عنوان مقاله [English]
Exposure to noise pollution in closed occupational and non-occupational places can cause disturbances in human well-being, comfort and health. The sound pressure level index (Lp) inside the building is affected by the sound power of sources outside and inside the building and the resonance caused by the reflection of the internal surfaces. The amount of sound energy inside the building caused by these real sources inside and outside the building is determined. In order to determine the effect of internal reflective surfaces as a virtual source of sound, on the amplification of energy in the closed environment and consequently the amplification of the sound pressure level, it is necessary to provide models for the prediction of the final sound pressure level. The existing calculation models show that the control intervention on the internal surfaces of the building through sound absorbing materials can theoretically reduce the ambient noise up to 30 dB and objectively up to 20 dB. So far, no valid model has been presented to separate the role of the interior surfaces of the building in the amount of sound amplification of the total of real sources. In this article, while introducing the acoustic analysis indicators inside the building, the room index (RI) is introduced to determine the role of the virtual source in the sound amplification inside the building, and an experimental model is presented to determine this index.