According to the invention, n incident acoustic waves Ei(t), obtained by linearly combining n elemental incident waves E0i(t) with an encoding matrix Hc are consecutively transmitted in a medium to be imaged. n reverberated waves Ri(t) from the medium to be imaged are then consecutively detected, following the transmission of the n incident waves; then n elemental reverberated waves R0i(t) are determined by linearly combining the detected n reverberated waves Ri(t) with a decoding matrix Hd. The Hc and Hd matrices are such that Hc·Hd=D, where D is a diagonal matrix of order n, all the diagonal elements of which are greater than 1.