A method for mapping fibrous media by propagation of ultrasound from a set transducers, wherein: a number of unfocused incident ultrasonic waves having different wavefronts are emitted; the signals reverberated by the medium toward each transducer are captured; coherent signals respectively corresponding, for each transducer, to contributions coming from different fictitious focal points in the medium are determined; and then the orientation of the fibers is determined by comparing a spatial coherence between said coherent signals, in a plurality of directions.