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Background and Aim: Nowadays, auditory perception is not a complete method to assess vowels quality and we need to use more objective instruments.In this study we want to determine and compare the persian vowels formants in normal and hearing Impaired students in 7ـ9 year old children of Isfahan.
Materials and Methods: This cross sectional study was performed on 64 normal and hearing impaired students. Background information was by interview and then, vowel production test was performed. First three formants of each vowel were obtained and recorded by speech studio soft ware and Dr. Speech device Data were compared between groups.
Results: Mean F₁ and F₂, and F₂/F₁ and F₃/F₁ ratio of Persian vowels between these three studied groups were different significantly. Mean F₃ of /o/, /e/ and /a/ in all groups was different significantly. Although we could not find such a significant differences for /u/, /i/ and /æ/ between these groups(p<0.05).
Conclusion: The most important difference between normal and hearing impaired children is their vowel Space, and we found that, the more sever the hearing impairment is, the closer vowel space will be seen. The hearing impaired children rely mostly on their proprioceptive sense because of their hearing deficiency and it causes less movement of the tongue, so they usually substitute vowels which have similar F₁ and F₂.

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Background and Aim: Hearing aid users complain about a phenomenon called "occlusion effect". The aim of this study was to compare the occlusion effect in normal hearing individuals and those with slight and mild sensory neural hearing loss via Real Ear Measurement.
Methods: Sixty volunteers (30 male, 30 female) aged 18-55 years were enrolled in this study. Subjects were instructed to vocalize /e/ and /i/ for 5 seconds. Sound pressure level was measured by a probe- microphone and recorded in the ear canal. Occlusion effect and the frequency in which maximum occlusion effect occurs were obtained for each individuals for further analysis.
Results: The peak of occlusion effect for /e/ was 10.25 dB and 9.77 dB respectively in 751.9 Hz and 542.98 Hz frequencies in female and male individuals. The maximum occlusion effect occurred with 19.03 dB and 19.10 dB for /i/ and in 518.88 Hz and 440.28 Hz in female and male individuals, in respect. In addition, no significant difference was seen among hearing levels and between genders.
Conclusion: The peak of occlusion effect varies significantly among hearing aid users so that the hearing aid must be tuned. Probe-microphone measures will assist in determination where frequency- specific adjustments are needed.

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Background and Aim: Formant structure and vowel space are the most important acoustic characteristics of speech sounds. The purpose of this study was to determine formant frequency and vowel space in six Persian vowels.
Methods: This cross-sectional descriptive-analytic study was performed on 60 Persian students of Tehran University of Medical Sciences (30 males, 30 females) with their age ranging from 18 to 24 years. The subject articulated six Persian vowels in isolation and data was recorded by real-analyzer software. Then, the first three formant frequency of each vowel was determined for each subject. Vowel formant frequency averages were measured separately for each vowel and each gender. Vowel space was plotted. The difference between F0 in two groups was compared by Leven and independent sample t tests.
Results: Maximum and minimum values of F0 in both group was related to /æ/ and /a/ (135 Hz in males and 239 Hz in females) and /i/ (146 Hz in males and 239 Hz in females). Besides, F0 in females was significantly higher than males (p<0.001). Maximum and minimum values of F1 were related to /æ/ and /i/. Furthermore, maximum and minimum values of F2 were related to /i/ and /u/. Maximum and minimum values of F3 were related to /i/ and /u/.
Conclusion: The lowest vowels were /æ/ and /a/ and the highest was /i/. The frontest was /i/ and the backest was /u/. the spreadest vowel was /i/ and the roundest was /u/.

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Background and Aim: Hearing-impairment leads to problems in language perception which in turn results in difficulties in language production. The present study investigated hearing-impaired children&aposs ability to discriminate Persian vowels. It aimed to describe the extent to which children have difficulty comprehending and discriminating phonetic features of vowels.
Methods: To fulfill this aim, a researcher-made test, which was based on the Auditory Perception Test 2001, investigated the phonetic discrimination of vowels in Persian-speaking and hearing-impaired children aged five to eight years. The test has two sections, auditory-visual and just auditory discrimination of vowels, which included five subtests assessing discrimination of front and back vowels. Through this test, the phonetic discrimination ability of 22 hearing-impaired children was evaluated. The gathered data were analyzed using matched t-test and repeated measures ANOVA.
Results: The findings showed that there is a significant difference between correct responses to the sections on front and back vowels (p<0.05). The audio-visual test showed that the /â/ vowel is easier to discriminate than other back vowels. Moreover, in the auditory test the /â/ vowel had the highest mean. The audio-visual test showed that the /i/ vowel is easier to discriminate than the other front vowels (/e/ /æ/). However, the discrimination of front vowels in the auditory test was the same.
Conclusion: The results revealed that back vowels were more easily discriminated than front vowels by hearing-impaired children.

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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: Autism is a pervasive developmental disorder with several speech disorders such as prosodic and pragmatic impairments. Melodic intonation therapy (MIT) based on Albert et al. model (1973) is a rehabilitation method, developed on prosodic features. The aim of this study was to investigate the effects of MIT on Persian autistic children’s prosody.

Methods: An easy version of MIT, adopted for Persian language was designed by researchers. Then, after a successful pilot study on a 10-years-old boy for one month, 13 subjects were selected for the main study. All the subjects were autistic, male, right-handed, 7-10-years-old Persian children studied for 48 sessions (16 weeks). Background information gathered from the parents by a questionnaire. As pre- and post-test, some assessments about children’s fundamental frequency (Fº) and intensity of the Persian vowel sounds and declarative and interrogative sentences were accomplished. The data analysis was done using Praat and SPSS softwares.

Results: There was a statistically significant increase in acoustic features, such as intensity, and fundamental frequency of declarative and interrogative sentences also all six vowels of Persian, excluding /â/ and /æ/ (p<0.05 for all).

Conclusion: The widely reported unusual prosody in autistic children was quantified by this study, too. In addition, there was convincing evidence of the positive effects of melodic intonation therapy on acoustic features in Persian autistic children.