A device (16; 16') for imaging defects in a structure by transmitting and receiving mechanical waves in this structure, including: - a plurality of N transmitters (18; 18') of mechanical waves intended to propagate in the structure, to be distributed over at least one surface of the structure, - a plurality of P receivers (18; 18') of mechanical waves after their propagation in the structure, to be distributed over said at least one surface of the structure, - a central unit (22, 30) for controlling the N transmitters (18; 18') and P receivers (18; 18') programmed to record Q ≤ N×P signals obtained from electrical signals respectively provided by the receivers of Q different transmitter/receiver pairs of the plurality of transmitters and receivers, after reception of mechanical waves transmitted by the transmitters of said Q different pairs, - means for storing Q corresponding first reference signals (S REF1), representative of the structure without defects, - a central unit (22, 38) for processing the Q signals obtained, programmed to correlate each signal obtained with the first reference signal (S REF1) that corresponds to it, in such a way as to obtain Q first values of correlations, and to construct an image (Im INIT) of probabilities of defects in the structure from the Q first values of correlations, characterized in that it further includes means for storing Q corresponding second reference signals (S REF2), also representative of the structure without defects but differing from the Q first reference signals (S REF1) by random noise, and in that the central unit (22, 38) for processing the Q signals obtained is further programmed to: - correlate each first reference signal (S REF1) with the second reference signal (S REF2) that corresponds to it, in such a way as to obtain Q second values of correlations, - construct a reference noisy image (Im REF) from the Q second values of correlations, and - subtract the reference noisy image (Im REF) from the image (Im INIT) of probabilities of defects. - a plurality of N transmitters (18; 18') of mechanical waves intended to propagate in the structure, to be distributed over at least one surface of the structure, - a plurality of P receivers (18; 18') of mechanical waves after their propagation in the structure, to be distributed over said at least one surface of the structure, - a central unit (22, 30) for controlling the N transmitters (18; 18') and P receivers (18; 18') programmed to record Q ≤ N×P signals obtained from electrical signals respectively provided by the receivers of Q different transmitter/receiver pairs of the plurality of transmitters and receivers, after reception of mechanical waves transmitted by the transmitters of said Q different pairs, - means for storing Q corresponding first reference signals (S REF1), representative of the structure without defects, - a central unit (22, 38) for processing the Q signals obtained, programmed to correlate each signal obtained with the first reference signal (S REF1) that corresponds to it, in such a way as to obtain Q first values of correlations, and to construct an image (Im INIT) of probabilities of defects in the structure from the Q first values of correlations, - correlate each first reference signal (S REF1) with the second reference signal (S REF2) that corresponds to it, in such a way as to obtain Q second values of correlations, - construct a reference noisy image (Im REF) from the Q second values of correlations, and - subtract the reference noisy image (Im REF) from the image (Im INIT) of probabilities of defects.