A Comparison of Acoustic Features of Speech of Typically Developing Children and Children with Autism Spectrum Disorders

The goal of this study is to find out the acoustic features specific for ASD children vocalizations and speech. Three types of experiments were conducted: emotional speech, spontaneous speech, and the repetition of words. Participants in the study were children with ASD (F 84.0 according to ICD-10), biologically aged 5–14 years (n = 25 children) and typically developing (TD) children aged 5–14 years (n = 60). We compare acoustic features that are widely used in speech recognition and speech perception: pitch values, max and min values of pitch, pitch range, formants frequency, energy and duration. Formant triangles were plotted for vowels with apexes corresponding to the vowels [a], [u], and [i] in F1, F2 coordinates, and their areas were compared. For all children with ASD voice and speech is characterized by high values of pitch, abnormal spectrum, and well-marked high-frequency. Stressed vowels from the words of children (TD & ASD), spoken in discomfort, have higher values of pitch and the third (emotional) formants than spoken in a comfortable condition. ASD children showed higher values of pitch in spontaneous speech than in repetition speech. The current results are a first step toward developing speech based bio-markers for early diagnosis of ASD.