The present invention provides a negative pressure generator comprising a vacuum pump having an intake end and an exhaust end, a soundproofing module having a compartment for accommodating the vacuum pump, the soundproofing module being configured to insulate noise and vibration generated when the vacuum pump is in operation, and a silencing tube module comprising a flexibly intake tube having one open end communicating with the intake end of the vacuum pump and a flexible exhaust tube having one open end communicating with the exhaust end of the vacuum pump, the silencing tube module being configured to reduce noise generated at the intake end and/or the exhaust end of the vacuum pump when the vacuum pump is in operation. The negative pressure generator can provide a vacuum source to an oral interface device to favorably create a negative pressure environment in a users oral cavity so that the patency of the users upper airway is maintained.
