基于声带振动模型和声门波的嘶音研究

本文根据嘶音的主要病理表现为声带的病变、声门波反映了声带的运动状态，提出基于非对称四质量块声带振动模型及声门波分析一合成的嘶音研究方法。将嘶音信号波形与其声门波、声带振动模型联系起来，通过对正常语音和嘶哑病人术前术后语音信号的声门波和声带振动模型特征参数的研究，给出了常态语音和嘶音的声门波周期性、声带两侧参数对称性等参数的对比结果，分析了模型参数与嘶音生理与病理因素之间的关系。实验表明，基于声门波和声带振动模型的嘶音研究可以揭示嘶音的声学特征参数与病理因素的关系，为实现喉科疾病无接触诊断以及嘶音音质的改善提供理论和实验依据。     

男女嗓音源特性的比较研究

以男女性发声生理差异为基础,采用作者研制的嗓音测试系统无侵入地获取电声门波波形图、反滤波声门波波形图、扰动、声门发声效率等稳态和动态图谱与参数,对男女声带振动和嗓音源特性的差异进行了定量的比较研究,在男女性稳态发声声问波波形图时相参数对比、声门发声效率、浊音起声声带振动动态特性等方面获得了较多新的实验结果。这些结果与男女喉部解剖、发声生理解释相一致,对发声基础研究、言语工程技术和艺术嗓音学等领域有重要意义。     

嗓音多频带非线性分析的声带病变识别

提出了一种嗓音多频带非线性分析的声带病变识别方法,以提高声带病变嗓音的识别率。首先采用Gammatone听觉滤波器组对嗓音信号进行滤波,求取每个频带下的最大李雅普诺夫指数;对映射到核空间的数据采用高斯最大似然度准则优化核函数,然后采用优化核主成分分析算法实现特征抽取。识别实验表明,多频带最大李雅普诺夫指数的识别率比传统的MFCC和最大李雅普诺夫指数分别有6.52%和8.45%的提高,且采用优化核主成分分析算法比传统核主成分分析算法有更好的抽取效果.将多频带非线性分析和优化核主成分分析算法结合,识别率提升至97.82%。      

息肉与麻痹喉声源分类中非线性动力学发声系统模型研究

提出一种非线性动力学建模仿真发声系统,分类息肉和麻痹喉声源的方法,为声带疾病分类时参数选择提供了依据。首先介绍息肉和麻痹声带力学模型,耦合声门气流产生喉声源,求取喉声源频率(基频)、基频微扰;提出用庞加莱截面,分岔图对模型振动进行非线性分析;改变声带病理参数及声门下压,分析频率参数和混沌参数李雅普诺夫指数的变化。仿真实验结果表明,声带麻痹减小了发声基频,且只在一定压力范围内出现混沌振荡;息肉声带的混沌则分布在整个压力范围内。根据最大李雅普诺夫指数随声门下压变化的差异性分布,有助于识别并分类声带息肉和声带麻痹。      

息肉与麻痹喉声源分类中非线性动力学发声系统模型研究

提出一种非线性动力学建模仿真发声系统,分类息肉和麻痹喉声源的方法,为声带疾病分类时参数选择提供了依据。首先介绍息肉和麻痹声带力学模型,耦合声门气流产生喉声源,求取喉声源频率(基频)、基频微扰;提出用庞加莱截面,分岔图对模型振动进行非线性分析;改变声带病理参数及声门下压,分析频率参数和混沌参数李雅普诺夫指数的变化。仿真实验结果表明,声带麻痹减小了发声基频,且只在一定压力范围内出现混沌振荡;息肉声带的混沌则分布在整个压力范围内。根据最大李雅普诺夫指数随声门下压变化的差异性分布,有助于识别并分类声带息肉和声带麻痹。     

嗓音的测试与处理系统

本文介绍了一种无侵入、直接、客观、定量地反映发声过程中声带振动特性及嗓音嘶哑程度的自动测试与处理系统．该系统具有多路生理信号检测，电声门图参数提取，诣波噪声比分析，扰动分析，频谱分析，语话图分析等多种信息处理功能．实验与临床使用结果表明，本系统在正常与病变发声检查、艺术嗓音测试等方面具有重要应用价值．     

光声门图理论、实验与应用

首次建立了光声门图数学模型。以相乘同态信号模型和对声带振动的研究结果为基础,提出、研究并实现了光声门图信号数字处理。仪器使用结果表明,光声门图技术对喉科学、艺术嗓音、语言学、语音声学及语言信号数字处理等领域具有广泛和重要的应用价值。     

采用小生境遗传算法反演浅海声速剖面研究*

针对浅海声速剖面反演问题,采用小生境遗传算法,结合声线搜索的最快本征声线匹配反演,实现浅海负跃层条件下的声速剖面估计。利用经验正交函数对声速剖面的多参数不确定性降维,依据声场计算模型获取的最快特征声线传播时延与观测声传播时长进行匹配,采用小生境遗传优化算法,获取最优经验正交函数估计,实现声速剖面反演。按上述方法反演处理浅海声传播实验数据,结果表明,该方法针能够有效反演浅海声速剖面,并且显著优于传统遗传算法反演结果。     

