The Vietnamese sentence test is developed on the basis of linguistics (phonetics, vocabulary, Vietnamese grammar) and audiology (the process of receiving and understanding of the speech signals), consisted of 100 sentences, divided into 10 groups that are phonetic and audiologists balance, each group consists of 10 questions: 4 sentences in medium timbre, 3 sentences in low timbre and 3 sentences in high timbre (4 - 3 - 3 ratio).