Central Controlled Residential Ventilation: Supply and Exhaust Air, Door Bottom Gap

See e.g. in #23. Otherwise, search for "pressure relief valve for wall installation," the manufacturer should be able to specify the sound insulation. Or pressure relief over the door frame (google it, must be made by the carpenter/door builder, you will not be guaranteed to get a sound insulation rating), or "innoperform pressure relief seal" for the door (google it).