Speaker
Description
A recurring issue in standardized building acoustic measurements is determining the number of sampling positions required to achieve a prescribed confidence interval. Although measurement uncertainty can be reduced by increasing the number of samples, practical constraints limit the feasible number of excitation and measurement positions. This paper examines the measurement of the velocity level difference of rigid heavyweight junctions according to ISO 10848-1, currently under revision. Monte Carlo simulations with a wave based model are used to quantify the error and uncertainty associated with different numbers of excitation and measurement positions. While the results are influenced by junction type, transmission direction and plate properties, clear general trends emerge. Increasing the number of excitation positions is most effective in reducing uncertainty, whereas increasing the number of measurement positions beyond four provides only limited additional improvement. General formulations are proposed to determine the required sampling for a specified maximum allowable error or uncertainty. The current ISO 10848-1 requirement for Type A elements, namely a minimum of four excitation positions and three measurement positions per excitation position, appears to be an efficient compromise between accuracy and practical feasibility.