【助成 38 - 25】
表現力豊かな音声の声質を決める声門流波形と声道伝達関数特徴の解析

代表研究者 富山県立大学工学部 教授 MOKHTARI Parham
共同研究者 富山県立大学工学部 講師 森川大輔
共同研究者 富山県立大学工学研究科 大学院生 河内太一
共同研究者 富山県立大学工学研究科 大学院生 松本幸輝

〔研究の概要〕This research aimed towards automatic analysis and synthesis of speech that is rich in expressivity. In line withthe classical source-filter model of speech production, we sought improvements in the performance of algorithms
designed to separate the influence of the glottal flow and the vocal-tract on the speech signal. We improved abenchmark algorithm for estimation of the glottal flow from the speech signal, and we quantified the relationshipbetween physiological parameters of Titze’s vocal fold model and acoustic parameters describing the shape ofthe simulated glottal flow.

that algorithm. However, the conventional method〔研究経過および成果〕
Aiming toward physiologically relevant analysis,

typically analyses a frame of speech spanningmodelling and synthesis of expressive human voices,30-50 ms, which includes several glottal cycles; it

our research prioritizes automatic estimation of thetherefore suffers from inaccuracy due to the inclusion

laryngeal source (glottal flow) from the acousticof the glottal open phase, during which there is

speech signal, and its synthesis with physiologicalacoustic influence of the sub-glottal tract (themodels and computer simulation methods.
In the mid-term report we summarized our research
results on automatic formant estimation [1], glottal
flow estimation [2][3], and a new database of recorded
voice qualities [4]. Here below, we additionallysummarize our subsequent research results obtainedsince the mid-term report.
Iterative adaptive inverse filtering (IAIF) is abenchmark method for estimating the glottal flow fromthe speech signal, and iterative optimal preemphasis(IOP) has also been proposed as an improvement of

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Fig.1

Glottal flow estimation error

decreased with closed-phase (CP) analysis [5]glottal flow waveforms, then extracted 3 acoustic
parameters describing the shape of the glottal flow
pulse (OQ, NAQ, and openNAQ). As a result, wewere able to quantify the relationship between thevocal-fold model (physiological) parameters and theglottal flow (acoustic) parameters [6].
〔発表論文〕
Fig.2

１． 河口竜馬、モクタリパーハム、森川大輔（22021.6）

Titze’s vocal-fold model [6]「ラーモニック減算法を用いたフォルマント周波trachea) and the glottis itself. We therefore proposed数の自動推定法の検討」、情報処理学会研究報

to combine the benchmark IAIF algorithm with

告、Vol.2021-SLP-137 No.22、5 pages.

closed-phase (CP) analysis, so that the vocal-tract

２． 平野雄大、モクタリパーハム、森川大輔(22021.9)

characteristics and therefore the glottal flow signal「プリエンファシスの適用回数が IAIF に基づく声

too, could be potentially derived more accurately. As

門流推定の精度に与える影響」、日本音響学会

shown in Fig.1, evaluation using the OpenGlot

講演論文集、939-940.

dataset revealed overall lower errors for the proposed

３． 平野雄大、モクタリパーハム、森川大輔(22021.9)

methods involving CP analysis, and the lowest overall「音声のスペクトル傾斜モデリングが IAIF に基error was obtained for the IOP-IAIF-CP method [5].

づく声門流推定の精度に与える影響」、日本音

Another ongoing project in our laboratory is

響学会音声研究会資料 Vol.1 No.2 SP-2021-26、

physiologically-based modelling and synthesis of135-137.

various voice qualities, aiming at expressive speech

４． Mokhtari P., Morikawa D.（22022.3） “Introducingsynthesis. For this purpose, we investigated thea Japanese multi-talker database of laryngeal

characteristics of a vocal-fold simulation model

voice qualities,” 日本音響学会講演論文集.

originally proposed by Titze, to assess whether it is

５． 河内太一、モクタリパーハム、森川大輔(22023.9)

capable of producing various voice qualities. As「声門の閉鎖期の音声信号による IAIF に基づく

shown in Fig.2, Titze’s model is represented by 3

声門流推定」、日本音響学会講演論文集、

parameters Qa, Qs, and Qb that describe the1115-1116.

pre-phonatory posture of the vocal folds, plus one

６． 松本幸輝、モクタリパーハム、森川大輔(22023.11)

additional parameter Qp that controls the phase「Titze の声帯モデルのパラメータが声門流波形

difference between the upper and lower folds duringの音響特徴に与える影響の検討」、日本音響学

dynamic oscillation. We used this model with a wide

会音声研究会資料 Vol.3 No.5 SP-2023-42、range of parameter settings to synthesize numerous

9-14.

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