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Biomedical subjects

C Berger-Vachon

Publications and source records attributed to C Berger-Vachon.

At least 19 recordsLinked to original sources
PubMed1999

Evaluation of cochlear implanted children's voices.

Cochlear implant (CI) is a good means in developing communication in deaf children. Nevertheless, compared to children with the same age, CI patients' voices are far from being similar. In this work, the voice of CI children has been compared with the voice of corresponding normal children (same age, same sex) included in the main stream. Six girls and two boys participated to the experiment. The phonetic material was a paragraph of the French standard text La bise et le soleil (The North Wind and the Sun). An objective and a subjective analysis of the voice were done and parameters were compared between both groups of people (implantees and control). Studied parameters were voice pitch, intensity, fluency, pauses, articulation and pleasantness in the objective analysis, and voice pitch, formants, and duration for the objective study. It appeared that intensity variations were different between control and implanted subjects. Also voice formants were not situated in the same region regarding the normal ranges, but differences were difficult to assess. Globally, the main change was in the speaking duration. This method is open for further studies and points out some relevant items for an efficient use in rehabilitation sessions.

Adolescent↗
PubMed1999

Acoustical recognition of laryngeal pathology: a comparison of two strategies based on sets of features.

The efficiency of sets of acoustical features discriminating pathological voices from control voices is reported. Two strategies were compared. The first (called the 'distance strategy') was built upon a statistical distance of voice features to reference values obtained for a set of healthy (reference) voices. The second strategy (called the 'range strategy') is based on the position inside or outside normal ranges established from a reference population; results based on this strategy were presented in a previous paper. Reference values were calculated from a database of 200 healthy voices distributed into 10-year age groups ranging from 20 to 70. Comparisons were made using a second database of 220 voices, including 65 control, 51 functional dysphonia, 50 with nodules on the vocal folds and 54 recurrent nerve palsy. The phonetic material was compared of 17 French vowels: 11 vowels in a sentence, three isolated vowels and three segments (beginning, middle and end) of the sustained vowel /a/. Four acoustical features were considered for each vowel: the voice fundamental (f0) and the first three formant frequencies. Acoustical features were calculated on an ILS (Interactive Laboratory System) analysis system (workstation). The separation of each pathological group from the control group, using sets of acoustical features, was statistically assessed. From the strategy point of view, results indicated that (i) the fundamental frequency f0 was the best measure to separate normal from pathological voices with the distance strategy; (ii) when the formants were taken, the range strategy performed better in separating the voices. For classification of pathologies, the best separation coefficients were obtained with nodules and the worst with recurrent nerve palsy. Overall, it was seen that the separation between control and pathological voices was most efficient when measured using the distance strategy for f0. The range strategy was useful with formant frequencies.

Female↗
PubMed1999

Temporal loudness integration and spectral loudness summation in normal-hearing and hearing-impaired listeners.

The aim of this study was to test for differences between normal-hearing and hearing-impaired listeners regarding two fundamental aspects of intensity perception: loudness integration and loudness summation. Loudness functions for three different stimuli were measured using categorical loudness scaling in 8 normal-hearing and 12 hearing-impaired subjects. The results indicated that temporal loudness integration, defined as the difference in SPL between 16.25-ms and 300-ms noise bursts of equal loudness, was larger in the hearing-impaired than in the normal-hearing listeners. Loudness summation, defined as the difference in SPL between a 300-ms, 1,600-Hz tone pip and a white noise burst of the same duration and loudness, did not differ between the two groups. Implications of these results for hearing aid fitting strategies based on loudness normalization are discussed.

Adult↗
PubMed1997

Acoustical recognition of laryngeal pathology using the fundamental frequency and the first three formants of vowels.

