Measurement uncertainty analysis of sound intensity using double-coupler calibration system

•Created plane-wave measurement model to obtain intensity with associated uncertainty.•Detailed experimental and analytical evaluation of component uncertainties.•Revealed contribution of each component uncertainty to combined uncertainty.•Provided a guide to evaluate the uncertainty in sound intensity measurements.•Improved quality of intensity measurements in multi-input measurement models. Currently, sound intensity instrument calibrations consist of a paired microphone phase and pressure calibrations, and the general uncertainty analysis focuses on how to calculate and express the uncertainty in the pressure lever and phase difference. However, no guidance for intensity level uncertainty is available. A significant barrier is the requirement to develop a measurement model that constitutes a relationship between the output quantities and input quantities, known to be the paired microphone pressure levels and phase difference. The Beijing Aerospace Institute of Metrology and Measurement Technology (AIM) is addressing this issue using a double-coupler calibration system, which is the incentive for the systematic evaluation of the associated measurement uncertainty in this study. A set of methodologies based on the plane-wave model is developed for estimating intensity and particle velocity uncertainty for sound intensity instruments.