بررسی هم‌ بستگی بین وضوح گفتار و سنجش ‌های آکوستیکی واکه‌ها در کودکان فارسی زبان دارای دیزآتری ناشی از فلج مغزی اسپاستیک

یکی از ویژگی ‏های گفتار فلجی (دیزآرتری)، تولید غیردقیق واکه‏ها و همخوان‏هاست که عامل اصلی وضوح پایین گفتار است. با این حال هنوز مشخص نیست کدام شاخص‏های آکوستیکی با وضوح گفتار در این اختلال ارتباط قوی‏تری دارد. از طرف دیگر تعداد واکه‏ها، ویژگی‏های تولیدی و آکوستیکی آن‌ها در زبان‏های مختلف متفاوت است. تاآنجاکه می‏دانیم مطالعه‏ای روی تولید واکه‏ها در دیزآرتری دوران رشد در فارسی وجود ندارد، بنابراین درمورد جزئیات حرکتی که باعث بی‏دقتی‏ در تلفظ آن‌ها می‏شود اطلاعات کافی موجود نیست. ازاین‏رو مطالعۀ حاضر با هدف بررسی برخی شاخص‏های آکوستیکی شامل فرمنت واکه‏ها، شاخص‏ آکوستیکی فضای واکه‏ای (vsa)، نسبت مرکزی ‏شدن فرمنت‏ها (fcr) و شاخص تولید واکه (vai) و نیز رابطۀ آن‏ها‏ با وضوح گفتار در کودکان فارسی‌زبان مبتلا به دیزآرتری ناشی از فلج‏مغزی اسپاستیک انجام شد. در این مطالعۀ مقطعی، 11 کودک تک‌زبانه دارای دیزآرتری ناشی از فلج مغزی سفت 9 3 ساله و همتایان سالم به روش در دسترس انتخاب شدند. برای هر یک از 6 واکۀ زبان فارسی 2 کلمۀ تک‏هجایی از طریق نرم‌افزار praat مورد تحلیل آکوستیکی قرار گیرد. وضوح کلمه و واکه نیز به‌صورت میانگین درصد موارد قابل تشخیص محاسبه شد.  نتایج آزمون نشان داد تفاوت معنادار بین دو گروه در فرمنت سوم واکه‏های /a/ و /u/ و فرمنت دوم واکه /o/ وجود داشت. فضای واکه‏ای و وضوح گفتار در کودکان دیزآرتری به‌طور معناداری کاهش داشت. vas بیشترین هم‌بستگی را با وضوح داشت و شاخص آکوستیکی مناسبی برای بررسی وضوح گفتار در دیزآرتری است. با‏این‏حال هر سه شاخص آکوستیکی مورد مطالعه رابطۀ معنادار متوسطی با وضوح داشت.

a correlation between speech intelligibility and vowel acoustic measurements in persian speaking spastic cerebral palsy children with dysarthria

one of the dysarthria features is inaccurate articulation of consonants and vowels, which is the main cause of speech unintelligibility. however, it is not clear what acoustic measures are more related to speech intelligibility in dysarthria. on the other hand, the number of vowels, their articulation and acoustic characteristics are various in different languages. as far as we know, no study investigated vowels articulation in developmental dysarthria in persian, so there is not enough information about movement details which make their inaccuracies articulation. hence, the present study aimed to investigate some acoustic measures including vowel formants, vowel space area (vsa), formant centralization ratio (fcr) and vowel articulation index (vai) and aim to study their correlation with speech intelligibility in persian speaking children with dysarthria due to spastic cerebral palsy. in this cross sectional study, 11 monolingual children with dysarthria aged 3 9 years and their typically developing matched peers were selected through convenience sampling. for each of the six persian vowels, two monosyllable words were acoustically analyzed using praat software. to determine intelligibility of words and vowels, the percentage of correct detected ones was calculated. results showed a significant difference between the two groups in the third formant of the vowels /a/ and /u/ and the second formant of the vowel /o/. the vowel space area and intelligibility were significantly reduced in dysarthria. vas was more correlated with intelligibility and is a good acoustic measurement to assess speech intelligibility in dysarthria. however all three studied acoustic indices had moderate significant correlation with intelligibility.1. introductionabnormalities in power, speed, range, muscle tone, stability, and accuracy of movements necessary for respiration, phonation, production, articulation, or prosodic aspects of speech lead to dysarthria (duffy, 2019). depending on the location of the damage in the nervous system, there are different types of dysarthria and each creates different speech characteristics (duffy, 2019). cerebral palsy is one of the main causes of dysarthria in children. one of the main and distinctive features of dysarthria is imprecise production, which is the main factor for low speech intelligibility (de bodt et al., 2002). however, there is limited information on the motor features that cause this inaccuracy in children’s production, and awareness of these motor events is a prerequisite for providing appropriate therapeutic approaches (allison et al., 2017). if we consider syllables as speech motor units (yunusova et al., 2008) and vowels as the core components of syllables, vowel distortion can affect the structure of syllables and consequently speech. describing the vowels of a language has more auditory aspects than articulatory ones. however, gradually linguistics realized that if the vowels of a language are displayed based on f1 and f2 features, the result will be a two-dimensional space that they named vowel space. since speech intelligibility is the primary goal of clinical interventions, and since vowels are a good predictor of speech intelligibility in dysarthria, it is necessary to accurately determine the correctness and accuracy of vowels with the help of appropriate diagnostic or perceptual tools to assess the effects of direct and indirect therapies on the proper production of vowels and the improvement of speech intelligibility. this diagnosis guides therapists in selecting appropriate treatment methods or continuing therapy.