Biomedical subjects

Floris L Wuyts

Publications and source records attributed to Floris L Wuyts.

23 records · Page 2Linked to original sources

PubMed2003

The interutricular distance determined from external landmarks.

Knowledge of the exact distance between the utricles is important in new vestibular tests, such as the unilateral centrifugation (UC) test for the unilateral examination of the utricles. During this test, subjects are rotated at constant velocity and simultaneously laterally displaced along an interaural axis so that one labyrinth becomes aligned with the axis of rotation. When the axis of rotation crosses precisely through one labyrinth, only the opposite labyrinth is stimulated. To achieve this setup, precise knowledge of the interutricular distance is needed. The purpose of this study is to investigate the correlation between the interutricular distance (IUD), measured on T2-weighted magnetic resonance images, and specific external measures of head dimensions such as distance nasion-inion, intermastoid distance (IMD), distances between the temporomandibular joints and between the lateral margins of the orbits. Data have been collected in a series of 50 subjects (25 men and 25 women). On MR images we found a mean IUD of 7.22 cm (SD = 0.42 cm). There was a strong correlation between the IUD measured on MR images and the intermastoid distance. A linear combination of the IMD, nasion-inion distance and height of the subjects could predict the IUD very satisfactory (R = 0.85, adjusted R2=0.723). We also determined a measure of eccentricity of the vestibular labyrinths. The 95% prediction interval for the asymmetry appeared to be less than 4.3%.

Adolescent↗

PubMed2003

Utricular sensitivity and preponderance assessed by the unilateral centrifugation test.

Utricular sensitivity and preponderance of the right or left utricle can be assessed by means of the unilateral centrifugation test. In this test, subjects are rotated about an earth vertical axis at a velocity of 400 degrees per second. During the ongoing rotation, the subject is gradually translated 4 cm first to the right, and then to the left, along an interaural axis, to a position at which one utricle becomes aligned with the axis of rotation, and at this point is subjected only to gravitational forces. At this eccentric position, the contralateral utricle is exposed to the combination of gravity and a centrifugal acceleration of 0.4g, corresponding to an apparent roll-tilt of 21.7 degrees. This stimulus induces ocular counterrolling (OCR), which is measured on-line using three-dimensional video-oculography (VOG). We observed that ocular counterrolling appears as a linear function of the gravito-inertial acceleration tilt of the head centre (GIA(HC)) during the lateral translation. We present a theoretical model for this linear relationship that contains two parameters: 1) the slope of the linear regression is a measure for the utricular sensitivity and 2) the intercept of the linear regression is a measure of the preponderance of the right or left utricle. The strength of the model is supported by data obtained from 28 healthy subjects and 14 patients with unilateral vestibular deafferentiation (UVD) due to acoustic neuroma surgery.

Acceleration↗

PubMed2002

Normative voice range profiles of untrained boys and girls.

Normative voice range profiles (VRPs) are calculated for a group of untrained boys and girls between 6 and 11 years based on 35 and 39 recordings, respectively. All individuals had healthy voices. These normative VRPs contain 95% prediction intervals (PI) for both frequency and intensity. They are based on a series of mathematical transformations of the original individual VRPs in order to maintain in the normative VRPs the typical oval VRP shape including the dip between modal and falsetto register. The presented normative VRPs are directly applicable in the clinical practice of otolaryngologists and speech-language pathologists.

Child↗

PubMedDate not supplied

Correlation of instrumental voice evaluation with perceptual voice analysis using a modified visual analog scale.

Various rating scales have been used for perceptual voice analysis including ordinal (ORD) scales and visual analog (VA) scales. The purpose of this study was to determine the most suitable scale for studies using perceptual voice analysis as a gold standard for validation of objective analysis protocols. The study was carried out on 74 female voice samples from 68 dysphonic patients and 6 controls. A panel of 4 raters with experience in perceptual analysis was asked to score voices according to the G component (overall quality) of the GRBAS system. Two rating scales were used. The first was a conventional 4-point ORD scale. The second was a modified VA (mVA) scale obtained by transforming the VA scale into an ORD scale using a weighted conversion scheme. Objective voice evaluation was performed using the EVA workstation. Objective measurements included acoustic, aerodynamic, and physiologic parameters as well as parameters based on nonlinear mathematics (e.g., Lyapunov coefficient). Instrumental measurements were compared with results of perceptual analysis using either the conventional ORD scale or mVA scale. Results demonstrate that correlation between perceptual and objective voice judgments is better using a mVA scale than a conventional ORD scale (concordance, 88 vs. 64%). Data also indicate that the mVA scale described herein improves the correlation between objective and perceptual voice analysis.

Adult↗

PubMedDate not supplied

Training outcome in future professional voice users after 18 months of voice training.

The goal of this study is to define the long-term influence of vocal hygiene education and the effectiveness of voice training in 46 students. Half of the subjects, called the trained group (n = 23), received vocal hygiene education during 1 school year and voice training during 2 school years (18 months). The other half, also 23 subjects, received neither vocal hygiene education nor voice training as such (called the untrained group). The voice training is made up of technical workshops (30 h a year in groups of 5-8 subjects) and vocal coaching in the radio and drama projects (30 h whole class). In the lectures (30 h) a theoretical background on breathing, articulation, voicing and vocal hygiene was discussed. A multidimensional test battery containing the GRBAS scale, videolaryngostroboscopy, maximum phonation time, jitter, lowest intensity, highest frequency, Dysphonia Severity Index (DSI) and Voice Handicap Index (VHI) was applied before and after 18 months to evaluate the effect of voice training over time. A questionnaire on daily habits was presented before the lectures, and after 18 months to detect the long-term effect of the lectures. The objectively measured voice quality (DSI) of the trained group improved significantly over time (p < 0.001) due to training (p = 0.008), which was not the case in the untrained group. The self-assessed VHI, on the other hand, changed over time (p < 0.001) in both groups. For the trained group the VHI changed from 18.4 to 14.4 and in the untrained group from 20.1 to 15.3. It is important to note that the VHI scores of both groups remained high. The interpretation of the results of the daily habit questionnaire is disturbing: the initial high degree of smoking, vocal abuse, stress and late meals was not influenced by the lectures or training and remained high. This study proves the positive outcome and emphasizes the need for a well-organized voice training program in future professional voice users. However, the lectures and training on vocal hygiene failed to improve voice-conserving habits.

Adult↗