Exerting mechanical loads on soft periodic porous phononic crystals provides a unique opportunity to control the propagation of waves through the peculiar band gaps. However, it is quite difficult to experimentally confirm the band gaps in soft materials owing to their viscosity and instability-prone character. We investigate here via experiments the effect of regulation of uniaxial tension on the band gaps in a 2D soft phononic crystal with criss-crossed elliptical holes which was designed based on the contrarian thinking to our previous study. The results show that the soft phononic crystal has rich initial band gaps and can be tuned by harnessing uniaxial tension to achieve continuous control of elastic band gaps. Moreover, the effect of the uniaxial tension on the effective Poisson's ratio of the structure is also studied. The present study confirms the feasibility of the design of soft tunable phononic crystals and acoustic devices by harnessing uniaxial tension.