利用声带动力学模型参数反演方法进行病变嗓音分类

提出一种声带动力学模型参数反演方法,从发声机理角度对声带病变嗓音进行有效区分。依据声带生理组织和伯努利定律构建声带动力学模型,确定模型优化参数向量,耦合声门气流获取模型声门波;利用迭代自适应逆滤波算法获得实际嗓音声门波作为目标声门波;采用遗传优化算法提出通过匹配目标和模型声门波特征参数实现模型参数反演。实验结果表明,表征声门波的各时频域参数匹配相对误差不超过2%;依据反演所获模型参数提出去除声门下压影响的平均归一化缩放系数,克服声带非对称性特征在区分病变嗓音方面的不足,实现病理嗓音的全面有效区分。      

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。      

高速摄影成像分析声带振动发声的前后不对称性

高速摄影成像直接观察到声带振动的前后不对称性。将11个离体狗喉声带进行发声实验,设置3组声门下压分别为10 cm H₂O,20 cm H₂O和30 cm H₂O,利用高速摄像仪和传声器,分别记录不同声门下压的声带振动图像和声信号.对高速摄影成像与同步采集的声信号基频进行定量分析和比较,基频均随声门下压的增大而增加。此外,对两种测量方法得到的基频进行相关分析比较,得到在同一声门下压下两种方法的基频相关系数均大于0.9,表明高速摄影成像得到的基频与声信号的基频具有高度相关性。高速摄影成像能直观地测量声带振动行为,对研究声带振动发声机理提供了有价值的测量手段。高速摄影获得的声带线性结构上25%,50%,75%位置处的振动幅度,显示了声带前后振动不对称且声门下压较低时振动不对称较明显。      

喉发声功能评价方法的探讨

通过对喉发声机理的物理分析及病变对声喉功能影响的分析，寻找能够客观评价喉发声功能的途径——同步测量发声效率与频域相对谐噪比，将上述两参数结合可较全面地对喉发声功能进行量化评价。     

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。     

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。      

声带上表面振动黏膜波波速的激光测振估计方法

发声过程中声带组织振动的黏膜波测量对于声带组织力学特性和病理机制研究具有重要意义。本研究利用多普勒激光测振(Laser Doppler Vibrometer,LDV)和电声门图时间同步方法,对声带上表面的振动过程进行了重建,并基于该结果估计了黏膜波传播速度。通过离体犬喉发声实验,激光测振方法能够得到与高速光学方法相一致的黏膜波速度估计,并且能够重建不同时刻的声带上表面形态,证明了该方法应用于声带上表面振动特性研究的可行性和有效性。然而,由于单点测振的局限和时间同步的要求,稳态发声是保证该方法测量准确性的重要条件。      

幼年蝙蝠与母亲之间的超声沟通

众所周知,蝙蝠善于利用超声回声定位来探测环境和捕捉猎物,但鲜为人知的是幼年蝙蝠与成年蝙蝠之间也可以通过超声进行沟通。近期,日本科学家Shizuko Hiryua和Hiroshi Riquimaroux实验研究了一种叫作Pipistrellus Abramus的蝙蝠,通过观     

中国粤剧旦角发声特性实验研究

戏曲演员发声特性是厅堂音质研究的重要基础数据。为研究中国粤剧旦角演员发声特性,在全消声室内以4位花旦、2位青衣和1位老旦为例,针对念白、清唱和语言三种发声方式,在大、中、小三种发声力度下,分析不同旦角演员在0.3 m处的声压级、动态范围和频率特性曲线,探讨发声特性与发声方式、发声内容、发声力度和行当之间的关系。结果显示在相同的发声力度下,声压级由大到小的发声方式依次为清唱、念白和语言;老旦的动态范围最大,其次是青衣和花旦;清唱内容对发声频率特性曲线影响较小,而发声方式和行当影响较大;演员以不同力度发声时各频率特性曲线形状相似。该文的实验结果将为戏曲厅堂音质设计、建筑物隔声设计和电声系统设计提供科学依据。     

Analysis of pain-related vocalization in young pigs

The assessment of pain constitutes a major issue for animal welfare research. The objective of this study was to classify vocalizations during castration pain and to assess alterations in vocalizations under local anaesthesia. The alterations in vocalization were measured by multiparametric call analysis. A total of 4537 calls of 70 young pigs were evaluated. With the data of this study three call types are distinguishable (grunt, squeal, scream). A high percentage (94.64%) of calls that could be classified in one of the three call types during the castration process within the confidence level of 95% was found. The comparison of the occurrence of the call types during treatments gives evidence for pain-related use of screams. The piglets castrated without local anaesthesia produced almost double the number of screams as piglets castrated with anaesthesia. The comparison of the recorded sound parameters reveals the particular position of screams in the call repertoire of young pigs. Screams are significantly different in their sound parameters than grunts or squeals. Castration in comparison to mere restraint produced a comprehensive change in sound parameters, with castration calls becoming more extended and more powerful. The findings in this study also show differences in the effectiveness of the parameters which indicate pain. Parameters that describe a single event in a call, such as peak level or peak frequency give better results than parameters that describe an average, such as weighted frequency and main frequency. The research indicated that pain-related changes of calls in piglets can be identified. On the basis of the results, automatic classification of call types during management operations may be developed. This could contribute to objective animal welfare assessment.     

