A role for the second subglottal resonance in lexical access

Acoustic coupling between the vocal tract and the lower (subglottal) airway results in the introduction of pole-zero pairs corresponding to resonances of the uncoupled lower airway. If the second formant (F2) passes through the second subglottal resonance a discontinuity in amplitude occurs. This work explores the hypothesis that this F2 discontinuity affects how listeners perceive the distinctive feature [back] in transitions from a front vowel (high F2) to a labial stop (low F2). Two versions of the utterances "apter" and "up there" were synthesized with an F2 discontinuity at different locations in the initial VC transition. Subjects heard portions of the utterances with and without the discontinuity, and were asked to identify whether the utterances were real words or not. Results show that the frequency of the F2 discontinuity in an utterance influences the perception of backness in the vowel. Discontinuities of this sort are proposed to play a role in shaping vowel inventories in the world's languages [K. N. Stevens, J. Phonetics 17, 3-46 (1989)]. The results support a model of lexical access in which articulatory-acoustic discontinuities subserve phonological feature identification.     

The effect of subglottal resonance upon vocal fold vibration

An experiment with excised larynges was undertaken to investigate theinteraction between acoustic pressures in a pseudotrachea and the amplitude of vibration of the vocal folds. Pressure was measured beneath the vocal folds at three specific moments of the vibratory cycle: (a) when the superior margin of the vocal folds began to separate, (b) when the vocal folds were maximally apart, and (c) when the inferior margin of the vocal folds began to touch. Results indicate that in half the larynges investigated, the maximum amplitude of vibration increased as a function of: (a) increased positive pressure at the moment of opening, and (b) reduced subglottal pressure when the vocal folds were maximally apart. The implications of these experiments regarding involuntary register transitions related to trachea resonance are discussed in light of a previously proposed register theory.     

Significance of mechanoreceptors in the subglottal mucosa for subglottal pressure control in singers

According to Wyke and Kirchner (Wyke B, Kirchner J. Neurology of the larynx. In: Hinchcliffe R, Harrison D, eds. Scientific foundation of otolaryngology. London: William Heinemann Medical Books, 1976:546–66) mechanoreceptors in the subglottal mucosa play a significant role in the control of laryngeal muscle activity in response to changes of subglottal pressure during phonation. In singers this pressure is adapted not only to phonatory loudness but also to fundamental frequency. By spraying Xylocaine solution with a needle inserted into the trachea through the anterior gap between the cricoid and thyroid cartilages, the subglottal mucosa was anesthetized in three singers. The effects on subglottal pressure and fundamental frequency of this anesthesia were examined. The pressure effects varied between the subjects, whereas the fundamental frequency accuracy was adversely affected in all three subjects. The implications of these findings are discussed.     

Resonances and wave propagation velocity in the subglottal airways

Previous studies of subglottal resonances have reported findings based on relatively few subjects, and the relations between these resonances, subglottal anatomy, and models of subglottal acoustics are not well understood. In this study, accelerometer signals of subglottal acoustics recorded during sustained [a:] vowels of 50 adult native speakers (25 males, 25 females) of American English were analyzed. The study confirms that a simple uniform tube model of subglottal airways, closed at the glottis and open at the inferior end, is appropriate for describing subglottal resonances. The main findings of the study are (1) whereas the walls may be considered rigid in the frequency range of Sg2 and Sg3, they are yielding and resonant in the frequency range of Sg1, with a resulting ~4/3 increase in wave propagation velocity and, consequently, in the frequency of Sg1; (2) the "acoustic length" of the equivalent uniform tube varies between 18 and 23.5 cm, and is approximately equal to the height of the speaker divided by an empirically determined scaling factor; (3) trachea length can also be predicted by dividing height by another empirically determined scaling factor; and (4) differences between the subglottal resonances of males and females can be accounted for by height-related differences.     

On the relation between subglottal pressure and fundamental frequency in phonation

The change in fundamental frequency with subglottal pressure in phonation is quantified on the basis of the ratio between vibrational amplitude and vocal fold length. This ratio is typically very small in stringed instruments, but becomes quite appreciable in vocal fold vibration. Tension in vocal fold tissues is, therefore, not constant over the vibratory cycle, and a dynamic tension gives rise to amplitude-frequency dependence. It is shown that the typical 2-6 Hz/cm H2O rise in fundamental frequency with subglottal pressure observed in human and canine larynges is a direct and predictable consequence of this amplitude-frequency dependence. Results are presently limited to phonation in the chest register.     

