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Reduction of comb-filter effects by alternating measurement orientations in automotive environments

: Hess, W.; Beyer, T.; Schoeffler, M.

Informationstechnische Gesellschaft im VDE:
Speech Communication : 11. ITG-Fachtagung Sprachkommunikation, 24. – 26. September 2014 in Erlangen, CD-ROM
Berlin: VDE-Verlag, 2014 (ITG-Fachbericht 252)
ISBN: 978-3-8007-3640-9
4 S.
Fachtagung Sprachkommunikation <11, 2014, Erlangen>
Fraunhofer IIS ()

Loudspeakers in car cabins often are installed in positions primarily regarding design aspects. Acoustical aspects are mostly subordinate. For this reason loudspeakers frequently radiate against a window, the dashboard or the rear shelf, also a radiation to the floor room is common. Acoustical reflections at short distances causing interferences of direct and reflected sounds are the main reason for comb-filter effects at the listening position. For the measurements in this work two stimuli were used: a pseudorandom pink noise, recursively averaged over 15 seconds, when the measurement position was changed, and a sine sweep when the position was fixed during the measurement process. Both, microphone movements and head movements, lead to a robust averaging of the measured magnitude response, reducing significantly both the variations in the response and the comb-filter effects in the car cabin. Frequency responses measured by the process described here require less filtering effort to equalize the loudspeakers in the car cabin.