The ability for English Language Learners (ELL) to communicate in a native-like manner can be vital when seeking to improve job opportunities and social interactions. Native Japanese ELL speakers commonly struggle with identifying and producing the English consonants /r/ and /l/ as separate phonemes, even for experienced Japanese ELLs. Traditional means of second language (L2) learning has primarily used auditory feedback. Electropalatography (EPG) is a visual biofeedback system designed to visualize lingua-palatal contact in real time. This study explores the impact of using EPG technology in L2 Speech Learning with Japanese ELLs. Research has shown that EPG technology is an effective method of treating speech sound disorders in children, however there is sparse research available concerning the impact of EPG use in L2 learning for ELLs. This study analyzed four native Japanese speakers' ability to produce the /r/-/l/ contrast before and after L2 learning treatment utilizing EPG technology. Target stimuli containing the /r/ and /l/ phonemes were produced by each participant in three different tasks: nonsense words, words, and spontaneous speech. The /r/ and /l/ phonemes were produced in word-initial and word-final position. The EPG technology and computer software were used to record lingua-palatal contact patterns in order to collect data on each participants' productions of the /r/-/l/ phonemic contrast. In general, all four participants demonstrated increased center of gravity (COG) difference of /r/ and /l/ in 50%-100% of testing conditions from baseline to post treatment and in 33%-100% of testing conditions from post treatment to follow-up. In combination with future research, results from this study will help deepen the knowledge of L2 learning in ELLs specifically related to EPG technology use in treatment.

The main purpose of this study was to investigate the effects of form-focused instruction (FFI) on prosody with or without self-assessment on the prosodic and global aspects of L2 speech by Japanese EFL learners using a pre-post design. In addition, native English speaking (NS) and non-native English speaking (NNS) raters with high levels of English proficiency were compared to examine the influence of raters’ L1 backgrounds on their comprehensibility ratings. Sixty-one Japanese university students from four intact English presentation classes participated in the study. The comparison group (n = 16) practiced making one-minute speeches in class (45 minutes x 8 times) without explicit instruction on prosody, while the two experimental groups (n = 17 for the FFI-only group; n = 28 for the FFI + SA group) received FFI on word stress, rhythm, and intonation, practiced the target prosodic features in communicative contexts, and received metalinguistic feedback from the instructor. In total, the experimental groups received six-hours of instruction in class, which was comparable to the comparison group. Additionally, the experimental groups completed homework three times; only the FFI + SA group recorded their reading performance and self-assessed it in terms of word stress, rhythm, and intonation. Three oral tasks were employed to elicit the participants’ speech before and after the treatment: reading aloud, one-minute speech, and picture description. The speech samples were rated for comprehensibility by NS and NNS raters and were also analyzed with four prosodic measurements: word stress, rhythm, pitch contour, and pitch range. Instructional effects on prosody were observed clearly. The FFI-only group improved their controlled production of rhythm and pitch contour, while the FFI + SA group significantly improved all of the prosodic features except pitch range. Moreover, the instructional gains for the FFI + SA group were not limited to the controlled task but transferred to the less-controlled tasks. The results showed differential instructional effects on the four prosodic aspects. The FFI in this study did not help the participants widen their pitch range. The FFI on prosody, which was focused on the cross-linguistic differences between Japanese and English, tended to be more effective in terms of improving rhythm and pitch contour, which were categorized as rule-based, than an item-based feature, word stress. The study offered mixed results regarding instructional effects on comprehensibility. The FFI-only group did not significantly improve comprehensibility despite their significant prosodic improvements on the reading aloud task. Their significant comprehensibility growth on the picture description task was not because of the development of prosody, but of other linguistic variables that influence comprehensibility such as speech rate. The FFI + SA group made significant gains for comprehensibility on the three tasks, but the effect sizes were small. This finding indicated that the effects of FFI with self-assessment on comprehensibility were limited due to the multi-faceted nature of comprehensibility. The data elicited from the post-activity questionnaires and students’ interviews revealed that not all the participants in the FFI + SA group reacted positively to the self-assessment practice. Individual differences such as previous learning experience and self-efficacy appeared to influence the learners’ perceptions of the self-assessment practice and possibly their instructional gains. The two groups of raters, L1 English raters (n = 6) and L2 English raters with advanced or native-like English proficiency (n = 6) did not differ in terms of consistency and severity. These findings indicated that NNS raters with high English proficiency could function as reliably as NS raters; however, the qualitative data revealed that the NS raters tended to be more sensitive to pronunciation, especially at the segmental level, across the three tasks compared to the NNS raters. This study provides evidence that FFI, especially when it is reinforced by self-assessment, has pedagogical value; it can improve learners’ production of English prosody in controlled and less-controlled speech, and these gains can in turn contribute to enhanced L2 comprehensibility. / Teaching & Learning

