Typically developing @ - to @-yr-old children and children with speech sound disorder were separated into four groups : a trained control group ( TDT ; n = @ , age @ @ yr ) , a nontrained control group ( TDNT ; n = @ , age @ @ yr ) , a trained study group ( SSDT ; n = @ , age @ @ yr ) , and a nontrained study group ( SSDNT ; n = @ , age @ @ yr ) .