The acoustic absorption of sand and soil with varying amounts of water (dry to saturated) has been investigated the 10‐ to 100‐kc range. Two methods were used. In one, the source and a number of equally spaced probe microphones were imbedded in the medium. In the other method the source and receiver were in air and the transmission loss was obtained for samples of varying thickness. The unsaturated media were found to have attenuation coefficients ranging from 2 db/cm for nodulous, loose soils to greater than 25 db/cm for finely divided soils and sand, the value for any particular sample depending in an important way on its flow resistance. In water‐saturated media the attenuation was found to depend markedly on the amount of gas present in the mixture. Air‐free mixtures prepared in an evacuated chamber had attenuation coefficients which were too small to be measurable—probably less than 2 db/cm. On the other hand, for mixtures prepared in the presence of air the attenuation coefficient immediately after mixing were extremely large. For one sample it ranged from 26 db/cm at 10 kc to 64 db/cm at 30 kc. When a source and microphone, separated by a distance of one centimeter, were immersed in such a freshly stirred mixture and then left undisturbed, the intensity level increased in time—as much as 50 db at 30 kc over a period of 100 hr.