Effect of the losses in the vocal tract on determination of the area function

In this work, the cross-sectional areas of the vocal tract are determined for the lossy and lossless cases by using the pole-zero models obtained from the electrical equivalent circuit model of the vocal tract and the system identification method. The cross-sectional areas are used to compare the lossy and lossless cases. In the lossy case, the internal losses due to wall vibration, heat conduction, air friction and viscosity are considered, that is, the complex poles and zeros obtained from the models are used directly. Whereas, in the lossless case, only the imaginary parts of these poles and zeros are used. The vocal tract shapes obtained for the lossy case are close to the actual ones.     

Nordic rattle: the hoarse vocalization and the inflatable laryngeal air sac of reindeer (Rangifer tarandus)

Laryngeal air sacs have evolved convergently in diverse mammalian lineages including insectivores, bats, rodents, pinnipeds, ungulates and primates, but their precise function has remained elusive. Among cervids, the vocal tract of reindeer has evolved an unpaired inflatable ventrorostral laryngeal air sac. This air sac is not present at birth but emerges during ontogenetic development. It protrudes from the laryngeal vestibulum via a short duct between the epiglottis and the thyroid cartilage. In the female the growth of the air sac stops at the age of 2-3 years, whereas in males it continues to grow up to the age of about 6 years, leading to a pronounced sexual dimorphism of the air sac. In adult females it is of moderate size (about 100 cm3), whereas in adult males it is large (3000-4000 cm3) and becomes asymmetric extending either to the left or to the right side of the neck. In both adult females and males the ventral air sac walls touch the integument. In the adult male the air sac is laterally covered by the mandibular portion of the sternocephalic muscle and the skin. Both sexes of reindeer have a double stylohyoid muscle and a thyroepiglottic muscle. Possibly these muscles assist in inflation of the air sac. Head-and-neck specimens were subjected to macroscopic anatomical dissection, computer tomographic analysis and skeletonization. In addition, isolated larynges were studied for comparison. Acoustic recordings were made during an autumn round-up of semi-domestic reindeer in Finland and in a small zoo herd. Male reindeer adopt a specific posture when emitting their serial hoarse rutting calls. Head and neck are kept low and the throat region is extended. In the ventral neck region, roughly corresponding to the position of the large air sac, there is a mane of longer hairs. Neck swelling and mane spreading during vocalization may act as an optical signal to other males and females. The air sac, as a side branch of the vocal tract, can be considered as an additional acoustic filter. Individual acoustic recognition may have been the primary function in the evolution of a size-variable air sac, and this function is retained in mother-young communication. In males sexual selection seems to have favoured a considerable size increase of the air sac and a switch to call series instead of single calls. Vocalization became restricted to the rutting period serving the attraction of females. We propose two possibilities for the acoustic function of the air sac in vocalization that do not exclude each other. The first assumes a coupling between air sac and the environment, resulting in an acoustic output that is a combination of the vocal tract resonance frequencies emitted via mouth and nostrils and the resonance frequencies of the air sac transmitted via the neck skin. The second assumes a weak coupling so that resonance frequencies of the air sac are lost to surrounding tissues by dissipation. In this case the resonance frequencies of the air sac solely influence the signal that is further filtered by the remaining vocal tract. According to our results one acoustic effect of the air sac in adult reindeer might be to mask formants of the vocal tract proper. In other cervid species, however, formants of rutting calls convey essential information on the quality of the sender, related to its potential reproductive success, to conspecifics. Further studies are required to solve this inconsistency.     

Wavelet time-frequency analysis and least squares support vector machines for the identification of voice disorders

This work describes a novel algorithm to identify laryngeal pathologies, by the digital analysis of the voice. It is based on Daubechies' discrete wavelet transform (DWT-db), linear prediction coefficients (LPC), and least squares support vector machines (LS-SVM). Wavelets with different support-sizes and three LS-SVM kernels are compared. Particularly, the proposed approach, implemented with modest computer requirements, leads to an adequate larynx pathology classifier to identify nodules in vocal folds. It presents over 90% of classification accuracy and has a low order of computational complexity in relation to the speech signal's length.     

