| Both frequency and explicit instruction are believed to play important roles in the language learning classroom. Although some research has been conducted on their effects on the oral English learning, not enough empirical studies have been conducted on the learning of suprasegmental features. This dissertation reported a study that explored the effects of frequency effects and the effect of explicit instruction on EFL learners’ production of English stress patterns.Stress is a property of syllables that makes them stand out as more prominent than others. In one tone group, there is almost always a peak of stress called "tonic stress" or "nucleus." Nuclear stress is normally found in a content word in utterance-final position. It can also be found in other positions. Stresses other than tonic stress are called non-nuclear stresses. The rest of the syllables are unstressed syllables. The different distributions of stress directly affect the rhythmic features of English.It is believed by many that misuse or inappropriate use of stress patterns can lead to problems in understanding. The learning of appropriate stress patterns, therefore, seems essential before a second language learner can have successful communication with native speakers. Chinese EFL speakers are often described as producing less differentiation between stressed and unstressed syllables and stressing more syllables than do native speakers. Previous studies on the learning of English stress patterns by Chinese EFL learners have involved descriptive analysis of learners’ speech patterns. Chen (2005) has studied the nuclear stress placement by Chinese EFL learners and Bi (2009) has examined the development of stress patterns of some Chinese EFL learners. Yet they have not touched upon the effect of explicit instruction on the learning of stress patterns. More studies are needed to enrich our understanding of the process of learning English suprasegmental features.The present study explored the frequency effects and explicit instruction on12first-year English majors’ command of stress patterns within a tone group. The treatment materials consisted of quasi-spontaneous dialogues between native speakers. The imitations of learners were examined for stress placement, the contrast between syllables of different prominence levels and the rhythmic features. The participants received treatment at two stages. At Stage One, they listened to and imitated the native model dialogues for different times. At Stage Two, in addition to repeated listening and imitation, they also received teacher instruction on the necessary information on English stress patterns. Recorded data were analyzed acoustically. An analysis of the recordings revealed the following findings:1. Repeated listening and imitation is found to have affected the participants’stress patterns in various ways. Before such treatment, there was an overuse of stress on syllables regardless of their information status. The treatment produced some limited effect on the stress patterns, but it had almost no effect on the problem of placing stress on copula "be" and some of the function words. The treatment can only help learners improve the correctness rates of the placement of unmarked nuclei but not those of the placement of marked nuclei. Although there was some improvement made in the non-nuclear placement, the improvement was not seen on all the sentences.With regard to the contrast between nuclear and non-nuclear stresses, the treatment may have helped the learners make negligible progress in the pitch ratio and limited progress in the duration ratios of nuclear to non-nuclear stressed syllables. As for the contrast between the stressed and unstressed syllables, the treatment seemed to help them make improvement in the mean duration ratios but failed to help them make improvement in the mean pitch ratios of stressed to unstressed syllables.Repeated listening and imitation does not have any effect on the duration of inter-stress intervals (ISIs). With continued treatment, no progress could be observed in terms of inter-stress intervals.The treatment produced some improvements in the proportion of vocalic intervals (%V) and variability of vocalic intervals (nPVI). Some limited progress was also made in consonantal variability (AC).2. Repeated listening and imitation accompanied by teacher instruction can improve the correctness rates of the stress placement. It can improve the stress placement for sentences of various lengths. It can enhance the participant’s consciousness of the stressed and unstressed syllables. The instruction pushes learners to pay attention to the way native speakers stress words and reduce stress on those words that are not supposed to be emphasized.Teacher instruction can help learners make noticeable improvement in the mean syllable durations. As a result, the duration ratios of nuclear to non-nuclear stressed syllables and stressed to unstressed syllables can get closer to those of the native speaker.Teacher instruction can lead to greater improvement in pitch ratios than mere listening and imitation. The pitch ratio of the nuclear to non-nuclear stressed syllables and the ratio of stressed to unstressed syllables were both raised and thus closer to those in the speech of native speakers.Repeated listening and imitation accompanied by teacher instruction appears advantageous over mere listening and imitation in helping learners make progress in inter-stress intervals. Before receiving teacher instruction, almost all the durations of ISIs were longer than those of native speakers. After the instruction, the participants often produced shorter ISIs. In contrast, for those who continued to listen and imitate without teacher instruction, there was only limited improvement.Repeated listening and imitation accompanied by teacher instruction seems more useful in helping learners make progress in the four indices of rhythmic features than mere listening and imitation.The findings of the present study have rich theoretical and pedagogical implications. Theoretically, the present study implies that frequency has limited effects on L2speech learning, but it is explicit instruction that directs learners’attention to the target forms and enables them to make progress. Therefore the findings give support to the noticing hypothesis. The repeated experiences with target structure afford learners opportunity to pay attention to language form and notice the gap between one’s language production and the target form. Pedagogically, the practice of repeated listening and imitation can be widely implemented in the EFL classroom. Teacher instruction can better help learners make improvements in the production of English stress patterns. It also implies that much practice cannot replace teacher instruction. |
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