Abstract <p>This paper presents the results of a study on acoustic oscillations in a closed gas discharge tube with a dynamic loudspeaker connected via a confuser. Thermal expansion of the positive discharge column under considered conditions has been detected. As current increases, an increase in the average gas temperature <i>T</i>_av leads to an upward shift in the fundamental frequency of the gas discharge tube, since the resonant frequency is proportional to the speed of sound and the square root of the average temperature. A resonant frequency, <i>f</i>_s, has been revealed for the entire geometry under study. It has been found that <i>f</i>_s exhibits a relatively weak dependence on discharge current, which is due to Joule heat generation in only one part of the system—the gas discharge tube.</p>