A study has been made of three sound sources, each of which is constructed out of a plane wire gauze (positive electrode) and a great many needles (negative electrode) pointing toward it. Direct current coronas have appeared when a high de potential has been applied to the sound sources in the atmosphere. Various experiments have been performed on the acoustical characteristics of the sound sources as they are supplied with an ac current in the frequency range of 0.2–10 kHz, which is superposed on a de current. The sound sources are each considered as consisting of a resistance shunted by a capacitance, so far as the ac current is concerned. Theoretical formulas are obtained from the assumption that the sound is produced by a vibratory force which acts directly on the air between the electrodes and which has an rms value (d/b)I′, wheredis the gap length,b= 2.2 cm2/V‐sec andI′ is the rms value of an ac current through the resistance. It has been found the experimental results for 0.2–1 kHz are in good agreement with the calculated ones obtained from the formulas.