Research of the WeekI read this research summary and thought the findings were interesting. I got my hands on the original journal article and thought the research methodology and conclusions were well thought out and seemed sound.
Essentially, research shows that adults and preschoolers listen to the sound of their own voice and modify their speech based upon what they hear. If you put headphones on an adult or 4 year old child and feed a slightly modified version of their own voice back to them, the speech they produce changes as they try to "fix" the productions they are hearing.
If you do the same thing to a two year old, they do not modify their productions. Toddlers do not appear to monitor the sound of their own voices and adjust their speech production according to the auditory feedback provided by their own voice.
This has rather significant implications for therapy with toddlers. If you're expecting them to hear the difference between their own correct and incorrect productions that probably won't happen without some sort of additional feedback.
This study was done with typically developing two and four year old children and showed that adjusting speech due to auditory feedback develops between the ages of two and four. I wonder if you took a group of speech delayed children and conducted the same experiment, would you find that it takes even longer for self-monitoring to develop in these children? And further, would you find a difference between articulation, phonological, and apraxic children?