Language difficulties are common among people with autism, but the exact reason for this is still somewhat unclear. However, recent research suggests that an inability to distinguish the sound of one’s own name from other sounds may contribute to the difficulties many people with autism have with learning languages, staying engaged in conversations, and developing social connections.
Typically, a baby learns to turn their head toward someone saying their name at around four to nine months of age. Babies and children with autism, however, often fail to do this.
According to a new electroencephalography (EEG) study, people with minimally verbal autism are unable to differentiate the sound of their own name from the sound of a stranger’s name. They also struggle to filter out background noise so that they can properly hear the speech sounds that are relevant to them.
The study followed 27 verbally fluent and 20 minimally verbal autistic participants, as well as 27 control group participants who did not have autism. Researchers used EEG to measure three types of brain responses in these participants as they listened to a female voice saying their name and the names of other participants, sometimes with a male voice in the background reciting sentences.
The first brain response researchers attempted to record, which generally occurs 200 milliseconds after a noise occurs, determines whether the person has recognized the sound as being distinct from other sounds (for example, it may have been an exceptionally loud sound, or it may have sounded like the first syllable of the person’s name, thereby capturing their attention). It’s known as the mismatch response. The other two responses, which happen about 400 milliseconds later, determine whether the person ascribes a personal meaning to the sound (such as the recognition of one’s own name).
Neurotypical and fully verbal participants elicited a normal mismatch response when hearing their own names, even with background noise. However, those participants with minimal verbal skills did not show any sign of having recognized their own names amid the din of the background noise.
Interestingly, when it came to the other two brain responses, people with minimally verbal and fully verbal autism both had the same responses regardless of whether the name was their own or someone else’s. Neurotypical participants, on the other hand, registered a difference between their names and other people’s names.
According to study investigator Sophie Schwartz, a postdoctoral researcher at Boston University in Massachusetts, these findings suggest that people with autism who lack verbal skills may have difficulty determining which of the sounds around them to focus on. The inability to filter sounds may contribute dramatically to speech and language difficulties.
“If people with autism have trouble understanding that you’re trying to communicate with them, that’s huge.”
Additionally, a second study by the same researchers found that, among autistic people with minimal verbal skills, those who had weaker neural responses to unexpected sounds also had more atypical auditory behaviors. These are the people most likely to hum and cover their ears in loud environments, for example. Autistic people with a full range of verbal skills did not participate in these behaviors as often as those with fewer verbal skills.
“Taken together, these studies highlight how sensitivity to sounds, which are far more common among minimally verbal individuals with [autism], impact their ability to attend to and understand spoken language,” says principal investigator Helen Tager-Flusberg, professor of psychology at Boston University. “They also begin to identify the neural mechanisms that underlie these impairments.”
Another thing that these studies demonstrate is that minimally verbal autistic people can and should be included in autism research, as Timothy Roberts, professor of radiology at the University of Pennsylvania in Philadelphia.
“We can’t continue as a field to ignore minimally verbal participants just because of logistical difficulties,” says Roberts. “I think these two papers prove that it can be done and therefore it should be done. This is an enormous step forward for our field.”
We hope this research will serve to inform therapists and parents working with minimally verbal young people to help them better understand the people they’re working with. Future research should also dig deeper into whether auditory processing directly impacts the ability to learn a language.Whizzco