A new test for inner ear ‘dead regions’ causing deafness

Do you struggle to hear properly, even with hearing aids fitted? If you are one of the two million people in the UK who uses a hearing aid and still struggles to hear, hope may be on the horizon. A pioneering new project funded by Deafness Research UK is leading to a greater understanding of why hearing aids do not work for everyone as well as they should. The project is developing a new test for the hard of hearing via the latest research - exposing the secrets of dead regions of the cochlea.

Hearing impairment is often associated with damage to the hair cells of the cochlea (inner ear) and an area of the cochlea with complete loss of function is known as a ‘dead region’. People are often under the impression that hearing aids can ‘restore’ hearing, when in fact they can only ‘aid’ those areas not yet ‘dead’ and are only effective if they are tuned and programmed to compensate precisely for a wearer’s pattern of hearing loss.

Unfortunately, current hearing tests can often miss these dead regions, leading to people receiving hearing aids that amplify sounds at frequencies where the amplification provides no benefit, or in some cases, can even make their hearing worse. New research led by Brian Moore, Professor of Auditory Perception at the University of Cambridge and his group, including Professor Aleksander Sek, has led to the development of a rapid clinical test for detecting the presence of these dead regions – known as the ‘Psychophysical Tuning Curves’ (PTC) test. Funded by Deafness Research UK, Professor Moore and Professor Sek have developed a new PTC test capable of measuring the extent of these dead regions much more precisely than previously possible with existing tests. Developed as a computer program, this PTC test can run on any personal computer (with a good quality sound card and headphones), making it ready to use in the clinic immediately.

“Professor Moore’s work is vital in that it is leading to tangible benefits for those people who rely on hearing aids right now,” said Vivienne Michael, Chief Executive of Deafness Research UK. “Funding the development of tests of auditory function such as this that have a clinically applicable element is an important part of our work and thanks to the new PTC test, many more people who rely on hearing aids are going to benefit from enhanced performance and enhanced hearing ability.”

“This research gives us access to more accurate information about individual patterns of hearing loss at different frequencies and about the extent of dead regions, in turn enabling better fitting of hearing aids,” explained Professor Moore. “For example, if two people have the same audiogram, but one has dead regions, that person’s hearing aids will need to be programmed differently.”

The software for the PTC test is being made free to download from the website of the hearing group at Cambridge: http://hearing.psychol.cam.ac.uk/SWPTC/SWPTC.htm and a paper describing the software implementation of the test has been published in the respected International Journal of Audiology. Dr Ross Roeser, editor in chief of the journal, commented in an editorial that the test: “Represents a significant new opportunity for audiologists and hearing scientists to gain valuable knowledge of basic physiological processing of the auditory system, and potentially how to serve those with hearing impairment” and added: “What a great opportunity for IJA readers to be able to have this valuable information at their fingertips through innovative electronic media”.

Research shows that one in seven of the UK population, or nine million people have noticeable hearing loss and of these, some two million use hearing aids. It is estimated that double this number - four million people - could benefit from using a hearing aid, so in addition to providing grants for clinical projects like PTC tests, Deafness Research UK continues its mission to inform people about the dangers of noise-induced hearing loss - from its innovative Bionic Ear Show, to information leaflets and advice.

For more information, visit www.deafnessresearch.org.uk

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