Up to a million children are missing out in the classroom because they find it hard to distinguish speech against background noise, a charity has warned.
Dr Downs was surprised to find his daughter had a hearing impairment
Some 500 of the 2,000 children aged 10 to 14 who took a telephone hearing check had the impairment, the Royal National Institute for the Deaf said.
The problem is due to the brain's inability to pick out speech against background noise and corrects with age.
Schools should ensure they have good acoustic environments, the RNID said.
The check showed that one in five children under 14 who took the test showed hearing ability of below the normal level expected of adults.
This came as a shock, said RNID director of technology Mark Downs.
So he attempted to verify the results by asking a sample of 70 children at a London school to undertake the test.
"To our surprise we got the same results, " said Dr Downs.
"It's not a problem with the way their ears work it is a problem with the way their brain interprets sound.
"It shows that they cannot recognise speech well when there is background noise, which could be anything from chattering pupils, rustling papers, scraping chairs or traffic noise from outside the building."
He added: "The good news is that it is not a permanent condition and it gets better as they grow."
The surprising result backs up fully validated work carried out on seven year olds published last year by leading academics.
Dr Downs added: "The findings have important implications for the education of children. There are potentially one million youngsters in that age category across the UK who could be missing out in the classroom."
TIPS FOR TEACHERS
Speak clearly and slowly
Face the class
Reduce background noise
Provide speaker systems
Consider hearing loss if pupil not performing well
The research showed the temporary impairment was not unusual and that parents and teachers should be aware of it, he added.
Dr Downs was further surprised to discover his own daughter, Hannah, had the hearing impairment after a check on her hearing ability revealed a response below normal.
The 11-year-old said she was really quite worried when she found out.
"Then my dad explained it was just part of growing older."
"At first I thought something had gone wrong with the test because I didn't believe I had a problem.
"I was really worried in case it was a permanent thing," she said.
Hannah was then checked over by an audiologist who said it was not the ability of her ear to hear sounds that was impaired but the ability of her brain to distinguish sounds.
She added: "I didn't really notice it before but once I got the result I started to be a bit more wary.
"I started to notice that I was missing the odd word."
Hannah dealt with the problem by moving to the front of the class where she could hear the teacher's voice better.
But the RNID says for those children who are perhaps not confident enough to take a front seat, there are simple steps the school can take to improve the acoustics of the classroom.
These include encouraging teachers to face the class or wiring them up to microphone and speaker systems.
This would not only benefit the children who had hearing loss but also the teacher who would no longer have to shout to make himself heard at the back of the classroom, the charity says.
A DfES spokesman said it had already been working with the RNID to produce materials, helping to identify hearing impairments early.
He said: "The earlier special education needs in children are identified the better - this will dramatically improve the chances of successful inclusion of deaf children into mainstream schools and into society.
"That¿s why have issued clear guidance to raise awareness and spread good practice in helping the development of young children with hearing impairments, including producing specific information booklets on deafness with the RNID."
To take the RNID telephone hearing test call 0845 600 5555.