Reduction of Comb-Filter Effects by Alternating Measurement Orientations in Automotive Environments

Conference: Speech Communication - 11. ITG-Fachtagung Sprachkommunikation
09/24/2014 - 09/26/2014 at Erlangen, Deutschland

Proceedings: Speech Communication

Pages: 4Language: englishTyp: PDF

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Authors:
Hess, Wolfgang; Beyer, Thure (Fraunhofer Institute for Integrated Circuits IIS, Am Wolfsmantel 33, 91058 Erlangen, Germany)
Schoeffler, Michael (International Audio Laboratories Erlangen, Am Wolfsmantel 33, 91058 Erlangen, Germany)

Abstract:
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.