Influence of a measurement threshold level on the calculation of aircraft sound exposure levels

Abstract

A measurement threshold is used to ensure that an aircraft noise event is clearly distinguishable from the ambient sound in automatic aircraft noise monitoring devices. Any noise below the measurement threshold level is not considered when evaluating aircraft noise events. As a consequence, the edges of the level-time curve are cut off, which leads to a different sound exposure level compared to the actual level. The lesser the maximum level exceeds the measurement threshold level, the greater the difference. In this study, the influence of a measurement threshold level on the calculation of the sound exposure level is analyzed theoretically. In order to be able to quantify the differences to the actual levels, only calculated and not measured noiselevels are used for this study.