The vocal fold vibration, and hence acoustic source properties of voiced speech sounds, rely on the vocal folds elasticity which is therefore a crucial part of the underlying fluid-structure interaction for healthy as well as pathological conditions. The human vocal folds are an extremely complex structure. Therefore, physical studies often rely on simplified mechanical vocal folds replicas. Two types of replicas proposed in literature are considered, i.e. multi-layer silicone replicas and a pressurized latex replica. For both replica types, the mechanical properties are experimentally characterized by measuring their Young's modulus and frequency response. Next, a simple physical model is proposed and validated in order to predict the effective Young's modulus of silicone replicas from their individual constituents. This allows to account for their multi-layer composition characterising normal human vocal folds with different degree of detail. In the future, inclusions in the replica mimicking structural vocal fold pathologies for instance associated with polyps, scars, etc. can be accounted for.