The recognition of laryngeal pathology by analysis of the voice is investigated. The fundamental frequency and the first three formants are considered. The recognition strategy is based on comparison with normal ranges calculated over 200 ordinary voices, grouped in ten age classes ranging from 20 to 70 years, for males and females. 220 test voices are studied divided into four groups: normal voices, functional dysphonia, nodules and recurrent nerve palsy. Each subject is marked according to his/her normal range. Parameters (or items) are calculated on the Interactive Laboratory System workstation. The vocalic material is composed of 11 vowels taken from a sentence. Results are given in terms of the number of values out of the normal ranges. Statistical analysis considers both parameter ability and error rates in pathology recognition. Pathology recognition shows the following error percentages: 23% for dysphonia, 14% for nodules and 33% for recurrent nerve palsy. Parameters do not show the same efficiency for voice pathology characterisation. Formants appear to be better than the fundamental frequency.

Adult↗
PubMed1997

[Value of auditory evoked potentials of the brain stem in patients with a Digisonic cochlear implant].

We report our techniques of electrically elicited Auditory Brainstem Responses (eABR) in Digisonic DX 10 cochlear implanted patients and summarize the theoretical interests of objectives measures in pre-, per- and post-operative periods of the cochlear implantation process. This report demonstrates the major interest of eABR during rehabilitation with a cochlear implant. EABR allowed us to detect the lack of device integrity in one electrode in one patient. The quality of electrically elicited responses can contribute to appreciate the electrophysiological responses during electrical stimulation. We found a very strong correlation between the objective thresholds (obtained by means of eABR) and subjective ones (obtained by means of behavioral methods); this is of major interest in the pediatric populations.

Acoustic Stimulation↗
PubMed1996

Spectral and cepstral properties of vowels as a means for characterizing velopharyngeal impairment in children.

This study investigated spectral differences in the phonation of vowels between a group of 21 children with velopharyngeal impairment and a paired control group of 42 subjects. The speech material was composed of the isolated vowels /a/, /i/, and /u/, a sustained vowel /a/, and four vowels included in spoken words: two nasals /in/ and /on/ in "dindon," and two orals /a/ and /o/ in "gâteau." A bottom-up discriminant function analysis indicated that the cepstrum coefficients and the linear-FFT were the most efficient tools in the test to classify the set of children. They were superior to the results obtained with the formant-representation of the vowels. The use of a perceptive scale (barks) did not improve the results. Discrimination over the total group showed percentages lower than those obtained when boys and girls were assessed separately. The best discriminating results were obtained with the /a/ of "gâteau" for the girls and with the isolated /i/ for the boys.

Case-Control Studies↗
PubMed1996

Ipsilateral ABR with cochlear implant.

Ipsilateral ABR recording technique was developed with the MXM DIGISONIC DX10 cochlear implant, involving, firstly, setting of recording variables with regard to implant and ABR constraints, and, secondly, enhancement of recording quality by signal processing. The resulting recording quality then enabled us to characterize ABR latency, amplitude and wave reproductibility according to stimulus intensity and stimulation site (electrode stimulated). The findings agree with those of the literature on contralateral human and ipsilateral animal studies. Waves III and V amplitude increased with stimulus intensity. Waves III and V latency was insensitive to stimulus intensity or site. ABR quality diminished basally.

Cochlear Implants↗
PubMed1995

Analytic importance of the coding features for the discrimination of vowels in the cochlear implant signal.

The present study considers the analytic importance of the excitation pulse features delivered by a Nucleus cochlear implant using the F0F1F2 strategy. Four cochlear implant patients and 10 speakers uttering two 48-item lists constructed from four basic French vowels participated in this study. Patterns were presented to the patients and played at the input of an acquisition system in order to record the pulse features. Confusion matrices obtained with the patients and with automatic recognition procedures were then compared in order to find out the best-matching models simulating the patients' performances, out of 255 possibilities. The automatic recognition was carried out according to fuzzy logic based on the elementary features of the pulses coding the vowels. Results show that the essential features strongly depended on the subject.

Adult↗
PubMed1995

[Acoustic characterization of velar insufficiency in young children].

