Aspects of voice irregularity measurement in connected speech

Applications of the use of connected speech material for the objective assessment of two primary physical aspects of voice quality are described and discussed. Simple auditory perceptual criteria are employed to guide the choice of analysis parameters for the physical correlate of pitch, and their utility is investigated by the measurement of the characteristics of particular examples of the normal-speaking voice. This approach is extended to the measurement of vocal fold contact phase control in connected speech and both techniques are applied to pathological voice data

Closing and opening phase variability in dysphonia

Four examples of the use of vocal fold contact phase measurement are discussed for unilateral paresis. In each case this aspect of voice quality is of greater importance than the physical measurement of loudness and pitch related parameters. For three of the cases electro-stimulation has been used as a main part of the treatment. Phonation in both connected speech and, for comparison, in sustained sound production has been used with electro-laryngograph / egg signals providing the basis for measurement. The main new descriptors that have been found to be useful relate to: vocal fold closure and closure duration regularities and distributions; but reference is also made to related measures of peak acoustic amplitude. The new measures described give, in some cases, quite striking results that are of auditory significance and potentially of clinical value

Contributions of temporal encodings of voicing, voicelessness, fundamental frequency, and amplitude variation to audiovisual and auditory speech perception

Auditory and audio-visual speech perception was investigated using auditory signals of invariant spectral envelope that temporally encoded the presence of voiced and voiceless excitation, variations in amplitude envelope and F-0. In experiment 1, the contribution of the timing of voicing was compared in consonant identification to the additional effects of variations in F-0 and the amplitude of voiced speech. In audio-visual conditions only, amplitude variation slightly increased accuracy globally and for manner features. F-0 variation slightly increased overall accuracy and manner perception in auditory and audio-visual conditions. Experiment 2 examined consonant information derived from the presence and amplitude variation of voiceless speech in addition to that from voicing, F-0, and voiced speech amplitude. Binary indication of voiceless excitation improved accuracy overall and for voicing and manner. The amplitude variation of voiceless speech produced only a small increment in place of articulation scores. A final experiment examined audio-visual sentence perception using encodings of voiceless excitation and amplitude variation added to a signal representing voicing and F-0. There was a contribution of amplitude variation to sentence perception, but not of voiceless excitation. The timing of voiced and voiceless excitation appears to be the major temporal cues to consonant identity. (C) 1999 Acoustical Society of America. [S0001-4966(99)01410-1]

Contribution du giroflier à la sécurité alimentaire des exploitations agricoles dans la région de Fénérive-Est, Madagascar. Modélisation économique et analyse prospective

L'étude présentée ici fait partie du projet commandité par l'Union Africaine ASF4Food qui vise à renforcer la sécurité alimentaire et le bien-être des ménages ruraux africains via l'association entre cultures vivrières et systèmes agroforestiers. Cette étude s'est déroulée à Madagascar, dans le district de Fénérive-Est et a pour objectif de comprendre l'importance relative des différentes cultures et en particulier des girofliers, de l'élevage et des activités extra-agricoles dans la constitution des revenus et la robustesse des exploitations agricoles, ainsi que de comprendre comment la sécurité alimentaire est assurée par les systèmes d'activités, au sein de deux sites. L'analyse se base principalement sur une démarche quantitative de performances technico-économiques à travers deux échelles : les cultures et les systèmes d'activités. La caractérisation des structures d'exploitation agricole a mis en évidence les deux principales stratégies élaborées par les exploitants pour subvenir aux besoins alimentaires de leur ménage. La seconde s'appuie sur les revenus du ménage pour acheter la nourriture nécessaire, le giroflier fait alors figure de première source de revenu pour plus de la moitié des ménages enquêtés. Les girofliers fournissent deux produits, les clous et l'huile essentielle. La production d'huile essentielle est une variable d'ajustement stable dont la production à une grande influence sur les volumes et les fluctuations de la production de clous. La fluctuation de la production de clous impose aux ménages une gestion pluriannuelle du solde de trésorerie, l'élevage bovin à un rôle de capitalisation qui permet cette gestion particulière du solde de trésorerie. La gestion des girofliers entre production de clous et d'huile essentielle admet une marge d'amélioration. Enfin, les modélisations prospectives ont montré la grande robustesse des exploitations agricoles due à la flexibilité de leurs dépenses, mais parfois fragilisées par le trop grand rôle des girofliers

Accuracy and variability of acoustic measures of voicing onset

Five commonly used methods for determining the onset of voicing of syllable-initial stop consonants were compared. The speech and glottal activity of 16 native speakers of Cantonese with normal voice quality were investigated during the production of consonant vowel (CV) syllables in Cantonese. Syllables consisted of the initial consonants /ph/, /th/, /kh/, /p/, /t/, and /k/ followed by the vowel /a/. All syllables had a high level tone, and were all real words in Cantonese. Measurements of voicing onset were made based on the onset of periodicity in the acoustic waveform, and on spectrographic measures of the onset of a voicing bar (f0), the onset of the first formant (F1), second formant (F2), and third formant (F3). These measurements were then compared against the onset of glottal opening as determined by electroglottography. Both accuracy and variability of each measure were calculated. Results suggest that the presence of aspiration in a syllable decreased the accuracy and increased the variability of spectrogram-based measurements, but did not strongly affect measurements made from the acoustic waveform. Overall, the acoustic waveform provided the most accurate estimate of voicing onset; measurements made from the amplitude waveform were also the least variable of the five measures. These results can be explained as a consequence of differences in spectral tilt of the voicing source in breathy versus modal phonation. ©2003 Acoustical Society of America.published_or_final_versio

Critical Cooling Rate of Fast-Crystallizing Polyesters: The Example of Poly(alkylene trans-1,4-cyclohexanedicarboxylate)

Controlling the cooling rate experienced by a material during a manufacturing process is a challenge and a major issue. Industrial processing techniques are very diverse and may involve a whole range of cooling rates, which are sometimes extremely high for small and/or thin manufactured parts. For polymers, the cooling rate has consequences on both the microstructure and the time-dependent properties. The common cooling rates associated with conventional calorimetric measurements are generally limited to a few tens of degrees per minute. This work combines several calorimetric techniques (DSC, modulated-temperature DSC, stochastically-modulated DSC and Fast Scanning Calorimetry) to estimate the critical cooling rate required to melt-quench fast-crystallizing polyesters to their fully amorphous state, based on the example of a series of poly(alkylene trans-1,4-cyclohexanedicarboxylate) (PCHs) with a number of methylene groups in the main structure of the repeating unit (Formula presented.) varying from 3 to 6. The even-numbered ones require faster cooling rates (about 3000 K s−1 for (Formula presented.) = 4, between 500 and 1000 K s−1 for (Formula presented.) = 6) compared to the odd-numbered ones (between 50 K min−1 and 100 K s−1 for (Formula presented.) = 3, between 10 and 30 K min−1 for (Formula presented.) = 5)