The article reports the results of measurements of the acoustic pressure of acoustic waves generated by acoustic dust cleaners mounted in the convection pass of the 670MWth Circulating Fluidised Bed boiler. Based on measurements carried out and the spectral analysis of recorded signals it was found that the level of acoustic pressure generated by acoustic cleaners for the frequency of 100 Hz was too low for the efficient cleaning of the heated surfaces of the reheater RH2 and superheater SH3.