氏
学位名

持田 岳美

名

博士（システム情報科学）

学 位 記 番 号

第１６号

学位授与年月日

平成２３年３月１８日

学位論文題目A study on the mechanisms of sensorimotor interactions in production
and perception of speech phonemes

論文審査委員

主査 三木 信弘
副査 上野 嘉夫
副査 高橋 修副査 藤野 雄一
副査 誉田 雅彰（早稲田大学）
副査 鏑木 時彦（九州大学）

論

文 要 旨

In this thesis, aiming at elucidating the functional basis of phoneme production andperception processes enabling inter-human speech communication, interdependence
underlying speech motor control and auditory processing systems were studied based on
physiological and psychophysical experiments. The dynamic behavior of speech organs
during speech production has been found to be affected be self-produced auditory
feedback signals. However, the functional characteristics of auditory feedback-based
control of speech movements have not been fully elucidated. The involvement of speech
motor control system in speech perception has also been evident. However, there havebeen controversial arguments regarding how incoming auditory information isprocessed and interpreted by the motor system and triggers a specific phonemeperception. From the above viewpoints, this thesis investigated the interaction
mechanisms involved in the production and perception of speech phonemes, based on
the following two experimental approaches: (1) as for speech production, evaluatingchanges in articulatory lip movement during speaking the bilabial plosive ([p])
repetitively, which occurred when a sudden alteration in timing and context of auditory
feedback was introduced, and (2) as for speech perception, evaluating changes inphoneme intelligibility for bilabial, alveolar and velar plosives ([p], [t], and [k],

respectively), which occurred when hearing them simultaneously with whispering(silently articulating) incongruent phonemes, in comparison with viewing a mouth
motion producing incongruent phonemes.
The critical result of the first experiment was that the articulatory lip
movement quickened immediately when the auditory feedback virtually preceded theexpected timing by 50ms. Such articulatory change was not observed when the feedback
was presented more than 50ms earlier or later than the actual timing, or when thefeedback syllable was replaced by other one. These results suggest that errors between
the internally predicted and actually provided auditory information detected in a
temporallyasymmetricwindow

contributeto

thecompensationfor

theinter-articulatory timing in the syllable repetition task.
The critical result of the second experiment was that the silent articulation
affected the phoneme perception in a different way from the well-known visual effects(ex., McGurk effect). Viewing lip motion ([p]) degraded hearing of phonemes producedby the tongue ([t] and [k]), and viewing tongue motions degraded hearing of phoneme
produced by the lips, replicating the previous studies. On the contrary, articulatingphoneme with the lips ([p]) did not affect hearing of tongue-related phonemes ([t] and[k]), and articulating phonemes with the tongue did not affect hearing of phoneme
produced by the lips. More interestingly, articulating phonemes with the tongue ([t] and[k]) degraded hearing of the other tongue-related phonemes ([k] and [t], respectively).
These results suggest for the first time that motor interferential effect on speech
perception is mediated by a different mechanism from the visual one: theauditory-visual integration occurs across different speech organs, whereas theauditory-articulatory integration occurs within the same organ.

審査結果の要旨
従来の研究成果と著者が行った新規部分とが明確に説明され，著者が提案する音声生成と聴覚フィードバックの相互作用を検証する実験方法，実験結果による新しい知見など明確にされている内容である．予備審査時に指摘された論文内容の充実もなされていることを確認している．さらに学術論文誌への投稿，国際会議での発表など，対外活動も活発に行われている事を確認した．委員全員が論文内容から合格と判定した．また外部委員の誉田雅彰教授．鏑木時彦准教授からも十分な内容の論文であるとの判定を得ている．以上か
ら提出論文は，システム情報科学における学位論文として十分な内容と判断し，判定を「合」とする．