A novel auxetic acoustic metamaterial plate with tunable bandgap

•An acoustic metamaterial plate based on a negative Poisson's ratio structure (NP-AMP) is proposed.•The newly designed structure has a lower frequency bandgap and wider bandwidth compared with traditional structures.•Applying mechanical loading to the NP-AMP enables direct control of the bandgap for shifting to lower frequencies.•The range of bandgap variation is related to the auxetic behavior.