影响声带振动模式的喉疾病物理分类

通过分析声带的生理结构和喉疾病对声带振动模式的影响，从物理上将喉疾病根据其起因归纳为主要影响声带本体层振动和主要影响声带覆盖层振动的两大类；并认为频域相对信噪比是区分病态噪音和正常嗓音的有效参数，协同监视病态嗓音的频率微扰商和振幅微扰商参数的异常可基本识别上述两类疾病。     

非对称黏性空气动力学声带模型及其病理喉声源分类

二质量块模型(SH模型)在模拟病理发声时未考虑弹性力对发声系统的影响,也未考虑黏性气流在声门闭合阶段的作用,本文提出一种非对称黏性空气动力学声带模型(ISAC模型)。对非对称振动时的附加弹性系数和弹性形变进行分析,修正质量块所受的碰撞力,随位移量变化调节原始模型中的劲度系数,模拟环甲肌和甲杓肌的张力作用;通过声门倾角变化得到声门处的气流分布,以实现声带壁上的非对称气流压力作用。该模型应用于发声病理诊断,模型仿真和病理喉声源分类识别的实验结果显示,各声门特征参数相对误差不超过1.5%,ISAC模型的加权平均误差低于SH模型,二分类识别率和细分准确率均高于SH模型。      

Vocal quality factors: analysis, synthesis, and perception.

The purpose of this study was to examine several factors of vocal quality that might be affected by changes in vocal fold vibratory patterns. Four voice types were examined: modal, vocal fry, falsetto, and breathy. Three categories of analysis techniques were developed to extract source-related features from speech and electroglottographic (EGG) signals. Four factors were found to be important for characterizing the glottal excitations for the four voice types: the glottal pulse width, the glottal pulse skewness, the abruptness of glottal closure, and the turbulent noise component. The significance of these factors for voice synthesis was studied and a new voice source model that accounted for certain physiological aspects of vocal fold motion was developed and tested using speech synthesis. Perceptual listening tests were conducted to evaluate the auditory effects of the source model parameters upon synthesized speech. The effects of the spectral slope of the source excitation, the shape of the glottal excitation pulse, and the characteristics of the turbulent noise source were considered. Applications for these research results include synthesis of natural sounding speech, synthesis and modeling of vocal disorders, and the development of speaker independent (or adaptive) speech recognition systems.     

Three-dimensional biomechanical properties of human vocal folds: parameter optimization of a numerical model to match in vitro dynamics

The human voice signal originates from the vibrations of the two vocal folds within the larynx. The interactions of several intrinsic laryngeal muscles adduct and shape the vocal folds to facilitate vibration in response to airflow. Three-dimensional vocal fold dynamics are extracted from in vitro hemilarynx experiments and fitted by a numerical three-dimensional-multi-mass-model (3DM) using an optimization procedure. In this work, the 3DM dynamics are optimized over 24 experimental data sets to estimate biomechanical vocal fold properties during phonation. Accuracy of the optimization is verified by low normalized error (0.13 ± 0.02), high correlation (83% ± 2%), and reproducible subglottal pressure values. The optimized, 3DM parameters yielded biomechanical variations in tissue properties along the vocal fold surface, including variations in both the local mass and stiffness of vocal folds. That is, both mass and stiffness increased along the superior-to-inferior direction. These variations were statistically analyzed under different experimental conditions (e.g., an increase in tension as a function of vocal fold elongation and an increase in stiffness and a decrease in mass as a function of glottal airflow). The study showed that physiologically relevant vocal fold tissue properties, which cannot be directly measured during in vivo human phonation, can be captured using this 3D-modeling technique.     

Glottal opening in patients with vocal fold tissue changes

Synchronized videostroboscopy and electroglottography were applied to the measurement of anterior-to-posterior open glottal length in four groups of patients; two with no clinically significant voice disorder, one with vocal fold polyps, and one with vocal fold nodules. The data showed that the groups did not differ significantly when open glottal length was measured at the time of minimum glottal opening. The pathological groups had significantly lower open glottal length measurements, however, when measurements were obtained at the time that vocal fold contact was initiated during the glottal cycle. The findings are preliminary evidence that vocal fold neoplasms may not have the effect of reducing glottal closure, as previously suggested in the literature. The data also highlight the importance of examining differential effects of vocal fold neoplasms at various points throughout the glottal cycle.     

