教員・研究者詳細 - 北村　達也

論文 - 北村　達也

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Resonance characteristics of hypopharyngeal cavities

Kiyoshi Honda, Tatsuya Kitamura, Hironori Takemoto, Parham Mokhtari, Seiji Adachi

Journal of the Acoustical Society of America 123 ( 5 ) 3731 2008年7月

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MRI-Based Study on Morphological and Acoustic Properties of Mandarin Sustained Vowels

WANG Gaowu, KITAMURA Tatsuya, LU Xugang, DANG Jianwu, KONG Jiangping

J Signal Process 12 ( 4 ) 311 - 314 2008年7月

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J-GLOBAL

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Deformation of the hypopharyngeal cavities due to F0 changes and its acoustic effects 査読あり

Hironori Takemoto, Tatsuya Kitamura, Kiyoshi Honda, Shinobu Masaki

Acoustical Science and Technology 2008年4月

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Single-matrix formulation of a time domain acoustic model of the vocal tract with side branches

MOKHTARI Parham, TAKEMOTO Hironori, KITAMURA Tatsuya

Speech Communication 50 ( 3 ) 179 - 190 2008年3月

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DOI： 10.1016/j.specom.2007.08.001

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Effects of acoustic modification on perception of speaker characteristics for sustained vowels

Tatsuya Kitamura, Takeshi Saitou

Acoustical Science and Technology 2007年6月

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Vocal tract length perturbation and its application to male-female vocal tract shape conversion

Seiji Adachi, Hironori Takemoto, Tatsuya Kitamura, Parham Mokhtari, Kiyoshi Honda

Journal of the Acoustical Society of America 121 ( 6 ) 3874 - 3885 2007年6月

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DOI： 10.1121/1.2730743

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Principal components of vocal tract area functions and inversion of speech by linear regression of cepstrum coefficient

Parham Mokhtari, Hironori Takemoto, Tatsuya Kitamura, Kiyoshi Honda

Journal of Phonetics 2007年1月

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A bone-conduction system for auditory stimulation in MRI 査読あり

Yukiko Nota, Tatsuya Kitamura, Hironori Takemoto, Hiroyuki Hirata, Kiyoshi Honda, Yasuhiro Shimada, Ichiro Fujimoto, Yuko Syakudo, Shinobu Masaki

Acoustical Science and Technology 2007年1月

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Principal components of vocal-tract area functions and inversion of vowels by linear regression of cepstrum coefficients

Parham Mokhtari, Tatsuya Kitamura, Hironori Takemoto, Kiyoshi Honda

JOURNAL OF PHONETICS 35 ( 1 ) 20 - 39 2007年1月

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出版者・発行元：ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD

This paper addresses the following two hypotheses: (1) vocal-tract area functions of Japanese vowels can be accurately represented by a linear combination of only a few principal components which, furthermore, are similar to those reported in the literature for different languages; and (ii) the principal components' weights can be predicted and area functions thereby accurately estimated from acoustics by linear regression of cepstrum parameters. To test these hypotheses, synchronized acoustic and vocal-tract 3D MRI data were recorded from an adult male Japanese speaker for both sustained and dynamic vowel utterances. The first two principal components explained covariations in vocal-tract shape and length accounting for 94-97% of the total variance, and indeed provided a cross-linguistic validation of the two underlying components of vowel production emergent from the literature. Multiple linear regression models were then evaluated for their accuracy in reconstructing the area functions of the dynamic utterance by predicting the first two PC coefficients, using either carefully measured formants or cepstral coefficients defined in various frequency bands. The best formant-based regression model required all four formants, with a mean adjusted correlation of 0.93 and mean absolute errors of 0.187 cm(2) in area and 0.131 em in vocal-tract length. The best cepstrum-based regression model prescribed 24 cepstral coefficients defined in the frequency band 0-4 kHz, with a mean adjusted correlation of 0.92 and mean absolute errors of 0.102 cm(2) in area and 0.082 cm in vocal-tract length. These results suggest that vowel production features, properly constrained by PCA modeling, can be mapped with sufficient accuracy from easily measured cepstrum parameters. More work is required to reduce the dependence on MRI data, to extend the applicability of these methods to different voice qualities and different speakers, and to select a smaller subset of acoustic parameters for more robust, real-time inversion. (c) 2006 Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.wocn.2006.01.001

