Uncertainties of the frequency response of wet microphone windscreens

During outdoor measurements, specific windscreens are often used to prevent rain water to penetrate into the microphone and to damage its components, but some water can nevertheless remain in the foam of the windscreen. This paper presents an extensive experimental study of the influence of water in the foam of a windscreen on its frequency response. It is concluded that the presence of water inside a windscreen can significantly change the sensitivity of the system only for rain amount higher than 1 mm and for frequency above 1 kHz. Some disparities can be found between the different types of windscreens. Bias correction values, together with uncertainty estimations are given for different types of windscreens and an estimation of the duration during which correction and uncertainty must be applied is also proposed for several types of common windscreens.