María Eugenia Dajer

Relative entropy measures applied to healthy and pathological voice characterization

Abstract Nowadays, noninvasive methods of diagnosis have increased due to demands of the population that requires fast, simple and painless exams. These methods have become possible because of the growth of technology that provides the necessary means of collecting and processing signals. New methods of analysis have been developed to understand the complexity of voice signals, such as nonlinear dynamics aiming at the exploration of voice signals dynamic nature. The purpose of this paper is to characterize healthy and pathological voice signals with the aid of relative entropy measures. Phase space reconstruction technique is also used as a way to select interesting regions of the signals. Three groups of samples were used, one from healthy individuals and the other two from people with nodule in the vocal fold and Reinke’s edema. All of them are recordings of sustained vowel /a/ from Brazilian Portuguese. The paper shows that nonlinear dynamical methods seem to be a suitable technique for voice signal analysis, due to the chaotic component of the human voice. Relative entropy is well suited due to its sensibility to uncertainties, since the pathologies are characterized by an increase in the signal complexity and unpredictability. The results showed that the pathological groups had higher entropy values in accordance with other vocal acoustic parameters presented. This suggests that these techniques may improve and complement the recent voice analysis methods available for clinicians.

Nonlinear dynamical analysis of normal voices

Human voice has been the focus of study for different areas of sciences. Researches in the last two decades have established the existence of chaos in human voice production. The purpose of this paper is to use nonlinear dynamics methods in the analysis of normal voices from healthy subjects and correlate them to traditional acoustic parameters as well as perceptual analysis. Twelve human voice signals from healthy subjects, 6 males and 6 females, ranging in age from 19 to 39 years old were used. Sustained vowel sounds /a/, /e/ and /i/ if, from Brazilian Portuguese were recorded at a sampling rate of 22,050 Hz and analyzed in order to obtain acoustic perturbation measures (jitter, shimmer, coefficient of excess - EX, and pitch amplitude - PA), The phase space reconstruction method was used to describe the nonlinear dynamic characteristics of voice signal samples. This paper shows that nonlinear dynamical methods as phase space reconstruction seems to be a suitable technique for voice signals analysis, due to the chaotic component of the human voice. The results suggest that non-linear dynamic analysis does not replace existing techniques instead they may improve and complement the recent voice analysis methods available for health professionals, speech therapist and clinician.

Analysis of Voice Pathology Evolution Using Entropy Rate

In the last years the use of voice acoustical analysis has increased much. Also, other techniques are being applied, such as nonlinear methods and comparison of quantities obtained from information theory. The latter is the case of this paper, we analyze characteristics of the entropy rate curve and its asymptote to acquire knowledge about the evolution of pathological voice signals. Specifically signals from patients with nodule in the vocal folds. The analysis provided some differences between nodule and healthy signals that may be related to the level of evolution of the pathology.

Improvement of Vocal Pathologies Diagnosis Using High-Speed Videolaryngoscopy

Introduction The study of the dynamic properties of vocal fold vibration is important for understanding the vocal production mechanism and the impact of organic and functional changes. The advent of high-speed videolaryngoscopy (HSV) has provided the possibility of seeing the real cycle of vocal fold vibration in detail through high sampling rate of successive frames and adequate spatial resolution. Objective To describe the technique, advantages, and limitations of using HSV and digital videokymography in the diagnosis of vocal pathologies. Methods We used HSV and digital videokymography to evaluate one normophonic individual and four patients with vocal fold pathologies (nodules, unilateral paralysis of the left vocal fold, intracordal cyst, and adductor spasmodic dysphonia). The vocal fold vibration parameters (glottic closure, vibrational symmetry, periodicity, mucosal wave, amplitude, and glottal cycle phases) were assessed. Results Differences in the vocal vibration parameters were observed and correlated with the pathophysiology. Conclusion HSV is the latest diagnostic tool in visual examination of vocal behavior and has considerable potential to refine our knowledge regarding the vocal fold vibration and voice production, as well as regarding the impact of pathologic conditions have on the mechanism of phonation.

Parameters Acoustic and High-speed kymography identified effects of voiced vibration and vocal fry exercises

PURPOSE To analyze the difference between nonsmokers and smokers on the changes in the perceptions of smell and taste and to verify the influence of these aspects in the emergence of compensatory movements during swallowing. METHODS To evaluate these aspects, capabilities of olfactory and gustatory recognition were observed, as well as the compensation swallowing. Twenty-four patients were evaluated in each study group aged from 18 years, grouped in a stratified way. The olfactory evaluation consisted in presenting seven essences and one of three options should be chosen. For the taste test, 16 flavors were offered in a non-sequential and decreasing way in amount of solute. Swallowing solid and liquid was evaluated, in which aspects of compensation perioral muscles were observed. RESULTS Worst performance in olfactory and gustatory tests among smokers (p≤0.01) was found. Through the results of χ2 and Fishers exact tests, it was found that the contraction of the mentalis muscle is less observed in non-smokers, and smokers have an average degree of statistically significant change compared to nonsmokers. Furthermore, through the Spearman correlation coefficient, it was found that the worsening in the sensory tests implies increased compensation during swallowing in smokers. CONCLUSION These data allowed us to verify that the sensory changes have influence on swallowing pattern, indicating that these changes are aspects that should be considered in the differential diagnosis of changes in swallowing.PURPOSE To identify the immediate effects of voiced vibration and vocal fry exercises on healthy subjects by means of acoustic parameters and high-speed kymography. METHODS Thirty healthy subjects (18 women and 12 men, aged from 19 to 45 years old) participated in this study. The voices were recorded at the range of 44.100 samples/second, before and after of the vocal exercises. We developed a computational routine to extract jitter and shimmer. High-speed kymography was generated from laryngeal images for the analysis of the phase times: closed (CPh), open (OPh), of closing (cPh) and of opening (oPh) and used the paired t-Student test and the Mann-Whitney test, with a significance level of 0.05. RESULTS After voiced vibrations, acoustic parameters showed reduced jitter for both genders (p=0.018 for men and p<0.01 for women) and reduced shimmer for female voices (p<0.01). There was a decrease in CPh (p=0.046) and cPh (p=0.026) and an increase in OPh (p=0.05) in female vocal folds. After vocal fry, we identified decreased jitter (p<0.01) in female voices and cPh (p=0.026) in male vocal folds. CONCLUSION We observed more positive immediate effects of the voiced vibrations, mainly in voice quality and vocal folds among females. Nevertheless, studies with larger male sample and investigation of the appropriate time of vocal fry are necessary to confirm the results of this search.

