Communication disorders PhD researcher Martina Schaefer wanted to examine whether the way people hear themselves affects the way they speak. The study, supervised by Associate Professor Megan McAuliffe, worked with healthy New Zealanders of various ages and people with Parkinson’s Disease.
“Currently, most treatment focuses on speech production techniques to improve intelligibility. However, it appears to be difficult for people with neurological speech impairments to maintain immediate treatment effects. My research interest was in the role of speech perception: If people cannot detect their speech errors, then how can they correct them?
“It was important to differentiate between effects of age-related hearing loss and potential hearing deficiencies related to Parkinson’s Disease.
“Our first study focused on 60 healthy New Zealanders of various ages. The aim was to determine whether the ability to detect and correct speech errors changed with age. We therefore acoustically modified what participants heard through a set of headphones. This created a mismatch between what they intended to say and what they actually heard themselves say.
“The overall results showed that, as a group, people tended to correct for the speech error regardless of what age they were.”
Schaefer says New Zealanders tend to make less adjustments compared to Americans or Canadians, possibly due to the Kiwi dialect effect.
“We then compared the performance of people with neurological speech impairments to that of age-matched controls. Eight people with Parkinson’s Disease and eight healthy age-matched people were asked to mimic a model speaker and try to sound exactly like the model.
“My study suggests that older adults and those with Parkinson’s Disease are both able to modify their speech to approximate the acoustic characteristics of a model speaker.
“People in the study who had Parkinson’s Disease and more severe speech impairment were mimicking the model speaker less accurately compared to healthy speakers or those with mild speech impairment.
“So, while people with severe speech impairment were able to change their speech to some extent, it is important to explore if, and how, perceptual training may improve their error-detection, and hence, error-correction to improve their ability to mimic a model speaker.
“The overall initial findings showed that speech perception and speech production can at least, to some extent, be effectively integrated to induce error-correction mechanisms for people with Parkinson’s Disease.”
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