Longitudinal principal components analysis of patterns and predictors of growth in Guatemalan children

Longitudinal principal components (LPC) analysis was used to assess growth patterns in children from rural Guatemala in order to determine if this methodology could provide additional information regarding correlates of growth compared to more traditionally used methods based on attained size and increments. LPC analysis reduces measures at many points in time into a few parameters. However, LPC analysis requires complete data, and many cases may be lost due to missing values. Thus the potentially greater sensitivity of LPC analysis should be weighed against the reduced power resulting from smaller sample sizes. Component indices representing centile level and centile shift, attained size, and 3 to 36 month increments of growth in length and weight were used as the dependent variables in multiple regression models in order to examine the effects of environmental variables, such as home dietary intake, supplementation, and prevalence of diarrhea on growth. Regardless of which growth index, i.e., attained size, incremental change, or principal component, was used, regression results were similar; higher nutritional intakes were generally associated with greater and more rapid growth from birth to age 3 years. The possible advantages of LPC analysis over more traditional methods were not great; therefore, LPC analysis is not recommended as the method of choice in this population.     

A noninvasive estimation of hypernasality using a linear predictive model

The pronunciation of a speaker with a defective soft palate is marked by hypernasality and an operation may be necessary to repair the defective soft palate to reduce this hypernasality. An assessment of hypernasality is necessary to quantify the effect of the surgery. The current clinical methods for assessing hypernasality are uncomfortable or require expensive equipment. In this paper, a new quantitative method is proposed to estimate hypernasality. This method requires only a microphone and a personal computer equipped with a sound card. Zeros in the frequency response of the vocal tract system are one of the major characteristics of hypernasality. The proposed method made use of the fact that a linear predictive model with a typical order for the human vocal tract system is not accurate when the vocal tract system has zeros in its frequency response. Hypernasality was estimated by comparing the distance between the sequences of linear predictive cepstrum of low- and high-order linear predictive models. The proposed method provides a better correlation (0.58) with nasalance measured by a nasometer than Teager method (0.44) for all the data. Furthermore, the proposed method showed higher correlation of 0.84 than 0.71 of the Teager method for data with a nasalance higher than 35%. Since the proposed method needs only digitized speech data, it is much less invasive and provides an easy and cost-effective evaluation of hypernasality. © 2001 Biomedical Engineering Society. PAC01: 4370Dn, 4372Ar     

Effect of the Signal Measured from the Glottis on Determination of the Vocal Tract Shape

All-pole and pole-zero models for the vocal tract are developed. First an impulse train, then the pressure signal measured from the glottis, is used as the input in the models. The models for eight Turkish vowels produced by one male subject are studied to determine the effects of the presumed impulse train and the pressure signal measured from the glottis on the estimation of the vocal tract shape. The motion of the tongue is also examined for a whole word. © 1998 Biomedical Engineering Society. PAC98: 4372-p, 8710+e     

Kinetic analysis of a graft reaction induced in cell culture

A kinetic analysis was made of the graft reaction induced in culture by plating rat lymphocytes on monolayers of mouse fibroblasts. The immune cytolysis of the mouse fibroblasts, carried out by sensitized rat large pyroninophilic cells (LPC), was determined by the rate of ⁵¹Cr released from labelled target cells. The sensitivity and accuracy of the quantitative method employed in the present study was evident from: (a) the low spontaneous release of the ⁵¹Cr from the labelled fibroblasts, (b) the lack of re-utilizaiton of the released ⁵¹Cr by lymphocytes, and (c) the low standard deviation of replicate plates.

Experiments were made to determine the order of the lytic reaction with regard to the different cell reactants (LPC and fibroblasts). When the rate of lysis was measured while constant numbers of LPC interacted with different concentrations of fibroblasts, the reaction was of first order for fibroblasts. When measured while constant numbers of fibroblasts interacted with different concentrations of LPC—the reaction was of first order for LPC. This indicates that one LPC is required to lyse one fibroblast. The kinetic analysis of the lytic reaction also indicated that each fibroblast dies independently as a result of a single hit by a LPC. There was no latent period, or only a very short one, for the lytic effect. Thus, the lytic process of a target cell starts as soon as cell-contact between LPC and fibroblast is accomplished. The number of LPC is not decreased during the lytic reaction. Hence, LPC are not subjected to an `allergic death' after exerting a lytic effect on target cells.

