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