AES New York 2017
Product Development Track Event PD10
Saturday, October 21, 9:00 am — 10:30 am (1E14)
Product Development: PD10 - Is the Anechoic Chamber Obsolete?Presenter:
Christian Bellmann, Klippel GmbH - Dresden, Germany
Anechoic rooms have been considered as an expensive but optimum way for assessing loudspeakers under free field conditions. This tutorial discusses the physical limitations of the room and gives practical advice how to avoid systematic measurement errors. In the second part alternative techniques are discussed that allow to provide measurement results under simulated free field conditions. The tutorial also explains common errors generated when a relatively short window is applied to non-anechoic measurement data to extract the direct sound and harmonic distortion (Farina). The tutorial also shows the new opportunities of the holographic measurements based on near field scanning applied to drivers operated in a baffle and complete system. This technique provides highly accurate reference data which can be used for correcting other measurements performed at a single measurement point under non-anechoic conditions by applying inverse filtering of the microphone signal prior to the signal analysis. This tutorial illustrates the conventional and new method on practical examples.