Discrimination of Non-Native Speech Pitch and Autistic Traits in Non-Clinical Population

Background: Children with Autism Spectrum Disorders (ASD) shows enhanced discrimination of speech pitch. However, this enhancement seems no longer exist in adulthood due to a developmental increase in pitch discrimination abilities, which is associated with receptive vocabulary in native language, in individuals without ASD (Mayer, Hannent, & Heaton, 2014). If this is the case, it is possible that their increased discrimination of speech pitch is tied to native speech only and may not be carried over to non-native speech. Given that autistic traits are evident in individuals without ASD, those with higher levels of autistic traits may be more able to discriminate non-native speech pitch. 

Objectives: This study investigated the discrimination abilities of non-native speech pitch and its relationships with autistic traits in typically developed adults without ASD. 

Methods: One hundred English-speaking university students (52 females; mean age = 21.65 years, SD = 3.55 years, range = 18 – 35 years) participated in the study. All participants took a pitch discrimination task, in which they determined whether there were pitch differences between pairs of monosyllabic Cantonese words presented at either 0, 1, 2 or 3 semitone difference, and filled in the Autism Spectrum Quotient questionnaire (AQ; Baron-Cohen, Wheelwright, Skinner, Martin, & Clubley, 2001). 

Results: Participants’ performance in discriminating non-native speech pitch was significantly above chance level and was comparable to previous findings using native speech pitch (Mayer et al., 2014). Correct judgement of ‘same’ pitch was near ceiling and correct discrimination of ‘different’ pitches significantly improved with increases in semitone intervals. There was no correlation between pitch discrimination and overall autistic traits but pitch discrimination was negatively correlated with the social skill subscale in the AQ even after musical training was controlled. 

Conclusions: Contrary to our prediction, adults without ASD performed well in discriminating non-native speech pitch. Moreover, those who were less sociable were less able to discriminate non-native speech pitch. This finding suggests a link between autistic-like social traits and speech processing in general population.