The evaluation of the loudspeaker performance requires a measurement of the sound pressure output in the far field of the source under free field condition. If the available test room does not fulfil this condition, it is common practice to generate a simulated free field response by separating the direct sound from the room reflection based on windowing and holographic processing. This paper presents a new technique that performs a filtering of the measured sound pressure signal with a complex compensation function prior to other time and frequency analysis. The influence of room, nearfield and positioning error is compensated in the measured fundamental and nonlinear distortion characteristics. Different methods are presented for the generation of the compensation function based on a reference response measured under anechoic conditions and a test response measured under in-situ conditions. Benefits and particularities are demonstrated by practical measurements using different kinds of test signals. 

Authors: Bellmann, Christian; Klippel, Wolfgang
Affiliation: Klippel GmbH, Dresden, Germany
AES Convention: 143 (October 2017) Paper Number: 9825
Publication Date: October 8, 2017
Subject: Transducers—Part 1

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