     

Shared processing of planning articulatory gestures and grasping

It has been proposed that articulatory gestures are shaped by tight integration in planning mouth and hand acts. This hypothesis is supported by recent behavioral evidence showing that response selection between the precision and power grip is systematically influenced by simultaneous articulation of a syllable. For example, precision grip responses are performed relatively fast when the syllable articulation employs the tongue tip (e.g., [te]), whereas power grip responses are performed relatively fast when the syllable articulation employs the tongue body (e.g., [ke]). However, this correspondence effect, and other similar effects that demonstrate the interplay between grasping and articulatory gestures, has been found when the grasping is performed during overt articulation. The present study demonstrates that merely reading the syllables silently (Experiment 1) or hearing them (Experiment 2) results in a similar correspondence effect. The results suggest that the correspondence effect is based on integration in planning articulatory gestures and grasping rather than requiring an overt articulation of the syllables. We propose that this effect reflects partially overlapped planning of goal shapes of the two distal effectors: a vocal tract shape for articulation and a hand shape for grasping. In addition, the paper shows a pitch–grip correspondence effect in which the precision grip is associated with a high-pitched vocalization of the auditory stimuli and the power grip is associated with a low-pitched vocalization. The underlying mechanisms of this phenomenon are discussed in relation to the articulation–grip correspondence.     

ERP assessment of functional status in the temporal lobe: examining spatiotemporal correlates of object recognition.

We have previously used functional magnetic resonance imaging to assess specific anterolateral temporal regions involved in object recognition, providing a novel technique for evaluating functional status in temporal lobe epilepsy (i.e., a site directed approach). However, a method that combines high temporal resolution with spatial mapping is needed to isolate the specific processes associated with these regions (i.e., a process specific approach). In the current study, we evaluated the cognitive processes associated with object recognition and their relationship to the temporal lobe using high-density event-related potentials (ERPs). N300 and late positive component (LPC) responses were examined using a word-picture matching task, with three factors: congruity (match/mismatch), level of abstraction (basic/superordinate), and object category (natural/artificial). The N300 and LPC were analyzed in terms of their temporal characteristics as well as their spatial characteristics through source analysis. The results showed that the N300 primarily indexed processing of congruity and level of abstraction, whereas the LPC primarily indexed processing of object category. In agreement with previous functional imaging studies, N300 and LPC source analysis results confirmed temporal lobe involvement in object recognition. Importantly, LPC object category differences were detected in the anterior temporal lobe. Individual subject analyses revealed that these anterior temporal lobe differences were reliable--with greater activity for natural objects in 84% of subjects. The findings are discussed in terms of clinical applications that use spatiotemporal ERP differences to evaluate functional status of the temporal lobes.     

Cell membrane-derived lysophosphatidylcholine activates cardiac ryanodine receptor channels

Lysophosphatidylcholine (LPC) is metabolized from a membrane phospholipid and modulates a variety of channels in the plasma membrane (PM). We examined LPC modulation of cardiac ryanodine receptor (RyR) channels in the sarcoplasmic reticulum (SR) using the planar lipid bilayer method to measure the single-channel currents. Micromolar concentrations of LPC increased the open probability of the reconstituted RyR channels irrespective of whether LPC was added to the cis or trans chamber. LPC also increased the membrane capacitance of the bilayer. The effects of LPC contrasted well with those of sphingosylphosphorylcholine (SPC). Taken together, these results suggest that amphipathic lipid LPC does not bind directly to the RyR channel protein, but rather, is incorporated into the bilayer membrane and activates the channel. Thus, we consider cell membrane-derived LPC to be a putative endogenous mediator that activates not only plasma membrane channels but also RyR channels and induces arrhythmogenic Ca²⁺ mobilization in cardiomyocytes.     

Transient vocal cord palsy caused by hypoperfusion of unilateral hemisphere

We report a 68-year-old man who exhibited mild dysarthria and mild right hemiparesis resulted from hypoperfusion of the left hemisphere. An MR angiography showed a severe stenosis at the second portion of left middle cerebral artery (MCA). After the beginning of treatment, the patient suffered from hoarseness, followed by breathing failure. The laryngeal fiber exhibited right vocal cord paresis. Unilateral cortico-bulbar tract dysfunction does not typically cause vocal cord palsy. However, several cases indicate the involvement of a dominant projection from the contralateral cortico-bulbar tract to the vocal cord. In the present case, hypoperfusion of the left hemisphere might have temporarily produced right vocal cord palsy, considering the stenosis of the left MCA.     

