A medium is equipped with sources adapted for emitting a wave and sensors adapted for receiving the wave emitted. The method for locating an appearance of a defect in the medium comprises an initialization step in which reference impulse responses of the wave between the sources and sensors are determined, then at least one defect detection step in which the impulse responses of the wave between the sources and the sensors are measured, a decorrelation coefficient between the impulse responses and the reference impulse responses is calculated, a probability of exploration of a position is calculated, an error function for each source-sensor pair is calculated, and a product of at least some of the error functions of the source-sensor pairs is calculated. The product represents a map of a probability of the appearance of the defect at each position in the medium.