Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method.Variations of the magnification factors of fluctuating internal pressures were analyzed using 96 model cases under random fluctuating external pressure,and then corresponding design equations were fitted.The results show that the Helmholtz resonance peaks of the admittance functions in both compartments increase with increasing the area of windward or partition wall opening.With increasing the volume of the compartment with an external opening,the resonance peak in this compartment at the higher Helmholtz frequency significantly decreases,at the same time,the resonance peak in the other compartment at the lower Helmholtz frequency also decreases.With increasing the volume of the compartment with background porosity,both resonance peaks in this compartment at the lower and higher Helmholtz frequencies decrease,meanwhile,the resonance peak at the lower Helmholtz frequency for the other compartment also decreases,whereas the resonance peak at the higher Helmholtz frequency increases.Both resonance peaks of the admittance functions in the two compartments decrease with increasing the amplitude of fluctuating external pressure coefficients or reference wind speed. Analyses of the effects of some parameters were performed to determine the admittance functions in a common two-compartment building with background porosity by the imposed excitation method. Variations of the magnification factors of fluctuating internal pressures were analyzed using 96 model cases under random fluctuating external pressure , and then corresponding design equations were fitted. The results show that the Helmholtz resonance peaks of the admittance functions in both compartments increase with increasing the area of ​​windward or partition wall opening. With increasing the volume of the compartment with an external opening, the resonance peak in this compartment at the higher Helmholtz frequency significant decreases, at the same time, the resonance peak in the other compartment at the lower Helmholtz frequency also reduces. With increasing the volume of the compartment with background porosity, both resonance peaks in this compartment at the lower and higher Helmholtz frequenci es decrease, meanwhile, the resonance peak at the lower Helmholtz frequency for the other compartment also decreases, while the resonance peak at the higher Helmholtz frequency increases.Both resonance peaks of the admittance functions in the two compartments decrease with increasing the amplitude of fluctuating external pressure coefficients or reference wind speed.