Descended and mobile larynx, vocal tract elongation and rutting roars in male goitred gazelles (Gazella subgutturosa Güldenstaedt, 1780)

Similar to male humans, Homo sapiens, the males of a few polygynous ruminants - red deer Cervus elaphus, fallow deer Dama dama and Mongolian gazelle Procapra gutturosa- have a more or less enlarged, low-resting larynx and are capable of additional dynamic vocal tract elongation by larynx retraction during their rutting calls. The vocal correlates of a large larynx and an elongated vocal tract, a low fundamental frequency and low vocal tract resonance frequencies, deter rival males and attract receptive females. The males of the polygynous goitred gazelle, Gazella subgutturosa, provide another, independently evolved, example of an enlarged and low-resting larynx of high mobility. Relevant aspects of the rutting behaviour of territorial wild male goitred gazelles are described. Video and audio recordings served to study the acoustic effects of the enlarged larynx and vocal tract elongation on male rutting calls. Three call types were discriminated: roars, growls and grunts. In addition, the adult male vocal anatomy during the emission of rutting calls is described and functionally discussed using a 2D-model of larynx retraction. The combined morphological, behavioural and acoustic data are discussed in relation to the hypothesis of sexual selection for male-specific deep voices, resulting in convergent features of vocal anatomy in a few polygynous ruminants and in human males.     

Savannah roars: The vocal anatomy and the impressive rutting calls of male impala (Aepyceros melampus) – highlighting the acoustic correlates of a mobile larynx

A retractable larynx and adaptations of the vocal folds in the males of several polygynous ruminants serve for the production of rutting calls that acoustically announce larger than actual body size to both rival males and potential female mates. Here, such features of the vocal tract and of the sound source are documented in another species. We investigated the vocal anatomy and laryngeal mobility including its acoustical effects during the rutting vocal display of free-ranging male impala (Aepyceros melampus melampus) in Namibia. Male impala produced bouts of rutting calls (consisting of oral roars and interspersed explosive nasal snorts) in a low-stretch posture while guarding a rutting territory or harem. For the duration of the roars, male impala retracted the larynx from its high resting position to a low mid-neck position involving an extensible pharynx and a resilient connection between the hyoid apparatus and the larynx. Maximal larynx retraction was 108 mm based on estimates in video single frames. This was in good concordance with 91-mm vocal tract elongation calculated on the basis of differences in formant dispersion between roar portions produced with the larynx still ascended and those produced with maximally retracted larynx. Judged by their morphological traits, the larynx-retracting muscles of male impala are homologous to those of other larynx-retracting ruminants. In contrast, the large and massive vocal keels are evolutionary novelties arising by fusion and linear arrangement of the arytenoid cartilage and the canonical vocal fold. These bulky and histologically complex vocal keels produced a low fundamental frequency of 50 Hz. Impala is another ruminant species in which the males are capable of larynx retraction. In addition, male impala vocal folds are spectacularly specialized compared with domestic bovids, allowing the production of impressive, low-frequency roaring vocalizations as a significant part of their rutting behaviour. Our study expands knowledge on the evolutionary variation of vocal fold morphology in mammals, suggesting that the structure of the mammalian sound source is not always human-like and should be considered in acoustic analysis and modelling.     

一种喉部疾病口语声诊断新方法

本文提出了声带的三质量块模型,并应用这种模型模拟病嗓产生的嘶哑语声。这些嘶声包括有声带闭合不全、声带小结、声带麻痹、喉炎、声带淀粉样变和声门癌等十六种典型情况。采用快速傅里叶变换、线性预测、倒谱技术和离散余弦变换等方法,分析各类喉病引起的嘶哑语声,实验结果表明声带模型分析法是喉病诊断的一种有效方法。     

