Purpose: This study examined voice onset time (VOT) in children with and without vocal fold nodules (VFN). The purpose of this study was to provide further evidence regarding the need for individualized research and treatment dedicated to the pediatric population. The pediatric population has a distinctly different laryngeal mechanism than adults, as they are still developing. Although the pediatric system is anatomically different from that of a fully mature adult system, treatment for children with VFN is largely based on adult research. This study examined the VOTs of voiceless consonants, as the transition from the voiceless consonant to the subsequent vowel requires significant vocal and articulatory control and coordination. Measures of VOT change throughout the maturation as VOT follows a significant developmental pattern. Children with and without VFN were enlisted in order to examine the effects VFN have on VOT. Hypotheses: We hypothesize that children with VFN would have differences in 1) average VOT values compared to the control group, with no prediction for direction of difference (shorter and longer), and 2) between-word variability of VOT values compared to the control group, with no prediction for direction of difference (more variable and less variable). Methods: Participant data were retrospectively collected and included children between 6 and 12 years old with VFN and age- and sex-matched controls. Participants were recorded producing the six CAPE-V sentences. Four voiceless consonants were selected for VOT analysis. Praat was utilized to manually mark the vocal onset of the stop consonant by the current researcher. A previous researcher identified the vocal offset, and each placement was confirmed by the current researcher. VOT was calculated as the time between the stop consonant burst and the vocal onset of the vowel. Results: There was no significant difference between the VFN and the control groups in average VOT or VOT variability. Within the VFN group, participants who were more dysphonic (lower cepstral peak prominence (CPP) values) had more variable VOT values. Participants in the VFN group had lower CPP values than the control group, suggesting that CPP measures are a reliable indicator of dysphonia. Additionally, within the VFN group, male children had lower CPP values than female children. Conclusion: Although no group difference was found, the within-group analyses indicated that VFNs impacted productions. Children with VFN who were more dysphonic had increased VOT variability. This may suggest that VFN impact a child’s ability to phonate therefore causing more variability within productions. Future research is needed to study the impact dysphonia treatment for children with VFN may have on VOT values. Additionally, a longitudinal study of the impact of VFNs on VOT values during developmental stages may be warranted. / Public Health

The aim of this study was to describe the laryngeal anatomy, perceptual, acoustic and aerodynamic vocal characteristics of school-aged children with and without ADHD. The predisposition that children with ADHD have for laryngeal injuries are recurrent in nature and are more often than not overlooked as laryngitis. Previous studies have reported varied results on the prevalence rates of paediatric VFN within the school-aged ADHD population. A static, two-group comparison was used in the study to investigate the clinical, perceptual, acoustic and aerodynamic vocal characteristics of children between 7 and 9 years old with and without ADHD. The study replicated the protocol as executed by Barona-Lleo and Fernandez (2016) with additions. The Multidimensional Voice Program (MDVP) and the Voice Range Profile (VRP) as additions to the assessment of vocal parameters were used with which comparable dysphonia severity index (DSI) scores were calculated. Once-off clinical, perceptual, acoustic and aerodynamic voice assessments were conducted on 20 age-gender matched participants. The difference in assessment results between the vocal characteristics of children without a history of ADHD (control group) and those of children with ADHD (ADHD group) was then investigated and described. Forty five percent (n=9) of the total sample population had laryngeal pathology. Comparable parent reported etiological voice symptoms and vocal habits were seen across both groups. Both groups performed similarly across both perceptual and aerodynamic voice assessments. Acoustically, the control group achieved significantly higher producible pitches than the ADHD group (p=0.028) and were found to have more dysphonic DSI scores than their ADHD group peers (p=0.034). Prepubertal, school-aged children with or without ADHD may have similar vocal characteristics than previously thought. This variation in school-aged children warrants further research into larger sample sizes with this population with a special focus on the effect that CNS stimulants may have on the voice. / Dissertation (MCommunication Pathology)--University of Pretoria, 2019. / Speech-Language Pathology and Audiology / MCommunication Pathology / Unrestricted

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A quantidade de mÃtodos nÃo invasivos de diagnÃstico tem aumentado devido à necessidade de exames simples, rÃpidos e indolores. Por conta do crescimento da tecnologia que fornece os meios necessÃrios para a extraÃÃo e processamento de sinais, novos mÃtodos de anÃlise tÃm sido desenvolvidos para compreender a complexidade dos sinais de voz. Este trabalho de dissertaÃÃo apresenta uma nova ideia para caracterizar os sinais de voz saudÃvel e patolÃgicos baseado em uma ferramenta matemÃtica amplamente conhecida na literatura, a Transformada Wavelet (WT). O conjunto de dados utilizado neste trabalho consiste de 60 amostras de vozes divididas em quatro classes de amostras, uma de indivÃduos saudÃveis e as outras trÃs de pessoas com nÃdulo vocal, edema de Reinke e disfonia neurolÃgica. Todas as amostras foram gravadas usando a vogal sustentada /a/ do PortuguÃs Brasileiro. Os resultados obtidos por todos os classificadores de padrÃes estudados mostram que a abordagem proposta usando WT à uma tÃcnica adequada para discriminaÃÃo entre vozes saudÃvel e patolÃgica, e apresentaram resultados similares ou superiores a da tÃcnica clÃssica quanto à taxa de reconhecimento. / The amount of non-invasive methods of diagnosis has increased due to the need for simple, quick and painless tests. Due to the growth of technology that provides the means for extraction and signal processing, new analytical methods have been developed to help the understanding of analysis of the complexity of the voice signals. This dissertation presents a new idea to characterize signals of healthy and pathological voice based on one mathematical tools widely known in the literature, Wavelet Transform (WT). The speech data were used in this work consists of 60 voice samples divided into four classes of samples: one from healthy individuals and three from people with vocal fold nodules, Reinkeâs edema and neurological dysphonia. All the samples were recorded using the vowel /a/ in Brazilian Portuguese. The obtained results by all the pattern classifiers studied indicate that the proposed approach using WT is a suitable technique to discriminate between healthy and pathological voices, since they perform similarly to or even better than classical technique, concerning recognition rates.