INFLUENCE OF WALL SURFACE AND AIR MODELLING IN FINITE-ELEMENT ANALYSIS OF SOUND TRANSMISSION BETWEEN ROOMS IN LIGHTWEIGHT BUILDINGS

摘要

Noise is a nuisance in the built environment, and to avoidundesirable transmission of sound and vibration within abuilding, its vibro-acoustic performance must be addressed inthe design phase. For heavy structures, a reliable assessment ofthe sound pressure levels can be made by statistical energyanalysis—especially at high frequencies. However, for lightweightbuildings a numerical approach, e.g. the finite-elementmethod, must be applied. A problem in this regard is thecomputational complexity. Even at low frequencies, manydegrees of freedom are required in a model accounting for allpossible paths for transmission of sound in a building—inparticular when finite elements are employed for the air. Thispaper examines whether a rigorous model of the acoustic fieldin each room is necessary in order to obtain accurate estimatesof the sound pressure, or if a simpler approach may be adopted.Five different cases are compared: A model that only includesthe structure, a model with semi-infinite elements to accountfor radiation from the structure into the air, a model introducingfinite elements for the acoustic field, a model with dissipationof sound inside the room, and finally a model with soundabsorption on the surfaces of walls, floors and ceilings.