コンピュータによる英語文リズムの習得 : 音を視覚的にとらえて

For Japanese learners, it seems to be difficult to acquire the rhythm of an English utterance. This is because the rhythm pattern of an English sentence, which is made up of the alternation of strongly and weakly stressed syllables, is different from anything found in the Japanese sound system. Since this English rhythmic pattern of stressed syllables tends to recur at regular intervals, English is known as a stress-timed language. On the other hand, Japanese, with a rhythm based on the syllable, is known as a syllable-timed language. In order to maintain this stress-timed rhythm in English sentences, various modifications can occur in connected speech such as linking, assimilation, elision, and reduction resulting from the squeezing together of unstressed syllables. For Japanese learners, it is essential not only to study and understand the character of English rhythm, but also to practice it over and over again, if they are to improve their production of spoken English. However, to capture these characteristics of English sentence rhythm in any spoken utterance is difficult because sounds disappear in an instant. The purpose of this paper is to prove that visual aids such as waveforms produced by the computer enable students to improve their English sentence rhythm. Here it is explicated with some improved illustrative wave forms of the phonetics class students in Tokyo Joshi Daigaku which have resulted from repetitious practice using sound spectrograms in the multi-media language laboratory. The vertical dimension of a waveform presents a representation of air-pressure variations termed amplitude, while the horizontal dimension represents the period of time. By segmenting and adding phonetic annotations to a raw waveform on a graph, we can predict such prosodic features as intensity, duration and modifications in connected speech. A sound spectrogram machine used to be an expensive tool suitable only for researchers, but nowadays we can easily and cheaply use such speech-analysis tools as a means of study by downloading them from the Internet as free software. Thus equipped with such speech-analysis tools, students can by comparing the waveforms of their utterances with those of a native speaker be convinced of the practical value of what they have previously learned in theory in the phonetics classroom. Also, students can comprehend exactly how their pronunciation is different from that of a native speaker and can learn how to improve their utterances. This understanding generates student motivation for learning, leading the students to practice through trial-and-error to produce waveforms more similar to those of the native speaker. By using visual aids as feedback on their performances, computers help students produce more intelligible and instantaneous sentences than when tape recorders are used and help them make progress in English sentence rhythm whilst working autonomously