Vocalizations in the cat: behavioral methodology and spectrographic analysis

Summary Attempts to understand the neural mechanisms underlying mammalian vocal behaviors, including speech, require study of the neural activity and anatomy of vocalization-controlling brain structures. Such studies necessitate the application of invasive neurobiological techniques in animal models. In the current study, cats are used in the development of an animal model of vocal tract control. The animals are instrumentally conditioned to vocalize for food reward. Acquisition of this task can occur within a few minutes, although additional training generally is required to solidly establish the behavior and to train subjects to produce consistently high rates of vocalization for prolonged periods of time. Following training, animals can generally sustain a rate of two calls per minute for a period of over two hours. Optimal task performance is partly dependent on motivation level. Although there is considerable variation between animals, the vocalizations produced have an average duration of 600 ms and a fundamental frequency of around 500 Hz. In addition, during a typical vocalization, there are dynamic variations of about 150 Hz for fundamental frequency and 17 dB for sound intensity. These variations provide opportunities for relating neural and muscular activity to different aspects of the vocal behavior they control. Based on a number of considerations, the model and techniques discussed here probably are most applicable to studying the neurobiology of sub-cortical nuclei subserving vocal control. Similar mechanisms might well be present in other species, including humans. Thus, data obtained from study of this model may be applicable to understanding the processes underlying vocal tract control during human speech.     

Vocalization by extant nonavian reptiles: A synthetic overview of phonation and the vocal apparatus

Among amniote vertebrates, nonavian reptiles (chelonians, crocodilians, and lepidosaurs) are regarded as using vocal signals rarely (compared to birds and mammals). In all three reptilian clades, however, certain taxa emit distress calls and advertisement calls using modifications of regions of the upper respiratory tract. There is no central tendency in either acoustic mechanisms or the structure of the vocal apparatus, and many taxa that vocalize emit only relatively simple sounds. Available evidence indicates multiple origins of true vocal abilities within these lineages. Reptiles thus provide opportunities for studying the early evolutionary stages of vocalization. The early literature on the diversity of form of the laryngotracheal apparatus of reptiles boded well for the study of form-function relationships, but this potential was not extensively explored. Emphasis shifted away from anatomy, however, and centered instead on acoustic analysis of the sounds that are produced. New investigative techniques have provided novel ways of studying the form-function aspects of the structures involved in phonation and have brought anatomical investigation to the forefront again. In this review we summarize what is known about hearing in reptiles in order to contextualize the vocal signals they generate and the sound-producing mechanisms responsible for them. The diversity of form of the sound producing apparatus and the increasing evidence that reptiles are more dependent upon vocalization as a communication medium than previously thought indicates that they have a significant role to play in the understanding of the evolution of vocalization in amniotes.     

流固耦合作用下真实人体上呼吸道气溶胶扩散沉积的仿真与实验

通过构建真实人体上呼吸道三维规范模型,运用大涡模拟数值方法和Lagrangian随机轨道模型,对考虑流固耦合作用时循环呼吸模式下上呼吸道内气溶胶的扩散沉积进行数值仿真,分析气流涡结构演化对气溶胶扩散的影响,并通过实验对气溶胶在人体上呼吸道的沉积率进行测量,验证仿真方法的正确性。结果表明:循环吸气时,0.3 μm气溶胶颗粒比6.5 μm气溶胶颗粒更容易通过上呼吸道而进入更深层次的支气管;循环呼气时,部分进入上呼吸道的颗粒在呼出气流夹带下,在气道中折返、回旋、沉积,而有些则从口腔中呼出;0.3和6.5 μm气溶胶颗粒在咽、喉以及气管内沉积较多,而在口腔内沉积较少;6.5 μm气溶胶颗粒在上呼吸道不同部位的沉积率明显高于0.3 μm气溶胶;流固耦合作用时咽部、喉部的壁面形变可缓冲气流冲击,气溶胶颗粒在咽喉部位的沉积率有所下降;大粒径气溶胶颗粒沉积受惯性碰撞影响较大,而小粒径气溶胶颗粒沉积受湍流扩散及涡流夹带的影响较大。     

The role of small intestinal antigen-presenting cells in the induction of T-cell reactivity to soluble protein antigens: association between aberrant presentation in the lamina propria and oral tolerance.

