Welsh deaf school pupils 'underachieve' at key stages
Deaf school pupils in Wales underachieve at every key stage and face being left behind without urgent action, a charity has said.
The latest Welsh Government figures suggest the attainment gap widened again at GCSE level.
National Deaf Children's Society Cymru is calling for more support and awareness in classrooms.
Ministers said they were raising educational standards and investing in pupils with additional learning needs.
The attainment results for deaf children in the last three years fluctuated, according to figures obtained by BBC Wales.
In 2014, 48% of deaf children achieved a grade A* to C in the core subjects at key stage four - English/Welsh, maths and science - compared to 64% of peers who can hear.
The following year the attainment gap narrowed - but last year it grew again with 48.5% of deaf pupils achieving the grades, compared to 69.5% of hearing children.
And the problem is not confined to Year 11.
Over the last three years, the attainment gap has remained the same or worsened at foundation phase and for primary school children aged 7 to 11.
The figures come as organisations across the UK mark Deaf Awareness Week, which runs from 15 to 21 May.
Four years ago, the National Deaf Children's Society Cymru launched the Close the Gap petition following a poor set of results.
Debbie Thomas, policy and campaigns officer, said the latest results were "unacceptable".
"Deafness is not a learning disability so that gap shouldn't be there and we need to make sure that deaf children and young people are appropriately supported so they can reach their full potential," she said.
"There's no reason why they should be underachieving - other than the fact they're not accessing the appropriate support."
Ms Thomas said there were also practical steps which could be taken.
"The big thing that deaf children and young people tell us time after time is about raising deaf awareness and also about improving acoustics in the classroom but it's also about making sure that deaf children and their families are supported from the start," she added.
The Welsh Government said its "national mission" was to improve attainment for all children, including those with additional learning needs (ALN), aims to raise standards via a range of reforms.
A spokesman said: "Our ambitious Additional Learning Needs (ALN) Bill, if passed, will completely overhaul the system for supporting pupils with additional learning needs, including learners with hearing impairments.
"The bill will place the learner at the heart of that process and will make the system far simpler and less adversarial for those involved."
A £20m package of reforms will support the bill's implementation and wider plans, the spokesman added.