Automatic resonance recognition method in solar wind

Summary The principal objective of the Sounder experiment aboard ISEE 1 is to study the plasma frequency along the spacecraft trajectory. This represents a considerable amount of data for the duration of the mission (3 years). Thus an automatic method is necessary to recognize the plasma resonances. We present here a resonance recognition methodology based on the Sebestyen's discrimination approach. The preliminary results of this method, obtained from a set of known resonances, show a good efficiency (more than 90% of the known plasma resonances are recognized). This method will be used in the future to identify other resonances in the magnetosphere.

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Riassunto L'obiettivo principale dell'esperimento di Sounder a bordo dell'ISEE 1 è uno studio della frequenza del plasma lungo la traiettoria della navicella spaziale. Ciò significa una considerevole quantità di dati per la durata della missione (3 anni). Perciò è necessario un metodo automatico per riconoscere le risonanze del plasma. Si presenta qui una metodologia di riconoscimento della risonanza basata sull'approccio di discriminazione di Sebestyen. I risultati preliminari di questo metodo, ottenuti da una serie di risonanze note, mostra una buona efficienza (più del 90% delle risonanze note del plasma è riconosciuto). Questo metodo sarà usato in futuro per identificare altre risonanze nella magnetosfera.

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Резюме Главная цель эксперимента на борту ISEE-1—исследование плазменной частоты вдоль траектории космического аппарата. В эксперименте получено большое количество данных в течение полета (3 года). Поэтому необходим автоматический метод распознавания плазменных резонансов. В этой работе мы предлагаем методику распознавания резонансов, основанную на подходе дискриминации Себестьена. Предварительные результаты этого метода, полученные для системы известных резонансов обнаруживают хорошую эффективность (более чем 90% для известных плазменных резонансов). Этот метод будет использоваться в дальнейшем для идентификации других резонансов в магнитосфере.

     

The influence of subglottal acoustics on laboratory models of phonation

Many previous laboratory investigations of phonation involving physical models, excised larynges, and in vivo canine larynges have failed to fully specify the subglottal system. Many of these same studies have reported a variety of nonlinear phenomena, including bifurcations (e.g., various classes of phonation onset and offset, register changes, frequency jumps), subharmonics, and chaos, and attributed such phenomena to the biomechanical properties of the larynx. However, such nonlinear phenomena may also be indicative of strong coupling between the voice source and the subglottal tract. Consequently, in such studies, it has not been clear whether the underlying mechanisms of such nonlinear phenomena were acoustical, biomechanical, or a coupling of the acoustical and biomechanical systems. Using a physical model of vocal fold vibration, and tracheal tube lengths which have been commonly reported in the literature, it is hypothesized and subsequently shown that such nonlinear phenomena may be replicated solely on the basis of laryngeal interactions with the acoustical resonances of the subglottal system. Recommendations are given for ruling out acoustical resonances as the source of nonlinear phenomena in future laboratory studies of phonation.     

Spectrum effects of subglottal pressure variation in professional baritone singers

The audio signal from five professional baritones was analyzed by means of spectrum analysis. Each subject sang syllables [pae] and [pa] from loudest to softest phonation at fundamental frequencies representing 25%, 50%, and 75% of his total range. Ten subglottal pressures, equidistantly spaced between highest and lowest, were selected for analysis along with the corresponding production of the vowels. The levels of the first formant and singer's formant were measured as a function of subglottal pressure. Averaged across subjects, vowels, and F0, a 10-dB increase at 600 Hz was accompanied by a 16-dB increase at 3 kHz.     

Photoproduction of charged pions on deuterium in the first resonance region

Photoproduction of π⁺ and π^? on deuterium has been measured in the photon energy range from 240 to 400 MeV and for pion c.m. angles between 15° and 180°. The pions were analysed in angle and momentum by a magnetic spectrometer. From the measured π^?/π⁺ ratio, corrected for Coulomb interactions in the final state, differential cross sections of the reaction γ+n→π^?+p were calculated. Together with the π⁺ photoproduction our data show no isotensor contribution. Comparison of our data with the recent experiments done on the inverse reaction shows no evidence of a violation of time reversal invariance. With the measured π⁺ photoproduction on deuterium, a test of the spectator model has been made. Using the closure-approximation of Chew and Lewis our data agree within a range of ±10%.     

