Sound absorption measurements on haired mice, hairless mice, rats, and guinea pigs have been made using reverberation chambers. The initial reverberation‐time experiments on haired and hairless mice were conducted in a cylindrical chamber using a Brüel and Kjaer recorder. Later measurements on all types of animals were made in an asymmetrical chamber using an oscilloscope and an electronic counter. The absorption coefficients were measured in the frequency band from 1 to 20 kc. All experiments showed that the absorption coefficients rise between 6 and 20 kc. Those for the haired animals approach 100%. Hairless mice had lower absorption coefficients approaching 20% at 20 kc.