Students with speech impediments are falling dramatically behind their peers in NAPLAN testing and NSW has among the worst conditions for students with language disabilities in the country, new research has found.

In a paper due to be tabled at the Senate inquiry into students with disabilities on Friday, researchers from Charles Sturt University and Speech Pathology Australia found that children with speech problems had poorer outcomes for every year of testing and that they were up to 17 times more likely to be excluded from NAPLAN exams altogether.

The researchers concluded that the gap in NAPLAN results between children of typical language development and those with speech difficulties showed no signs of closing.