Fans and sound waves

Will fans restrict sound from traveling through an air duct. I'm planning on putting a heat and air duct to my drum room and wondering, if I put a fan in the duct blowing into the room, if it might keep some of the sound from traveling back through the duct. I plan on hooking it up to the lights so when I turn on the lights on the fan will come on, like a bathroom vent, only it will blow into the room. Any ideas on this?

Real world difference will be minimal. Sound waves travel much faster than the air travelling in the opposite direction. You'd be much better off not having the vent in the wall.

Sound is a variation in air pressure. Pressurizing the duct will attenuate it by the differential. In real world, not a lot. There are absorbent materials HVAC people use to quiet ductwork but that is mostly high frequency fan noise. Low frequency rumble is usually handled by isolation with rubber rings joining the ducts. The only way to attenuate airborne noise going though the duct is with absorbent baffles. Your create a labyrinth that the air goes though where the panels are covered with some sort of absorbent material. Note that this significantly increases the back pressure.

In my studio I have flexible insulated ducting. The inner surface is absorbent and a few bends tends to attenuate a lot. All this feeds into a separate doghouse outside the studio where an air conditioner either cools or heats the air and pumps it back into the room. There is a lot of CFM loss in the length of the duct but it works reasonably well and is quiet. Both what leaks out and the noise of the AC inside.

Thanks guys. I thought I would get some intelligent answers here. I was planning on using flexible duct tubing, but I never considered making it longer and snake shaped. Sounds like a good idea.