An exemplary mouthpiece assembly includes a mouthpiece. The mouthpiece includes a sucking end, a connecting end, and an air passage. The sucking end defines an air outlet, and the connecting end defines an air inlet. The mouthpiece assembly further includes a partition element dividing the air passage into an air intake chamber and an air outlet chamber. The mouthpiece further includes a sidewall defining at least one first through hole and at least one second through hole, the first through hole is in communication with the air intake chamber, and the second through hole is in communication with the air outlet chamber. The mouthpiece assembly further includes an air adjusting ring defining at least one gap. The air adjusting ring is rotatable relative to mouthpiece, to adjust the area of at least one opening formed by some or all of the first through hole, the at least one gap, and the second through hole.
