Acoustic Feature-Based Pronunciation Test On English Stop Consonants

Pronunciation testing, being part of speaking testing, has long been lagged behind other aspects of speaking tests. Little attention is given to the theoretical development as well. The insufficient development of pronunciation tests becomes more obvious upon the backdrop of fast development of speaking test. However, pronunciation test nowadays is now facing more and more favorable situation including the increasing need of pronunciation test and the development of technologies such as acoustic visualization and pronunciation recognition. Three big problems can be identified in pronunciation testing, namely, subjectivity, expensiveness and low efficiency. Interview has high validity in assessing pronunciation, but unavoidable mistakes are embedded in the subjective rating; the cost is also high and one-to-one or even several-to-one direct interview is only making the test less efficient. In terms of consonant testing, the main problems lie in being lack of reasonable rating standards and sufficient, economic and efficient rating methods.To solve these problems, this research proposes an English pronunciation test based on acoustic features. Six English stop consonants are tested and their rating standards and rating methods are discussed. The thesis mainly focuses on the following research questions:1. Can acoustic features of the consonants, i.e. VOT, duration of aspiration, be applied to the test of stop consonants? 2. What are the CAP boundaries for scoring stop consonants by Praat, or provided that there is no boundary, then to what extent CAP can be distinguished by the acoustic features? 3. What problems do Chinese students usually encounter in pronouncing stop consonants?In this study, pronunciations are segmented and acoustic features are extracted by Praat. A comparison between the test participants and standard pronunciation is conducted. Correct, acceptable and problematic pronunciations in both word-initial and word-final contexts are compared and analyzed.The data has shown that it is feasible to apply acoustic features to English pronunciation tests. It is most significant in distinguishing correct pronunciations from incorrect ones in both word-initial and word-final contexts. The biggest problem for Chinese students is the pronunciation of stop consonants, especially the unaspirated stop consonants, in the word-final positions.