A multipole analysis of pion photoproduction in the first resonance region

An energy-independent multipole analysis of pion photoproduction in the first resonance region has been performed in which special care has been taken in the selection and normalization of the data. The results obtained are a significant improvement on those of earlier analyses. Three features are of particular interest: a zero in the $\text{E}{}_{\mathrm{1+}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ multipole at resonance; a smooth $\text{M}{}_{\mathrm{1?}}{}^{\mathrm{<mtext>1</mtext><mtext>2</mtext>}}$ multipole showing the onset of the P₁₁(1470) resonance; and evidence for the position of the Δ⁺ resonance being different from those of the Δ⁺⁺ and Δ^o resonances. A comparison is made with the recent energy-dependent analyses, indicating agreement in the gross features of the multipoles but showing significant differences in essential details.     

A comparison of subglottal and intraoral pressure measurements during phonation

Intraoral pressure and subglottal pressure, derived from tracheal puncture, were recorded with the electroglottographic signal for one normal speaking male during phonation. The mean subglottal pressure for vowels was also estimated by interpolating the intraoral pressure from surrounding /p/ occlusions. The pressure measurements were highly correlated (r = 0.98) and there were small pressure value differences (on average <2%). The effects of varying speech rate and mode of phonation on the pressure measurements are discussed. A decrease in pressure from the mean subglottal pressure for the open phase and an increase for the closed phase was found during the glottal vibratory cycles.     

An anatomically based, time-domain acoustic model of the subglottal system for speech production

A time-domain model of sound wave propagation in the branching airways of the subglottal system is presented. The model is formulated as an extension to an acoustic transmission-line modeling scheme originally developed for simulating the supraglottal system in the time-domain during speech production [Maeda (1982). Speech Commun. 1, 199-229; Mokhtari et al. (2008). Speech Commun. 50, 179-190]. The approach allows for predictions of time-varying acoustic pressure and volume velocity at any point along the various generations of subglottal airways from trachea to alveoli. In addition, the model can be configured so that its overall structure simulates different geometric forms, including airways that branch in a symmetric or asymmetric pattern. Three subglottal configurations, two symmetric and one asymmetric, were represented based on reported anatomical dimensions of the subglottal airways. Estimates of the acoustic input impedances of these subglottal configurations revealed resonant characteristics similar to those found in the previous studies. Simulations of voiced sound propagation into the subglottal airways, achieved by coupling the subglottal model to a two-mass vocal fold model and a supraglottal tract configured for different vowels, yielded predictions of time-domain sound pressure waveforms below the vocal folds that compare favorably to previous measurements in human subjects.     

Coherent π0-photoproduction on deuterium in the first resonance region

Differential cross sections for coherent π⁰-photoproduction from deuterium have been measured in the photon energy range from 240 to 400 MeV and for pion c.m. angles between 70 ° and 160 °. The recoil deuterons were analysed in angle and momentum by a magnetic spectrometer. The cross sections obtained were higher by a factor of about 2 compared with the results from Stanford [7], the only data available up to now in the first resonance region. Below the resonance the measured cross sections give a smooth extension to the low energy data from Glasgow [5] and Orsay [6].     

随机共振法估计二水听器时延差

针对二元阵航船目标方位估计问题,提出了一种基于随机共振滤波的航船辐射噪声双水听器时延差估计方法。设计了一种随机共振滤波器,提取航船螺旋桨旋转噪声在水听器接收信号中出现的本地时间,并通过滤波结果的互相关来估计目标辐射噪声分别到达两个水听器的时延差。在5 dB的输入信噪比下进行200次仿真,提出方法时延估计的归一化均方误差要低于互谱方法一个数量级。对于海试中的非合作航船,提出的方法可以在1 km距离下准确估计出目标辐射噪声到达双水听器的时延差,从而为在二元阵上实现对航船目标的准确测向提供基础。     

利用随机共振技术的微弱信号方位估计

提出了基于随机共振技术的微弱目标方位估计方法。通过自适应调节系统参数,包括两种方法:自适应调节系统结构参数和自适应调节外加噪声,使系统进入随机共振状态,经随机共振器输出后得到信噪比较大提高的阵列信号,再由方位估计算法估计出目标方位。并进行了仿真和实验研究,结果表明:实验结果与理论分析符合良好,该方法可应用于微弱低频信号的目标方位估计。     