<p>The question of whether second languages (L2s) are best learned implicitly or explicitly has been a topic of much empirical discourse, with the majority of studies pointing to the benefits of explicit instruction when learning L2 grammar rules. However, given the focus on grammar, it is unclear how generalizable these findings are to other linguistic domains, such as L2 speech and L2 vocabulary. The previous focus on laboratory-based settings, and the language bias in the literature, also make it unclear how ecologically valid and applicable these findings are to the real world. To address these macro research questions, two experiments were carried out on English-speaking L2 learners of German.</p> <p>Experiment I (ExI) investigated the effects of implicit and explicit learning on the acquisition of Final Obstruent Devoicing and Dorsal Fricative Assimilation. The effect of the two learning conditions on L2 perception was also measured using a perceptual discrimination task and a perceptual identification task. Experiment II (ExII) investigated the effects of explicit historical instruction on the learning of English-German cognates, which were compared to the effects of a non-explicit learning condition. To examine whether declarative knowledge of relevant historical changes can aid in vocabulary learning, an explicit condition received instruction on the Second Germanic Sound Shift, Ingvæonic Palatalization, and relevant historical semantic changes. Both experiments followed a pre-/post-/delayed-post-test design.</p> <p>Results indicate that the two explicit conditions significantly outperformed the non-explicit conditions, suggesting that explicit learning and explicit instruction can be beneficial when learning L2 speech and L2 vocabulary. In ExI, acoustic analyses of learner speech samples indicate that the explicit condition was more successful in the learning of the two phonological rules. In ExII, the explicit condition was more successful in the identification and learning of cognates, suggesting that knowledge of language history, and instruction on applied historical linguistics, can be beneficial when learning a language that is historically related to a language that learners already speak. The results from this dissertation are discussed in the context of implicit and explicit learning and instruction, the role of attention, and the role of declarative knowledge, with concluding remarks pointing to the importance of metacognitive and metalinguistic awareness in adult or university-level language courses.</p>

本論文は第二言語話者の発話を高精度で認識するための音素セットの構成方法に関する研究結果を述べている．本論文では，第二言語話者の発話をネイティブ話者の発話とは異なる音響特徴量の頻度分布を持つ情報源とみなし，これを表現する適切な音素セットを構築する手法を提案している．具体的には，対象とする第二言語と母語との調音位置や調音様式などの類似性に加え，同音異義語の発生による単語識別性能の低下を総合した基準に基づき，最適な音素セットを決定する．提案手法を日本人学生の英語発話の音声認識に適用し，種々の条件下で認識精度の向上を検証した． / This dissertation focuses on the problem caused by confused mispronunciation to improve the recognition performance of second language speech. A novel method considering integrated acoustic and linguistic features is proposed to derive a reduced phoneme set for L2 speech recognition. The customized phoneme set is created with a phonetic decision tree (PDT)-based top-down sequential splitting method that utilizes the phonological knowledge between L1 and L2. The dissertation verifies the efficacy of the proposed method for Japanese English and shows that the feasibility of building a speech recognizer with the proposed method is able to alleviate the problem caused by confused mispronunciation by second language speakers. / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University