The invention relates to a sound dampening device (1) comprising a frame(2), a rear layer (4) and a front layer (6) arranged on opposite sides of the frame(2), such that the frame(2), the rear layer (4) and the front layer (6) forms an enclosed space, wherein a first sound absorbing layer (8) is arranged between the rear layer (4) and the front layer (6). A cavity (10) is formed between the rear layer (4) and the first sound absorbing layer (8) and an air purifying device (12) is arranged in fluid communication with said cavity(10), such that purified air from the air purifying device (12) is supplied to the cavity (10) via an inlet (14) and is discharged through at least one opening (16) in the first sound absorbing layer (8) and at least one output zone (18) in the front layer(6).