The dependence of subjective acoustic indicators on frequency and position of the sound source

Abstract

The values of C50 and C80 indexes is slight at the front of the hall but it is considerable in the middle and at the back of the hall. As the distance between the orchestra and the listener is increased, the values of the C80 index decrease from 0 dB in the front rows to –8 dB in the back rows. When the organ is playing, the change in the index values is not so significant: from –8 to –12 dB. The largest difference in C50 and C80 indexes is seen in the front rows, with large negative values. In the middle and back rows, the values of this different become positive and almost stable. When the orchestra is playing, the variation of the low frequency index C80 (3L) is slight in the front rows is slight but they decrease sharply as the distance from the sound source S1 becomes larger. In case of organ music the values of the index are only negative and are almost not dependent on the listeners’ position. The character of change in the high frequency index C80 (3H) is similar to that of the C80 (3L). When the orchestra is playing the values of the time centre of gravity are relatively low in the front rows but they increase as the distance from the sound source becomes larger. In case of organ music the largest values are obtained in the front rows and they increase along with the increasing distance from the sound source.