Abstract:

In the investigation,subjective Chinese speech intelligibility was evaluated by the students from grades 2,4 and 6 ( nominally seven to twelve years old) in 28 classrooms of nine elementary schools.At the same time，boththe room impulse response and the background noise level were measured at the same time and the useful-to-detrimentalsound ratios ( U_t) with different early sound limits were calculated under different listening conditions at eachlistening position in these classrooms.The relationships between the subjective Chinese speech intelligibility scoresand Ut for different age groups were also obtained.The results indicate that Ut with the early sound limits of 50ms and 80ms,namely U₅₀ and U₈₀,can achieve better evaluation of the Chinese speech intelligibility in the classrooms forchildren of different age groups,and children's Chinese speech intelligibility scores increase with the age under thesame condition of U₅₀ .In addition,in order to obtain a Chinese speech intelligibility score of more than 95%,the U₅₀ values for the children from grades 2,4,and 6 are required to be respectively more than 7.4,4.5 and 2.8 dB.

Key words: Chinese speech intelligibility, useful-to-detrimental sound ratio, elementary school classroom, children