band 23 defining a through passage 24 for receiving the breathing gas duct 5 the forehead support element 6 also has connecting members 7 which u2014 as already indicated with reference to fig1 u2014 serve for the further connection of a forehead band the electrode elements 9 10 and 11 are again fitted in the region of the contact surface 8 of the forehead support element 6 the electrode elements 9 10 and 11 can be repeatably applied in an accurate position in the forehead region of the corresponding patient as a consequence of the breathing mask being coupled to the forehead support element 6 fig5 indicates in a simplified manner the fashion in which the individual electrode elements 9 10 and 11 are coupled to the signal processing device 16 by way of the connecting lines 14 17 and 18 in this case the signal processing device 16 includes a directly connected data transmission device 24 by way of which the measurement data obtained can be cordlessly forwarded to a suitable system for further processing in the embodiment illustrated here all of the specified components are sealingly embedded in the base member of the forehead support element 6 the base member being formed from an elastomer material fig6 a shows a particularly preferred embodiment of the signal processing device 16 which is here accommodated in an outer casing 25 and has a plurality of contact.