Noise reduction device for respiratory apparatus

A respiratory apparatus comprising a noise reduction device, wherein the noise reduction device comprises:

• a body configured to be mounted on the respiratory apparatus, the body comprising a side wall and a gas outlet supported by a supporting structure, the supporting structure having a plurality of upright protrusions on an inner surface of the body connecting to the gas outlet;
• and
• a cover configured to be detachably engageable with the body for forming a gas inlet and a gas passage, the cover comprising a guiding member defining at least a part of the gas passage,
• wherein the guiding member is configured to be coupled with the side wall of the body to form the gas passage between the body and the cover;
• and
• wherein the body is arranged to house a filter therein, the plurality of upright protrusions on the inner surface of the body being configured to support the filter, and the filter is sandwiched between the guiding member and the plurality of upright protrusions provided on the inner surface of the body.