In a first object the present invention provides a method for the inspection of the quality of the sealing of a packages and more specifically the method of the present invention allows the on-line inspection of the air-tightness of a package. Said method comprising the following steps of (i) acquiring the noise signal generated by the sealing equipment during the sealing of the package, (ii) analyzing the signal in order to determine the values of at least one physical parameter characterizing the noise signal and (iii) deciding on the quality of the sealing by comparing the determined value to a reference value for said physical parameter.