Acoustic attenuation device provided with inserts made of acoustically absorbent material

An acoustic attenuation device including:

• two inserts made of acoustically absorbent material, the two inserts being distinct from each other and being separated from each other so as to delimit between them a longitudinal slot, each of the two inserts including a front surface intended to be oriented towards a space to be acoustically attenuated, and
• two support elements which are made of substantially acoustically impermeable material and which at least partially delimit an internal cavity in which the two inserts are disposed, each support element of the two support elements including a cover part partially covering the front surface of a respective insert of the two inserts such that the front surfaces of the two inserts are partially exposed, the two cover parts delimiting at least one passage opening which emerges into the internal cavity and which is located at least partially opposite the longitudinal slot so as to clear an access to the longitudinal slot.