Abstract: A hydrophone is provided having at least one flexible piezoelectric sensitive element applied to a support, each sensitive element being formed of a flexible piezoelectric film associated with two electrodes and is applied to a synthetic plastic material support one face at least of which has hollow parts of very different shapes, for example an homogeneous distribution of cups, honeycombs, holes, etc, whose dimensions are determined as a function of the mechanical characteristics of the films used. The stresses applied thereto result in deforming each film inwardly of the hollow parts, which very greatly increases the sensitivity.

Abstract: A method and device are provided for improving the sensitivity and signal to noise ratio of transducers including several piezo-electric sensors interconnected in parallel to the input of an electric charge amplifier, said process consisting essentially in reducing the electric capacity of the combination of parallel sensors at the input of the amplifier so as to reduce the amplification gain applied to the noise without changing that which is applied to the signals picked up. This operation is achieved by means of an impedance transformer or else by means of at least one charge transfer capacitor connected by at least one switch alternately to the sensors and to the capacitor of the amplifier.

Abstract: A pressure wave sensor device is provided including at least two sensitive flexible piezoelectric elements wound in two helices in opposite directions of a tubular support and a method for manufacturing same, said device including a copper conducting ribbon wound helically between the two windings of opposite direction and in the same direction as the underlying winding so as to avoid short circuits at the crossing points of the turns and to improve the electric and mechanical couplings between the two sensitive elements, said tubular support being provided with collector assemblies at regular intervals and wound over the whole of its length with the sensitive elements and the conducting ribbon, the different windings then being cut to the right length at the level of the collector assemblies and connected electrically thereto.