The invention concerns a device (1) for the insonification of an environment or medium, which is designed to generate a beam of focussed waves around a point in a so-called focus zone (20), used for imaging the medium or changing the properties of the medium, with the insonification device (1) having an intrinsic or extrinsic support structure on which is installed a network of a predetermined number of ultrasound transducers (12) that are designed to be controlled independently for generation of the focussed wave beam.According to the invention, the transducers (12) used for the generation of the focussed wave beam are located in a homogeneous spatial distribution along at least two concentric spirals (11) that are wound onto a three-dimensional concave area (10) whose shape and size are chosen to allow optimal focusing of the beam at a predetermined focal length, and whose concave side is oriented toward the focus zone (20).