Intercomparison Measurements of Room Acoustical Parameters and Measures for Speech Intelligibility in a Room with a Sound System.

Kurt Eggenschwiler, Laboratory of Acoustics, Empa Materials Science and Technology, CH-8600 Duebendorf, Switzerland
Rainer Machner,  Hearing Technology and Audiology, University of Applied Science Oldenburg, D-26121 Oldenburg, Germany

J. Audio Eng. Soc., Vol. 53, No. 3, 2005 March, p. 193-204

Intercomparison measurements of room acoustical parameters and speech intelligibility measures were performed in a 1500 m3 room containing a sound system. The parameters included the octave-band reverberation times T20 and T30 averaged over the entire room, the speech intelligibility indices STI, STI(mod), STI(male), STI(female), RASTI, and %ALcons, the frequency response in one-third-octave bands, and the room acoustical parameters EDT, C80, C50, D50, and Ts at various positions in accordance with ISO 3382. The measurements carried out by 15 participants from Switzerland were compared. As far as can be ascertained, two main factors appear to be responsible for the spread in results. On the one hand, the noise disturbances, at times quite strong, seemed to pose difficulties for the participants. Frequently too little attention was paid to achieving an adequate signal-to-noise ratio. Furthermore, for some measurements the results of certain participants diverged greatly from those of others, partly as a result of incorrect settings of the instruments. In the measurement analysis the standard deviations were compared to the perception thresholds. When the data from a few conspicuous participants were eliminated, the standard deviations were often within the region of the perception thresholds.

Audio Engineering Society

Kurt Eggenschwiler
EMPA Abteilung Akustik
Überlandstrasse 129
CH-8600 Dübendorf
Tel. +41 44 823 41 77
Fax. +41 44 823 47 93
E-Mail: kurt.eggenschwiler@empa.ch