Effects of subglottal pressure variation on professional baritone singers' voice sources

Five professional operatic baritone singers' voice-source characteristics were analyzed by means of inverse filtering of the flow signal as captured by a flow mask. The subjects sang a long sustained diminuendo, from loudest to softest, three times on the vowels [a:] and [ae:] at fundamental frequencies representing 25%, 50%, and 75% of their total pitch range as measured in semitones. During the diminuendos, they repeatedly inserted the consonant [p] so that associated subglottal pressures could be estimated from the oral pressure during the p-occlusions. Pooling the three takes of each condition, ten subglottal pressures, equidistantly spaced between highest and lowest, were selected for analysis. Sound-pressure levels (SPL), peak-to-peak glottal airflow, maximum flow declination rate, closed quotient, glottal dc flow, and the level difference between the two lowest partials of the source spectrum (H1-H2) were determined. All parameters except the glottal dc flow showed a systematic variation with subglottal pressure or the fractional excess pressure over threshold. The results are given in terms of equations representing the average across subjects for the relation between subglottal pressure and each of the mentioned voice-source parameters.     

Automatic detection of hippocampal atrophy on magnetic resonance images.

An automatic method for identifying hippocampal atrophy on magnetic resonance (MR) images obtained from patients with clinical evidence of temporal lobe epilepsy (TLE) is described. The method is based on the analysis of image intensity differences between patients and controls within a volume of interest (VOI) centred on the hippocampus. The core of the method is a fully automatic signal intensity-based inter-subject image registration technique. In particular, a global affine registration to a reference image is performed, followed by a local affine registration within the VOI. A mask produced by manual segmentation of the mean hippocampus for 30 control subjects enabled investigations to be restricted to a specified region of the VOI approximately corresponding to the hippocampus. Normal variations of hippocampal signal intensity were computed from images obtained for the 30 control subjects. The manual method of hippocampal volumetry, currently an important component of the pre-surgical evaluation of patients with clinical evidence of medically intractable TLE, is used to determine the lower 1st percentile limits of normal hippocampal volume. Hippocampi with volumes below this limit are defined as atrophic. We investigated whether the automatic method can correctly distinguish between 15 patients with significant hippocampal atrophy according to absolute volumes and a further 14 controls. ROC curves enabled evaluation of sensitivity and specificity in respect of an intensity threshold. 100% specificity is required when determining suitability of patients for neurosurgery, resulting in levels of 50% and 70% sensitivity in detecting atrophy in the right and left hippocampus, respectively. We propose that the method can be developed as an automatic screening procedure.     

Volume estimation of symmetrical branching structures by resonance mode analysis

An exact resonance condition is derived for rigid symmetric second-order bifurcating structures. In the low-frequency range, the resonance condition can be reduced into forms that facilitate volume estimation of bifurcating structures. Two such volume approximation techniques are presented: (1) a fundamental frequency method, in which the lowest resonant frequency is inversely proportional to the structure volume, and (2) an equivalent-length method, in which an equivalent length of two daughter branches is calculated for all branches distal to the first bifurcation. An experimental study to determine the resonance modes of seven bifurcating glass structures was performed. The volume estimates obtained by either method were in very close agreement with the true volumes.     

Motion estimation of magnetic resonance cardiac images using the Wigner-Ville and hough transforms

Myocardial motion analysis and quantification is of utmost importance for analyzing contractile heart abnormalities and it can be a symptom of a coronary artery disease. A fundamental problem in processing sequences of images is the computation of the optical flow, which is an approximation of the real image motion. This paper presents a new algorithm for optical flow estimation based on a spatiotemporal-frequency (STF) approach. More specifically it relies on the computation of the Wigner-Ville distribution (WVD) and the Hough Transform (HT) of the motion sequences. The latter is a well-known line and shape detection method that is highly robust against incomplete data and noise. The rationale of using the HT in this context is that it provides a value of the displacement field from the STF representation. In addition, a probabilistic approach based on Gaussian mixtures has been implemented in order to improve the accuracy of the motion detection. Experimental results in the case of synthetic sequences are compared with an implementation of the variational technique for local and global motion estimation, where it is shown that the results are accurate and robust to noise degradations. Results obtained with real cardiac magnetic resonance images are presented. The text was submitted by the authors in English.