REDUCTION OF THE STRUCTURAL NOISE OF AN OUTDOOR AIR CONDITIONER IN A RESIDENTIAL BUILDING

The outdoor units of the air conditioner of a cell phone amplifier station were mounted on the roof (attic) ceiling of a residential brick building. The residents that live in the apartment under the outdoor unit complain about high noise levels. By a local study, carried out in the building, we measured the noise generated in the residential room, the structural-noise component of the immission noise and the way of propagation of that noise. The machine foundation of the outdoor unit had insufficient vibration and structural noise absorption. This insufficient nature of the machine foundation was the cause of the high noise. We designed a modified machine foundation on the ceiling, which provided sufficient protection against structural noise. This modified foundation achieved a noise reduction of Delta L-Lambda = -10dB in the residential room.