Speech intelligibility enhancement by early reflections


  • Iris Arweiler Centre for Applied Hearing Research, Department of Electrical Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark
  • Jörg Buchholz Centre for Applied Hearing Research, Department of Electrical Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark
  • Torsten Dau Centre for Applied Hearing Research, Department of Electrical Engineering, Technical University of Denmark, DK-2800 Lyngby, Denmark


Early reflections in a room can improve speech intelligibility for normal-hearing listeners, because the auditory system integrates them with the direct sound which results in an increased speech level. The present study investigated the underlying mechanisms involved in early re ection processing. Monaural and binaural speech intelligibility tests were performed with 9 normal- hearing listeners in a loudspeaker-based virtual auditory environment where the amplitude of the direct sound and the early reflections could be varied independently. The re ection pattern was taken from a classroom simulated with the room acoustic software Odeon [Odeon (2008)]. The Danish sentence test Dantale II [Wagener, Int. J. Aud. 42, 10-17 (2003)] was used. The sentences were presented from the loudspeaker at 0° azimuth and speech intelligibility was measured with a diffuse speech shaped noise (SSN). Different signal-to-noise ratios were obtained by changing either the direct sound level or the early reflection level of the speech signal. Increased early reflection levels improved speech intelligibility but the effect was smaller than for increased direct sound levels. No binaural processing of early reflections other than a summation of the signals at the two ears could be observed for the diffuse SSN interferer.


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How to Cite

Arweiler, I., Buchholz, J., & Dau, T. (2009). Speech intelligibility enhancement by early reflections. Proceedings of the International Symposium on Auditory and Audiological Research, 2, 289–298. Retrieved from https://proceedings.isaar.eu/index.php/isaarproc/article/view/2009-29



2009/3. Speech processing and perception under adverse conditions