How To Reduce Noise From Air Conditioning Unit

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Air conditioning units can be noisy sometimes, due to the unit itself or to it's particular position around the house. The noise will increase by bouncing to itself if the houses are close to each other or if the A/C unit is near an internal corner. We could build a fence around the A/C unit but as far as possible, at least a meter away if not more because it generates hot air, trapped, recycled and will reduce the performance of the unit as well as increasing electricity consumption. One option is to provide acoustic treatment on the fence. If the fence is high enough we can get away by using only the mass loaded vinyl directly fixed on the fence but adding sound absorbers will increase the efficiency of the system.
I've used a mass loaded vinyl 8kg/m2, the heavier the better, with STC 32, means 32db sound reduction in theory; knowing that 10db is reducing the sound by half, we are halving three times the noise, even more by using the sound absorbers.