A pick‐up device for measuring the standing wave ratio of transverse acoustic waves is described. One of the important features of this device is the elimination of interference from the residual plane wave. An experimental study of the attenuation characteristics of (1,0) transverse acoustic waves propagated in air in a rectangular metal tube employing such a pick‐up device is presented in this paper. This study reveals that three losses are important contributors to the attenuation. The results are in good agreement with a tube wall effect predicted by Kirchhoff. In evidence is a gaseous absorption in the medium due to thermal equilibrium adjustments. The remaining attenuation is appreciable and appears to vary with frequency asf2[1−fc2/f2]−12. This factor is here attributed to a vibration of the tube walls.