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Background and Aim: Parkinson’s disease (PD) is a progressive neurological disorder resulting from significant decrease of dopamine in the brain. The main and most common symptom of speech disorder associated with Parkinson’s disease, which is kind of dysarthria, is reduction in speech intelligibility. Since this disorder represents damages to acoustic aspects, researchers are attracted to study the relationship between these two disorders. In this study, we assessed the comparison of speech vowels between normal people and patients with Parkinson’s disease.

Methods: In this cross-sectional study, 18 voice samples of patients with Parkinson’s disease and the same number of samples from normal people in a voiceless environment were recorded and analyzed by Praat software. Data analysis was performed by independent samples and Mann-Whitney tests.

Results: All variables investigated in two groups showed significant differences. In adults with Parkinson’s disease , F1-F0 in low vowels showed a considerable reduction in respect to normal people (p <0.001). In addition, F2-F1 in high vowels represented a significant decrease in these patients (p<0.05).

Conclusion: The results indicate that Parkinson’s disease affects formant frequency in patients compared with normal people. Reduction in speech intelligibility can be accurately measured using acoustic procedure.

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Background and Aim : Nasalization of a vowel refers to the addition of nasal resonance to the vocal tract transfer function. Also, vowel nasalization occurs because of coarticulation. Coupling of the nasal resonating space to the oropharyngeal cavity alters the vocal tract formants in complex ways. The purpose of this study was to investigate the effect of nasalization on /a/ vowel formants in before and after nasal consonant.

Methods: In current cross-sectional study, voice samples of 60 normal children ranging the age of four-nine years were investigated. Participants were asked to repeat / ʔ ama/ three times and vowel /a/ after presentation of an auditory model. Then, obtained samples were analyzed using Praat 5.3.13 . Average of F₀, F₁, F₂ and F₃ were calculated for /a/ comes before and after /m/ in production of / ʔ ama/ over three trials.

Results: There were statistically significant differences of F₁, F₂ and F₃ between / a/ which proceeds nasal consonant and /a/ follows nasal consonant , the before nasal consonant /a/ versus single /a/ and the after nasal consonant /a/ versus single /a/ (p=0.001 for all).

Conclusion : F₁, F₂ and F₃ in /a/ before nasal consonant affected by anticipatory nasal coarticulation and in /a/ after nasal consonant affected by carry-over nasal coarticulation . This study showed nasal coarticulation and nasalization result in decreasing F₁, F₂ and F₃ in /a/ vowel.

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Background and Aim: The ways in which words are phonologically stored and organized change with maturation. Hence, most researchers agree on the issue of phonological representations abilities evolve over time . This study aimed to determine the quality of phonological representations in normal Persian-speaking boys and girls.

Methods: In this cross-sectional study , quality of phonological representations of 240 normal children at the age of 54 to 77 months was investigated using descriptive - analytical method s . The subjects were randomly selected among the children in kindergartens and preschoolers in Arak city, Iran. The study tool was a researcher-made quality of phonological representations test.

Results: Significant differences were found between age groups in the scores of quality of phonological representations (p<0.01). Subjects in the first ( aged 54 to 59 months ) and fourth (aged 72 to 77 months ) age-group had the lowest and highest scores, respectively. The differences in mean scores between 54 to 59 month- and 66 to 71 month-old and between 66 to 71 month- and 72 to 77 month-old children were not significant. There were significant differences in other group mean scores (p<0.001). In all groups of syllables (i.e., words with two , three and four syllables ), o lder children have better performance. The mean scores of quality of phonological representations in the two groups of boys and girls in any of the age groups were not significantly different from each other.

Conclusion: It seems that subjects' performances have improved with increase in age and gender does not affect the quality of phonological representations.

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Background and Aim: Hearing impairment can have an impact on adolescents’ quality of life and can lead to their isolation and depression. The main purpose of this research was to study the effectiveness of a mental rehabilitation program based on positive thinking skills training on increasing happiness in a group of hearing impaired girls and boys.

Methods: In this experimental study, pre- and post-test plan with a control group was used. All of the hearing impaired students (girls and boys) in all high schools of southern parts of Tehran, Iran, in year 2012-13 were our statistical research community. 48 hearing impaired girls and boys were selected by multistage sampling including stratified, purposive, and random sampling. They were randomly divided into two groups of experimental and control. Each group consists of 12 boys and 12 girls. Positive thinking skills were trained to experimental groups during eight 45-minutes sessions, twice a week. We used the Oxford happiness questionnaire to assess the level of happiness.

Results: Using analysis of covariance showed that positive thinking skills training had meaningful and positive effect on increasing happiness of hearing impaired boys and girls in the experimental groups (p<0.01). Also, the mean happiness scores of boys and girls were meaningfully different (p<0.01).

Conclusion: Positive thinking skills training increases the happiness scores of hearing impaired adolescents. So, the approach taken in this study can be considered as an appropriate method for psychological-education interventions, counseling and treatment in hearing impaired adolescent.