A method for manufacturing a hearing device (100, 200) is disclosed. The hearing device (100, 200) comprises a speaker (2), a first chamber (4), and a sound channel (6) arranged between the first chamber (4) and the surroundings of the hearing device (100, 200) or a second chamber (8). An element (10) of a thermoplastic material being in a solid state is arranged in the sound channel (6). A laser light (12) is applied to the element (10) to thereby activate the element (10) to change from the solid state to a liquid state. The element (10) then changes from the solid state to the liquid state filling out a cross-section of the sound channel (6) and thereby sealing the sound channel (6). Finally, cooling of the element (10) is allowed leading to a change of the element (10) from the liquid state to solid state while filling out the cross-section of the sound channel (6).