Ventilation system

A ventilation system comprising:

• a ventilation path;
• and
• a silencer that is disposed at an intermediate position of the ventilation path,
• wherein the silencer includes
• a housing that has an inlet opening and an outlet opening and in which an in-housing ventilation path extending from the inlet opening to the outlet opening is provided inside the ventilation path,
• a sound absorbing member that is disposed in the housing in a state of surrounding the in-housing ventilation path,
• an upstream tube body that forms an upstream ventilation path of the ventilation path, which is on an upstream side of the inlet opening,
• a downstream tube body that forms a downstream ventilation path of the ventilation path, which is on a downstream side of the outlet opening,
• a tubular first connecting portion that is connected to the upstream tube body and that links the upstream ventilation path and the inlet opening to each other, and
• a tubular second connecting portion that is connected to the downstream tube body and that links the downstream ventilation path and the outlet opening to each other,
• each of the first connecting portion and the second connecting portion includes an opening portion therein, and
• the closer to the in-housing ventilation path, the smaller a size of a cross section of the opening portion of at least one connecting portion of the first connecting portion or the second connecting portion.