Around 2.5m people in the UK have a communication disorder
Agenda for Change, an NHS reform programme, aims to improve patient care by adjusting pay and working conditions for staff.
But there are fears that the changes will prompt many speech therapists to leave the profession.
Frances Ridgway spent a decade dreaming of being a speech therapist.
After deciding to swap her secretarial job for a place on a four-year degree course - and the student debts this entailed - she fulfilled her ambition.
But now she is considering leaving her dream career because of Agenda for Change, an NHS reform initiative under which new job evaluation rules will determine the pay earned by a member of staff.
"It is a setback. We feel like an undervalued, hidden profession," said Mrs Ridgway, 43, who is a speech therapist based at the Royal National Throat, Nose and Ear hospital in London.
An estimated one in 10 children have problems communicating
"They will increase the number of working hours with no extra pay," she went on.
"We all work long hours anyway, but it is the principle. That extra time that we will be working is worth money."
"More therapists will leave the profession because they could do something else where they would make more money," she added, saying that she had considered taking up work in the private sector.
Her sentiments were echoed by Tom Morris, a speech therapist based in north London, who says he is set to lose around £8, 000 from his annual salary as a result of the reform.
He said: "I'm now left feeling betrayed and uncertain as to whether or not my future still lies within the health service."
Around 2.5m people in the UK suffer from a communication disorder of some kind, according to the Royal College of Speech and Language Therapists (RCSLT) - the professional body representing specialists in this field.
Speech therapists use a number of techniques to assess and diagnose patients in order to develop a programme of care to break down communication barriers.
The RCSLT estimates that there are around 9, 221 therapists working in the country, but fears this number is set to fall.
It claims that in one local service alone, four experienced speech and language therapists will lose £7, 000 a year.
"Anecdotal evidence is already being reported of senior therapists leaving posts because of concerns around Agenda for Change," said Kamini Gadhok, RCSLT's chief executive.
She says there has been an increase in the number of NHS therapists enquiring about private work or moving to locum agencies, where they enjoy better pay.
An estimated 1.2m children - one in 10 - in the UK have some form of communication problem.
The Basic Skills agency is encouraging parents to talk to children, after a survey in Wales suggested half of children starting school lacked the vital skills needed to begin learning effectively.
The RCSLT says a current shortage of specialists treating children means there should be around 1, 890 more therapists - a problem they fear will be exacerbated by the new reforms.
Fewer therapists would mean poorer availability for specialist care and longer waiting times, according to Ms Gadhok.
But the Department of Health (DoH) insists that the pay reforms will benefit, rather than penalise, many therapists.
Kamini Gadhok fears many speech therapists will leave the profession
The DoH said under Agenda for Change a speech and language therapist on the minimum basic grade will (in 2005/6) see their basic pay rise to between £18,698 and £24,198 depending upon their skills and experience.
Meanwhile, there are signs that the grievances voiced by the RCSLT have been heeded.
A Department of Health spokesman said: "After feedback from earlier implementer sites, the speech and language therapists profiles are being reviewed."