The effect of different acoustical treatment in a classroom

Abstract

A common room acoustic measure in classrooms and other common public spaces is a suspended sound absorbing ceiling. However, the acoustical condition in the classroom not only depends on the suspended ceiling. The size and shape of the room as well as the properties of building material and the interior fittings and furniture will also affect the room acoustical conditions. Another circumstance is the non-fulfillment of the conditions for the classic diffuse field theory in rooms with absorbent ceiling treatment due to the non-uniform distribution of the absorbing material. This makes the calculation of room acoustic parameters more complex. This paper addresses the effect of different factors that are of importance for the acoustical conditions in a classroom. Outgoing from the unfurnished classroom without suspended ceiling the effect of introducing a suspended ceiling, adding furniture, adding wall panels, as well as extra low frequency absorption will be exemplified based on measurements in a full scale classroom. The room acoustic parameters that are analyzed are the reverberation time T20, the Speech Clarity C50 and the Sound Strength G. A calculation model adapted for the non-diffuse conditions in rooms with ceiling treatment will be briefly mentioned.