The resonance enhancement of photoaconstic signals due to the frequency response of the photoacouatic sample cell in FTIR-PAS measurements was observed for the first time. The frequency response analysis of the cell shows that this effect originates from the unflat response of the pressure transducer of gas in the chamber. The possibility of improving the sensitivity and the S/N ratio of the photoacoustic measurements with the resonance enhancement method was discussed in this paper, and an example of using this method to analyze structure defects of SPs in the conducting polymer PTh samples was also given.