In June 2011, Polish Section of the Audio Engineering Society will celebrate its 20th anniversary. On this occasion, the society officers, ending their second, two-year term, present a short summary of the Section's activity during the past four years. The Section's structure comprises the main unit - that is the Polish AES section, and three student sections, associated with the Department of Multimedia Systems at the Gdansk University of Technology, the Chair of Acoustics at the Wroc?aw University of Technology, and the Department of Mechanics and Vibroacoustics at the AGH University of Science and Technology in Cracow. The latter section began its activity only last year. In addition to formal student sections, in the activities of the Polish AES Section also participate students of the Department of Sound Engineering, at the The Fryderyk Chopin University of Music in Warsaw, and students of the Department of Elecroacoustics, at the Warsaw University of Technology.

The purpose of the study was to compare auditory judgments of sound clarity of music examples recorded in a concert hall with predictions of clarity made from the impulse response signal recorded in the same hall. Auditory judgments were made with the use of two methods: by rating sound clarity on a numerical scale with two endpoints, and by absolute magnitude estimation. Results obtained by both methods were then compared against the values of clarity indices, C80 and C50, determined from the impulse response of the concert hall, measured in places in which the microphone was located during recording of music examples. Results show that auditory judgments of sound clarity and predictions made from the C80 index yield a similar rank order of data, but the relation between the C80 scale and perceived sound clarity is nonlinear. The data also show that the values of C80 and C50 indices are in very close agreement.