The paper presents the results of acoustic and vibration studies of a model of a two-shaft GTU exhaust duct. The testing was carried out together with the model of the last stage providing real boundary conditions at the duct inlet. The intensity of the pressure ripple near the walls of the exhaust duct for two turbine modes was determined as a result of the tests. Vibrations of the exhaust duct walls were measured. The amplitude of the pressure ripple in the flow of collector box corresponding to the experimentally determined amplitude of the vibrations of its side wall was determined by alternative calculations. The measured intensity of the pressure ripple was compared with the results of measurements of pulsations in the flow of diffuse areas of nozzles. The impact of the GTU mode on the level of the pressure ripple in flow was found.