Acoustic attenuation device for an intake line of a thermal engine, flexible tube and intake line comprising such a device

The device (101) has a tubular section (110) and formation units of acoustic chambers that radially prolong a section towards outer side. A tubular connection end (20) of a flexible pipe i.e. rubber hose, is connected to a line. The section is fixed in the tubular connection end by a part (13) of the formation units, where the part of the formation units is formed in an end (111) of the section, and divides a flow of the air at the connection end of the pipe.