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An MRI-based time-domain speech synthesis system 査読あり

Tatsuya Kitamura, Hironori Takemoto, Parham Mokhtari, Toshio Hirai

Journal of the Acoustical Society of America 120 ( 5 ) 3037 2006年12月

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Changes in vocal tract resonance during a pitch cycle 査読あり

Tatsuya Kitamura, Seiji Adachi

Journal of the Acoustical Society of America 120 ( 5 ) 3351 2006年12月

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光マイクロホンを用いたMRI撮像時の騒音測定

北村達也, 正木信夫, 島田育廣, 藤本一郎, 赤土裕子, 本多清志

日本音響学会誌 62 ( 5 ) 379 - 382 2006年5月

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MRI装置の普及と高磁場化に伴い,撮像時の騒音は無視できない問題となっている。しかし,装置内の騒音測定には磁性体を含む一般的な装置を利用することができない。また,強磁場下で利用可能な測定装置を使っても,その一部に導電体が含まれていればRFパルス(電磁波)に起因するノイズが混入する可能性がある。本研究では非導電体のみで構成された光マイクロホンを用いてこの問題を解決し,1.5TのMRI装置を対象にしてSpin-echo T1強調,Fast spin-echo T2強調,RF-FAST,及びSingle-shot EPIの4種の撮像シーケンスの騒音を測定した。その結果,これらの騒音の音圧レベルはそれぞれ112.6dB,112.5dB,107.8dB,110.6dBであった。

DOI： 10.20697/jasj.62.5_379

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有限要素法による声道伝達特性推定の有効性に関する検討

西本博則, 赤木正人, 北村達也, 鈴木規子

日本音響学会誌 62 ( 4 ) 306 - 315 2006年4月

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有限要素法と声道等価回路モデルの声道伝達特性の推定精度の調査を行うため,MR計測から得られた声道モデルより推定された伝達特性のピークと実音声のホルマントの比較を行った。その結果,健常な被験者では両推定法とも精度良く推定された。一方,複雑で左右非対称な声道形状の被験者では,有限要素法を用いれば音声ホルマントの個数が同じであり,ホルマント周波数と伝達特性のピーク周波数に大きな差がなかったが,等価回路モデルでは伝達特性のピークの数と音声ホルマントの数が一致しなかった。複雑で左右非対称な声道の伝達特性推定には,等価回路モデルは不適切であり,有限要素法が有効であることが示された。

DOI： 10.20697/jasj.62.4_306

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Acoustic roles of the laryngeal cavity in vocal tract resonance 査読あり

Hironori Takemoto, Seiji Adachi, Tatsuya Kitamura, Parham Mokhtari, Kiyoshi Honda

Journal of the Acoustical Society of America 2006年4月

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Cyclicity of laryngeal cavity resonance due to vocal fold vibration 査読あり

Tatsuya Kitamura, Hironori Takemoto, Seiji Adachi, Parham Mokhtari, Kiyoshi Honda

Journal of the Acoustical Society of America 120 ( 4 ) 2239 - 2249 2006年4月

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DOI： 10.1121/1.2335428

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Difference in vocal tract shape between upright and supine postures: Observations by an open-type MRI scanner

KITAMURA Tatsuya, TAKEMOTO Hironori, HONDA Kiyoshi, SHIMADA Yasuhiro, FUJIMOTO Ichiro, SYAKUDO Yuko, MASAKI Shinobu, KURODA Kagayaki, OKU-UCHI Noboru, SENDA Michio

Acoustical Science and Technology 26 ( 5 ) 465 - 468 2005年9月

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DOI： 10.1250/ast.26.465

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Individual variation of the hypopharyngeal cavities and its acoustic effects

Tatsuya Kitamura, Kiyoshi Honda, Hironori Takemoto

Acoustical Science and Technology 26 ( 1 ) 16 - 26 2005年1月

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A method of tooth superimposition on MRI data for accurate measurement of vocal tract shape and dimensions 査読あり

Hironori Takemoto, Tatsuya Kitamura, Hironori Nishimoto, Kiyoshi Honda