A respiratory ventilation device intended to send an air flow, generated by a fan, into a conduit, with the conduit extending between the device and a respiratory mask intended to be used by a user, the device comprising an enclosure extending around a longitudinal axis and comprising: - an air inlet intended to admit air into the enclosure; - an upstream air circulation zone extending between the air inlet and the fan; - an air outlet, the air outlet being configured to be connected to the conduit, so that, when the fan operates, air successively flows from the air inlet through the upstream air circulation zone, the fan and the air outlet, the device being such that: - the fan is arranged in a ventilation chamber; - the ventilation chamber is retained by a first flexible membrane extending between a first periphery (41 6) and the ventilation chamber, the first periphery being fixedly retained relative to the enclosure, the first membrane defining a first central opening, through which the ventilation chamber, or a support connected to the ventilation chamber, extends; - the device being characterized in that: - the ventilation chamber is retained by a second flexible membrane, separate from the first membrane, the second membrane extending between a second periphery (42 6) and the ventilation chamber, the second periphery (42 6) being fixedly retained relative to the enclosure at a non-zero distance from the first periphery (41 6), the second membrane comprising a second central opening (42 5), through which the ventilation chamber, or a support connected to the ventilation chamber, extends. - an air inlet intended to admit air into the enclosure; - an upstream air circulation zone extending between the air inlet and the fan; - an air outlet, the air outlet being configured to be connected to the conduit, so that, when the fan operates, air successively flows from the air inlet through the upstream air circulation zone, the fan and the air outlet, the device being such that: - the fan is arranged in a ventilation chamber; - the ventilation chamber is retained by a first flexible membrane extending between a first periphery (41 6) and the ventilation chamber, the first periphery being fixedly retained relative to the enclosure, the first membrane defining a first central opening, through which the ventilation chamber, or a support connected to the ventilation chamber, extends; - the device being characterized in that: - the ventilation chamber is retained by a second flexible membrane, separate from the first membrane, the second membrane extending between a second periphery (42 6) and the ventilation chamber, the second periphery (42 6) being fixedly retained relative to the enclosure at a non-zero distance from the first periphery (41 6), the second membrane comprising a second central opening (42 5), through which the ventilation chamber, or a support connected to the ventilation chamber, extends. - the fan is arranged in a ventilation chamber; - the ventilation chamber is retained by a first flexible membrane extending between a first periphery (41 6) and the ventilation chamber, the first periphery being fixedly retained relative to the enclosure, the first membrane defining a first central opening, through which the ventilation chamber, or a support connected to the ventilation chamber, extends; - the device being characterized in that: - the ventilation chamber is retained by a second flexible membrane, separate from the first membrane, the second membrane extending between a second periphery (42 6) and the ventilation chamber, the second periphery (42 6) being fixedly retained relative to the enclosure at a non-zero distance from the first periphery (41 6), the second membrane comprising a second central opening (42 5), through which the ventilation chamber, or a support connected to the ventilation chamber, extends. - the ventilation chamber is retained by a second flexible membrane, separate from the first membrane, the second membrane extending between a second periphery (42 6) and the ventilation chamber, the second periphery (42 6) being fixedly retained relative to the enclosure at a non-zero distance from the first periphery (41 6), the second membrane comprising a second central opening (42 5), through which the ventilation chamber, or a support connected to the ventilation chamber, extends.