There has been a study of resonant gas oscillations in a closed tube with different vertex angle of the cone-shaped end. Amplitude-frequency responses of the tubes have been obtained. It has been discovered that a decrease in the vertex angle of the cone-shaped end leads to a shift in the resonant frequency decreasingly, i.e., to dispersion. There has been found a range of vertex angles of the cone-shaped end, when the gas pressure oscillation amplitude increases in all sections of the tube comparing to oscillations in a uniform tube of the equivalent length.