The following study concerns the acoustic parameters marking the difference between the phonation of children with velar incompetency and a corresponding control group. Population is made of 64 children aged 5 and 6; 32 are in the control group and 32 in the pathological group. Each child was required to repeat several words; 10 vowels and 9 consonants were taken from those words. Acoustic signal was recorded and studied using a standard speech assessment work station. 63 parameters for the vowels and 6 for the consonants were studied. Results showed that the best parameters concerned the vowels and that cepstrum coefficients were an efficient tool to perform the separation of the two groups. On the contrary, formants, voice pitch and jitter did not appear to be efficient enough to do this task. It was, then, deduced a check form for velopharyngeal incompetency, form which will be tested in future work.

Case-Control Studies↗
PubMed1993

Acoustic discrimination of velar impairment in children.

Cepstral coefficients calculated out of a linear prediction have been used to discriminate two groups of 19 control children and 12 patients with velar impairment. French vowels /a/, /i/, /u/ had been studied using the cepstral coefficients. Vowels /i/ and /u/ appeared to be efficient to perform the separation on acoustic grounds. A 100% recognition score can be reached when the two vowels are considered together. Modifications of the cepstrums dealing with velar incompetence are also discussed. A way to make an automatic grading of the pathology is finally presented.

Articulation Disorders↗
PubMed1992

Model for understanding the influence of some parameters in cochlear implantation.

Considering the recognition performance obtained by an implanted patient, the authors have developed models to explain the decrease in performance when the number of open channels on the prosthesis is increased. The French cochlear implant Chorimac was used in this experiment. Two models have been developed. The first is monodimensional and the second is multidimensional. They respectively represent an increase in information and its superposition. Results suggest that for the patient, the superposition factor prevails and is detrimental to recognition. Its elimination should be a major goal. A good selection of electrodes in a relatively small number seems to be the best policy. This is already done in some cochlear implants. Some other parameters in the signal that seem worth being analyzed are introduced.

Cochlear Implants↗
PubMed1992

Evoked otoacoustic emissions: relative importance of age, sex and sensorineural hearing-loss using a mathematical model of the audiogram.

The influence of age, sex and of hearing loss on the EOAEs were studied in 140 subjects. The EOAEs were never found when hearing loss on the best hearing frequency was above 40 dB HL and when the threshold of intelligibility was above 45 dB HL. The presence of EOAEs therefore does not only give specific information on the midfrequencies, but also shows a hearing loss below or equal to 40 dB HL on at least one frequency. In addition, there is a relation between the audiometric curve and the spectrum analysis of EOAEs. These seem to be promising results for clinical applications.

Acoustic Stimulation↗
PubMed1992

[Reduction laryngoplasty by external approach for glottic incompetence. Current role, demonstration of its efficacy by objective analysis of parameters of vocal quality].

Authors talk about the place of surgical treatments with cervicotomy in abducted vocal cord, about the statistics of the department of Phoniatrics of the Hospital Edouard Herriot in Lyon. These techniques have actually a marginal place. But the analysis of a recent case shows us that endoscopic treatment for vocal fold augmentation with biomaterials such as collagen or teflon can fail. So ENT surgeons have to absolutely know the Guerrier's technique to improve the quality of the voice when injectable biomaterials fail. With the description of this case, we will describe the objective analysis methods of the voice parameters that we use in the department.

Adult↗
PubMedDate not supplied

Soccer accidents in the French Rhône-Alpes Soccer Association.

The analysis of 6153 accidents reported to the insurance company of the French Rhône-Alpes Soccer Association, for the 1980-81 season was undertaken, providing a survey of acute pathology in French soccer accidents and an estimation of the cost of this pathology to French society. Findings from this study include: injuries--ankle sprain is the most common; fractures prevail in the young players pathology; exposure--the average risk is one accident for 20 matches; the highest risk is for the senior category; collisions with opponents is the main cause of accidents; the first 5 minutes of the second half have a peak of accidents; the players exposure is roughly the same whatever their position on the ground; risk--winter should not increase the risk if the matches are played under good conditions; the risk is unevenly distributed according to the level of practice; cost--the cost for France over 1 year was estimated at US$20,000,000 and the total number of sick leave days at 2000 years; games with several accidents are very common in January and for the adult category. Consequently, tightening up the safety measures would be a very good investment.

Acute Disease↗