Acoustic metamaterials are artificially engineered smart structures designed to achieve unusual properties that cannot be possible to obtain through natural materials. Hence, with the advancement of technology, metamaterials have received tremendous focus in recent days. Phononic and sonic crystals are the two classes of acoustic metamaterial. The frequency stopband is one of the common and primary features that can be attained from both the classes of acoustic metamaterials. Unit cell sonic crystals are composed of stiff resonators, placed inside comparatively softer matrix material. The frequency bandgap in a sonic crystal is a result of Bragg scattering and local resonance of the resonators in the unit cell. In this study, a comprehensive analysis is performed to understand the influence of resonators on frequency stopbands and the range/width of the bandgap. Two frequency bands in a dispersion curve form a bandgap. How and why those two bands shift up/down in a dispersion curve to increase/decrease the bandgap width, is studied extensively. It is established that resonator geometry and dimension in the unit cell possess a vital role in manipulating the frequency bands. To advance the understanding, this study is focused on analyzing the influence of volume percentage of resonators in a unit cell. Mode shapes are studied extensively to better understand the results and make conclusive arguments.