate these viscoelastic properties through the minimization of errors between the biodynamic model responses and a target response function derived from the measured responses from experiments. Most existing studies consider measured vertical apparent mass (AM) as a target response function due to the rapid convergence of the AM optimization problem. A few studies also adopted seat-to-head transmissibility (STHT) in the parameter's optimization problem [6; 8]. However, model parameter identification with AM does not often describe the contributions of low inertia upper body segments to the total response [13]. Studies by [PERSON] and [PERSON] [8] and [PERSON] and [PERSON] [14] established that transmissibility is more appropriate for predicting transmitted vibration to selected body segments. Therefore, it is necessary to directly measure the response of each body segment to whole-body vibration in order to access the distinct response of the body segments to vibration, and so far, there are limited studies in this area. Existing studies adopt either gradient-based or evolutionary-based algorithms to estimate the parameters of biodynamic models. However, there is still an exhaustive search for the appropriate optimization method that produces reliable estimates of these human parameters.