Effects of acoustical parameters on speech intelligibility for second language students in classrooms

Abstract

This study addressed the issues of enhancing teaching and learning activities in students' speech intelligibility, which was studied the relationship with acoustical parameters in 20 classrooms in Hong Kong. The speech intelligibility tests in English were conducted with Hong Kong local residential students aged from 12 to 21 in these classrooms. Besides, room acoustic measurements were performed in four listening positions under two different testing conditions in each classroom. The relationships between subjective speech intelligibility scores and acoustical parameters (such as signal-to-noise ratio (SNR), reverberation time (RT), early decay time (EDT), etc.) were discussed based on regression models. The effects of different age groups on the speech intelligibility were compared. The results show that speech intelligibility scores increase with SNR values for all age groups. The speech intelligibility scores increase as the age increases under the same SNR condition. While the differences between ages groups are decreased with the increase of SNR values. The results in this study were compared with the ones conducted in other native language speaking countries. English speech intelligibility scores in Hong Kong are always lower than those native students' speech intelligibility at the same age groups under the same values of SNR. It is mainly because English is not the native language for students in Hong Kong but the official educational language. Better SNR values and better acoustical environment are needed for enhancing teaching and learning activities in classrooms.