Coventry University found 25 per cent of participants aged between eight and 10 who had reading difficulties showed mild or moderate hearing impairment, of which their parents and teachers were unaware.
In a study of 196 youngsters, a quarter of dyslexics had undiagnosed hearing problems, while one third of the children who had repeated ear infections had problems with reading and writing.
Researchers say that hearing issues can stop pupils being able to understand how sounds and language translate into words on a page.
Report author Dr Helen Breadmore said: “Many children in school may have an undetected mild hearing loss, which makes it harder for them to access the curriculum.
“Current hearing screening procedures are not picking up these children, and we would advise that children have their hearing tested in more detail and more often.
“A mild-moderate hearing loss will make the perception of speech sounds difficult, particularly in a classroom environment with background noise and other distractions.
"Therefore, children who have suffered repeated ear infections and associated hearing problems have fluctuating access to different speech sounds precisely at the age when this information is crucial in the early stages of learning to read.”
The research was published in Developmental Science.