A sound damping device adapted to be arranged inside a duct, comprises a first element (40a) including at least one first wall (20a) of a first channel (12a) having a first channel inlet (13a) and a first channel outlet (13b), a second element (40b) including at least one second wall (20a) of a second channel (16a) having a second channel inlet (14b) and a second channel outlet (14b), said and outlet regions being substantially opposite to one another, wherein at least a portion of at least one of said first and second elements (40a, 40b) comprises an acoustic energy dissipative sheet material. In accordance with the invention, said first element (40a) comprises a guide means (21) further defining said first channel (12a); said second element (40b) comprises a second guide means (21) further defining said second channel (16a); and said first and second guide means (21) are arranged in relation to one another in such a way that the first channel (12a) forms a first angle in relation to the second channel (16a).