Evaluation of measurement value and uncertainty of sound pressure level difference obtained by active device noise reduction

Acoustic insulation of a device from the environment can be enhanced by appropriate control of its casing vibrations. The level of noise reduction obtained in such way is considered as the main point for evaluating the performance of the active control system, hence its appropriate measurement constitutes a vital issue. In this study, measurement uncertainty evaluation of the sound pressure level difference is presented. Three independent components of the Type A evaluated uncertainties are derived. Many sets of conducted experiments allow to estimate the components, while information read from the calibration certificate of the employed sound level meter allow to estimate the Type B components. Prepared uncertainty budgets show that the most contributing source is the location dependency. Recommendations for appropriate performance measurement of an active control system are stated basing on the obtained results.