We developed a sonic permeameter that can quickly measure the intrinsic permeability of dry unconsolidated porous materials in the laboratory. It consists of a control box, a loudspeaker, and an external waveguide filled with the sample. Sound wave attenuation and dispersion are measured by two microphones recessed in the inner wall of the waveguide. They receive a sound pulse that is sent down to the waveguide from the loudspeaker. The permeability of the sample is then calculated from the attenuation and dispersion spectra using our mathematical model. Test results obtained over several dry Ottawa sand and glass bead samples agree very well with the results obtained using a conventional constant‐head permeameter. The advantage of this apparatus is its rapid and automated measurement, easy operation, and potential workability in the field. Theoretical analysis is also extended to a hypothetical case where the porous material is totally saturated with wate