Abstract: A respiratory therapy device comprises a respiratory air channel having a narrowing that has a variable passage cross section, a pressure sensor designed and arranged to detect the value of a pressure prevailing within the respiratory air channel, an adjustment apparatus designed and arranged to change the passage cross section of the narrowing, a control apparatus having a signal input for supplying the pressure value detected by the pressure sensor and a signal output for outputting an adjustment signal to the adjustment apparatus, wherein a portion of the wall defining the respiratory air channel is formed by a resilient hose piece, and wherein the adjustment apparatus acts on the resilient hose piece from the outside in order to change the passage cross section thereof.