The oral administration of soluble protein antigen results in profound immunological tolerance. However, the tissue location and function of antigen-presenting cells (APC) that stimulate this response remain unclear. We have hypothesized that the properties of cells presenting antigen to naive T cells within the gut are involved, and therefore gut APC should stimulate T-cell responses with different characteristics to those induced by other APC. To test this, we studied in vitro primary T-cell responses following presentation of soluble protein antigen by cells from the Peyer's patches (PPC) and lamina propria (LPC) of the murine small intestine and the spleen (SPLC). Each APC population stimulated antigen-specific proliferative responses with similar anamnestic characteristics; however, analysis of the cytokines produced revealed marked differences. Whereas SPLC stimulated the balanced production of T-helper type 1 (Th1) and Th2 cytokines, PPC induced a profile consistent with the provision of T-cell help for IgA production. Interestingly, presentation of antigen by LPC stimulated high levels of interferon-gamma (IFN-gamma) and transforming growth factor-beta (TGF-beta) in the absence of other cytokines [interleukin-2 (IL-2), IL-4, IL-5]. Evidence from analysis of cell activation and division within the cultures suggested that this profile may result from the preferential activation of CD8+ T cells by LPC; however, the lack of conventional CD4+ T-cell cytokines indicated a defect in the normal function of these cells. Adoptive transfer of antigen-pulsed LPC to syngeneic animals abrogated the induction of delayed-type hypersensitivity (DTH) responsiveness, which followed a subsequent conventional antigen challenge further suggesting a role for lamina propria APC in tolerance induction.     

Roars,groans and moans: Anatomical correlates of vocal diversity in polygynous deer

Eurasian deer are characterized by the extraordinary diversity of their vocal repertoires. Male sexual calls range from roars with relatively low fundamental frequency (hereafter f_o) in red deer Cervus elaphus, to moans with extremely high f_o in sika deer Cervus nippon, and almost infrasonic groans with exceptionally low f_o in fallow deer Dama dama. Moreover, while both red and fallow males are capable of lowering their formant frequencies during their calls, sika males appear to lack this ability. Female contact calls are also characterized by relatively less pronounced, yet strong interspecific differences. The aim of this study is to examine the anatomical bases of these inter-specific and inter-sexual differences by identifying if the acoustic variation is reflected in corresponding anatomical variation. To do this, we investigated the vocal anatomy of male and female specimens of each of these three species. Across species and sexes, we find that the observed acoustic variability is indeed related to expected corresponding anatomical differences, based on the source-filter theory of vocal production. At the source level, low f_o is associated with larger vocal folds, whereas high f_o is associated with smaller vocal folds: sika deer have the smallest vocal folds and male fallow deer the largest. Red and sika deer vocal folds do not appear to be sexually dimorphic, while fallow deer exhibit strong sexual dimorphism (after correcting for body size differences). At the filter level, the variability in formants is related to the configuration of the vocal tract: in fallow and red deer, both sexes have evolved a permanently descended larynx (with a resting position of the larynx much lower in males than in females). Both sexes also have the potential for momentary, call-synchronous vocal tract elongation, again more pronounced in males than in females. In contrast, the resting position of the larynx is high in both sexes of sika deer and the potential for further active vocal tract elongation is virtually absent in both sexes. Anatomical evidence suggests an evolutionary reversal in larynx position within sika deer, that is, a secondary larynx ascent. Together, our observations confirm that the observed diversity of vocal behaviour in polygynous deer is supported by strong anatomical differences, highlighting the importance of anatomical specializations in shaping mammalian vocal repertoires. Sexual selection is discussed as a potential evolutionary driver of the observed vocal diversity and sexual dimorphisms.     

Optimized transformation of the glottal motion into a mechanical model

During phonation the human vocal folds exhibit a complex self-sustained oscillation which is a result of the transglottic pressure difference, of the characteristics of the tissue of the folds and of the flow in the gap between the vocal folds (Van den Berg J. Myoelastic-aerodynamic theory of voice production. J Speech Hearing Res 1958;1:227-44 [1]). Obviously, extensive experiments cannot be performed in vivo. Therefore, in literature a variety of model experiments that try to replicate the vocal folds kinematics for specific studies within the vocal tract can be found. Here, we present an experimental model to visualize the fluid dynamics which result from the complex motions of real human vocal folds. An existing up-scaled glottal cam model with approximate glottal kinematics is extended to replicate more realistically observed glottal closure types. This extension of the model is a further step in understanding the fluid dynamical mechanisms contributing to the quality of human voice during phonation, in particular the cause (changed glottal kinematics) and its effect (changed aero-acoustic field). For four typical glottal closure types cam geometries of varying profile are generated. Two counter rotating cams covered with a silicone membrane reproduce as well as possible the observed glottal movements.