Brain mechanisms involved in the control of vocalization

This article reviews recent experimental and clinical literature on the central neural mechanisms involved in vocalization. Various parts of the cerebral cortex, limbic system, basal ganglia, and extrapyramidal system have been shown in human and animal studies to be important in vocalization, but the exact function of these areas with regard to vocal control is unclear. The limbic system and diencephalon project to the midbrain periaqueductal gray (PAG), which may be important for coordination of various muscle groups involved in vocalization. The PAG neurons project to the reticular formation, nucleus retroambiguus, and nucleus ambiguus. Neurons in the nucleus retroambiguus seem to be involved in control of neurons related to the respiratory or laryngeal systems. Different types of motoneurons of the laryngeal muscles in the nucleus ambiguus are related to various functions such as vocalization, swallowing, and respiration.     

Nonlinear oscillation of pathological vocal folds during vocalization

The extended two-mass model is adopted to analyze the nonlinear oscillation of pathological vocal folds during vocalization. Redundant tissue or area in laryngeal patients is modeled as a massless rigid connected to the upper mass of the vocal folds, and a parameter Q is introduced to represent the change of glottal configurations and tension imbalance between the left and right sides of vocal folds. Numerical simulations demonstrate that the pathological vocal-fold decreases the threshold of Q to generate nonlinear vocal oscillation, indicating the improvement of the sensitivity of vocal folds to asymmetries and enhancing the coupling between two sides. Furthermore, the pathological vocal-fold can lower the fundamental frequency and eliminate high-order harmonics, For example, the fundamental frequency decreases from 119.94 Hz to 84.95 Hz when Q=0.58 and the sub-glottal pressure 1450 Pa. However, there are no prominent effects on the amplitudes of sub-harmonic and low-order harmonics.     

Neural control of vocalization: Respiratory and emotional influences

Previous research has shown that a region of the midbrain, the periaqueductal gray matter (PAG), is critical for vocalization. In this review, we describe the results of previous investigations in which we sought to find out how PAG neurons integrate the activity and precise timing of respiratory, laryngeal, and oral muscle activity for natural-sounding vocalization using the technique of excitatory amino acid microinjections in cats. In these studies, all surgical procedures were carried out under deep anaesthesia. In the precollicular decerebrate cat two general types of vocalization, classified as voiced and unvoiced, could be evoked by exciting neurons in the lateral part of the intermediate part of the PAG. The patterns of evoked electromyographic activity were strikingly similar to previously reported patterns of human muscle activity. Coordinated patterns of activity were evoked with just-threshold excitation leading to the conclusion that patterned muscle activity corresponding to the major categories of voiced and voiceless sound production are represented in the PAG. In a parallel series of human and animal experiments, we also determined that the speech and vocalization respiratory patterns are integrated and coordinated with afferent signals related to lung volume. These data have led to the proposal of a new hypothesis for the neural control of vocalization: that the PAG is a crucial brain site for mammalian voice production, not only in the production of emotional or involuntary sounds, but also as a generator of specific respiratory and laryngeal motor patterns essential for human speech and song     

Determination of West Indian manatee vocalization levels and rate

The West Indian manatee (Trichechus manatus latirostris) has become endangered partly because of a growing number of collisions with boats. A system to warn boaters of the presence of manatees, based upon the vocalizations of manatees, could potentially reduce these boat collisions. The feasibility of this warning system would depend mainly upon two factors: the rate at which manatees vocalize and the distance in which the manatees can be detected. The research presented in this paper verifies that the average vocalization rate of the West Indian manatee is approximately one to two times per 5-min period. Several different manatee vocalization recordings were broadcast to the manatees and their response was observed. It was found that during the broadcast periods, the vocalization rates for the manatees increased substantially when compared with the average vocalization rates during nonbroadcast periods. An array of four hydrophones was used while recording the manatees. This allowed for position estimation techniques to be used to determine the location of the vocalizing manatee. Knowing the position of the manatee, the source level was determined and it was found that the mean source level of the manatee vocalizations is approximately 112 dB (re 1 microPa) @ 1 m.     

