Influence of sound source positions and spatial sampling in the measurement of façade sound insulation with large receiving rooms

At present, ISO 16283-3 describes procedures for the measurement of façade sound insulation for room volumes up to 250m3. However, it is common in some buildings (e.g. universities, schools, offices) to find larger room volumes up to 500 m3 where it is necessary to measure the façade sound insulation to check conformity with National regulations or guidance. This paper initially assesses the spatial variation of sound pressure level in a 460m3 university lecture room with a façade that includes windows with a relatively low sound insulation. These results indicate higher levels near windows and standard deviations for the spatial variation that is higher than would be expected for a reverberant field. Consideration is then given to the potential of sub-dividing a large receiving room volume into smaller sub-volumes when taking measurements with different external loudspeaker positions using a 1080m3 computer laboratory as an example.