针对2、4、6 年级学生( 7 ～ 12 岁儿童) 在9 所小学的28 间教室进行汉语语言清晰度主观评价，并测量听音位置的房间脉冲响应和背景噪声，计算不同听音条件下不同听音位置的不同早期声能时间限值的有益有害声能比U_t，从而得到不同年龄段儿童的主观汉语语言清晰度得分与有益有害声能比之间的关系． 结果表明: 对不同年龄段的儿童而言，早期声能时间限值为50ms 和80ms 时的有益有害声能比( U₅₀、U₈₀ ) 均能较好地评价儿童教室室内汉语语言清晰度;在相同的有益有害声能比条件下，儿童主观汉语语言清晰度得分随着年龄增加而增加; 2、4、6 年级儿童在教室内达到95%的汉语语言清晰度得分需要的U₅₀值分别为7． 4、4． 5、2． 8 dB．

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.