Generalized perceptual linear prediction features for animal vocalization analysis

A new feature extraction model, generalized perceptual linear prediction (gPLP), is developed to calculate a set of perceptually relevant features for digital signal analysis of animal vocalizations. The gPLP model is a generalized adaptation of the perceptual linear prediction model, popular in human speech processing, which incorporates perceptual information such as frequency warping and equal loudness normalization into the feature extraction process. Since such perceptual information is available for a number of animal species, this new approach integrates that information into a generalized model to extract perceptually relevant features for a particular species. To illustrate, qualitative and quantitative comparisons are made between the species-specific model, generalized perceptual linear prediction (gPLP), and the original PLP model using a set of vocalizations collected from captive African elephants (Loxodonta africana) and wild beluga whales (Delphinapterus leucas). The models that incorporate perceptional information outperform the original human-based models in both visualization and classification tasks.     

Laryngeal and respiratory activity during vocalization in macaque monkeys

The present study describes the laryngeal and respiratory muscle activity associated with vocalizations in macaque monkeys. During the bark vocalization, a short, aperiodic call, the cricothyroid, thyroarytenoid, rectus abdominis, and intercostals were active while the posterior cricoarytenoid and diaphragm were quiet. During the coo vocalization, a longer, clear call, the cricothyroid, thyroarytenoid, intercostals, rectus abdominis, and diaphragm were active. In one monkey, the posterior cricoarytenoid was also active during the call, while in another monkey it was not. Laryngeal muscle activity was correlated with the amplitude and duration of the coo call. Results suggest that the amplitude and duration differences between calls are determined primarily by laryngeal modification of the airflow, and that the differences in posterior cricoarytenoid activity may be due to differences in voice intensity.     

Localization and visual verification of a complex minke whale vocalization.

A recently described population of minke whales (Balaenoptera acutorostrata) offered a unique opportunity to study its acoustic behavior. The often-inquisitive dwarf minke whale is seen on the Great Barrier Reef nearly coincident with its suspected calving and breeding seasons. During drifting encounters with whales, a towed hydrophone array was used to record sounds for subsequent localization of sound sources. Shipboard and in-water observers linked these sounds to the closely circling minke whale. A complex and stereotyped sound sequence, the "star-wars" (SW) vocalization, was recorded during a series of visual and acoustic observations. The SW vocalization spanned a wide frequency range (50 Hz-9.4 kHz) and was composed of distinct and stereotypically repeated units with both amplitude and frequency-modulated components. Broadband source levels between 150 and 165 dB re 1 microPa at 1 m were calculated. Passive acoustic studies can utilize this distinct vocalization to help determine the behavior, distribution, and movements of this animal. While the SW vocalization's function remains unknown, the regularly repeated and complex sound sequence was common in low latitude, winter month aggregations of minke whales. At this early stage, the SW vocalization appears similar to the songs of other whale species and has characteristics consistent with those of reproductive advertisement displays.     

Sex-related differences in vocal responses to pitch feedback perturbations during sustained vocalization

The present study assessed the effect of sex on voice fundamental frequency (F(0)) responses to pitch feedback perturbations during sustained vocalization. Sixty-four native-Mandarin speakers heard their voice pitch feedback shifted at ± 50, ± 100, or ± 200 cents for 200 ms, five times during each vocalization. The results showed that, as compared to female speakers, male speakers produced significantly larger but slower vocal responses to the pitch-shifted stimuli. These findings reveal a modulation of vocal response as a function of sex, and suggest that there may be a differential processing of vocal pitch feedback perturbations between men and women.     

Steady inter and intra-annual decrease in the vocalization frequency of Antarctic blue whales

Time averaged narrow-band noise near 27 Hz produced by vocalizations of many distant Antarctic blue whales intensifies seasonally from early February to late October in the ocean off Australia's South West. Spectral characteristics of long term patterns in this noise band were analyzed using ambient noise data collected at the Comprehensive Nuclear-Test-Ban Treaty hydroacoustic station off Cape Leeuwin, Western Australia over 2002-2010. Within 7 day averaged noise spectra derived from 4096-point FFT (～0.06 Hz frequency resolution), the -3-dB width of the spectral peak from the upper tone of Antarctic blue whale vocalization was about 0.5 Hz. The spectral frequency peak of this tonal call was regularly but not gradually decreasing over the 9 years of observation from ～27.7 Hz in 2002 to ～26.6 Hz in 2010. The average frequency peak steadily decreased at a greater rate within a season at 0.4-0.5 Hz/season but then in the next year recovered to approximately the mean value of the previous season. A regression analysis showed that the interannual decrease rate of the peak frequency of the upper tonal call was 0.135 ± 0.003 Hz/year over 2002-2010 (R(2) ≈ 0.99). Possible causes of such a decline in the whale vocalization frequency are considered.