Abstract: The acoustic thickness correction coefficients of perforated plates are calculated using the finite element method (FEM).The effects of perforation porosity,plate thickness,hole diameter and pattern on the acoustic thickness are studied,and the acoustic thickness correction coefficients of perforated plates with porosity lower than 40% are determined.The results show that the influences of the plate thickness,hole diameter and pattern on the acoustic thickness are small,while the perforation porosity influences the acoustic thickness a lot.Based on the calculated results,an approximate expression is provided for the acoustic thickness correction coefficient of perforated plate.The transmission loss of perforated tube silencers is predicted by using the perforate acoustic impedance formed from the present approximate expression,and the numerical predictions agree well with the experimental results.The agreement shows that the present expression is valid for the acoustic performance predictions of perforated tube silencers.