The "ACOUSALLE" software allows a first sizing of various indoor spaces (offices, class rooms, small auditoriums, industrial halls etc.) in accordance with the established rules of geometrical, wave and statistical acoustics. It also analyses the users' individual proposals through a built-in expert system. A data bank of the acoustic properties of building materials allows quick calculation of the reverberation time of the planned or existing acoustic spaces. Furthermore, ACOUSALLE can very easily verify the compliance of a given project with the Swiss acoustics regulations.