Written Adding a RegisterBest option would be to add an additional register and vent in the bedroom if the existing central heating and air can handle the load. If this would require upgrading to a large or additional unit, you may want to look at split units.Adding a Split UnitA split unit is made for this type of scenario. It works much like a conventional AC. The key difference is that there is no duct work. A small pipe and electrical connection run from a unit placed on your wall to the small condenser on the outside.The noise would be comparable to a small fan depending upon the model. Since the compressor \ condenser is located outside, this eliminates the main noise culprit.Portable Unit \ Window UnitAny portable unit regardless if it is a window unit or not is going to be extremely loud.Here is a little chart to give you an idea:Subway Station Platform                     100 dBWindow Air Conditioner                       50 dBSplit Unit(Based on Model)           21 - 36 dBConventional AC - New Register     8 - 12 dBOverall, most units, split and portable, list the noise level and you should look for this in the specifications before purchasing whatever solution you choose.

Written If your looking to install an air conditioner in a bedroom you basically have two options:1.  portable air conditioner that will cool the air in the room and expel the hot exhaust air out of a small opening that will sit in the window or vent through a hole in the wall.2. A window air conditioner that will attach to the window frame and cool the room by drawing outside air in, cooling it, then circulating it throughout the room.///ai... there seem to be a couple models that are praised as being decently quiet. I recommend using ctrl+f and searching the webpage for the word quiet, it turns up more than a few times.Written Looking for a quiet air conditioner for bedroom, the first principles of selection the best bedroom air conditioner still apply. The bedroom air conditioner must be sufficiently large (in terms of BTU) to be able to cool the space of the size of your bedroom. Bedrooms get very hot too! Additional requirements for a bedroom air conditioner are the energy saving features such as sleep mode.

The sleep mode will start by bringing the temperature of the bedroom to the desired level, then in a short amount of time, say about an hour, bring the temperature up by a few degrees, and then keep the temperature at that elevated level for 6-7 hours, supposedly while you sleep. best portable ac unitThe sleep mode will then bring the temperature down to the desired, original level, just in time to wake up.general electric hvac unitsThat way, the sleep mode will save you energy while letting you sleep at a higher temperature, which suits the body.how to charge your central ac unitI have investigated the quietest A/C units for bedrooms. In my research, Sharp CV2P10SX with its "Library Quiet" cooling, and Frigidaire FRA086AT7 come out as winners.