A method for determining the state of tension of a material at a given time, including the step of calculating the value of at least one parameter extracted from the ultrasonic signal received after propagation of an ultrasonic wave emitted in the material between an ultrasound source and at least an ultrasound emitter located at a fixed distance from the source, the value of the at least one parameter varying with the state of tension of the material, the variation of the at least one parameter being proportional or inversely proportional to the variation of the state of tension of the material.