An experimental investigation of the attenuation of sound in two air‐filled tubes of 0.238 and 0.0292 cm inside radius in the frequency range from 3.8 to 20 kc was conducted, and the results were compared with values of attenuation calculated from the Kirchhoff theory for rigid walled tubes. Agreement of experimental with theoretical values was found within the accuracy of the experiment, provided that the comparison made only with the portion of attenuation proportional to square root of frequency, as suggested by Fay. The attenuation was determined by a method which was different, in some respects, from those previously employed. The variable length, closed tube was driven with a high‐impedance source, and the input pressure was sampled with a high‐impedance microphone probe. The input pressure was recorded as a function of closed tube length. Since the input pressure can be assumed to be proportional to input impedance for these conditions, the attenuation can readily be determined from the ratio of the pressure maxima or minima.