Thermoformed sound or thermal insulation panel

A panel, comprising one layer (12) of a thermoformed plastic material shaped to form cylindrical, parallel-piped, truncated conical or truncated pyramidal resonator cells (14) between 10 and 30 mm deep, has the open side of the cells covered by a plastic film (20) with at least one adhesive surface for attaching it to a support (10). The film can be attached to the thermoformed plastic layer by thermal or ultrasound welding or adhesive.