Air conditioners can contribute a great deal to the noise level in your house. The amount of noise depends on the age of the machine, the type of air conditioner and its condition. Generally, expect older machines to be noisier. The decibel levels may go up as the older machines wear out, and newly designed air conditioners are built with noise reduction in mind.

Central air conditioner
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Outdoor air conditioners are often as loud as 80 or 90 decibels.

Understanding Decibels

Decibels indicate the volume of a given sound based on a logarithmic system. Basically, a 10-decibel differential equals a sound twice as loud as the sound 10 decibels lower. Noise at 60 decibels, which would be roughly the loudness of a loud window air conditioner, seems twice as loud as something at 50 decibels. To achieve this doubled sense of loudness, a sound 10 times more intense is required, which is why the doubling occurs every 10 decibels.

Air Conditioner Decibels

On average, air conditioners run through the same range of noise levels as the dishwashers but are often perceived as quieter because decibels are related to distance. If you're in the kitchen when the dishwasher runs, it will sound as loud as 60 decibels. An air conditioner won't sound that loud unless you're standing right next to it. Local ordinances regulate how loud an air conditioner can be. In the city of Los Angeles, for example, an air conditioner can't be more than 5 decibels louder than the ambient noise.

Sound Range

Air conditioner decibel levels range widely. A very quiet air conditioner might only make around 25 decibels of noise, which is just louder than a whisper. Portable air conditioning units get as loud as 55 decibels. This is slightly louder than a normally humming refrigerator, which is typically around 40 decibels.

Decibel Ratings

Air conditioner manufacturers give the machines a decibel rating, which is listed on its label. The decibel rating typically describes the sound output heard by a person standing near the air conditioner in a noninsulated setting. Air conditioners with a high cooling output often produce high decibels. Some air conditioners equipped with special sound reduction technology are also more expensive than regular conditioners. Sound insulation and distance will reduce the perceived loudness.

Quieting Air Conditioners

Steps can be taken to reduce the noise produced by air conditioners. Window models should have a shield with a layer of sound-absorbing foam mounted on the outside of the air conditioner. If you have central air, covering your ducts with closed-cell foam helps reduce noise levels. If an outdoor air conditioner is making extra noise, a sound-blocking wall and insulating blankets between the unit and the nearest point of entry, such as a window, could solve the problem. These measures can reduce the sound level of air conditioners by as much as 10 decibels.