We propose a system for achieving some adjustable quantum coherence effects,including the normal-mode splitting (NMS),the optomechanically induced transparency (OMIT),and the optomechanically induced absorption (OMIA).In this system,two tunnel-coupled optomechanical cavities are each driven by a coupling field and coupled to an atomic ensemble.Besides,one of the cavities is also injected with a probe field.When the system works under different conditions,we can obtain the NMS,the OMIT,and the OMIA,respectively.These effects can be flexibly adjusted by the tunnel coupling between the two cavities,the power of the coupling lasers,and the coupling strength between the atomic ensembles and the cavity fields.Furthermore,we can realize the OMIT even if the oscillating mirrors have relatively larger decay rates.