A non-destructive inspection method for non-destructively inspecting an adhesively bonded assembly of a first material having a first thickness (e1), a top face , and a bottom face , of a second material having a second thickness (e2) and a top face , and of an adhesive third material having a third thickness (e3), the adhesive third material being arranged between the bottom face of the first material and the top face of the second material so as to assemble the first and second materials together by adhesive bonding, the method comprising: a) a step in which an ultrasound transducer is placed on the top face of the first material; b) a step in which guided waves are generated in the adhesively bonded assembly; c) a step in which a dispersion curve plot is established in a first reference frame on the basis of receiving the guided waves generated in the adhesively bonded assembly; d) a step in which a plurality of reference dispersion curves that are provided that have been established in the first reference frame, each of said reference dispersion curves being obtained by generating guided waves in a reference assembly of the first and second materials adhesively bonded by the adhesive third material, the adhesively bonded reference assembly presenting calibrated thicknesses; e) a step in which the dispersion curve plot of the adhesively bonded assembly under inspection is compared with said plurality of reference dispersion curves; and f) a step in which at least one of the first, second, and third thicknesses in the adhesively bonded assembly under inspection is estimated, and g) the method further including a step of iteratively optimizing a comparison zone for the dispersion curve plot of the adhesively bonded assembly under inspection that is adapted for comparing said dispersion curve plot with said plurality of reference dispersion curves. a) a step in which an ultrasound transducer is placed on the top face of the first material; b) a step in which guided waves are generated in the adhesively bonded assembly; c) a step in which a dispersion curve plot is established in a first reference frame on the basis of receiving the guided waves generated in the adhesively bonded assembly; d) a step in which a plurality of reference dispersion curves that are provided that have been established in the first reference frame, each of said reference dispersion curves being obtained by generating guided waves in a reference assembly of the first and second materials adhesively bonded by the adhesive third material, the adhesively bonded reference assembly presenting calibrated thicknesses; e) a step in which the dispersion curve plot of the adhesively bonded assembly under inspection is compared with said plurality of reference dispersion curves; and f) a step in which at least one of the first, second, and third thicknesses in the adhesively bonded assembly under inspection is estimated, and g) the method further including a step of iteratively optimizing a comparison zone for the dispersion curve plot of the adhesively bonded assembly under inspection that is adapted for comparing said dispersion curve plot with said plurality of reference dispersion curves. <EOS>