Who makes the quietest AC unit?

The quietest AC units are made by Lennox, Carrier, Trane, and Daikin, with Lennox and Carrier often rated as the quietest by decibel measurements and consumer reports. Lennox is particularly known for quiet operation, with its Signature Collection SL28XCV variable-speed air conditioner operating as low as 59 decibels, which is about as loud as a quiet conversation, thanks to SilentComfort technology, insulated compressor compartments, and variable-speed fans that avoid loud on-off cycling. Carrier Infinity series with Greenspeed variable-speed technology is also extremely quiet, operating around 58 to 65 decibels on low speed, with similar noise reduction features. Trane XV and XL variable-speed models are also very quiet, around 55 to 75 decibels depending on speed, using Climatuff compressors and insulated cabinets. Daikin FIT and Goodman GVXC variable-speed side-discharge units are also among the quietest, with sound levels as low as 56 decibels due to their unique compact design and variable-speed inverter technology. Quiet operation comes from variable-speed inverter compressors that run continuously at low speed rather than loudly cycling on and off, as well as insulated compressor blankets, swept-wing fan blades, and vibration isolation. For absolute quietest, Lennox SL28XCV and Carrier Infinity 26 are often cited as top choices, but any premium variable-speed model from these brands will be much quieter than basic single-stage units.