Air Conditioners and Heat Pumps. There's a good chance you won't ever think about the sound level of your air conditioner or heat pump ... until, that is, you try to enjoy a quiet conversation with some friends in your back yard. Sometimes noise from condensing (outdoor) units even interferes with your peace and quiet indoors, so it's a factor you should at least look at when you're comparing different models.
The sound level of outdoor units is measured in bels (similar to decibels), on a scale from 0 (barely perceptible sound) to 13 (the threshold of pain). Most air conditioners and heat pumps operate at 8 to 9 bels; some units' ratings are as low as 6.8. That may not sound like a wide range, but consider this: 9 bels sounds 10 times louder than 8 bels. That means one 9-bel air conditioner is as loud as 10 units rated at 8 bels. So we at Clark's think taking the time to compare bel ratings is pretty "sound" advice.
