If sound traveling from room to room through the ducts is a problem you can reduce the noise by treating the ducts.
Reduce noise entering room.
An advanced method for achieving noise isolation is to construct a room within a room using decoupling techniques which is a rather major proposition but extremely effective.
While most types are designed to stop noise from bouncing off hard surfaces others are very effective at blocking racket from entering through a door or window.
Traditionally to reduce noise transfer between rooms you d use a resilient channel.
The easiest way to prevent sound from entering or leaving a room is to seal any gaps.
Doing this can take time but is well worth it.
For example the acousticdoor from residential acoustics is a retractable panel that can reduce noise transmitted through an entrance like your bedroom door by 30 decibels.
When soundproofing a room start with the walls.
Wall panels are the perfect acoustic shield which can successfully protect you from the noise coming from the outside and reduce echo in the room.
Arrange furniture against the walls to reduce noise entering the room.
However the more money you re willing to spend on a project the better a job you ll do.
The fabric and material of the furniture will absorb sound waves coming in and help to reduce the noise in the room.
If you share a wall with a loud neighbor or if you have a lot of ambient noise coming into your room from outside line your couches and chairs against the wall.