A system for detecting labels arranged on a support and spaced apart from one another by a spacing, the system including a transmitter part including a transmitter arranged to transmit a beam of ultrasonic waves towards the support which carries the labels, a receiver part, separated from the transmitter part, such that the support carrying the labels can pass along a plane located between the transmitter part and the receiver part, the transmitter part or the receiver part being arranged so that the beam of ultrasonic waves transmitted by the transmitter covers, on the support carrying the labels, a total surface area in which the surface area occupied by the spacing between two labels is greater than the surface area occupied by the labels.