Investigations on the Influence of Source Directivity for measurements of in-situ Sound Absorption

摘要

The European project QUIESST is dealing with the development of an improved methodrnfor measuring the in-situ sound absorption of noise barriers. In the frame of the activitiesrncarried out in work package 3, the Austrian Institute of Technology has performed severalrnmeasurements in order to investigate the influence of the source directivity on this method.rnDuring a first investigation a directional sound source and an omnidirectional one havernbeen experimentally compared by using different microphone positions and differentrnsetups. After a second measurement campaign the use of an additional free fieldrnmeasurement in a distance of 1.75 m has been proposed in order to overcome the mainrnissues related to the source directivity. The present paper explains the assumptions basedrnon the proposed method and shows the first experimental results comparing different postprocessingrnoptions.