A detecting device comprises a band member (1) that is passed around a torso region that widens and narrows in response to respiration of a person to be examined. The band includes a structure configured as buckle member (2) and is loaded upon narrowing and widening of torso region to causes a change in the volume of a measuring space device (3) depending on a tensile forces acting on the band member. An independent claim is included for a measuring arrangement comprising the detecting device, a measuring tube and a measuring device.