Analysis of Vocal-fold Vibrations from High-Speed Laryngeal Images Using a Hilbert Transform-Based Methodology

This paper presents a Hilbert transform-based approach to analyze vocal fold vibrations in human subjects exhibiting normal and abnormal voice productions. This new approach is applied to the analysis of glottal area waveform (GAW) and is capable of providing useful information on the vocal fold vibration. The GAW is extracted from high-speed laryngeal images by delineating the glottal edge for each image frame. An analytic signal is generated through the Hilbert transform of the GAW, which yields a recognizable pattern of the vocal fold vibration in the analytic phase plane. The vibratory pattern is comprehensive and can be correlated with specific voice conditions. Quantitative measures of the glottal perturbation are introduced using the analytic amplitude and instantaneous frequency obtained from the analysis. Examples of clinical voice recordings are used to evaluate and test the effectiveness of this approach in providing qualitative representation and quantitative characteristics of vocal fold vibratory behavior. The results demonstrate the potential of using this new analytical tool incorporated with the high-speed laryngeal imaging modality for clinical voice assessment.     

Perceptual and Acoustic Assessment of Voice Pathology and the Efficacy of Endolaryngeal Phonomicrosurgery

Values for acoustic voice measurements were obtained from 88 normal individuals and 98 pathological cases of mass lesions of vocal fold and 50 cases of unilateral vocal fold paralysis. Overall, all items reflecting perturbations of pitch and amplitude as well as glottal noise were significantly higher in the groups of patients compared with the normal group. The measurement of normalized noise energy (NNE) was found to be an optimum parameter for discrimination of normal/abnormal voices. The voices of patients with vocal fold nodules and vocal fold polyps were analyzed before endolaryngeal phonomicrosurgery (EPM) and 2 weeks after. Statistically significant (p < 0.01) improvement was achieved both in perceptual and acoustic analysis. EPM resulted in a significant decrease of mean jitter, shimmer, and NNE. Clinically, these measures provided documentable and measurable evidence of vocal function and were helpful for comparing patients with normal speakers. They also were useful for a thorough documentation of patient's voice pathology and for evaluation of the presurgical and postsurgical voice status.     

Spatiotemporal classification of vocal fold dynamics by a multimass model comprising time-dependent parameters

A model-based approach is proposed to objectively measure and classify vocal fold vibrations by left-right asymmetries along the anterior-posterior direction, especially in the case of nonstationary phonation. For this purpose, vocal fold dynamics are recorded in real time with a digital high-speed camera during phonation of sustained vowels as well as pitch raises. The dynamics of a multimass model with time-dependent parameters are matched to vocal fold vibrations extracted at dorsal, medial, and ventral positions by an automatic optimization procedure. The block-based optimization accounts for nonstationary vibrations and compares the vocal fold and model dynamics by wavelet coefficients. The optimization is verified with synthetically generated data sets and is applied to 40 clinical high-speed recordings comprising normal and pathological voice subjects. The resulting model parameters allow an intuitive visual assessment of vocal fold instabilities within an asymmetry diagram and are applicable to an objective quantification of asymmetries.     

Polyps and paralysis phonation classification with nonlinear dynamics model

In order to provide the basis for parameter selection of vocal diseases classification,a nonlinear dynamic modeling method is proposed.A biomechanical model of vocal cords with polyp or paralysis,which couples to glottal airflow to produce laryngeal sound source,is introduced.And then the fundamental frequency and its perturbation parameters are solved.Poincare section and bifurcation diagram are applied to nonlinear analysis of model vibration.By changing the pathological parameters or subglottal pressure,the changes of fundamental frequency and Lyapunov exponents are analyzed.The simulation results show that,vocal cord paralysis reduces the fundamental frequency,and the chaos occurs only within a certain pressure range;while vocal cord with a polyp don't reduce the fundamental frequency,chaos distributes throughout the entire range of pressure.Therefore this study is helpful for classification of polyp and paralysis by the acoustic diagnoses.     

Measures of spectral slope using an excised larynx model

Spectral measures of the glottal source were investigated using an excised canine larynx (CL) model for various aerodynamic and phonatory conditions. These measures included spectral harmonic difference H1-H2 and spectral slope that are highly correlated with voice quality but not reported in a systematic manner using an excised larynx model. It was hypothesized that the acoustic spectra of the glottal source were significantly influenced by the subglottal pressure, glottal adduction, and vocal fold elongation, as well as the resulting vibration pattern. CLs were prepared, mounted on the bench with and without false vocal folds, and made to oscillate with a flow of heated and humidified air. Major control parameters were subglottal pressure, adduction, and elongation. Electroglottograph, subglottal pressure, flow rate, and audio signals were analyzed using custom software. Results suggest that an increase in subglottal pressure and glottal adduction may change the energy balance between harmonics by increasing the spectral energy of the first few harmonics in an unpredictable manner. It is suggested that changes in the dynamics of vocal fold motion may be responsible for different spectral patterns. The finding that the spectral harmonics do not conform to previous findings was demonstrated through various cases. Results of this study may shed light on phonatory spectral control when the larynx is part of a complete vocal tract system.