1. Introduction

Emphasis was placed on the importance of rhythm in second language acquisition, pointing out that intonation is a challenge for Chinese English learners. Existing research focuses more on syntactic acquisition, while there is relatively little research on intonation training and a lack of consideration for neural mechanisms. This study aims to explore the effects of explicit and implicit training on Chinese learners' English intonation acquisition and its relationship with memory through experimental phonetics methods and DP model.

2. Literature review

Firstly, the DP model was introduced, which suggests that adults and children rely on two different memory systems, declarative memory and procedural memory, during the learning process. Declarative memory grows in early adulthood, stabilizes in mid adulthood, and declines in late adulthood; Procedural memory remains stable in childhood and adulthood, but declines in old age. The psychological lexicon processing and acquisition of native speakers mainly rely on declarative memory, while the learning of syntax, speech sound categories, vocalization and speech production, as well as the perception of speech, mainly rely on procedural memory. Adult second language learners tend to rely on declarative memory to acquire a second language, but for complex syntactic phenomena, relying solely on declarative memory is difficult to reach the level of native speakers. The DP model also points out that learning environment and training methods can affect second language learners' dependence on two types of memory. Classroom teaching environment, explicit guidance, and attention to input stimuli can promote knowledge learning in declarative memory, while immersive learning environment, implicit guidance, and attention inhibition to input stimuli can shift learning towards dependence on procedural memory.

3. Research methods

This study selected first-year non English major students as participants, excluding those who had received phonetic training or had studied abroad. They were randomly divided into an explicit group and an implicit group, and there were no significant differences in age, years of English learning, and English proficiency between the two groups. The training corpus includes declarative sentences and general interrogative sentences, with the use of introductory sentences to achieve changes in broad focus and narrow focus. The experimental process includes pre-test, training, post test, and delayed post test, using xPerception software for training and testing. The explicit group participants will see sentence text and corresponding intonation maps during training, while the implicit group only sees text. The training effect is evaluated based on three aspects: core stress position, stress implementation method, and boundary tone.

4. Data analysis

In the data analysis section of the paper, it was found through two factor analysis of variance that testing time has a significant impact on English intonation acquisition, while the impact of training methods (explicit or implicit) is not significant, indicating that both training methods are effective. Further multivariate analysis of variance showed that there was a significant interaction effect between the training method and the focal position in terms of core stress location, especially in the focal position at the beginning of the sentence, where explicit training had a better effect. In terms of stress implementation, the main and interactive effects of the training method are significant, and explicit training performs better at the beginning and focal position of general interrogative sentences. The analysis of boundary tone shows that the interaction effects of training methods, sentence patterns, and focal positions are close to significant, and implicit training has slightly better results at the focal position at the beginning of the sentence. Delay post test analysis shows that the training effect is persistent, but there is no significant difference between the two groups. Finally, the relationship between training methods and memory was explored through multiple linear regression models, and it was found that implicit training was positively correlated with working memory and procedural memory, and negatively correlated with declarative memory; The trend of explicit training is opposite to that of declarative memory and procedural memory. These results reveal the roles of explicit and implicit training in second language intonation acquisition and their complex relationship with the memory system.

5. Discussion

Both explicit and implicit training can improve Chinese learners' English intonation acquisition, but there are differences in their effectiveness. Explicit training is more effective in general interrogative sentences at the beginning and focus of the sentence, helping learners grasp the core stress positions and implementation methods through capitalization prompts and intonation maps. Implicit training is slightly inferior to explicit training in the persistence of core stress positions. Explicit training promotes intonation acquisition by enhancing phonological awareness, while implicit training relies on procedural memory and working memory. Future research should explore a combination of explicit guidance and implicit training to more effectively promote intonation acquisition.

6. Conclusion

Experimental phonetics research shows that both explicit and implicit training can improve Chinese learners' English intonation acquisition, but the effect is influenced by sentence patterns and focal positions. Explicit training is more effective in the beginning and middle of interrogative sentences. The training effect is long-lasting, but the implicit training persistence is slightly weaker. Intonation acquisition relies on perceptual accuracy, and visual presentation of acoustic cues helps with acquisition. Implicit training is positively correlated with procedural memory and working memory, explicit training is positively correlated with declarative memory, and procedural memory is negatively correlated. Successful intonation acquisition may require a combination of explicit guidance and implicit training.