Korelasi Empirik Waktu Kerdam dan Kebisingan dengan Speech Intelligibility dalam Ruang Kuliah Jurusan Sastra Inggris Fakultas Sastra dan Seni Rupa Universitas Sebelas Maret

Abstract

This research is conducted to evaluate empirical correlation of speech intelligibility with the conditions of background noise and reverberation time. Sound pressure of source is measured as signal to noise ratio (SN) and reverberation time (RT) is measured in actual class rooms in building of faculty of English Letter Department of Sebelas Maret University.

            SN is measured with SPL meter using dBA and dBC modes in order to determine gross dominant frequency of background noise. RT is evaluated using impulse method according to the ISO Standard 3382 (1997). Data records impuls and the responses of room are acquired in personal computer and evaluate with digital signal processing program. The development of program is part of this own researcher. Output of program is plot of SPL against time and then it is used to determine the room’s reverberation time (RT₃₀).

            Measurement and analysis which conducted in this research conclude that empirical correlation SI with SN and RT for specified rooms is according to SI (%) = 0,2774 SN + 0,2774 RT₃₀ (500 Hz) – 69,258%. Value of SI determines the acoustic condition of class room to provide students good hearing condition for every words of the lecturer spoken. Higher SI means class room is suitable for learning activities and the lower SI is considered not suitable and not comfortable for learning activities. By the equations, SI could be improve by adjust RT and decrease background noise.