Graphical Evaluation of Vocal Fold Vibratory Patterns by High-Speed Videolaryngoscopy

OBJECTIVE To characterize the voice and vocal fold function of an individual, it is essential to evaluate vocal fold vibration. The most widely used method for this purpose has been videolaryngoscopy. METHODS This article proposes a digital image processing algorithm to estimate the glottal area (ie, the space between the vocal folds) and produce graphs of the opening and closing phases of the glottal cycle. In eight subjects without voice disorders, vocal fold movements were recorded by high-speed videolaryngoscopy at 4000 frames per second. The video data were processed by a combination of image segmentation techniques that estimate the glottal area. The segmented area was used to construct the glottal waveform. RESULTS The graphs revealed important properties of vocal fold vibration, including amplitude, velocity, and other characteristics that have a major influence on voice quality. CONCLUSIONS The combination of the high-speed technology with the proposed method improves the vocal fold analysis given a numerical feedback through graphical representation of the real vibratory patterns of the folds.

Cognitive Vocal Program applied to individuals with signals presbylarynx: preliminary results

PURPOSE To propose and verify the feasibility of a vocal program intervention in patients with presbylarynx signs with or without vocal complaints. METHOD Among 20 elder participants of the current research, 3 female patients with median age of 67 years were chosen for the pilot study. Laryngological examination, vocal recording with CAPE-V (Consensus Auditory-Perceptual Evaluation of Voice) protocol, and Screening Protocol of Risk of Dysphonia (SPRD) were conducted before and after the program intervention. They joined the Cognitive Vocal Program for presbyphonia based on the genetic epistemology by Jean Piaget associated with vocal techniques based on scientific literature. This program is structured with six sessions and each one of them is focused in different aspects of vocal production. RESULTS After the program intervention, some aspects such as loudness, coordination between breathing and speaking, accuracy in articulatory movements, jitter, and harmonics-to-noise ratio improved with parameters within the expected range for the age group. Three female participants were observed for better vocal quality, higher fundamental frequency, and better maximum phonation time. In two cases, tension related to loudness elevation and better scores on SPRD was observed. Using by high-speed laryngeal image, we also observed reduction of presbylarynx signs, and remarkable improvement in glottis closure competence and mucosal wave movement of the patients with and without vocal complaints. CONCLUSION The preliminary results suggest encouraging prospects for the proposal with improvement in the aspects analyzed. This program was well designed and did not require any further adjustments.

Vocal Dynamic Visual Pattern for voice characterization

Voice assessment requires simple and painless exams. Modern technologies provide the necessary resources for voice signal processing. Techniques based on nonlinear dynamics seem to asses the complexity of voice more accurately than other methods. Vocal dynamic visual pattern (VDVP) is based on nonlinear methods and provides qualitative and quantitative information. Here we characterize healthy and Reinkes edema voices by means of perturbation measures and VDVP analysis. VDPD and jitter show different results for both groups, while amplitude perturbation has no difference. We suggest that VDPD analysis improve and complement the evaluation methods available for clinicians.

Application of autoregressive decomposition and pole tracking to pathological voice signals

In this paper, it is presented an insight of the effects of the application of autoregressive (AR) decomposition and pole tracking to voice signals. The AR model is used to decompose the signals in a set of poles which has a correspondence to the peaks of the signals power spectral density function (PSD). The aim of this work is to show the differences in the behavior of these poles for voice signals collected from two groups of people, one with healthy glottal tract and another with nodule pathology in vocal folds.

High-speed kymography identifies the immediate effects of voiced vibration in healthy vocal folds

Summary Introduction: The effects of voiced vibration technique can be assessed by laryngeal imaging. Kymographic images derived from high-speed videoendoscopy allow actual visualization of vocal folds vibration. Purpose: The aim of this study is to identify the immediate effects of the voiced vibration technique in healthy vocal folds using high-speed digital laryngeal imaging. Methods: Samples were obtained from 15 healthy subjects with no history of voice disorders (6 men and 9 women aged 21 to 43 years). High-speed videoendoscopy recordings were performed before and after the voiced vibration technique. Kymographic images were obtained using high-speed videoendoscopy. The vocal folds were examined in their open and closed positions and the characteristics of the opening and closing phases were determined. A customize computational routine was used quantify these parameters. The closing, opening, and speed quotients were also calculated. Results: In this study, women displayed statistically significant differences in opened phase (P = 0.05*), closed phase (P = 0.046*), and closing phase (P = 0.026*) phase characteristics. Men displayed the highest difference rate in opening time characteristics (P = 0.06). The closing and opening quotients for the female group showed significant differences (P = 0.029* and P = 0.049*, respectively). The speed quotient exhibited statistically significant differences in the male group (P = 0.048*). Conclusion: The kymographic images indicated that the immediate effect of the voiced vibration technique was smooth contact in healthy vocal fold vibration.