Pitch Perception in Adults with Autism Spectrum Disorder Speaking a Tone Language

Background:  

Some individuals with Autism Spectrum Disorders (ASD) possess enhanced auditory perception ability when compared to neurotypical individuals. There is higher incidence of superior auditory processing and perfect pitch in individuals with ASD than the general population. These phenomena have been explained by theories of Weak Central Coherence and Enhanced Perceptual Functioning. Emerging evidence also showed that variations in the stimuli context (e.g., pure tone, speech, music) have differential effects on their performance in auditory perception tasks.

Cantonese Chinese is a tone-language which makes use of pitch differences to encode lexical meaning. Given the heavy functional load of pitch in the language, much evidence attested that tone-language speakers demonstrate superior ability in pitch processing tasks. It would be interesting to investigate if superior auditory perception in individuals with ASD would also be observed in population speaking tone languages. 

Objectives:  

To compare pitch perception performance of Cantonese-speaking adults with and without high-functioning ASD.

Methods:  

Participants were all native Cantonese speakers with average intellectual functioning. They included 20 adults with ASD and 20 matched neurotypical (NT) controls. The matching parameters included gender, age, education background, and experience of formal musical training. Participants received a series of pitch discrimination tasks with auditory stimuli including monosyllabic real words, nonsense words, and non-speech analogues. The stimuli were paired according to different levels of pitch differences. Participants had to determine whether the stimuli in a pair were the same or different.

Results:  

There was no significant difference between ASD and control groups in discriminating the pitch differences in all the three stimulus types. Across both groups, participants made significantly more errors in speech conditions (real word and nonsense word stimuli) than non-speech condition. Regardless of group membership, individuals with formal musical training showed better performance in detecting small differences in pairs in all three stimulus types. 

Conclusions:  

Cantonese-speaking individuals with ASD did not show superior pitch perception ability when compared to NT controls with real word, nonsense word, and non-speech stimuli. It may be possible that the native use of tone enhances pitch perception ability in speakers in general population, diluting the effect of enhanced performance in the ASD group. This claim may also be supported by the significant effect of musical training in both ASD and NT individuals. Future research may investigate pitch perception in Cantonese population in broader contexts, such as detecting pitch differences in speech intonation and musical melody.