A hearing device includes a BTE unit and a thin acoustic tube. The BTE unit includes a microphone, an amplifier, a power source, and a receiver and is configured to mount behind or on a user's ear. The tube includes a proximal end and a distal end with the proximal end and the distal end being connected to the receiver and to a flexible mounting insert respectively. The insert comprises a dome shape part and at least one core hole permeable for sound transmitted from the tube, which is configured to arrange in a user's ear canal to transmit sound generated by the BTE unit to a tympanic membrane of the user. The inserts diameter is adapted to at least have the same diameter as user's ear canal diameter to close the ear canal of the user and has at least one internal vent pathway located on the circumference of the core hole.