Method for automatically identifying an acoustic source based on an acoustic signal S(t) produced by the occurrence or the evolution of a defect in a structure, this method comprising the following steps: a) kitting out the structure by attaching at least one sensor to this structure, and then b) using the sensor to measure an ultrasound signal F j (t) caused by the acoustic signal produced by the occurrence or the evolution of the defect in the structure, this measured ultrasound signal being linked, in the frequency domain, to the produced acoustic signal by the following relationship: F j (w) = R j (w)G j (w)S(w), where: - j is an index identifying the sensor, - w is the angular frequency in radians, - F j (w) is the Fourier transform of the ultrasound signal F j (t) measured in the time domain by the sensor j, - S(w) is the Fourier transform of the acoustic signal S(t) produced by the occurrence or the evolution of the defect in the structure, - R j (w) is the response, in the frequency domain, of the sensor j, - G j (w) is the propagation function, in the frequency domain, of the acoustic signal in the structure between the position of the defect and the location of the sensor j, and then c) automatically classifying the acoustic source into a class of acoustic sources chosen from a plurality of possible classes of acoustic sources, characterized in that: - the method also comprises, between steps b) and c), a step d) of reconstructing (58; 88) the acoustic signal produced upon the occurrence or the evolution of the defect, this reconstruction step comprising constructing an estimate S e (w) of the signal produced at the position of the defect based on the ultrasound signal F j (t) measured by the sensor and using an estimate or a measurement of the product R j (w)G j (w) that, in the frequency domain, links the measured ultrasound signal F j (w) to the produced acoustic signal S(w), and - the automatic classification is carried out based on the estimate of the acoustic signal obtained at the end of step d). a) kitting out the structure by attaching at least one sensor to this structure, and then b) using the sensor to measure an ultrasound signal F j (t) caused by the acoustic signal produced by the occurrence or the evolution of the defect in the structure, this measured ultrasound signal being linked, in the frequency domain, to the produced acoustic signal by the following relationship: F j (w) = R j (w)G j (w)S(w), where: - j is an index identifying the sensor, - w is the angular frequency in radians, - F j (w) is the Fourier transform of the ultrasound signal F j (t) measured in the time domain by the sensor j, - S(w) is the Fourier transform of the acoustic signal S(t) produced by the occurrence or the evolution of the defect in the structure, - R j (w) is the response, in the frequency domain, of the sensor j, - G j (w) is the propagation function, in the frequency domain, of the acoustic signal in the structure between the position of the defect and the location of the sensor j, and then - j is an index identifying the sensor, - w is the angular frequency in radians, - F j (w) is the Fourier transform of the ultrasound signal F j (t) measured in the time domain by the sensor j, - S(w) is the Fourier transform of the acoustic signal S(t) produced by the occurrence or the evolution of the defect in the structure, - R j (w) is the response, in the frequency domain, of the sensor j, - G j (w) is the propagation function, in the frequency domain, of the acoustic signal in the structure between the position of the defect and the location of the sensor j, and then c) automatically classifying the acoustic source into a class of acoustic sources chosen from a plurality of possible classes of acoustic sources, characterized in that: - the method also comprises, between steps b) and c), a step d) of reconstructing (58; 88) the acoustic signal produced upon the occurrence or the evolution of the defect, this reconstruction step comprising constructing an estimate S e (w) of the signal produced at the position of the defect based on the ultrasound signal F j (t) measured by the sensor and using an estimate or a measurement of the product R j (w)G j (w) that, in the frequency domain, links the measured ultrasound signal F j (w) to the produced acoustic signal S(w), and - the automatic classification is carried out based on the estimate of the acoustic signal obtained at the end of step d). - the method also comprises, between steps b) and c), a step d) of reconstructing (58; 88) the acoustic signal produced upon the occurrence or the evolution of the defect, this reconstruction step comprising constructing an estimate S e (w) of the signal produced at the position of the defect based on the ultrasound signal F j (t) measured by the sensor and using an estimate or a measurement of the product R j (w)G j (w) that, in the frequency domain, links the measured ultrasound signal F j (w) to the produced acoustic signal S(w), and - the automatic classification is carried out based on the estimate of the acoustic signal obtained at the end of step d).