CAJ | 학술논문

研究了发音评估系统中通用的置信度测度——后验概率算法,针对它存在的不足,提出了两种改进方案.首先,为了降低计算复杂度,传统算法采用了求最大值算法代替求和算法,在被测发音偏离目标音素集的情况下,这会严重降低后验概率的计算精度,本文提出基于扩展的音素混淆网络的后验概率算法.其次,为使置信度能评估不同语音段长的发音质量优劣,传统算法采用了后验概率的段长规整策略,研究分析发现声学似然值与时间的关系更为紧密,所以本文提出了基于声学似然值的时间规整方案.试验结果表明:与传统算法相比,采用改进的置信度算法能使平均打分错误率相对降低35%左右,有效地改善了计算机辅助语言学习系统的性能.
연구료발음평고계통중통용적치신도측도——후험개솔산법,침대타존재적불족,제출료량충개진방안.수선,위료강저계산복잡도,전통산법채용료구최대치산법대체구화산법,재피측발음편리목표음소집적정황하,저회엄중강저후험개솔적계산정도,본문제출기우확전적음소혼효망락적후험개솔산법.기차,위사치신도능평고불동어음단장적발음질량우렬,전통산법채용료후험개솔적단장규정책략,연구분석발현성학사연치여시간적관계경위긴밀,소이본문제출료기우성학사연치적시간규정방안.시험결과표명:여전통산법상비,채용개진적치신도산법능사평균타분착오솔상대강저35%좌우,유효지개선료계산궤보조어언학습계통적성능.
As the most effective confidence measure in computer assisted language learning system, the posterior probability is used widely, in which some tricks are applied to reduce the computation complexity. It analyzes the defect of the traditional algorithm and proposes some improvements. First, the traditional algorithm adopts the method of maximum instead of sum in the calculation of the denominator, which seriously reduces the accuracy of posterior probability. Therefore, taking into account both computation complexity and system performance, it proposes an algorithm based on phoneme confusion extended network. Second, in the traditional algorithm, the posterior probability is normalized by its segment time. In fact, the acoustic likelihood is more related with time and grows with the frame number. So, it proposes the acoustic likelihood based normalization algorithm. The experimental results show that compared to traditional algorithm, the proposed algorithm can improve system performance significantly, about 35% average score error rate relatively, and the computation complexity does not increased.