Biomedical subjects

B Teston

Publications and source records attributed to B Teston.

8 recordsLinked to original sources

PubMed2000

Laryngeal pathology detection by means of class-specific neural maps.

Most of the existing systems and methods for laryngeal pathology detection are characterized by a classification error. One of the basic problems is the approximation and estimation of the probability density functions of the given classes. In order to increase the accuracy of laryngeal pathology detection and to eliminate the most dangerous error--classification of a patient with laryngeal disease as a normal speaker--here an approach based on modeling of the probability density functions (pdf's) of the input vectors of the normal and pathological speakers by means of two prototype distribution maps (PDM), respectively, is proposed. The pdf of the input vectors of an unknown normal or pathological speaker is also modeled by such a prototype distribution neural map--PDM(X)--and the pathology detection is done by means of a ratio of specific similarities rather than by a direct comparison of some type of distance/similarity with a threshold. The experiments show an increased classification accuracy and that the proposed method can be used for screening the laryngeal diseases. The method is applied in a consulting system for clinical practice.

Algorithms↗

PubMed1998

Non linear behavior of vocal fold vibration in an experimental model of asymmetric larynx: role of coupling between the two folds.

One of the main factors involved in the laryngeal dynamic's non-linearity is the coupling between the two vocal folds. Evaluation of the different coupling elements requires various investigations. The present work evaluate the non-linearity effects in clinical situations such as unilateral laryngeal paralysis using Lyapunov's coefficients. It also demonstrate the coupling effects on excised larynx made experimentally asymmetrical, using a specially designed device to measure vibrations from each vocal fold (opto-reflectometer).

Animals↗

PubMed1996

Objective evaluation of dysphonia: preliminary results of a device allowing simultaneous acoustic and aerodynamic measurements.

Voice quality analysis was performed in 88 normal speakers and 157 dysphonic speakers using a device that allows simultaneous study of acoustic and aerodynamic parameters during pronunciation of a sustained /a/. We compared the results with those of voice quality grading by a jury. The Mann-Whitney test showed significant differences between the grades of dysphonia for all the parameters chosen. Comparison of results (using discriminant factorial analysis) with perceptual evaluation by a jury showed concordance in 66.1%. Based on these preliminary results, the authors conclude that their protocol overlooks some relevant voice parameters like middle-term variations. Further study will be undertaken to take into account this type of variations.

Adolescent↗

PubMed1996

[Preliminary study of acoustic and aerodynamic parameters after Tucker frontal anterior laryngectomy].

Currently, not objective method has been demonstrated to be reliable for the evaluation of vocal handicap after partial laryngectomy. Such a tool would allow objective assessment of the post-operative voice and its clinical course as well as a comparison of different surgical techniques in terms of voice quality. We used a EVA device to measure simultaneously acoustic and aerodynamic parameters. We included 23 normal subjects and 34 patients who had undergone a Tucker laryngectomy. All subjects were males. At sustained voice production, acoustic measures of vibration stability (jitter, coefficient of variation in the fundamental frequency, shimmer, coefficient of variation in intensity) and air leak from the glottis (buccal air flow over intensity). The quality of voice in operated patients was judged by a jury of listeners who assigned a global score to voice quality. Results were analyzed to verify the correlation between objective measurements and the jury's score, taken as the reference measurement. The pertinence of the objective measurements was demonstrated for the stability of the frequency and the glottal air leak. Multiple regression analysis demonstrated that total variance of the objective measurements accounted for 84.7% of the scores provided by the jury (R2 = 0.847, p < 0.0001). These satisfactory results emphasize the interest of multiparametric analysis including aerodynamic measurements. These preliminary results led to the hypothesis that objective and subjective measurements could be useful in techniques aimed at improving voice quality (temporal organization of vibratory instability, work on intralaryngeal pressures).

Acoustics↗

PubMed1995

[Objective vocal evaluation of dysphonia by simultaneous measurement of acoustic and aerodynamic parameters with the EVA device].

Authors present the analysis of the voice in 88 normal subjects and 159 dysphonic patients by simultaneously measurements of Jitter (acoustical short-term indicator of aperiodicity) and "Glottal Leakage" (aerodynamic parameter calculated by the ratio of Oral Airflow and Intensity). All the measurements were performed, with EVA apparatus, on the most stable part of a steady-state vowel /a/. The reference method was the rating by a jury along a global perceptual scale. Statistical tests confirm that Jitter and "Glottal Leakage" are relevant to evaluate the quality of the voice. Discriminant analysis allows to find out a fairly-good rate of discrimination of 63.1% (Randomly rating would have been 25%) The authors conclude on the interest of such a protocol and present suggestions to improve it by taking in count phénomena during the vocal attack and middle-term variations.

Acoustics↗

PubMed1993

[Multiparameter analysis of dysphonia using the equipment Physiologia].

The purpose of the multiparametric analysis of the vocal phenomenon is to evidence the instability of the signal in amplitude and in frequency, together with the aerodynamic phenomena related to the glottic air leakage. Statistical analysis has made it possible to establish a correlation between the data of the apparatus, as from 9 variables, and the clinical classification. The main diagnostic categories are relatively close, evidencing the various biomechanical anomalies of the laryngeal vibrator. A certain number of issues remain to be addressed: the physiopathology of the vibrator, the choice of the phonetic sample, and the different methods of instrumental analysis.

Biomechanical Phenomena↗

PubMed1992

[How to evaluate velar insufficiency?].

The evaluation of velar insufficiency is absolutely necessary in order to assess the results of surgery of the labial palatal cleft. In addition to the clinical examination which remains indispensable, the aerophonometer, applicable to adults and children as from the age of 3, enables simultaneous measurement of the flow of buccal air, the flow of nasal air, and the buccal phonogram. The comparison of the lines, the relation of the nasal air and buccal air flows, upon the emission of two standard sentences with and without nasal components, enables an objective assessment of velar functioning.

Child, Preschool↗

PubMed1992

[A multiparameter method of computer-assisted objective vocal evaluation].

The aim of this study is to validate an aid for the evaluation of dysphonia with objective measurements. We recorded exhaled airflow, fundamental frequency and sound level pressure, for a sustained vowel "a", with 51 dysphonic subjects and 15 normal subjects. The following measurements are made on these three parameters: mean value, standard deviation and coefficient of variation. The exhaled airflow volume was also computed for a duration of 2 seconds. A principal components analysis of the measurements indicated that it is possible to recognise the classes of vocal evaluation and vocal pathology. These findings reinforce on objective aid for the vocal evaluation of dysphonia.

Diagnosis, Computer-Assisted↗