Comparative Analysis of Persian Vowels Features in Congenitally Blind and Sighted Students in Acoustic Phonetics

Abstract

Congenital visual impairment deprives children of an important source of information affecting acquired concepts as well as speech production. The primary aim of the research was to evaluate the extent to which blindness may affect vowel features (intensity, height, pitch, tongue movements, and lip protrusion). In the present paper 1728 speech samples from the natural production of the three repetitions of Persian vowel uttered by eight congenitally blind individuals and their equivalent sighted peers (all ranging from 10 to 15 years with mean age of 13± 1.69) were recorded under similar prosodic conditions. Significancy of differences in the interaction of vowel type and degree of blindness in the values of second and third frequency is indicated. Also vowel space is different in the two groups. Results of acoustic data analyses reveal thatblindness may affect speech. Results of post-hoc testes show that contrary to the previous research findings more dynamic lip gestures and less dynamic tongue movements have been explored by the values of Persian blind speakers. Also more constricted vowel space in blind speakers may lead to less their diminished intelligibility of speech.

Keywords

• blindness
• persian vowels
• lip protrusion and tongue movements