The effect of the wearer's person as an acoustic baffle on the response of a hearing aid, under free-field and diffuse-field conditions, has been studied with a number of hearing aids and wearers. A characteristic effect is found for each model of hearing aid when it is worn at center-chest position in free field. The character of the effect does not appear to be strongly correlated with the size and shape of the wearer. In a sound field of “random” direction of incidence, the body-baffle effect appears to be negligible. Within the limits of linear amplification of a hearing aid, one of the most pronounced of the body-baffle effects had little or no influence on the intelligibility of speech, as determined with four hard-of-hearing subjects.