A hearing aid, in particular a BTE hearing aid, includes a base part and an ear hook which can be attached to the base part. In an assembled state, the base part and the ear hook are connected by a nozzle and a receptacle. A sound channel runs through the nozzle. The nozzle has a circumferential outer wall and the receptacle has a circumferential inner wall. In the assembled state, a circumferential sealing ring having a thickness is disposed between the outer wall and the inner wall. The sealing ring lies in particular in an annular groove and the inner wall preferably has two reduction sections which compress the sealing ring.