Room Acoustics Calculator. The Room Acoustics Calculator enables you to design the acoustics of a room according to DIN 18041 and ÖNORM B 8115-3. After the usage and the appropriate standard have been selected the calculator derives the relevant design quantities, tolerance ranges or limits, and the corresponding state of the room (furnished, unfurnished, occupied or unoccupied). Where a room is required to provide good audibility over greater distances, such as, for example, in a lecture hall, both standards require compliance with a reverberation time T within a given tolerance range. Www.bobgolds.com/Mode/RoomModes.htm.